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 Annals of Nuclear MedicineJournal Prestige (SJR): 0.687 Citation Impact (citeScore): 2Number of Followers: 4      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1864-6433 - ISSN (Online) 0914-7187 Published by Springer-Verlag  [2626 journals]
• Role of carbonated water technique to enhance Tc-99m tetrofosmin
myocardial perfusion imaging by reducing subdiaphragmatic artefacts
• Abstract: Objective Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is confounded by the extracardiac artefacts cause by hepatobiliary clearance of the radiotracers. Various techniques have been evaluated to lessen those artefacts. In this study, we endeavoured to determine the effect of carbonated water in reducing such infracardiac artefact so to improve MPI image quality, sensitivity and specificity. Methods A total of 1000 patients were prospectively enrolled and randomised into two equal groups as A and B. Group A were given 250 ml of carbonated beverages and Group B were given 250 ml plain water immediately after radiotracer injection. Images were evaluated qualitatively and quantitatively for the interfering extracardiac artefacts. Results The qualitative analysis favoured carbonated water in reducing the interfering intestinal activity during rest as well as stress (p = 0.005 and p < 0.001, respectively). Quantitative calculation showed significant improvement of myocardium to extracardiac ratio with carbonated water ingestion in rest (p = 0.031) and vasodilator stress studies (p = 0.004). However, for exercise stress studies quantitative evaluation were not statistically different between the two protocols (p = 0.855). Conclusion Carbonated water ingestion is an easy and effective way to enhance SPECT image quality by mitigating extracardiac artefacts.
PubDate: 2020-08-04

• Development of 68 Ga-labeled tin colloids for evaluating phagocytic
function of Kupffer cells using preclinical PET imaging
• Abstract: Objective This study aimed to investigate the optimal conditions for producing 68Ga-labeled tin colloid and the feasibility of 68Ga-tin colloid positron emission tomography (PET) for visualization and evaluation of the phagocytic function of Kupffer cells (KCs) in vivo. Methods 68Ga-tin colloid was prepared by adding tin solution (1 mM, 0.2 mL) to 68Ga solution (1.0 mL), followed by pH adjustment with sodium acetate (1 M, 0.2 mL). Various labeling times were tested to find the optimal one. Colloid size was measured by filtering the solution through three-ply membrane filters (with pore sizes of 200, 3000, and 5000 nm), and radioactivity was measured in the whole filtrate and the filters using a gamma counter. The in vitro stability of the colloid was evaluated by the size measurement after incubation under ambient conditions for up to 60 min. PET scanning was performed for 30 min after intravenous administration of 68Ga-tin colloid solution (4 MBq) to healthy rats. Time-activity-curves for the liver, spleen, and blood pool were generated. Finally, liver uptake was compared before and after the establishment of KC-depletion and non-alcoholic steatohepatitis (NASH) rat models. Results Colloid size increased with increasing labeling time. After pH adjustment, the colloid sizes remained nearly unchanged. The optimal labeling time was determined as 30 min. PET imaging of healthy rats revealed that liver uptake of the 68Ga-tin colloid increased with increasing colloid size. In KC-depleted rats, liver uptake significantly decreased (n = 4, p < 0.01). NASH model rats showed significantly decreased uptake of 68Ga-tin colloid in the livers (n = 5, p < 0.01). Conclusions 68Ga-tin colloid, prepared by a simple radiolabeling method, enabled in vivo PET imaging to evaluate the phagocytic function of KCs.
PubDate: 2020-08-04

• Detectable size of melanoma metastases to brain on PET/CT
• Abstract: Objective We aimed to determine at what size melanoma metastases become detectable by PET/CT. Methods We reviewed a total of 293 whole-body PET/CT studies performed on 212 patients for staging of melanoma where there was an MRI within a month of the PET/CT. MR and PET/CT were reviewed independently by separate readers. Results PET/CT revealed an overall incidental true-positive rate of 1% on a per-patient basis, consistent with other studies, with ‘hot’ lesions (more avid than brain parenchyma) visible at smaller sizes than ‘cold’ lesions. Conclusions PET/CT can detect metastatic melanoma lesions over about 2 cm in size, with hot lesions generally visible at smaller sizes.
PubDate: 2020-08-01

