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Journal Cover Ultrasound in Medicine & Biology
   Journal TOC RSS feeds Export to Zotero [8 followers]  Follow    
   Full-text available via subscription Subscription journal
     ISSN (Print) 0301-5629
     Published by Elsevier Homepage  [2563 journals]   [SJR: 0.864]   [H-I: 85]
  • Ultrasound in Assessing the Efficacy of Propranolol Therapy for Infantile
           Hemangiomas
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Huijuan Shi , Hongbin Song , Jianjun Wang , Li Xia , Jing Yang , Yuanyuan Shang , Hui Zhou
      This study was aimed at assessing the efficacy of propranolol treatment in infantile hemangiomas (IHs) by ultrasound. Thirty-one patients with IHs were administered propranolol and were assessed by ultrasound before treatment, 3 mo after treatment and at the end of treatment. Longitudinal and transverse diameters, as well as thickness of hemangiomas measured by clinical observation differed significantly (p < 0.05) from measurements obtained by ultrasound. Ultrasound also revealed that longitudinal and transverse diameters, thickness, vascular density, blood flow velocity (arterial and venous) and arterial peak systolic blood flow velocity of hemangiomas were significantly decreased (p < 0.05) after treatment compared with before treatment. The resistive index and systolic/diastolic blood flow velocity in IHs were significantly higher (p < 0.05) after treatment than before treatment. In conclusion, ultrasound can evaluate the efficacy of propranolol at the termination of therapy.


      PubDate: 2014-09-12T19:57:57Z
       
  • Middle Cerebral Artery Blood Flows by Combining TCD Velocities and MRA
           Diameters: In Vitro and In Vivo Validations
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): K.A. Yonan , E.R. Greene , J.M. Sharrar , A. Caprihan , C. Qualls , C.A. Roldan
      Non-invasive transcranial Doppler (TCD) is widely used for blood velocity (BV, cm/sec) measurements in the human middle cerebral artery (MCA). MCABV measurements are accepted as linear with MCA blood flow (MCABF). Magnetic resonance angiography (MRA) provides measurements of MCA lumen diameters that can be combined with TCD MCABV to calculate MCABF (mL/min). We tested the precision and accuracy of this method against a flow phantom and in vivo proximal internal carotid artery blood flow (ICABF). In vitro precision (repeated measures) and accuracy (vs. time collection) gave correlations coefficients of 0.97 and 0.98, respectively (both p < 0.05). In vivo precision (repeated measures) and accuracy (vs. ICABF) gave correlation coefficients of 0.90 (left and right), 0.94 (left) and 0.93 (right) (all p < 0.05). Bilateral MCABF in 35 adults were similar (left, 168 ± 72 mL/min; right, 180 ± 69 mL/min; p > 0.05). Results suggest that blood velocity by TCD and lumen diameter by MRA can be combined to estimate absolute values of MCABF.


      PubDate: 2014-09-12T19:57:57Z
       
  • An Improved Tissue-Mimicking Polyacrylamide Hydrogel Phantom for
           Visualizing Thermal Lesions with High-Intensity Focused Ultrasound
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Sitaramanjaneya Reddy Guntur , Min Joo Choi
      A recipe was created to improve the tissue-mimicking (TM) bovine serum albumin (BSA) polyacrylamide hydrogel (PAG) reported in our previous study (Choi MJ, Guntur SR, Lee KI, Paeng DG, Coleman AJ. Ultrasound Med Biol 2013; 29:439–448). In that work, the concentration of acrylamide in TM BSA PAG was increased to make its attenuation coefficient the same as that of a tissue. However, this increase made the PAG stiffer and less homogeneous. In addition, the increase in acrylamide caused a significant increase in temperature over the denaturation threshold of BSA during polymerization, which required forced cooling so that the PAG did not become opaque at room temperature after polymerization. To eliminate those shortcomings, we substituted the increased acrylamide with a viscous polysaccharide liquid (corn syrup). The concentration of corn syrup was optimized to 20% (w/v, tested in the volume of 50 mL), so that the acoustic properties of the PAG would be close to those of human liver. The improved TM (iTM) BSA PAG constructed in this study had a speed of sound of 1588 ± 9 m/s, an attenuation coefficient of 0.51 ± 0.06 dB cm−1 at 1 MHz and a backscattering coefficient of 0.22 ± 0.09 × 10−3 sr−1 cm−1 MHz−1. The density and acoustic impedance were 1057 kg/m3 and 1.68 MRayl, respectively, and the non-linear parameter (B/A) was 5.9 ± 0.3. The thermal, optical and mechanical properties were almost the same as those of the BSA PAG (Lafon et al.2005). Experimental verification indicated that the thermal lesions visualized in the proposed iTM BSA PAG by high-intensity focused ultrasound were highly reproducible. In conclusion, iTM BSA PAG was proven to eliminate TM BSA PAG shortcomings effectively and is expected to be a promising test phantom for clinical high-intensity focused ultrasound device.


      PubDate: 2014-09-12T19:57:57Z
       
  • Computed Ultrasound Tomography in Echo Mode for Imaging Speed of Sound
           Using Pulse-Echo Sonography: Proof of Principle
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Michael Jaeger , Gerrit Held , Sara Peeters , Stefan Preisser , Michael Grünig , Martin Frenz
      The limitations of diagnostic echo ultrasound have motivated research into novel modalities that complement ultrasound in a multimodal device. One promising candidate is speed of sound imaging, which has been found to reveal structural changes in diseased tissue. Transmission ultrasound tomography shows speed of sound spatially resolved, but is limited to the acoustically transparent breast. We present a novel method by which speed-of-sound imaging is possible using classic pulse-echo equipment, facilitating new clinical applications and the combination with state-of-the art diagnostic ultrasound. Pulse-echo images are reconstructed while scanning the tissue under various angles using transmit beam steering. Differences in average sound speed along different transmit directions are reflected in the local echo phase, which allows a 2-D reconstruction of the sound speed. In the present proof-of-principle study, we describe a contrast resolution of 0.6% of average sound speed and a spatial resolution of 1 mm (laterally) × 3 mm (axially), suitable for diagnostic applications.


      PubDate: 2014-09-12T19:57:57Z
       
  • Ultrasound Visibility of Spinal Structures and Local Anesthetic Spread in
           Children Undergoing Caudal Block
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Seokyung Shin , Ji Young Kim , Won Oak Kim , Seung Hyun Kim , Hae Keum Kil
      This study assessed ultrasound visibility of spinal structures in children and observed the extent of local anesthetic spread within the epidural space during caudal block. Spinal structures were evaluated with ultrasound from the sacral area to the thoracic area in 80 children, and drug spread levels were observed after caudal injection of 0.5, 1.0, 1.25 and 1.5 mL/kg local anesthetic. The conus medullaris, dural sac and dura mater were easily identified with ultrasound in most children. However, ligamentum flavum visibility declined with increasing vertebral level and markedly decreased at the thoracic level in children older than 7 mo or heavier than 8.5 kg. Drug spread was higher with increasing volume (p < 0.001) and in children ≤12 mo more than children >12 mo (p < 0.001); drug spread was significantly correlated with age (R 2 = 0.534). Spread levels assessed with ultrasound were roughly two to three segments lower than those in previous radiologic studies.


      PubDate: 2014-09-12T19:57:57Z
       
  • Standard Plane Localization in Ultrasound by Radial Component Model and
           Selective Search
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Dong Ni , Xin Yang , Xin Chen , Chien-Ting Chin , Siping Chen , Pheng Ann Heng , Shengli Li , Jing Qin , Tianfu Wang
      Acquisition of the standard plane is crucial for medical ultrasound diagnosis. However, this process requires substantial experience and a thorough knowledge of human anatomy. Therefore it is very challenging for novices and even time consuming for experienced examiners. We proposed a hierarchical, supervised learning framework for automatically detecting the standard plane from consecutive 2-D ultrasound images. We tested this technique by developing a system that localizes the fetal abdominal standard plane from ultrasound video by detecting three key anatomical structures: the stomach bubble, umbilical vein and spine. We first proposed a novel radial component-based model to describe the geometric constraints of these key anatomical structures. We then introduced a novel selective search method which exploits the vessel probability algorithm to produce probable locations for the spine and umbilical vein. Next, using component classifiers trained by random forests, we detected the key anatomical structures at their probable locations within the regions constrained by the radial component-based model. Finally, a second-level classifier combined the results from the component detection to identify an ultrasound image as either a “fetal abdominal standard plane” or a “non- fetal abdominal standard plane.” Experimental results on 223 fetal abdomen videos showed that the detection accuracy of our method was as high as 85.6% and significantly outperformed both the full abdomen and the separate anatomy detection methods without geometric constraints. The experimental results demonstrated that our system shows great promise for application to clinical practice.


