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Purpose: To develop a deep learning (DL) model for generating automated regions of interest (ROIs) on 99mTc-diethylenetriamine pentaacetic acid (DTPA) renal scans for glomerular filtration rate (GFR) measurement. Methods: Manually-drawn ROIs retrieved from a Picture Archiving and Communications System were used as ground-truth (GT) labels. A two-dimensional U-Net convolutional neural network architecture with multichannel input was trained to generate DL ROIs. The agreement between GFR values from GT and DL ROIs was evaluated using Lin's concordance correlation coefficient (CCC) and slope coefficients for linear regression analyses. Bias and 95% limits of agreement (LOA) were assessed using Bland-Altman plots. Results: A total of 24,364 scans (12,822 patients) were included. Excellent concordance between GT and DL GFR was found for left (CCC 0.982, 95% confidence interval [CI] 0.981–0.982; slope 1.004, 95% CI 1.003–1.004), right (CCC 0.969, 95% CI 0.968–0.969; slope 0.954, 95% CI 0.953–0.955) and both kidneys (CCC 0.978, 95% CI 0.978–0.979; slope 0.979, 95% CI 0.978–0.979). Bland-Altman analysis revealed minimal bias between GT and DL GFR, with mean differences of − 0.2 (95% LOA − 4.4–4.0), 1.4 (95% LOA − 3.5–6.3) and 1.2 (95% LOA − 6.5–8.8) mL/min/1.73 m² for left, right and both kidneys, respectively. Notably, 19,960 scans (81.9%) showed an absolute difference in GFR of less than 5 mL/min/1.73 m². Conclusion: Our DL model exhibited excellent performance in the generation of ROIs on 99mTc-DTPA renal scans. This automated approach could potentially reduce manual effort and enhance the precision of GFR measurement in clinical practice. [ABSTRACT FROM AUTHOR]

We aimed to examine the associations of cardiovascular risk factors with myocardial perfusion reserve (MPR) in patients with type 2 diabetes and stable coronary artery disease. The study patients were retrospectively identified from a database of patients with diabetes and stable coronary artery disease at Asan Medical Center (Seoul, Republic of Korea), covering the period from 2017 to 2019. The primary outcome variable was MPR assessed by dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT. Univariable and stepwise multivariable analyses were performed to assess the associations of cardiovascular risk factors with MPR. A total of 276 patients (236 men and 40 women) were included. The median global MPR was 2.4 (interquartile range 1.9–3.0). Seventy-five (27.2%) patients had an MPR < 2.0. Multivariable linear regression showed that smoking (ß = − 0.44, 95% confidence interval − 0.68 to − 0.21, P < 0.001), hypertension (ß = − 0.24, 95% confidence interval − 0.47 to − 0.02, P = 0.033), and summed difference score (ß = − 0.05, 95% confidence interval − 0.07 to − 0.03, P < 0.001) were independently associated with MPR. Abnormal MPR (< 2.0) was associated with a higher incidence of cardiac death or myocardial infarction (P = 0.034). MPR assessed by dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT was impaired in a large cohort of patients with diabetes. After adjusting for risk variables, including standard myocardial perfusion imaging characteristics, smoking, and hypertension were associated with MPR. Our results may aid in identifying patients with impaired MPR and stratifying patients with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether tumor uptake of 18F-fluorodeoxyglucose (18F-FDG) is associated with invasive disease-free survival (IDFS) in patients with hormone receptor (HR)-positive ERBB2-negative early-stage breast cancer treated with adjuvant chemotherapy. Methods: This is a single-center cohort study of women with breast cancer who underwent surgery between 2008 and 2015 at Asan Medical Center, Seoul, Korea. Patients were enrolled if they were diagnosed with HR-positive ERBB2-negative breast cancer with histology of invasive ductal carcinoma, had an American Joint Committee on Cancer pathologic tumor stage of T2N1 with 1–3 positive axillary nodes, underwent preoperative 18F-FDG positron emission tomography/computed tomography (PET/CT), and underwent breast cancer surgery followed by anthracycline- or taxane-based adjuvant chemotherapy. The primary outcome measure was IDFS. The maximum standardized uptake