• Applying Wells score to inconclusive perfusion only modified PIOPED II
(Prospective Investigation of Pulmonary Embolism Diagnosis II) readings in
order to optimize the lung scintigraphy diagnostic yield in acute
pulmonary embolism detection
• Abstract: Objective When using perfusion only modified PIOPED II criteria for PE detection, generated non-diagnostic scans are found to be the main diagnostic restriction. The objective of current study is to identify the role of Wells criteria added to inconclusive readings with the intent of enhancing the lung scintigraphy diagnostic yield. Methods CTPA was performed in 34 suspected PE patients with inconclusive lung scintigraphy. They also were evaluated by Wells score and classified as low, intermediate and high probability. Overall prevalence and the rate of PE for each probability were calculated. Furthermore, NPV for scores < 2 and PPV for scores > 6 were computed. Results Having a mean age of 59.75 ± 17.38 years, 7 (20.6%), 23 (67.6%) and 4 (11.8%) of cases had total criteria point count < 2, 2–6 and > 6, respectively. Using CTPA, 5 patients (14.7%) were diagnosed with PE. None of the patients with scores < 2 had PE with an associated NVP of 100%. Patients with scores 2–6 had a PE rate of 4.3% and 100% of patients with scores > 6 were diagnosed with PE, implying that the PPV of scores > 6 was 100%. Conclusion Adding Wells score to non-diagnostic scans allowed identification of PE to be done reliably, and provided further insight into how lung scintigraphy in conjunction with clinical assessment is a practical strategy not only for the patients unfit for performing CTPA but also in all the patients referred for PE evaluation.
PubDate: 2020-08-01

• Biodistribution and internal radiation dosimetry of a novel probe for
thymidine phosphorylase imaging, [ 123 I]IIMU, in healthy volunteers
• Abstract: Objective We evaluated the radiation dosage, biodistribution, human safety, and tolerability of the injection of a single dose of [123I] 5-iodo-6-[(2-iminoimidazolidinyl)methyl]uracil (IIMU), a new radiotracer targeting thymidine phosphorylase (TP), in healthy volunteers. Methods Potential participants were tested at our hospital to confirm their eligibility. Two healthy male adults passed the screening tests. They were injected with 56 and 111 MBq of [123I]IIMU, respectively. Safety assessments were performed before and at 1, 3, 6, 9, 24, 48 h, and 1-week post-injection. Whole-body emission scans were conducted at 1, 3, 6, 24, and 48 h post-injection. Regions of interest were manually drawn to enclose the entire body at each time point, identifying high-uptake organs to obtain the time-activity curves. Urine and blood samples were collected at 1, 2, 3, 4, 5, 6, 9, 24, and 48 h post-injection. The radiation dose for each organ and the effective doses were estimated using OLINDA/EXM 1.1 software. Results No adverse events were observed as of the follow-up visit > 1-week post-injection. In both subjects, the highest uptake of [123I]IIMU occurred in the liver, with peak injected activity (%IA) values of 17.7% and 15.1%, respectively. The second highest uptake was in the thyroid (0.35% and 0.66% IA). The %IA decreased gradually toward the end of the study (48 h) in all organs except the liver and thyroid. By the end of the study, 52.5% and 51.5% of the injected activity of [123I]IIMU had been excreted via the subjects’ renal systems. The estimated mean effective doses of [123I]IIMU were 9.19 μSv/MBq and 10.1 μSv/MBq, respectively. Conclusion In this preliminary study, [123I]IIMU was safely administered to healthy adults, and its potential clinical use in TP imaging was revealed.
PubDate: 2020-08-01

• Physiological 18F-FDG uptake in the normal adult anal canal: evaluation by
PET/CT
• Abstract: Objective Despite their benefit for detecting primary tumors, data for normal 18F-fluoro-2-deoxy-d-glucose (FDG) uptake in the anal canal are insufficient. Here we used positron emission tomography–computed tomography (PET/CT) to determine the uptake of FDG in the normal adult anal canal (AC) and to evaluate its clinical significance compared with that of anal cancer. Methods We conducted a retrospective study of–PET/CT images in the anal region, of 201 consecutive patients without symptoms or pathology taken from January 2015 to August 2019, after excluding two patients (one each with Crohn’s disease and hemorrhoid). These patients were included in the normal group, and data of eight patients with anal cancer were collected from January 2011 to August 2019 for comparison. FDG uptake was quantitatively evaluated (compared with the maximum standardized uptake value [SUVmax] to the SUVmax values of liver and distal rectum) and qualitatively (compared with background) in early and delayed phases. Normal grade 3 uptake was qualitatively defined as FDG uptake higher than the surrounding muscles. Results In the normal group, mean anal canal SUVmax of early phase was: 2.26 (range 1.00–6.30), and delayed phase: 2.52 (range 1.00–8.80). Their ratios to liver SUVmax were early: 0.74 (range 0.24–2.25), and delayed: 0.81 (range 0.23–2.32); ratios to rectal SUVmax were early: 0.87 (range 0.30–1.89), and delayed: 0.90 (range 0.30–1.27). Qualitatively, 25 patients (15.4%) had normal grade 3 uptake during the early and delayed phases. In contrast, qualitative data showed that all patients with anal cancer exhibited high FDG uptake in the anal canal. The mean early- and delayed-phase values of SUVmax of the anal canal and anal cancer group were 11.09 (range 5.40–17.73) and 14.23 (range 6.70–22.85), respectively. There was a significant difference between the mean-early and -delayed anal SUVmax values of the normal grade 3 and anal cancer groups. Furthermore, the ratios to liver SUVmax were significantly different between the two groups. Conclusions PET/CT scans occasionally showed high FDG uptake in the anal canal of healthy adults. Comparing the SUVmax values of liver FDG uptake may help differentiate between normal tissue and anal cancer.
PubDate: 2020-08-01