      PubDate: 2014-09-12T19:57:57Z
       
  • Kidney Transplant: Usefulness of Real-Time Elastography (RTE) in the
           Diagnosis of Graft Interstitial Fibrosis
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Antonio Orlacchio , Fabrizio Chegai , Costantino Del Giudice , Alessandro Anselmo , Giuseppe Iaria , Giampiero Palmieri , Elena Di Caprera , Daniela Tosti , Elisa Costanzo , Giuseppe Tisone , Giovanni Simonetti
      The aim of this study is to evaluate the usefulness of real-time elastography (RTE) in the diagnosis of graft interstitial fibrosis. We prospectively enrolled 50 patients clinically suspected of graft fibrosis. RTE was performed with a broadband linear transducer using a dedicated ultrasound machine. Tissue mean elasticity (TME) was calculated by two blinded operators. All patients underwent biopsy after RTE. To determine cortical fibrosis Banff score was used. The receiver operating characteristic curves analysis was performed to evaluate the accuracy of TME to discriminate between patients with mild fibrosis (F1) versus patients with moderate to severe fibrosis (F2–F3). Inverse correlation between TME values and the degree of fibrosis has been shown (p < 0.05). Patients with F1 had mean TME values significantly higher compared with TME in patients with F2 (p = 0.005) and F3 (p = 0.004). The diagnostic accuracy of TME measurement for F2–F3 evaluated by area under the curve–receiver operating characteristic analysis was 0.95. RTE was able to evaluate kidney fibrosis in a non-invasive way and could be used as complementary imaging during follow-up of renal transplant patients.


      PubDate: 2014-09-12T19:57:57Z
       
  • Adding Blood to Agitated Saline Significantly Improves Detection of
           Right-to-Left Shunt by Contrast-Transcranial Color-Coded Duplex Sonography
           
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Mauro Gentile , Alessandro De Vito , Cristiano Azzini , Carmine Tamborino , Ilaria Casetta
      Contrast-transcranial Doppler and contrast-transcranial color-coded duplex sonography (c-TCCD) have been reported to have high sensitivity in detecting patent foramen ovale as compared with transesophageal echocardiography. An international consensus meeting (Jauss and Zanette 2000) recommended that the contrast agent for right-to left-shunt (RLS) detection using contrast-transcranial Doppler be prepared by mixing 9 mL of isotonic saline solution and 1 mL of air. The aim of our study was to determine whether adding blood to the contrast agent results in improved detection of RLS. We enrolled all consecutive patients admitted to our neurosonology laboratory for RLS diagnosis. For each patient, we performed c-TCCD both at rest and during the Valsalva maneuver using two different contrast agents: ANSs (1 mL of air mixed with 9 mL of normal saline) and ANSHBs (1 mL of air mixed with 8 mL of normal saline and 1 mL of the patient's blood). To classify RLS, we used a four-level visual categorization: (i) no occurrence of micro-embolic signals; (ii) grade I, 1–10 signals; (iii) grade II, >10 signals but no curtain; grade III, curtain pattern. We included 80 patients, 33 men and 47 women. RLS was detected in 18.8% at rest and in 35% during the Valsalva maneuver using ANSs, and in 31.3% and in 46.3% using ANSHBs, respectively (p < 0.0001). There was a statistically significant increase in the number of micro-embolic signals with the use of ANSHBs. The use of blood mixed with saline solution and air as a c-TCCD contrast agent produced an increase in positive tests and a higher grade of RLS compared with normal saline and air alone, either with or without the Valsalva maneuver.


      PubDate: 2014-09-12T19:57:57Z
       
  • Clinical and Imaging Characteristics of Papillary Neoplasms of the Breast
           Associated with Malignancy: A Retrospective Cohort Study
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Seon Hyeong Choi , Sangwon Jo , Dong-Hoon Kim , Jeong Seon Park , Yoonjung Choi , Shin-Ho Kook , Eun Chul Chung , So-Yeon Lee
      Papillary neoplasms of the breast comprise a broad range of pathologies ranging from papillomas to papillary carcinomas and have been associated with breast cancers. In this study, we evaluated the clinical, mammographic and sonographic features of papillary breast neoplasms from benign papillary breast lesions to malignancy-associated papillary lesions. A total of 194 lesions in 179 patients were analyzed, including 117 benign papillomas, 24 atypical papillomas, 41 benign papillomas with malignancies and 12 papillary carcinomas found between January 2003 and August 2011 in our institution. Statistically significant clinical factors included patient age (p = 0.001), lesion multiplicity (p = 0.009) and peripheral location (p = 0.003). Among these factors, the odds ratio for malignancy was 8.9 for bilateral multiple lesions. Visibility (p = 0.001) and density (p = 0.039) were significant factors for malignancy in mammograms, and echo patterns (p = 0.006), boundary (p = 0.001) and vascularity (p = 0.005) were significant features on ultrasound that differentiated malignancies from benign lesions. Overall, when papillary breast lesions are located bilaterally and peripherally in older patients, they are correlated with breast cancers. Additionally, for papillary breast lesions that appear highly dense on mammograms and/or exhibit positive vascularity on ultrasound, the probability of malignancy is relatively high.


      PubDate: 2014-09-12T19:57:57Z
       
  • Sonodynamically Induced Anti-tumor Effect of 5-Aminolevulinic Acid on
           Pancreatic Cancer Cells
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Yan Jing Li , Peng Huang , Cai Ling Jiang , De Xin Jia , Xiao Xue Du , Jian Hua Zhou , Yu Han , Hong Sui , Xiao Li Wei , Lei Liu , Heng Heng Yuan , Ting Ting Zhang , Wen Jie Zhang , Rui Xie , Xiao Hui Lang , Li Ying Wang , Tao Liu , Yu Xian Bai , Ye Tian
      Sonodynamic therapy (SDT), a promising modality for cancer treatment, involves the synergistic interaction of ultrasound and some chemical compounds termed sonosensitizers. However, its effect on pancreatic cancer cells remains unclear. In our study, we sought to identify the cytotoxic effects of ultrasound-activated 5-aminolevulinic acid on human pancreatic cancer Capan-1 cells. Cell viability was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) analysis; mitochondrial membrane potential was assessed using the fluorescent probe jc-1; apoptosis was evaluated by flow cytometry; cell morphology was investigated by scanning electron microscopy; apoptosis-related protein expression was analyzed by Western blot assay. We found that SDT significantly decreased the survival rate of cells, and this effect increased with 5-aminolevulinic acid concentration and ultrasound exposure time. The mechanism underlying the effect of SDT involves, in part, the induction of a conspicuous loss in mitochondrial membrane potential and, in part, the induction of apoptosis through upregulation of Bax expression, downregulation of Bcl-2 and increased activation of procaspase-3. These results indicate that the ultrasonically induced cell killing effect could be enhanced by 5-ALA and that the mitochondrial pathway might be involved in the cell damage process. We conclude that SDT is a promising new methodology for pancreatic cancer treatment.


      PubDate: 2014-09-12T19:57:57Z
       
  • Computerized Quantification of Ultrasonic Heterogeneity in Thyroid Nodules
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Kuen-Yuan Chen , Chiung-Nien Chen , Ming-Hsun Wu , Ming-Chih Ho , Hao-Chih Tai , Wen-Hong Kuo , Wen-Chang Huang , Yu-Hsin Wang , Argon Chen , King-Jen Chang
      To test whether computerized quantification of ultrasonic heterogeneity can be of help in the diagnosis of thyroid malignancy, we evaluated ultrasonic heterogeneity with an objective and quantitative computerized method in a prospective setting. A total of 400 nodules including 271 benign thyroid nodules and 129 malignant thyroid nodules were evaluated. Patient clinical data were collected, and the grading of heterogeneity on conventional gray-scale ultrasound images was retrospectively reviewed by a thyroid specialist. Quantification of ultrasonic heterogeneity (heterogeneity index, HI) was performed by a proprietary program implemented with methods proposed in this article. HI values differed significantly between benign and malignant nodules, diagnosed by a combination of fine-needle aspiration and surgical pathology results (p < 0.001, area under the curve = 0.714). The ultrasonic heterogeneity of these samples, as assessed by an experienced clinician, could not significantly differentiate between benign and malignant thyroid nodules. However, nodules with marked ultrasonic heterogeneity had higher HI values than nodules with homogeneous nodules. These results indicate that the new computer-aided diagnosis method for evaluation of the ultrasonic heterogeneity of thyroid nodules is an objective and quantitative method that is correlated with conventional ultrasonic heterogeneity assessment, but can better aid in the diagnosis of thyroid malignancy.