value (SUVmax) was dichotomized using a predefined cut-off of 4.14. Results: A total of 129 patients were included. The median follow-up period for IDFS in those without recurrence was 82 months (interquartile range, 65–106). Multivariable Cox analysis showed that SUVmax was independently associated with IDFS [adjusted hazard ratio 2.49; 95% confidence interval (CI), 1.06–5.84]. Ten-year IDFS estimates via the Kaplan–Meier method were 0.60 (95% CI, 0.42–0.74) and 0.82 (95% CI, 0.65–0.91) for high and low SUVmax groups, respectively. The overall association between SUVmax and IDFS appeared to be consistent across subgroups divided according to age, progesterone receptor status, histologic grade, or presence of lymphovascular invasion. Conclusion: High SUVmax on preoperative 18F-FDG PET/CT was independently associated with reduced long-term IDFS in T2N1 HR-positive ERBB2-negative breast cancer patients who underwent adjuvant chemotherapy. [ABSTRACT FROM AUTHOR]

We examined whether 18F-fluorodeoxyglucose metabolism is associated with distant relapse-free survival (DRFS) and overall survival (OS) in women with estrogen receptor (ER)-positive, HER2-negative breast cancer. This was a cohort study examining the risk factors for survival that had occurred at the start of the study. A cohort from Asan Medical Center, Korea, recruited between November 2007 and December 2014, was included. Patients received anthracycline-based neoadjuvant chemotherapy. The maximum standardized uptake value (SUV) of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) was measured. The analysis included 466 women. The median (interquartile range) follow-up period without distant metastasis or death was 6.2 (5.3–7.6) years. Multivariable analysis of hazard ratio (95% confidence interval [CI]) showed that the middle and high tertiles of SUV were prognostic for DRFS (2.93, 95% CI 1.62–5.30; P < 0.001) and OS (4.87, 95% CI 1.94–12.26; P < 0.001). The 8-year DRFS rates were 90.7% (95% CI 85.5–96.1%) for those in the low tertile of maximum SUV vs. 73.7% (95% CI 68.0–79.8%) for those in the middle and high tertiles of maximum SUV. 18F-fluorodeoxyglucose PET/CT may assess the risk of distant metastasis and death in ER-positive, HER2-negative patients. [ABSTRACT FROM AUTHOR]

Background: To evaluate the usefulness of quantitative findings of pretherapy lymphoscintigraphy in predicting the effects of complex decongestive therapy (CDT) in patients with upper extremity lymphedema after breast cancer treatment. Methods and Results: We retrospectively analyzed patients with unilateral breast cancer-related lymphedema (BCRL) who underwent pretherapy lymphoscintigraphy and completed 2 weeks of CDT. A total of 18 patients with unilateral BCRL clinical stage II underwent 30-minute sessions of CDT five times per week for 2 weeks. The quantitative asymmetry index (QAI) of the upper extremity, axillary lymph node (LN) uptake, and axillary plus supraclavicular LN uptake from lymphoscintigraphy were calculated. The volume of lymphedema was calculated by percentage excess volume (PEV) at initial and posttreatment. The CDT response was assessed using percentage reduction in excess volume (PREV). Correlation analyses were conducted using Kendall tau rank correlation. There was positive correlation between upper extremity QAI at 2 hours and initial PEV. Negative correlations were found between axillary LN QAI at 1, 2 hours, and initial PEV, and between axillary plus supraclavicular LN QAI at 1, 2 hours, and initial PEV. The PREV showed a positive correlation with axillary LN QAI at 2 hours after injection (tau-b = 0.354, p = 0.041). Conclusion: Quantitative findings of pretherapy lymphoscintigraphy have potential value for use in predicting the response to CDT in patients with upper extremity lymphedema after breast cancer treatment. Using QAIs from lymphoscintigraphy, we could estimate the excess volume of lymphedema. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine the diagnostic value of the relative filtration fraction (RFF) assessed by dynamic 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) renal scintigraphy after angiotensin-converting enzyme (ACE) inhibition for renovascular hypertension (RVHT) diagnosis. Methods: 99mTc-DTPA captopril renal scintigraphy performed in adolescents or adults (≥ 10 years) with suspected RVHT was retrospectively reviewed. The RFF of the affected kidney was qualitatively assessed as the relative glomerular filtration rate during the 2 to 3-min period compared with the relative perfusion during the first 60 s (qualitative RFF) and scored from 1 (definitely same) to 5 (definitely decreased). The quantitative RFF of the affected kidney was obtained by dividing the percentage of glomerular filtration rate by the percentage of renal perfusion. Results: Overall, 173 patients (high probability, n = 15; and low probability, n = 158) were included based on conventional captopril renal scintigraphic criteria. An abnormal qualitative RFF was observed in 12 patients with high probability, and the diagnostic sensitivity was 80.0% (95% CI, 51.9–95.7). The RFF was normal in 152 patients with low probability, and the diagnostic specificity was 96.2% (95% CI, 91.9–98.6). The RFF was lower in patients with high probability than in those with low probability (0.79 ± 0.15 vs. 1.02 ± 0.11, P < 0.0001). Conclusions: The RFF assessed by dynamic 99mTc-DTPA renal scintigraphy after ACE inhibition can detect patients with high probability for RVHT. The RFF after ACE inhibition might be a useful diagnostic criterion especially when baseline scintigraphy is not available for evaluating ACE inhibition-induced changes. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the value of 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for early prediction of standard anatomic response and survival outcomes in patients with metastatic colorectal cancer (mCRC) receiving Regorafenib. Methods: Sixty-eight patients with mCRC refractory to standard cytotoxic chemotherapy were enrolled and received Regorafenib (160 mg/day on days 1–21, following a 7-day break). Standard anatomical response was evaluated every 8 weeks. Both scans were performed before and on day 21 of Regorafenib. Results: Of the 61 patients included in per-protocol analysis, complete response was not observed, but partial response was observed in 8.2% (n = 5), stable disease in 67.2% (n = 41), and progressive disease in 24.6% (n = 15). The objective response rate was 8.2% and disease control rate 75.4%. Five responders (8.2%) and 13 non-responders (21.3%) met the CT and 18F-FLT PET/CT criteria (maximum standardized uptake value decrease ≥ 10.6% for responders). Forty-three (70.5%) exhibited discordant responses on CT and 18F-FLT PET/CT (McNemar test, P < 0.001). At a median follow-up of 8.9 months, median progression-free survival (PFS) and median overall survival (OS) were 3.6 months (95% confidence interval [CI], 3.34–3.80 months) and 8.5 months (95% CI, 6.95–10.10 months), respectively. Comparison of PFS and OS according to 18F-FLT PET/CT response revealed slightly longer PFS (P = 0.015) in responders, but the correlation with OS was not significant. The PET Response Criteria in Solid Tumours (PERCIST) of 18F-FDG PET/CT revealed differences in PFS and OS between partial metabolic response (PMR) and non-PMR (P = 0.048 and P = 0.014, respectively), and between progressive metabolic disease (PMD) and non-PMD (P = 0.189 and P = 0.007, respectively). Conclusions: Survival outcome was significantly associated with PERCIST using 18F-FDG PET/CT but the change of 18F-FLT uptake was only slightly associated with PFS. 18F-FDG PET/CT can be used as imaging biomarker to predict clinical outcomes early in patients with mCRC receiving Regorafenib. [ABSTRACT FROM AUTHOR]

Purpose: We evaluated the feasibility of dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT imaging using a cardiac camera equipped with cadmium-zinc-telluride detectors for the quantification of myocardial perfusion reserve (MPR).Methods: Subjects with stable known or suspected coronary artery disease (CAD) who had undergone or were scheduled to undergo fractional flow reserve (FFR) measurement were prospectively enrolled. Dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT imaging was performed using a dedicated multiple pinhole SPECT camera with cadmium-zinc-telluride detectors. MPR was derived using Corridor4DM software.Results: A total of 34 subjects were enrolled (25 men and 9 women; mean age 60.4 years). FFR was measured in 65 coronary arteries with intermediate