• Diagnostic performance of whole-body bone scintigraphy in combination with
SPECT/CT for detection of bone metastases
• Abstract: Objective This retrospective study investigated the performance of whole-body bone scintigraphy combined with SPECT/CT and established a grading diagnostic criterion for bone metastases. Methods We summarized signs of whole-body bone imaging combined with SPECT in nuclear medicine and CT signs of corresponding parts. Then we established a diagnostic criterion for bone metastases by using whole-body bone scintigraphy combined with local SPECT/CT. The criterion is classified into five grades. 120 patients with a total of 141 lesions underwent whole-body bone scintigraphy and SPECT/CT. Two reviewers read the images according to the diagnostic criterion. With pathological diagnosis as the “gold standard”, the diagnostic efficacy for bone metastases and the diagnostic agreement between the two reviewers were analyzed to validate the feasibility of the criterion. Diagnostic effectiveness was expressed in terms of sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Results The diagnostic accuracy of the two reviewers was 90.1% and 92.9% respectively, sensitivity was both 100%, specificity was 41.7% and 58.3%, positive predictive value was 89.3% and 92.1%, and negative predictive value was both 100%. The kappa value of the diagnostic tests performed by the two reviewers on whole-body bone scintigraphy combined with SPECT/CT was 0.919 (P < 0.001). Conclusion The grading diagnostic criterion for bone metastases by whole-body bone scintigraphy combined with SPECT/CT has high diagnostic accuracy and good consistency between reviewers, but the specificity was still low even with SPECT/CT.
PubDate: 2020-08-01

• Improvement of biodistribution profile of a radiogallium-labeled, αvβ6
integrin-targeting peptide probe by incorporation of negatively charged
amino acids
• Abstract: Objective Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. Since αvβ6 integrin has been reported as a promising target for PDAC diagnosis, we previously developed H-Cys(mal-NOTA-67Ga)-(Gly)6-A20FMDV2-NH2 ([67Ga]CG6) as an αvβ6 integrin-targeting probe. Although [67Ga]CG6 specifically binds to αvβ6 integrin-positive xenografts, the uptake of [67Ga]CG6 in the organs surrounding the pancreas, such as the liver and spleen, was comparable to that in the αvβ6 integrin-positive xenografts. We hypothesized that the undesirable accumulation of [67Ga]CG6 in those organs was caused by the positive charges of [67Ga]CG6 (+ 3). In this study, we aimed to decrease [67Ga]CG6 uptake in the liver and spleen by reducing the electric charges of the probe. Methods We synthesized H-Cys(mal-NOTA-67Ga)-(Asp)6-A20FMDV2-NH2 ([67Ga]CD6) and evaluated its affinity to αvβ6 integrin via in vitro competitive binding assay. Isoelectric points of the probes were determined by electrophoresis. Biodistribution study, autoradiography, and immunostaining for β6 integrin were conducted using αvβ6 integrin-positive and negative tumor-bearing mice. Results In vitro competitive binding assay showed that the alteration of the linker had a negligible impact on the affinity of [67Ga]CG6 to αvβ6 integrin. The results of electrophoresis revealed that [67Ga]CG6 was positively charged whereas [67Ga]CD6 was negatively charged. In the biodistribution study, the uptake of [67Ga]CD6 in the αvβ6 integrin-positive xenografts was significantly higher than that in the αvβ6 integrin-negative ones at 60 and 120 min. The uptake of [67Ga]CD6 in the liver and spleen was more than two-fold lower than that of [67Ga]CG6 at both time points. In the immunohistochemistry study, the radioactivity accumulated areas in the autoradiogram of the αvβ6 integrin-positive xenograft roughly coincided with β6 integrin-expressing areas. Conclusion We have successfully reduced the nonspecific uptake in the liver and spleen by altering the linker amino acid from G6 to D6. [67Ga]CD6 overcame the drawbacks of [67Ga]CG6 in its biodistribution.
PubDate: 2020-08-01