      PubDate: 2014-09-12T19:57:57Z
       
  • Therapeutic Ultrasound in Physical Medicine and Rehabilitation:
           Characterization and Assessment of Its Physical Effects on Joint-Mimicking
           Phantoms
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Elisa Edi Anna Nadia Lioce , Matteo Novello , Gianni Durando , Alessandro Bistolfi , Maria Vittoria Actis , Giuseppe Massazza , Chiara Magnetto , Caterina Guiot
      The aim of the study described here was to quantitatively assess thermal and mechanical effects of therapeutic ultrasound (US) by sonicating a joint-mimicking phantom, made of muscle-equivalent material, using clinical US equipment. The phantom contains two bone disks simulating a deep joint (treated at 1 MHz) and a superficial joint (3 MHz). Thermal probes were inserted in fixed positions. To test the mechanical (cavitational) effects, we used a latex balloon filled with oxygen-loaded nanobubbles; the dimensions of the oxygen-loaded nanobubbles were determined before and after sonication. Significant increases in temperature (up to 17°C) with fixed field using continuous waves were detected both in front of and behind the bones, depending on the US mode (continuous wave vs. pulsed wave) and on the treatment modality (fixed vs. massage). We found no significant differences in mechanical effects. Although limited by the in vitro design (no blood perfusion, no metabolic compensation), the results can be used to guide operators in their choice of the best US treatment modality for a specific joint.


      PubDate: 2014-09-12T19:57:57Z
       
  • Reference Characterisation of Sound Speed and Attenuation of the IEC
           Agar-Based Tissue-Mimicking Material Up to a Frequency of 60 MHz
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Srinath Rajagopal , Neelaksh Sadhoo , Bajram Zeqiri
      To support the development of clinical applications of high-frequency ultrasound, appropriate tissue-mimicking materials (TMMs) are required whose acoustic properties have been measured using validated techniques. This paper describes the characterisation of the sound speed (phase velocity) and attenuation coefficient of the International Electrotechnical Commission (IEC) agar-based TMM over the frequency range 1 to 60 MHz. Measurements implemented a broadband through-transmission substitution immersion technique over two overlapping frequency ranges, with co-axially aligned 50 MHz centre-frequency transducers employed for characterisation above 15 MHz. In keeping with usual practice employed within the technical literature, thin acoustic windows (membranes) made of 12-μm-thick Mylar protected the TMM from water damage. Various important sources of uncertainty that could compromise measurement accuracy have been identified and evaluated through a combination of experimental studies and modelling. These include TMM sample thickness, measured both manually and acoustically, and the influence of interfacial losses that, even for thin protective membranes, are significant at the frequencies of interest. In agreement with previous reports, the attenuation coefficient of the IEC TMM exhibited non-linear frequency dependence, particularly above 20 MHz, yielding a value of 0.93 ± 0.04 dB cm−1 MHz−1 at 60 MHz, derived at 21 ± 0.5°C. For the first time, phase velocity, measured with an estimated uncertainty of ±3.1 m s−1, has been found to be dispersive over this extended frequency range, increasing from 1541 m s−1 at 1 MHz to 1547 m s−1 at 60 MHz. This work will help standardise acoustic property measurements, and establishes a reference measurement capability for TMMs underpinning clinical applications at elevated frequencies.


      PubDate: 2014-09-12T19:57:57Z
       
  • Submental Ultrasound Measurement of Dynamic Tongue Base Thickness in
           Patients with Obstructive Sleep Apnea
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Jeng-Wen Chen , Chun-Hsiang Chang , Shou-Jen Wang , Yen-Teh Chang , Chih-Chung Huang
      Dynamic tongue base thickness (TBT) may be an important anatomic factor in airway narrowing in patients with obstructive sleep apnea (OSA). The development of an accurate clinical assessment of the retroglossal airway in patients with OSA is still evolving. Submental ultrasound was used to investigate the association between measurements of TBT in response to negative airway pressure and the existence of OSA. Twenty OSA patients and 20 control participants underwent ultrasound measurement of TBT on eupneic breathing and with the Mueller maneuver, as well as clinical and polysomnographic assessments. Logistic regression analyses indicated that after adjustment for confounding factors, independent predictors of OSA included TBT in response to negative airway pressure, as measured by submental ultrasound with the Mueller maneuver (odds ratio: 2.11, 95% confidence interval: 1.15–3.87, p < 0.05), and the difference between TBT with the Muller maneuver and that without the Mueller maneuver (odds ratio: 2.47, 95% confidence interval: 1.09–5.58, p < 0.05). Ultrasound measurement of TBT during the Mueller maneuver provides a quantitative assessment of the retroglossal airway in OSA patients with minimal invasiveness and easy accessibility.


      PubDate: 2014-09-12T19:57:57Z
       
  • Ultrasonographic Evaluation of Renal Resistive Index in Patients with
           Lupus Nephritis: Correlation with Histologic Findings
    • Abstract: Publication date: Available online 12 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Fabrizio Conti , Fulvia Ceccarelli , Antonietta Gigante , Biagio Barbano , Carlo Perricone , Laura Massaro , Francesco Martinelli , Francesca Romana Spinelli , Kostantinos Giannakakis , Guido Valesini , Rosario Cianci
      We analyzed the association between the renal arterial resistive index (RI) and the histologic features of lupus nephritis. All consecutive patients with systemic lupus erythematosus (SLE) who required a kidney biopsy were enrolled. The study protocol included ultrasonographic assessment to measure the RI and kidney biopsy (International Society of Nephrology/Renal Pathology Society classification). A RI > 0.7 was considered pathologic. Patients with non-renal SLE and healthy patients were studied as control groups. We enrolled 42 patients with renal SLE, 10 with non-renal SLE and 14 healthy patients: their mean (±standard deviation) RI values were 0.64 ± 0.08, 0.60 ± 0.04 and 0.59 ± 0.01, respectively (p = not significant). RIs > 0.7 were recorded only in patients with renal SLE (5/42, 11.9%). The percentage of patients with a pathologic RI was significantly higher in class IV nephritis in comparison with other classes (p < 0.009). In conclusion, we found a significant correlation between pathologic RI and class IV nephritis, suggesting a role for RI as a severity marker.


      PubDate: 2014-09-12T19:57:57Z
       
  • Breast Ultrasound Despeckling Using Anisotropic Diffusion Guided by
           Texture Descriptors
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Wilfrido Gómez Flores , Wagner Coelho de Albuquerque Pereira , Antonio Fernando Catelli Infantosi
      Breast ultrasound (BUS) is considered the most important adjunct method to mammography for diagnosing cancer. However, this image modality suffers from an intrinsic artifact called speckle noise, which degrades spatial and contrast resolution and obscures the screened anatomy. Hence, it is necessary to reduce speckle artifacts before performing image analysis by means of computer-aided diagnosis systems, for example. In addition, the trade-off between smoothing level and preservation of lesion contour details should be addressed by speckle reduction schemes. In this scenario, we propose a BUS despeckling method based on anisotropic diffusion guided by Log–Gabor filters (ADLG). Because we assume that different breast tissues have distinct textures, in our approach we perform a multichannel decomposition of the BUS image using Log–Gabor filters. Next, the conduction coefficient of anisotropic diffusion filtering is computed using texture responses instead of intensity values as stated originally. The proposed algorithm is validated using both synthetic and real breast data sets, with 900 and 50 images, respectively. The performance measures are compared with four existing speckle reduction schemes based on anisotropic diffusion: conventional anisotropic diffusion filtering (CADF), speckle-reducing anisotropic diffusion (SRAD), texture-oriented anisotropic diffusion (TOAD), and interference-based speckle filtering followed by anisotropic diffusion (ISFAD). The validity metrics are the Pratt’s figure of merit, for synthetic images, and the mean radial distance (in pixels), for real sonographies. Figure of merit and mean radial distance indices should tend toward ‘1’ and ‘0’, respectively, to indicate adequate edge preservation. The results suggest that ADLG outperforms the four speckle removal filters compared with respect to simulated and real BUS images. For each method—ADLG, CADF, SRAD, TOAD and ISFAD—the figure of merit median values are 0.83, 0.40, 0.39, 0.51 and 0.59, and the mean radial distance median results are 4.19, 6.29, 6.39, 6.43 and 5.88.


      PubDate: 2014-09-12T19:57:57Z
       
  • An In Vitro Comparison of Embolus Differentiation Techniques for
           Clinically Significant Macroemboli: Dual-Frequency Technique versus
           Frequency Modulation Method
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Caroline Banahan , Zach Rogerson , Clément Rousseau , Kumar V. Ramnarine , David H. Evans , Emma M.L. Chung
      The ability to distinguish harmful solid cerebral emboli from gas bubbles intra-operatively has potential to direct interventions to reduce the risk of brain injury. In this in vitro study, two embolus discrimination techniques, dual-frequency (DF) and frequency modulation (FM) methods, are simultaneously compared to assess discrimination of potentially harmful large pieces of carotid plaque debris (0.5–1.55 mm) and thrombus-mimicking material (0.5–2 mm) from gas bubbles (0.01–2.5 mm). Detection of plaque and thrombus-mimic using the DF technique yielded disappointing results, with four out of five particles being misclassified (sensitivity: 18%; specificity: 89%). Although the FM method offered improved sensitivity, a higher number of false positives were observed (sensitivity: 72%; specificity: 50%). Optimum differentiation was achieved using the difference between peak embolus/blood ratio and mean embolus/blood ratio (sensitivity: 77%; specificity: 81%). We conclude that existing DF and FM techniques are unable to confidently distinguish large solid emboli from small gas bubbles (<50 μm).


      PubDate: 2014-09-12T19:57:57Z
       
  • Hepatic Perfusion Parameters of Contrast-Enhanced Ultrasonography
           Correlate With the Severity of Chronic Liver Disease
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Dong Liu , Linxue Qian , Jinrui Wang , Xiangdong Hu , Lanyan Qiu
      In the study described here, we introduced a new ratio acquired with contrast-enhanced ultrasonography (CEUS): a liver parenchyma blood supply ratio that differentiates arterial and portal phases. Our purpose was to determine whether this ratio and other liver parenchyma perfusion parameters acquired with CEUS can be correlated with the severity of chronic liver disease. Twelve patients with non-cirrhotic chronic liver disease, 35 patients with cirrhosis (child class A: n = 10; child class B: n = 13; child class C: n = 12) and 21 healthy volunteers were examined by CEUS. Time–intensity curves were drawn for regions of interest located in liver parenchyma and right kidney cortex using QLAB quantification software. The arterial and portal phases were differentiated by the time to the maximum enhancement of right kidney and liver parenchyma perfusion data acquired from the time–intensity curves: the intensity of liver parenchyma perfused by hepatic arterial flow (I ap), the intensity of total perfusion of liver parenchyma (I peak), the intensity of liver parenchyma perfused by portal venous flow (I pp) and the ratio of portal perfusion to total perfusion of liver parenchyma expressed by the parameters I pp/I peak, I peak, I pp and I pp/I peak significantly decreased in patients with cirrhosis and in patients with non-cirrhotic chronic liver disease, whereas I ap increased. The parameters I pp, I peak, I pp/I peak and I ap correlated with the severity of chronic liver disease (r = −0.938, p < 0.001; r = −0.790, p < 0.001; r = −0.931 p < 0.001; r = 0.31, p < 0.05). The diagnostic accuracy rates for cirrhosis expressed as areas under receiver operating characteristic curves were 0.93 for I peak, 0.98 for I pp, 0.98 for I pp/I peak, and 0.69 for I ap. Liver parenchyma perfusion parameters obtained by CEUS were correlated with the severity of chronic liver disease and have the potential to assess cirrhosis non-invasively.


      PubDate: 2014-09-12T19:57:57Z
       
  • Effects of Noradrenaline and Adenosine Triphosphate on the Degree on
           Contrast Enhancement in a Rabbit Model of Atherosclerosis during
           Contrast-Enhanced Ultrasonography
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Jie Sun , You-Bin Deng , Kun Liu , Yu-Bo Wang
      The aim of the study is to assess the effects of vasoactive agents on the degree of contrast enhancement in experimental atherosclerotic plaque during contrast-enhanced ultrasonography (CEUS). Abdominal aortic atherosclerosis was induced in 25 New Zealand white rabbits by a combination of cholesterol-rich diet and balloon endothelial denudation. Standard ultrasonography and CEUS were performed at baseline and during intravenous infusion of noradrenaline or adenosine triphosphate (ATP). The degree of contrast enhancement of the plaque after injection of contrast material was quantified by calculating the enhanced intensity in the plaque. The infusion of noradrenaline induced significant increase in systolic blood pressure (84 ± 13 mm Hg vs. 112 ± 20 mm Hg, p = 0.011) and significant decrease in the enhanced intensity in the plaque (7.52 ± 1.32 dB vs. 5.88 ± 1.33 dB, p < 0.001) during CEUS. The infusion of ATP resulted in the significant decrease in systolic blood pressure (80 ± 13 mm Hg vs. 65 ± 11 mm Hg, p = 0.005) and increase in the enhanced intensity in the plaque (7.52 ± 1.32 dB vs. 8.84 ± 1.55 dB, p < 0.001) during CEUS. The degree of contrast enhancement within an experimental atherosclerotic plaque during CEUS can be influenced by vasoactive agents and hemodynamic status.


      PubDate: 2014-09-12T19:57:57Z
       
  • Novel Flow Quantification of the Carotid Bulb and the Common Carotid
           Artery with Vector Flow Ultrasound
    • Abstract: Publication date: Available online 11 September 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Mads Møller Pedersen , Michael Johannes Pihl , Per Haugaard , Kristoffer Lindskov Hansen , Theis Lange , Lars Lönn , Michael Bachmann Nielsen , Jørgen Arendt Jensen
      Abnormal blood flow is usually assessed using spectral Doppler estimation of the peak systolic velocity. The technique, however, only estimates the axial velocity component, and therefore the complexity of blood flow remains hidden in conventional ultrasound examinations. With the vector ultrasound technique transverse oscillation the blood velocities of both the axial and the transverse directions are obtained and the complexity of blood flow can be visualized. The aim of the study was to determine the technical performance and interpretation of vector concentration as a tool for estimation of flow complexity. A secondary aim was to establish accuracy parameters to detect flow changes/patterns in the common carotid artery (CCA) and the carotid bulb (CB). The right carotid bifurcation including the CCA and CB of eight healthy volunteers were scanned in a longitudinal plane with vector flow ultrasound (US) using a commercial vector flow ultrasound scanner (ProFocus, BK Medical, Denmark) with a linear 5 MHz transducer transverse oscillation vector flow software. CCA and CB areas were marked in one cardiac cycle from each volunteer. The complex flow was assessed by medical expert evaluation and by vector concentration calculation. A vortex with complex flow was found in all carotid bulbs, whereas the CCA had mainly laminar flow. The medical experts evaluated the flow to be mainly laminar in the CCA (0.82 ± 0.14) and mainly complex (0.23 ± 0.22) in the CB. Likewise, the estimated vector concentrations in CCA (0.96 ± 0.16) indicated mainly laminar flow and in CB (0.83 ± 0.07) indicated mainly turbulence. Both methods were thus able to clearly distinguish the flow patterns of CCA and CB in systole. Vector concentration from angle-independent vector velocity estimates is a quantitative index, which is simple to calculate and can differentiate between laminar and complex flow.


      PubDate: 2014-09-12T19:57:57Z
       
  • Diagnostic Breast Imaging: Mammography, Sonography, MRI, and
           Interventional Procedures (Third Edition) Sylvia Heywang-Koebrunner,
           Ingrid Schreer, and Susan Barter, editors, Thieme, Stuttgart, Germany,
           2014, 696 pages. ISBN number: 978-3-13-102893-8
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Kevin D. Evans



      PubDate: 2014-09-04T18:52:57Z
       
  • Masthead
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10




      PubDate: 2014-09-04T18:52:57Z
       
  • Contents
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10




      PubDate: 2014-09-04T18:52:57Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10




      PubDate: 2014-09-04T18:52:57Z
       
  • High-Definition Imaging of Carotid Artery Wall Dynamics
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Pieter Kruizinga , Frits Mastik , Stijn C.H. van den Oord , Arend F.L. Schinkel , Johannes G. Bosch , Nico de Jong , Gijs van Soest , Anton F.W. van der Steen
      The carotid artery (CA) is central to cardiovascular research, because of the clinical relevance of CA plaques as culprits of stroke and the accessibility of the CA for cardiovascular screening. The viscoelastic state of this artery, essential for clinical evaluation, can be assessed by observing arterial deformation in response to the pressure changes throughout the cardiac cycle. Ultrasound imaging has proven to be an excellent tool to monitor these dynamic deformation processes. We describe how a new technique called high-frame-rate ultrasound imaging captures the tissue deformation dynamics throughout the cardiac cycle in unprecedented detail. Local tissue motion exhibits distinct features of sub-micrometer displacements on a sub-millisecond time scale. We present a high-definition motion analysis technique based on plane wave ultrasound imaging able to capture these features. We validated this method by screening a group of healthy volunteers and compared the results with those for two patients known to have atherosclerosis to illustrate the potential utility of this technique.