• Preoperative F-18 fluorocholine PET/CT for the detection of
hyperfunctioning parathyroid glands in patients with secondary or tertiary
hyperparathyroidism: comparison with Tc-99m sestamibi scan and neck
ultrasound
• Abstract: Objectives Currently, neck ultrasound is the preferred preoperative imaging in patients with secondary/tertiary hyperparathyroidism, and the use of Tc-99m sestamibi scan is limited in these patients. We conducted this study to compare the diagnostic utilities of F-18 fluorocholine PET/CT, Tc-99m sestamibi scintigraphy, and neck ultrasound for localizing hyperfunctioning parathyroid glands in secondary/tertiary hyperparathyroidism. Methods We prospectively enrolled 30 dialysis patients with a diagnosis of secondary/tertiary hyperparathyroidism; of these, 27 participants underwent all three imaging modalities, including dual-phase F-18 fluorocholine PET/CT (PET acquired 5 and 60 min after tracer injection), dual-phase Tc-99 m sestamibi SPECT/CT, and neck ultrasound. All patients underwent parathyroidectomy after imaging. We compared the lesion-based sensitivity, specificity, and accuracy of the three image tools using histopathology as the reference. Results A total of 27 patients (107 lesions) underwent all three imaging modalities and entered the final analysis. The lesion-based sensitivities of F-18 fluorocholine PET/CT, Tc-99m sestamibi, and ultrasound were 86%, 55%, and 62%, respectively (both p < 0.001, when comparing F-18 fluorocholine PET/CT to Tc-99 m sestamibi scan and to ultrasound). F-18 fluorocholine PET/CT, Tc-99m sestamibi, and ultrasound had similar specificities of 93%, 80%, and 87%, respectively. The accuracy of F-18 fluorocholine PET/CT (87%) was significantly higher than that of Tc-99m sestamibi (59%) and ultrasound (65%) (both p < 0.001). F-18 fluorocholine PET/CT identified more hyperplastic glands than ultrasound in 52% (14/27) patients. The sensitivity of F-18 fluorocholine PET/CT reached 95% for hyperplastic parathyroid masses as low as 200 mg. Conclusions F-18 fluorocholine PET/CT shows superior accuracy over the conventional imaging modalities in patients with secondary or tertiary hyperparathyroidism. The combination of F-18 fluorocholine PET/CT and neck ultrasound may enable better surgical planning in these patients. Registration identification number NCT04316845.
PubDate: 2020-08-01

• Brain 18 F-FDG PET analysis via interval-valued reconstruction: proof of
concept for Alzheimer’s disease diagnosis
• Abstract: Objective We propose an innovative approach for 18F-FDG PET analysis based on an interval-valued reconstruction of 18F-FDG brain distribution. Its diagnostic performance for Alzheimer’s disease (AD) diagnosis with comparison to a validated post-processing software was assessed. Methods Brain 18F-FDG PET data from 26 subjects were acquired in a clinical routine setting. Raw data were reconstructed using an interval-valued version of the ML–EM algorithm called NIBEM that stands for Non-Additive interval-based expectation maximization. Subject classification was obtained via interval-based statistical comparison (intersection ratio, IR) between cortical regions of interest (ROI) including parietal, temporal, and temporo-mesial cortices and a reference region, the sub-cortical grey nuclei, known not to be affected by AD. In parallel, PET images were post-processed using a validated automated software based on the computation of ROI normalized uptake ratios standard deviation (SUVr SD) with reference to a healthy control database (Siemens Scenium). Clinical diagnosis made during follow-up was considered as the gold-standard for patient classification (16 healthy controls and 10 AD patients). Results Both methods provided cortical ROI indices that were significantly different between controls and AD patients. The area under the ROC curve for control/AD classification was statistically identical (0.96 for NIBEM IR and 0.95 for Scenium SUVr SD). At the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were, respectively, 100%, 88%, 92%, 83%, and 100% for both Scenium SUVr SD and NIBEM IR methods. Conclusion This preliminary study shows that interval-valued reconstruction allows self-consistent analysis of brain 18F-FDG PET data, yielding diagnostic performances that seem promising with respect to those of a commercial post-processing software based on SUVr SD analysis.
PubDate: 2020-08-01