      PubDate: 2014-09-04T18:52:57Z
       
  • Is the Frequent Sonographic Anechoic Area Distally
           in Metacarpophalangeal Joints a Sign of Arthritis'
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): David Folkert Ten Cate , Jolanda Jacoba Luime , Johanna Maria Wilhelmina Hazes , Gerrit-Jan Kleinrensink , Johannes Wilhelmus Gerardus Jacobs
      In clinical practice, ultrasonography (US) often reveals, in the dorsal scan, a small anechoic area distally in both inflamed and clinically non-inflamed metacarpophalangeal joints. This “distal anechogenicity in the metacarpophalangeal joint” (DAEM) might thus be scored false positively as arthritis. We aimed to investigate whether the DAEM is a sign of arthritis. We evaluated the prevalence of DAEMs in 24 non-arthritic subjects. We then compared the dimensions of the DAEM in 10 non-arthritic subjects with a DAEM and 7 consecutive rheumatoid arthritis (RA) outpatients, using 2-D and 3-D ultrasound. Furthermore, we dissected two fresh-frozen postmortem hand specimens after US. A DAEM was observed in the metacarpophalangeal 2 (MCP2) joints of 54% of the 24 non-selected non-arthritic individuals; in none of those did the joint exhibit a power Doppler signal. A DAEM was observed in 86% of the 7 RA patients. Dimensions of DAEMs did not statistically significantly differ between these groups. At 3-D imaging and dissection, the DAEM was found to be an extension of the metacarpophalangeal joint capsule. In conclusion, DAEMs occur frequently and are not a sign of arthritis, but are distal joint recesses. This should be taken into account when using current sensitive ultrasonographic scoring systems grading arthritis.


      PubDate: 2014-09-04T18:52:57Z
       
  • Computation of the Temperature Rise at the Corneal Endothelium during
           Cataract Surgery by Modeling of Heat Generation Inside the Anterior
           Chamber
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Steffen Buschschlüter , Christian Koch , Jörn von Eicken , Helmut Höh
      The corneal endothelium sustaining the transparency of the cornea is a vulnerable cell layer. Thermal exposure during phacoemulsification is considered to be a potential cause of post-operative cell loss. Knowledge of the temperature rise and particularly of its dependence on region and system settings could deliver useful information about a potential correlation with cell damage. However, there exists a lack of understanding of the process and location of heat generation. Analytical calculations and experiments enabled the quantification of different mechanisms acting as heat sources during phacoemulsification. Heat generation caused by viscous friction was estimated using both an analytical approach and a numerical simulation. In contrast to absorption of sound and self-heating of the probe, this effect was ascertained to be the main heat source. Calorimetric measurement of the power input verified this modeling. On the basis of these results, the local temperature distribution inside a porcine eye was computed time dependently using the finite-element method. Two different amplitude settings were compared with respect to the temperature increase at the corneal endothelium. Various conclusions on the mitigation of thermal exposure during treatment can be drawn from this finite-element simulation.


      PubDate: 2014-09-04T18:52:57Z
       
  • High-Intensity Focused Ultrasound Leads to Histopathologic Changes of the
           Inferior Turbinate Mucosa with Allergic Inflammation
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Hongquan Wei , Lei Shi , Jingru Zhang , Yan Xia , Jingjing Cuan , Yong Zhang , Wei Li , Aihui Yan , Xuejun Jiang , Ming-Fei Lang , Jing Sun
      This study was aimed at understanding the histopathologic changes that occur in the nasal mucosa of patients with perennial allergic rhinitis after high-intensity focused ultrasound (HIFU) treatment. Biopsy specimens of the inferior turbinate mucosa were taken from 11 PAR patients before, immediately after and 1 y after HIFU treatment. Morphometric analysis revealed that the density of eosinophils and other inflammatory cells increased immediately after treatment and then were decreased significantly 1 y post-treatment. Submucosal glands were swollen and venous sinusoids were dilated, but there was no statistically significant change in their density, immediately after treatment. However, both glands and venous sinusoids significantly decreased in number 1 y after HIFU treatment. The ciliated epithelium or basement membrane of the nasal mucosa was well preserved at all stages. In conclusion, HIFU is a tolerable and effective treatment to reduce inflammation of the inferior turbinate mucosa in patients with perennial allergic rhinitis.


      PubDate: 2014-09-04T18:52:57Z
       
  • Teles-operated Echocardiography Using a Robotic Arm and an Internet
           Connection
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Philippe Arbeille , Romain Provost , Kathryn Zuj , Dominique Dimouro , Monica Georgescu
      The objective was to design and validate a method of tele-operated echocardiography. The method was tested in a hospital facility with an expert sonographer located in a room 10 m away from the patient. An ultrasound probe, fixed to a motorized probe holder, was located on the patient by a non-sonographer and was remotely controlled by the expert sonographer via an Internet connection. Scans were performed on 41 cardiac patients. The quality of the cardiac views obtained using tele-echocardiography was lower than that of reference echocardiography, but generated similar measurements in 93%–100% of the cases. Bland–Altman plots and statistical comparison of tele- and reference echocardiography measures revealed no differences (p > 0.05). Of the 71 valve leaks or aortic stenoses present, 61 (86%) were detected using tele-echocardiography. These results indicate that tele-echocardiography provided reliable diagnoses and acceptable measurements in 86% and 93% of cases, respectively, with no false-positive diagnoses being reported.


      PubDate: 2014-09-04T18:52:57Z
       
  • Improved Tracking Performance of Lagrangian Block-Matching Methodologies
           Using Block Expansion in the Time Domain: In Silico, Phantom and
           in Vivo Evaluations
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): John Albinsson , Sofia Brorsson , Åsa Rydén Ahlgren , Magnus Cinthio
      The aim of this study was to evaluate tracking performance when an extra reference block is added to a basic block-matching method, where the two reference blocks originate from two consecutive ultrasound frames. The use of an extra reference block was evaluated for two putative benefits: (i) an increase in tracking performance while maintaining the size of the reference blocks, evaluated using in silico and phantom cine loops; (ii) a reduction in the size of the reference blocks while maintaining the tracking performance, evaluated using in vivo cine loops of the common carotid artery where the longitudinal movement of the wall was estimated. The results indicated that tracking accuracy improved (mean = 48%, p < 0.005 [in silico]; mean = 43%, p < 0.01 [phantom]), and there was a reduction in size of the reference blocks while maintaining tracking performance (mean = 19%, p < 0.01 [in vivo]). This novel method will facilitate further exploration of the longitudinal movement of the arterial wall.


      PubDate: 2014-09-04T18:52:57Z
       
  • Monitoring and Staging Abdominal Aortic Aneurysm Disease With Pulse Wave
           Imaging
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Sacha D. Nandlall , Monica P. Goldklang , Aubrey Kalashian , Nida A. Dangra , Jeanine M. D’Armiento , Elisa E. Konofagou
      The abdominal aortic aneurysm (AAA) is a silent and often deadly vascular disease caused by the localized weakening of the arterial wall. Previous work has indicated that local changes in wall stiffness can be detected with pulse wave imaging (PWI), which is a non-invasive technique for tracking the propagation of pulse waves along the aorta at high spatial and temporal resolutions. The aim of this study was to assess the capability of PWI to monitor and stage AAA progression in a murine model of the disease. ApoE/TIMP-1 knockout mice (N = 18) were given angiotensin II for 30 days via subcutaneously implanted osmotic pumps. The suprarenal sections of the abdominal aortas were imaged every 2–3 d after implantation using a 30-MHz VisualSonics Vevo 770 with 15-μm lateral resolution. Pulse wave propagation was monitored at an effective frame rate of 8 kHz by using retrospective electrocardiogram gating and by performing 1-D cross-correlation on the radiofrequency signals to obtain the displacements induced by the waves. In normal aortas, the pulse waves propagated at constant velocities (2.8 ± 0.9 m/s, r 2 = 0.89 ± 0.11), indicating that the composition of these vessels was relatively homogeneous. In the mice that developed AAAs (N = 10), the wave speeds in the aneurysm sac were 45% lower (1.6 ± 0.6 m/s) and were more variable (r 2 = 0.66 ± 0.23). Moreover, the wave-induced wall displacements were at least 80% lower within the sacs compared with the surrounding vessel. Finally, in mice that developed fissures (N = 5) or ruptures (N = 3) at the sites of their AAA, higher displacements directed out of the lumen and with no discernible wave pattern (r 2 < 0.20) were observed throughout the cardiac cycle. These findings indicate that PWI can be used to distinguish normal murine aortas from aneurysmal, fissured and ruptured ones. Hence, PWI could potentially be used to monitor and stage human aneurysms by providing information complementary to standard B-mode ultrasound.


      PubDate: 2014-09-04T18:52:57Z
       
  • Shunt Flow Evaluation in Congenital Heart Disease Based on Two-Dimensional
           Speckle Tracking
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Solveig Fadnes , Siri Ann Nyrnes , Hans Torp , Lasse Lovstakken
      High-frame-rate ultrasound speckle tracking was used for quantification of peak velocity in shunt flows resulting from septal defects in congenital heart disease. In a duplex acquisition scheme implemented on a research scanner, unfocused transmit beams and full parallel receive beamforming were used to achieve a frame rate of 107 frames/s for full field-of-view flow images with high accuracy, while also ensuring high-quality focused B-mode tissue imaging. The setup was evaluated in vivo for neonates with atrial and ventricular septal defects. The shunt position was automatically tracked in B-mode images and further used in blood speckle tracking to obtain calibrated shunt flow velocities throughout the cardiac cycle. Validation toward color flow imaging and pulsed wave Doppler with manual angle correction indicated that blood speckle tracking could provide accurate estimates of shunt flow velocities. The approach was less biased by clutter filtering compared with color flow imaging and was able to provide velocity estimates beyond the Nyquist range. Possible placements of sample volumes (and angle corrections) for conventional Doppler resulted in a peak shunt velocity variations of 0.49–0.56 m/s for the ventricular septal defect of patient 1 and 0.38–0.58 m/s for the atrial septal defect of patient 2. In comparison, the peak velocities found from speckle tracking were 0.77 and 0.33 m/s for patients 1 and 2, respectively. Results indicated that complex intraventricular flow velocity patterns could be quantified using high-frame-rate speckle tracking of both blood and tissue movement. This could potentially help increase diagnostic accuracy and decrease inter-observer variability when measuring peak velocity in shunt flows.


      PubDate: 2014-09-04T18:52:57Z
       
  • A New Method for Measuring the Speed of Sound in Rat Liver ex Vivo
           Using an Ultrasound System: Correlation of Sound Speed with Fat Deposition
           
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Hideki Kumagai , Koji Yokoyama , Kimito Katsuyama , Shoji Hara , Hiroaki Yamamoto , Takanori Yamagata , Nobuyuki Taniguchi , Norio Hirota , Kouichi Itoh
      The speed of sound correlates well with the fat content of the liver. Therefore, non-invasive quantification of sound speed in the liver might be of diagnostic value. Here we describe a new non-invasive method that would be clinically applicable for measurement of sound speed in the liver. Sprague–Dawley rats were divided into two groups: a control group and a fatty liver group prepared by keeping the rats on a choline-deficient diet for 6 wk. The livers were subjected to pathologic and biochemical analysis; the speed of sound through the liver tissue was measured using our proposed method and a pulser–receiver as standard. Our results indicated that use of the proposed method makes it feasible to diagnose fatty liver with good accuracy on the basis of sound speed. This approach would have considerable potential for non-invasive diagnosis of fatty liver and would be a valuable adjunct to conventional liver diagnostic procedures.


      PubDate: 2014-09-04T18:52:57Z
       
  • Assessment of the Viscoelastic and Oscillation Properties of a
           Nano-engineered Multimodality Contrast Agent
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Satya V.V.N. Kothapalli , Letizia Oddo , Gaio Paradossi , Lars-Åke Brodin , Dmitry Grishenkov
      Combinations of microbubbles (MBs) and superparamagnetic iron oxide nanoparticles (SPIONs) are used to fabricate dual contrast agents for ultrasound and MRI. This study examines the viscoelastic and oscillation characteristics of two MB types that are manufactured with SPIONs and either anchored chemically on the surface (MBs-chem) or physically embedded (MBs-phys) into a polymer shell. A linearized Church model was employed to simultaneously fit attenuation coefficients and phase velocity spectra that were acquired experimentally. The model predicted lower viscoelastic modulus values, undamped resonance frequencies and total damping ratios for MBs-chem. MBs-chem had a resonance frequency of approximately 13 MHz and a damping ratio of approximately 0.9; thus, MBs-chem can potentially be used as a conventional ultrasound contrast agent with the combined functionality of MRI detection. In contrast, MBs-phys had a resonance frequency and damping of 28 MHz and 1.2, respectively, and requires further modification of clinically available contrast pulse sequences to be visualized.


      PubDate: 2014-09-04T18:52:57Z
       
  • Erratum
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10




      PubDate: 2014-09-04T18:52:57Z
       
  • Transcranial Sonography and 123I-FP-CIT Single Photon Emission Computed
           Tomography in Movement Disorders
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Petra Bártová , Otakar Kraft , Jaromír Bernátek , Martin Havel , Pavel Ressner , Kateřina Langová , Roman Herzig , David Školoudík
      Diagnosis of Parkinson's disease (PD) can be difficult in the early stages of the disease. The aim of the study described here was to assess the correlation between transcranial sonography (TCS) and 123I-FP-CIT ([123I]ioflupane, N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-[123I]iodophenyl)nortropane) SPECT (single photon emission computed tomography) findings and the diagnosis of PD. A total of 49 patients were enrolled in the study: 29 patients with PD, 7 patients with other parkinsonian syndromes, 11 patients with essential tremor and 2 with psychogenic movement disorder. Substantia nigra echogenicity was measured using TCS. SPECT was performed using DaTSCAN ([123I]ioflupane). TCS and SPECT findings were correlated in 84% of patients, with κ = 0.62 (95% confidence interval: 0.38–0.86). TCS-measured substantia nigra echogenicity and SPECT-measured striatal binding ratio were negatively correlated (r = –0.326, p = 0.003). TCS/SPECT sensitivity, specificity and positive and negative predictive values for the diagnosis of PD were 89.7%/96.6%, 60.0%/70.0%, 76.5%/82.4% and 80.0%/93.3%, respectively. Both positive TCS and SPECT findings correlated significantly with the diagnosis of PD (κ = 0.52, 95% confidence interval: 0.27–0.76, and κ = 0.69, 95% confidence interval: 0.49–0.90, respectively).


      PubDate: 2014-09-04T18:52:57Z
       
  • Localized in Vivo Model Drug Delivery with Intravascular Ultrasound
           and Microbubbles
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Joseph P. Kilroy , Alexander L. Klibanov , Brian R. Wamhoff , Douglas K. Bowles , John A. Hossack
      An intravascular ultrasound (IVUS) and microbubble drug delivery system was evaluated in both ex vivo and in vivo swine vessel models. Microbubbles with the fluorophore DiI embedded in the shell as a model drug were infused into ex vivo swine arteries at a physiologic flow rate (105 mL/min) while a 5-MHz IVUS transducer applied ultrasound. Ultrasound pulse sequences consisted of acoustic radiation force pulses to displace DiI-loaded microbubbles from the vessel lumen to the wall, followed by higher-intensity delivery pulses to release DiI into the vessel wall. Insonation with both the acoustic radiation force pulse and the delivery pulse increased DiI deposition 10-fold compared with deposition with the delivery pulse alone. Localized delivery of DiI was then demonstrated in an in vivo swine model. The theoretical transducer beam width predicted the measured angular extent of delivery to within 11%. These results indicate that low-frequency IVUS catheters are a viable method for achieving localized drug delivery with microbubbles.