• Accuracy of metabolic volume and total glycolysis among six
threshold-based target segmentation algorithms
• Abstract: Objective This study aimed to evaluate the accuracy of six threshold-based segmentation methods with different target-to-background ratios (TBR), images with different voxel sizes and image noise, in measuring metabolic volume (MV) and total glycolysis (TG). Methods A standard body phantom consisting of six spheres (inner diameters of 37, 28, 22, 17, 13, and 10 mm) was filled with 18F-FDG solution. The background radioactivity level was 2.65 kBq/mL, and the TBRs were 4 and 8. PET data were acquired for 30 min with list mode. PET data for 30 and 3 min were reconstructed with a three-dimensional ordered subset expectation maximization algorithm plus time-of-flight information with images with 2 and 4 mm isotropic voxels. The six methods examined were absolute standardized uptake value (SUV) of 2.5 (SUV2.5), 41%, 50%, adaptive 41%, and adaptive 50% thresholds of maximum SUV (Th41, Th50, ThA41, and ThA50, respectively); and the contrast-oriented algorithm (ThCOA). Segmented MV and TG were compared with the actual inner volume and expressed as percentages (%MVseg and %TGseg, respectively). In addition, the segmented MV was converted to the diameter, and the differences of it from the reference diameter were compared among six methods. Results The ThCOA method yielded the most accurate measurements of %MVseg and %TGseg; the difference between %MVseg or %TGseg and its reference were smaller than 10% in 30-min and 15% in 3-min images, but the segmented contour was almost the same as the reference diameter. Measurements with Th50 and ThCOA were highly accurate for both %MVseg and %TGseg in the large spheres, and the adaptive threshold methods, including ThA41, ThA50, and ThCOA, were also highly accurate in the small spheres. The voxel sizes affected the accuracy of %MVseg and %TGseg with a TBR of 4 in any threshold-based methods. Conclusions Of the six threshold-based segmentation methods studied, ThCOA was the most accurate method for evaluating MV and TG and had only minor dependence on TBRs and sphere size. The small voxel sizes improved the variation of the accuracy in low TBR.
PubDate: 2020-08-01

• Assessing the effects of body weight on subchondral bone formation with
quantitative 18 F-sodium fluoride PET
• Abstract: Objectives The aim of this study was to quantify subchondral bone remodeling in the elbows, hands, knees, and feet using volumetric and metabolic parameters derived from 18F-sodium fluoride positron emission tomography (NaF-PET) and to assess the convergent validity of these parameters as an index of joint degeneration and preclinical osteoarthritis. Methods A retrospective analysis was conducted in 34 subjects (32 males, 2 females) with metastatic bone disease who underwent full-body NaF-PET/CT scans. An adaptive contrast-oriented thresholding algorithm was applied to segment NaF-avid regions in the bilateral elbows, hands, knees, and feet of each subject, and metabolically active volume (MAV), maximum standardized uptake value (SUVmax), mean metabolic volumetric product (MVPmean), and partial volume-corrected MVPmean (cMVPmean) of the segmented regions were calculated. Global parameters for MAV, SUVmax, MVPmean, and cMVPmean were defined as the sum of the corresponding values in all the joints of a subject. Inter-rater reliability was determined with Lin’s concordance correlation, and associations of global values with subject body weight and age were assessed with Pearson correlation and Spearman correlation analyses. Results Inter-rater reliability was observed to be the highest in SUVmax (ρc = 0.99), followed by MVPmean (ρc = 0.96), cMVPmean (ρc = 0.93), and MAV (ρc = 0.93). MAV, MVPmean, and cMVPmean were observed to significantly increase with weight (all p < 0.0001) determined by Pearson correlation. In addition, Spearman rank-order analysis demonstrated a significant correlation between SUVmax and weight in addition to MAV, MVPmean, and cMVPmean and weight (all p < 0.01). No significant association between age and any PET parameter was observed. Conclusions These preliminary data demonstrate the feasibility and reliability of assessing bone turnover at the joints using quantitative NaF-PET. Our findings corroborate the fact that biomechanical factors including mechanical loading and weight-bearing are contributors to osteoarthritis disease progression.
PubDate: 2020-08-01

• SPECT-CT visualization and biopsy of sentinel lymph nodes in patients with
stage IAB–IIA cervical cancer
• Abstract: Objective To evaluate the diagnostic accuracy of sentinel lymph node (SLN) biopsy and to determine clinical significance of preoperative single-photon emission computed tomography/computed tomography (SPECT-CT). Methods We retrospectively evaluate data and images of 55 women with stage IAB–IIA cervical cancer that underwent sentinel lymph node biopsy and subsequent lymph node dissection. 99mTc-phytate (300 MBq) was injected submucosally in 4 points and SPECT-CT started 2 h after the injection. All lymph nodes (LN) that accumulated radiocolloids were regarded as sentinel. Next day after the mapping radical hysterectomy with complete pelvic and parametrial LN dissection and SLN biopsy were performed according to the institute protocol. Results SPECT-CT identified SLNs in 51 of 55 patients. All SLNs were successfully detected during the surgery. The SLN mapping efficacy was 92.7%. LN metastases were diagnosed in 6/51 (11.8%) cases, including 2 patients with positive SLNs. Sensitivity, negative predictive value (NPV) and false-negative rate for SLN biopsy were as follows: 33.4%, 91.8% and 66.6%. In patients with unilateral SPECT-CT localization of SLNs, LN metastases were identified in 4 (20%) of 20 patients but SLN biopsy was false negative in all cases. In 31 women, SPECT-CT detected SLNs on both sides of the pelvis. In this group, regional LN metastases were diagnosed in 2 patients, and in both cases metastases were detected only in SLNs. Conclusions In women with SPECT-CT visualization of SLNs on both sides of the pelvis, SLN biopsy had high sensitivity and NPV. In patients with unilateral SLN localization, SLN biopsy cannot be used for the prediction of regional LN status.
PubDate: 2020-07-15

• The REICA method for quantification of cerebral blood flow is less
affected by lung washout of [ 123 I] IMP than the graph-plot method
• Abstract: Objective The $$\gamma$$ -Ray Evaluation with Iodoamphetamine for Cerebral blood flow Assessment (REICA) method is a new method for cerebral blood flow (CBF) quantification with SPECT and [123I] IMP, which does not require invasive arterial blood sampling, or the use of a regression formula. Moreover, it takes into consideration tracer retention, while the Graph-Plot (GP) method does not. This study aims to confirm the reliability of the REICA method in calculating CBF by accounting for pulmonary tracer retention artefact. Methods Data of 100 patients were retrospectively analyzed. Washout rate (WR) was defined as 1- (max count /min count) in the lungs. The bias due to WR was analyzed by dividing the data into high/low WR groups and a multiple regression analysis was also performed. Results The REICA method did not show significant bias according to the $$\chi ^2$$ test ( $$p=0.07$$ ), while the GP method showed significant bias ( $$p=0.0006$$ ). Both the REICA and GP methods showed significant correlation with autoradiography (ARG) method ( $$p<0.0001$$ , $$p<0.0001$$ ) and WR ( $$p=0.002$$ , $$p<0.0001$$ ) when analyzed via multiple regression analysis with covariates of age and sex. Conclusions The REICA method is a reliable method for CBF quantification, which is unaffected by tracer washout through the lungs unlike the GP method.
PubDate: 2020-07-13

• Sentinel lymph node biopsy in muscle-invasive bladder cancer:
single-center experience
• Abstract: Objective In this study, the validity of sentinel node biopsy procedure as our index test was assessed and compared with bilateral pelvic lymphadenectomy for staging and detecting the regional lymph nodes metastasis in patients with muscle-invasive bladder cancer (MIBC). Methods Consecutive series of cases with T1–T4 urothelial MIBC were included. Following the injection of radiotracer, sentinel nodes were sought using a handheld gamma probe and all hot nodes were harvested. Bilateral pelvic lymphadenectomy was done for all patients following sentinel node biopsy. The tumor specimen, sentinel nodes, and excised lymph nodes were evaluated histopathologically. Same as the other midline tumors, detection rate and false negative rates were calculated using patient basis and side basis methods. Results By evaluating each patient as a unit of analysis, sentinel nodes were detected in 35 of 41 patients (85%), 13/16 (81%) of the neoadjuvant chemotherapy (NAC) and 22/25 (88%) of the no-neoadjuvant chemotherapy (No-NAC) participants. The false negative rate was 3/7 (42%): 1/3 (33%) for NAC, and 2/4 (50%) for No-NAC patients. By evaluating each hemipelvis as a unit of analysis, sentinel nodes were detected in 53 of 82 hemipelves (65%), 19/32 (66%) of the NAC, and 34/50 (68%) of the No-NAC hemipelves. No false-negative result was found by assessing each hemipelvis as a unit of analysis. Conclusions Sentinel node biopsy is a feasible method for lymph node staging in MIBC, including patients with a history of NAC. To optimize the sensitivity, the decision regarding the lymphadenectomy is best to be based on the pathological status of sentinel node harvested from each hemipelvis separately as the unilateral finding of a sentinel node, does not rule out the possibility of metastatic involvement of contralateral pelvic lymph nodes.
PubDate: 2020-07-12