      PubDate: 2014-09-04T18:52:57Z
       
  • Reliability of Automatic Vibratory Equipment for Ultrasonic Strain
           Measurement of the Median Nerve
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Yuichi Yoshii , Tomoo Ishii , Fumihiko Etou , Shinsuke Sakai , Toshikazu Tanaka , Naoyuki Ochiai
      The objective of this study was to test the reliability of ultrasonic median nerve strain measurements using automatic vibratory equipment. Strain ratios of the median nerve in the carpal tunnel model and the reference coupler were measured at three different settings of the transducer: 0, +2 and +4 mm (+ = compressing the model down 2–4 mm initially). After measurement of the carpal tunnel model, a +4-mm setting was chosen for in vivo measurement. The median nerve strains of 30 wrists were measured by two examiners using the equipment. Intra- and inter-examiner correlation coefficients (CCs) for the strain ratios were calculated. The closest ratio was found in the +4-mm placement (strain ratio: 0.73, Young's modulus ratio: 0.79). The intra-examiner CC was 0.91 (p < 0.01), and the inter-examiner CCs were 0.72–0.78 (p < 0.01). The automatic vibratory equipment was useful in quantifying median nerve strain at the wrist.


      PubDate: 2014-09-04T18:52:57Z
       
  • Visual Screening of Muscle Ultrasound Images in Children
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Rick Brandsma , Renate J. Verbeek , Natasha M. Maurits , Johannes H. van der Hoeven , Oebele F. Brouwer , Wilfred F.A. den Dunnen , Huibert Burger , Deborah A. Sival
      In children, non-invasive muscle ultrasound (MU) imaging has become increasingly important for the detection of neuromuscular pathology, by either quantitative or visual assessment. MU quantification requires time, expertise and equipment. If application of visual MU screening provides reliable results, ubiquitous application could be advocated. Previously, we found that visual MU screening can reliably detect segmental neuromuscular alterations within a patient. Analogously, we reasoned that visual MU screening could discern pathologic MU images from healthy controls. We therefore investigated visual screening results by 20 clinical observers (involving 100 MU images, with [n = 53] and without [n = 47] neuromuscular pathology). MU screening revealed adequate sensitivity, specificity and negative predictive value (85%, 75% and 82%, respectively). MU-experienced observers revealed higher specificity than MU-inexperienced observers (86% vs. 69%, p = 0.005). We conclude that clinical observers can identify neuromuscular pathology by visual screening. To enhance specificity, a secondary view by an expert appears advisory.


      PubDate: 2014-09-04T18:52:57Z
       
  • Calendar
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10




      PubDate: 2014-09-04T18:52:57Z
       
  • Comparison of Strain and Shear Wave Elastography for the Differentiation
           of Benign From Malignant Breast Lesions, Combined With B-mode
           Ultrasonography: Qualitative and Quantitative Assessments
    • Abstract: Publication date: October 2014
      Source:Ultrasound in Medicine & Biology, Volume 40, Issue 10
      Author(s): Ji Hyun Youk , Eun Ju Son , Hye Mi Gweon , Hana Kim , Yun Joo Park , Jeong-Ah Kim
      Our aim was to compare the diagnostic performance of strain elastography (SE) and shear-wave elastography (SWE), combined with B-mode ultrasonography (US), in breast cancer. For 79 breast lesions that underwent SE and SWE, two radiologists reviewed five data sets (B-mode US, SWE, SE and two combined sets). Qualitative and quantitative elastographic data and Breast Imaging Reporting and Data System (BI-RADS) categories were recorded. The area under the receiver operating characteristic curve (AUC) was evaluated. No significant difference in the AUC between the two elastography methods was noted. After subjective assessment by reviewers, the AUC for the combined sets was improved (SWE, 0.987; SE, 0.982; B-mode US, 0.970; p < 0.05). When SE and SWE were added, 38% and 56% of benign BI-RADS category 4a lesions with a low suspicion of cancer were downgraded without false-negative results, respectively. SE and SWE performed similarly. Therefore, addition of SE or SWE improved the diagnostic performance of B-mode US, potentially reducing unnecessary biopsies.


      PubDate: 2014-09-04T18:52:57Z
       
  • Feasibility of Ultrasound Imaging of Osteochondral Defects in the
           Ankle: A Clinical Pilot Study
    • Abstract: Publication date: Available online 9 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): A.C. Kok , M.P. Terra , S. Muller , C. Askeland , C.N. van Dijk , G.M.M.J. Kerkhoffs , G.J.M. Tuijthof
      Talar osteochondral defects (OCDs) are imaged using magnetic resonance imaging (MRI) or computed tomography (CT). For extensive follow-up, ultrasound might be a fast, non-invasive alternative that images both bone and cartilage. In this study the potential of ultrasound, as compared with CT, in the imaging and grading of OCDs is explored. On the basis of prior CT scans, nine ankles of patients without OCDs and nine ankles of patients with anterocentral OCDs were selected and classified using the Loomer CT classification. A blinded expert skeletal radiologist imaged all ankles with ultrasound and recorded the presence of OCDs. Similarly to CT, ultrasound revealed typical morphologic OCD features, for example, cortex irregularities and loose fragments. Cartilage disruptions, Loomer grades IV (displaced fragment) and V (cyst with fibrous roof), were visible as well. This study encourages further research on the use of ultrasound as a follow-up imaging modality for OCDs located anteriorly or centrally on the talar dome.


      PubDate: 2014-07-25T19:18:46Z
       
  • Evaluation of Statin Therapy on Endothelial Function in
           Hypercholesterolemic Rabbits by Automatic Measurement of Arterial Wall
           Movement Using Ultrasound Images
    • Abstract: Publication date: Available online 10 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Tavoos Rahmani-Cherati , Manijhe Mokhtari-Dizaji , Alireza Vajhi , Abdorrazzagh Rostami
      The aim of this study was to evaluate arterial endothelial function, assessed as acetylcholine-mediated dilation (AMD), in a hypercholesterolemic atherosclerotic rabbit model to investigate the effects of atorvastatin in the atherosclerotic process, using a new computerized analysis model and ultrasound images. Twenty-seven rabbits were fed a high-cholesterol (2%) diet for 6 wk and then divided into three groups for an additional 9 wk: Group A received regular chow food, group B received a 2% cholesterol-rich diet plus atorvastatin drug, and group C received regular chow food plus atorvastatin. Ultrasound examinations of endothelial function of the rabbit abdominal aorta artery were performed immediately after the 6 weeks (0 wk) and then 3, 6 and 9 wk after that. For off-line analysis, a computerized analysis method for evaluating instantaneous changes in the wall of the rabbit abdominal aorta was used. As parameters of improvement resulting from treatment, endothelium-dependent acetylcholine-induced dilation and endothelium-independent nitroglycerin-induced dilation were evaluated in treated rabbits. Differences among groups were tested using analysis of variance. On histopathology, intima-media thickness decreased after treatment in all groups. There were no significant differences in arterial diameter and blood velocity changes among treated rabbits at 0, 3, 6 and 9 wk of treatment in all groups, except in end-diastolic velocity, radial strain percentage, pulse index and resistance index in group C. In group A, AMD did not significantly improve after 3, 6 and 9 wk, as compared with 0 wk. Atorvastatin treatment significantly increased AMD (18%) at 3 wk in group B, compared with week 0. AMD significantly increased after 3 (26%), 6 (124%) and 9 (182%) wk in group C, compared with 0 wk. It is concluded that the new automatic method enables accurate and repeated evaluation of endothelial function during the progression and regression of atherosclerosis. Also, the results obtained in this study indicate that short-term administration of atorvastatin can improve endothelial function in cholesterol-fed rabbits.


      PubDate: 2014-07-25T19:18:46Z
       
  • Dynamics of Targeted Microbubble Adhesion Under Pulsatile Compared with
           Steady Flow
    • Abstract: Publication date: Available online 9 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Charles A. Sennoga , John M. Seddon , Jennifer A. Frueh , Dong Zhang , Dorian O. Haskard , Robert J. Eckersley , Meng-Xing Tang
      Hemodynamic flow variations at low fluid shear stress are thought to play a critical role in local atherosclerotic plaque initiation and development and to affect plaque instability. Targeted microbubbles are being developed as intravascular agents for identifying atherosclerotic lesions using ultrasound. How variations in local hydrodynamic flow influence the adhesiveness of targeted microbubbles is not well understood. We postulated that rates of targeted microbubble binding and accumulation differ when subjected to steady flow (SF) as compared with oscillatory or pulsatile flow (PF), because PF imposes non-uniform blood rheology and periodic acceleration and deceleration of blood velocity, when compared with SF. We assessed the binding rates of targeted microbubbles in seven randomly assigned PF and seven matched SF replicate runs at low (<1 Pa) and intermediate (≥1 and <2.5 Pa) wall shear stress (WSS) by drawing 4.8 × 106 microbubbles mL−1 over streptavidin-coated substrates, immobilized within a parallel plate flow chamber at a calculated density of 81 binding sites μm-2. Selective binding and accumulation of targeted microbubbles was recorded in a single field of view using real-time video microscopy. Microbubble accumulation was modeled to obtain flow-mediated microbubble binding kinetics (amplitude, A, and rate constant, k). PF elicited higher microbubble accumulation rates, in comparison to SF. The rates of microbubble accumulation differed significantly between PF and SF (p < 0.05) at intermediate WSS but not at low WSS (p > 0.05). The rate of microbubble accumulation decreased as WSS increased.