• The relationship between cholecystokinin secretion and pancreatic [ 11
C]methionine uptake in patients after partial pancreaticoduodenectomy
• Abstract: Objective The pancreatic uptake of [11C]methionine ([11C]MET) is associated with beta-cell function and insulin secretion, but [11C]MET uptake and its relationship with exocrine pancreatic performance are less well studied. The postprandial release of cholecystokinin (CCK) depends on gastric emptying velocity and triggers exocrine pancreas secretion. Therefore, we assumed that high postprandial CCK concentrations stimulate the uptake of [11C]MET in the residual pancreas following pancreaticoduodenectomy. Methods Nineteen tumor-free patients after pancreaticoduodenectomy (median age: 64; 25/75 quantile: 56–67 years); ten males, nine females and ten healthy controls (median age: 24; 25/75 quantile: 23.8–26 years) were given a mixed meal. Plasma CCK, insulin and glucose concentrations were measured before and at 10, 20, 30, 60, 90, 150 and 180 min after ingestion. Simultaneously, 800 MBq of [11C]MET were administered and the activity [maximum tissue standardized uptake values (SUVmax)] over the pancreas was measured using PET-CT at 15, 30 and 60 min after injection. Results Integrated CCK (AUC30) correlated with SUVmax (AUC60, R2 = 0.45, p value = 0.0013). Multivariate analysis revealed postprandial insulin (AUC60) and CCK concentrations and young age as significant independent predictors of [11C] methionine uptake. Conclusion The association between CCK concentrations and pancreatic [11C]MET uptake might indicate a causal relationship. Further research should assess whether [11C]MET uptake could serve as a less invasive tool to assess exocrine pancreas activity.
PubDate: 2020-07-11

• Validation of the 3-variable prognostic score (3-PS) in mCRPC patients
treated with 223 Radium-dichloride: a national multicenter study
• Abstract: Objective Radium-223 (223Ra) has been approved for treatment in patients with metastatic castration-resistant prostatic cancer (mCRPC) and bone metastasis. This α-emitting radionuclide has a beneficial effect on pain and is also capable to increase overall survival (OS). Several studies evaluated the prognostic value of different biomarkers at baseline, such as serum values, imaging parameters or pain. To date, however, clinicians lack a validated and simple system to assess which patients will most likely benefit from 223Ra treatment. The 3-variable prognostic score (3-PS), proposed in a single-center study in 2017 classifies patients in five prognostic groups with a specific OS. This study aims to validate the 3-PS in a larger multicenter population. Methods Four hundred and thirty mCRPC patients treated with 223Ra from six different centers were analyzed. The 3-PS score consists of the collection of baseline hemoglobin, prostatic specific antigen and Eastern cooperative oncology group performance status and was initially applied to the whole population (total group). The score was then validated on the 338 patient’s subgroup (clean group) obtained by subtracting the 92 patients enrolled for the original study of the 3-PS score. This purified group served as further validation evidence. Results Statistical analysis showed that the 3-PS score was valid on the total group as well as in the clean group as the AUC estimated (0.74) falls within the CI of the AUC calculated on the validation sample (95% CI 0.66–0.82). Conclusion This study confirms the validity of the 3-PS score for mCRPC patients. This score is simple, noninvasive and affordable and can be easily used to select patients that will most probably complete 223Ra treatment. In addition, this tool provides an exact estimate of life expectancy in terms of OS.
PubDate: 2020-07-11

• Comparison of thyroid hormone withdrawal and recombinant human
patients with intermediate- to high-risk differentiated thyroid cancer
• Abstract: Objective To compare the clinical outcome in patients who received adjuvant therapy with radioactive iodine (RAI) using different preparation methods, namely, thyroid hormone withdrawal (THW) and recombinant human thyroid-stimulating hormone (rhTSH), after undergoing thyroidectomy for intermediate- to high-risk differentiated thyroid carcinoma (DTC) according to the American Thyroid Association criteria. Methods Between May 2012 and October 2018, 136 patients who underwent adjuvant therapy with high-dose (3700 MBq) RAI for DTC without any metastatic lesions or macroscopic residual lesions after surgical resection were retrospectively selected. Patients were excluded if distant metastasis was confirmed during adjuvant therapy or if the outcome could not be confirmed; thus, 112 patients were finally evaluated. Patients underwent either a 3-week I restriction with thyroxine withdrawal or a 2-week I restriction with rhTSH administration. The serum thyroglobulin (Tg) concentration was measured, and 131I scintigraphy (370 MBq) was performed 6–12 months after adjuvant therapy. The definition of the initial achievement of adjuvant therapy was the disappearance of the uptake of 131I at the thyroid bed and serum Tg concentration < 2.0 ng/mL. The results of the adjuvant therapy between the groups were compared using the Fisher’s exact test, and the TSH levels and estimated glomerular filtration rate (eGFR) were compared using the Welch’s t test. Results The THW and rhTSH groups included 47 and 65 patients, respectively, and the intermediate- and high-risk groups included 63 and 49 patients, respectively. No patient was assigned to the low-risk group. In the THW and rhTSH groups, the initial RAI adjuvant therapy goal was achieved in 30/47 (63.8%) and 46/65 patients (70.8%), respectively (p = 0.54); mean ± standard deviation of the TSH levels was 123.8 ± 46.4 µIU/mL and 274.5 ± 97.7 µIU/mL, respectively (p < 0.01), and eGFR (treatment/pre-treatment) was 0.81 and 0.99, respectively (p < 0.01). In the intermediate- and high-risk groups, the initial RAI adjuvant therapy goal was achieved in 43/63 patients (68.3%) and 33/49 (67.3%), respectively (p = 1.0). Conclusion No significant differences were observed between the preparation methods in the initial achievement of RAI adjuvant therapy. However, patients in the rhTSH group demonstrated higher TSH levels and retained eGFR.
PubDate: 2020-07-08

• Visualization of translocator protein (18 kDa) (TSPO) in the retina of
diabetic retinopathy rats using fluorine-18-DPA-714
• Abstract: Objectives To investigate the feasibility of a noninvasive method for imaging translocator protein (18 kDa) (TSPO) in the retina of diabetic retinopathy (DR) rats using fluorine-18-DPA-714 ([18F]-DPA-714) micro-positron emission tomography (PET)/X-ray computed tomography (CT). Methods Sprague–Dawley (SD) rats were intraperitoneally injected with streptozocin (STZ) (65 mg kg−1, ip) to induce diabetes mellitus (DM). The TSPO in both eyes was detected by PET/CT using [18F]-DPA-714 12 weeks after the establishment of the DM model. The mean standardized uptake value (SUVmean) was analyzed. Western blot and quantitative real-time polymerase chain reaction (PCR) were performed to detect the TSPO protein and mRNA levels in the retina. Results PET/CT results showed that the SUV of [18F]-DPA-714 was markedly reduced in the retina of DR rats compared with that of normal controls 12 weeks after diabetes induction. The SUVmean of regions of interest (ROIs) in the retinas of DR and normal control rats was 0.883 ± 0.078 and 2.525 ± 0.213 (P < 0.001), respectively. The results of PET/CT were in line with the Western blots and quantitative real-time PCR. Conclusions The PET results demonstrated that TSPO was decreased in the early stage of DR. [18F]-DPA-714 PET/CT appears to be a useful noninvasive imaging method for detecting TSPO in the retina. A decrease in the TSPO level in the retina may play an important role in the development of DR.
PubDate: 2020-07-06

• Cellular S values in spindle-shaped cells: a dosimetry study on more

• Abstract: Objective Cellular dosimetry plays a crucial role in radiobiology and evaluation of the relative merits of radiopharmaceuticals used for targeted radionuclide therapy. The present study aims to investigate the effects of various cell geometries on dosimetric characteristics of several Auger emitters distributed in different subcellular compartments using Monte Carlo simulation. Methods The Geant4-DNA extension of the Geant4 Monte Carlo simulation toolkit was employed to calculate the mean absorbed dose per unit cumulated activity (S value) for different subcellular distributions of several Auger electron-emitting theranostic radionuclides including 99mTc, 111In, 123I, 125I, and 201Tl. The simulations were carried out in various single-cell models of liquid water including spherical, ellipsoidal, spherical spindle, and ellipsoidal spindle cell models. The latter two models which are generalized from the first two models were inspired by the morphologies of spindle-shaped (fusiform) cells, and were developed to provide more realistic modeling of this common geometry observed in many healthy and cancerous cells. Results Evaluation of the S values calculated for the examined cell models reveals that the differences are small (less than 9%) for the cell ← cell, cell ← cell surface, and nucleus ← nucleus source–target combinations. However, moderate discrepancies are seen (up to 28%) when the nucleus is considered as the target, as well as the radioactivity is either internalized into the cytoplasm or bound to the cell membrane. Conclusions The findings of the present work suggest that the assumption of spherical cell geometry may provide reasonably accurate estimates of the cellular/nuclear dose for the considered Auger emitters, even for spindle-shaped cells. Of course, this approximation should be used with caution for the nucleus ← cytoplasm and nucleus ← cell surface configurations, since the S-value sensitivity to the cell geometry is somewhat significant in these cases.
PubDate: 2020-07-06

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Heriot-Watt University
Edinburgh, EH14 4AS, UK
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