      PubDate: 2014-07-25T19:18:46Z
       
  • Harmonic Imaging with Fresnel Beamforming in the Presence of Phase
           Aberration
    • Abstract: Publication date: Available online 10 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Man Minh Nguyen , Junseob Shin , Jesse Yen
      Fresnel beamforming is a beamforming method with a delay profile similar in shape to a physical Fresnel lens. The advantage of Fresnel beamforming is the reduced channel count, which consists of four to eight transmit and two analog-to-digital receive channels. Fresnel beamforming was found to perform comparably to conventional delay-and-sum beamforming. However, the performance of Fresnel beamforming is highly dependent on focal errors. These focal errors result in high side-lobe levels and further reduce the performance of Fresnel beamforming in the presence of phase aberration. With the advantages of lower side-lobe levels and suppression of aberration effects, harmonic imaging offers an effective solution to the limitations of Fresnel beamforming. We describe the implementation of tissue harmonic imaging and pulse inversion harmonic imaging in Fresnel beamforming, followed by dual apodization with cross-correlation, to improve image quality. Compared with conventional delay-and-sum beamforming, experimental results indicated contrast-to-noise ratio improvements of 10%, 49% and 264% for Fresnel beamforming using tissue harmonic imaging in the cases of no aberrator, 5-mm pork aberrator and 12-mm pork aberrator, respectively. These improvements were 22%, 57% and 352% for Fresnel beamforming using pulse inversion harmonic imaging. Moreover, dual apodization with cross-correlation was found to further improve the contrast-to-noise ratios in all cases. Harmonic imaging was also found to narrow the lateral beamwidth and shorten the axial pulse length by at least 25% and 21%, respectively, for Fresnel beamforming at different aberration levels. These results suggest the effectiveness of harmonic imaging in improving image quality for Fresnel beamforming, especially in the presence of phase aberration. Even though this combination of Fresnel beamforming and harmonic imaging does not outperform delay-and-sum beamforming combined with harmonic imaging, it provides the benefits of reduced channel count and potentially reduced cost and size of ultrasound systems.


      PubDate: 2014-07-25T19:18:46Z
       
  • A New Method of Measurement of Cerebral Circulation Time:
           Contrast-Enhanced Ultrasonography in Healthy Adults and Patients with
           Intracranial Shunts
    • Abstract: Publication date: Available online 10 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Xi Liu , Yi Lin Yang , Si Guo Sun , Rui Jing Yang , Jia Wang , Yi Li , Li Zhang , Yun You Duan
      Alterations in the cerebral circulation time (CCT) are observed in several cerebrovascular diseases. We designed a new method of global CCT measurement using gray-scale contrast-enhanced ultrasound and studied healthy Chinese adults and patients with intracranial shunts. Eighty-one healthy volunteers and eight patients with intracranial shunt disease were enrolled. The contrast agent Sonovue was used. Perfusion in the carotid artery and internal jugular vein bilaterally was recorded. Start and peak filling CCTs were calculated and analyzed. Imaging of carotid vessels was uncomplicated in all patients. The bilateral start CCT was 6.23 ± 1.39 s in healthy patients. There were no significant differences within subgroups and contrast-dosage groups. In the patient group, the mean start CCT was 3.0 ± 0.56 s. There was a significant difference between the control and patient groups (p < 0.001). This new method using gray-scale contrast imaging can measure CCT and cerebral blood volume accurately. It can be used to visualize blood flow differences in real time and is less dependent on the training of the operator.


      PubDate: 2014-07-25T19:18:46Z
       
  • Emerging Imaging Technologies in Medicine Mark A. Anastasio and Patrick La
           Riviere. CRC Press, Boca Raton, FL, USA, 2013, 361 pages. ISBN number:
           1439880417
    • Abstract: Publication date: Available online 9 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Meng-Xing Tang



      PubDate: 2014-07-25T19:18:46Z
       
  • Relationship between CHADS2 Score and Complex Aortic Plaques by
           Transesophageal Echocardiography in Patients with Nonvalvular Atrial
           Fibrillation
    • Abstract: Publication date: Available online 9 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Kenichi Sugioka , Suwako Fujita , Shinichi Iwata , Asahiro Ito , Yoshiki Matsumura , Akihisa Hanatani , Atsushi Doi , Masahiko Takagi , Takahiko Naruko , Makiko Ueda , Minoru Yoshiyama
      The CHADS2 score is widely used for risk stratification of thromboembolism in patients with non-valvular atrial fibrillation (NVAF). Although the correlation of CHADS2 score with left atrial (LA) abnormality as detected by transesophageal echocardiography (TEE) has been reported in previous studies, the relationship between CHADS2 score and complex aortic plaque, which is also a significant risk factor for thromboembolism, has not been fully investigated. We assessed aortic plaques by TEE in 150 patients age ≥ 55 y with NVAF. The prevalence of complex aortic plaques increased along with increases in CHADS2 score (p = 0.001). In a multivariate analysis that included atherosclerotic risk factors and LA abnormality, a CHADS2 score ≥2 was independently associated with the presence of complex aortic plaques (odds ratio [OR] 3.39; 95% confidence interval [CI], 1.29–8.90). A high CHADS2 score is closely associated with the presence of complex aortic plaques, which explains, in part, the increased risk of thromboembolism in NVAF patients with high CHADS2 score.


      PubDate: 2014-07-25T19:18:46Z
       
  • Elastography Can Effectively Decrease the Number of Fine-Needle Aspiration
           Biopsies in Patients with Calcified Thyroid Nodules
    • Abstract: Publication date: Available online 9 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Min-Hee Kim , Si Luo , Sun Hee Ko , So-Lyung Jung , Dong-Jun Lim , Yongmin Kim
      When calcification, frequently found in both benign and malignant nodules, is present in thyroid nodules, non-invasive differentiation with ultrasound becomes challenging. The goal of this study was to evaluate the utility of elastography in differentiating calcified thyroid nodules. Consecutive patients (165 patients with 196 nodules) referred for fine-needle aspiration who had undergone both ultrasound elastography and B-mode examinations were analyzed retrospectively. Calcification was present in 45 benign and 20 malignant nodules. On 65 calcified nodules, elastography had 95% sensitivity, 51.1% specificity, 46.3% positive predictive value and 95.8% negative predictive value in detecting malignancy. Twenty-three of 45 benign calcified nodules were correctly diagnosed with elastography compared with 4 of 45 by B-mode ultrasound. Although it is difficult to differentiate benign and malignant calcified thyroid nodules solely with B-mode ultrasound, elastography has the potential to reduce the number of fine-needle aspiration biopsies performed on calcified nodules.


      PubDate: 2014-07-25T19:18:46Z
       
  • Influence of Repetitive Contrast Agent Injections on Functional and
           Molecular Ultrasound Measurements
    • Abstract: Publication date: Available online 9 July 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Anne Rix , Moritz Palmowski , Felix Gremse , Karin Palmowski , Wiltrud Lederle , Fabian Kiessling , Jessica Bzyl
      Quantitative contrast-enhanced ultrasound plays an important role in tumor characterization and treatment assessment. Besides established functional ultrasound techniques, ultrasound molecular imaging using microbubbles targeted to disease-associated markers is increasingly being applied in pre-clinical studies. Often, repeated injections of non-targeted or targeted microbubbles during the same imaging session are administered. However, the influence of repeated injections on the accuracy of the quantitative data is unclear. Therefore, in tumor-bearing mice, we investigated the influence of multiple injections of non-targeted microbubbles (SonoVue) on time to peak and peak enhancement in liver and tumor tissue and of vascular endothelial growth factor receptor 2 (VEGFR2)-targeted contrast agents (MicroMarker) on specific tumor accumulation. We found significantly decreasing values for time to peak and a tendency for increased values for peak enhancement after multiple injections. Repeated injections of VEGFR2-targeted microbubbles led to significantly increased tumor accumulation, which may result from the exposure of additional binding sites at endothelial surfaces caused by mechanical forces from destroyed microbubbles.


      PubDate: 2014-07-25T19:18:46Z
       
 
 
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