lesions. The average global MPR was 2.58 ± 1.03. Global MPR was associated with the extent of CAD (P = 0.028) and global summed stress score (r = −0.60, P < 0.001). Regional MPR showed a significant correlation with diameter stenosis (r = −0.57, P < 0.001), minimum lumen diameter (r = 0.50, P < 0.001), summed stress score (r = −0.52, P < 0.001) and FFR (r = 0.52, P < 0.001). The area under the receiver operating characteristic curve of MPR for the diagnosis of functionally significant stenosis (FFR ≤0.8) was 0.79 (P < 0.001). The sensitivity and specificity of regional MPR were 67% and 83%, respectively, using a cut-off value of 2.0.Conclusion: Dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT imaging and quantification of MPR is feasible in patients with stable CAD. The preliminary results of this study in a small number of patients require confirmation in a larger cohort to determine their implications for bolstering the role of SPECT imaging in the diagnosis and risk prediction of CAD. [ABSTRACT FROM AUTHOR]

Structural reorganization in white matter (WM) after stroke is a potential contributor to substitute or to newly establish the functional field on the injured brain in nature. Diffusion tensor imaging (DTI) is an imaging modality that can be used to evaluate damage and recovery within the brain. This method of imaging allows for in vivo assessment of the restricted movements of water molecules in WM and provides a detailed look at structural connectivity in the brain. For longitudinal DTI studies after a stroke, the conventional region of interest method and voxel-based analysis are highly dependent on the user-hypothesis and parameter settings for implementation. In contrast, tract-based spatial statistics (TBSS) allows for reliable voxel-wise analysis via the projection of diffusion-derived parameters onto an alignment-invariant WM skeleton. In this study, spatiotemporal WM changes were examined with DTI-derived parameters (fractional anisotropy, FA; mean diffusivity, MD; axial diffusivity, DA; radial diffusivity, RD) using TBSS 2 h to 6 weeks after experimental focal ischemic stroke in rats ( N = 6). FA values remained unchanged 2-4 h after the stroke, followed by a continuous decrease in the ipsilesional hemisphere from 24 h to 2 weeks post-stroke and gradual recovery from the ipsilesional corpus callosum to the external capsule until 6 weeks post-stroke. In particular, the fibers in these areas were extended toward the striatum of the ischemic boundary region at 6 weeks on tractography. The alterations of the other parameters in the ipsilesional hemisphere showed patterns of a decrease at the early stage, a subsequent pseudo-normalization of MD and DA, a rapid reduction of RD, and a progressive increase in MD, DA and RD with a decreased extent in the injured area at later stages. The findings of this study may reflect the ongoing processes on tissue damage and spontaneous recovery after stroke. [ABSTRACT FROM AUTHOR]

Purpose: The present study assessed the positive predictive value (PPV) of F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for the detection of internal mammary node (IMN) metastasis in patients with clinical stage III breast cancer. Methods: Patients who were diagnosed with clinical stage III breast cancer and underwent pretreatment F-FDG PET/CT were retrospectively analyzed. The F-FDG PET/CT scans were prospectively reviewed by two board-certified nuclear medicine physicians in a blinded manner. The intensities of IMNs were graded into four categories (no activity and lower, similar, and higher activities than that of the mediastinal blood pool). IMNs were measured from the combined CT (largest diameter of the short axis). Histologic data of the IMNs were obtained by ultrasonography-guided fine-needle aspiration biopsy or surgical excision. The PPV was calculated for pathologically confirmed IMNs. Visual grade, maximum standardized uptake values (SUV), and sizes were analyzed according to the pathology results. Results: There were 249 clinical stage III breast cancer patients (age 48.0 ± 10.1 years, range 26-79 years) who had undergone initial F-FDG PET/CT prior to treatment. Excluding 33 cases of stage IV breast cancer, 62 of 216 patients had visible IMNs on F-FDG PET/CT, and histologic confirmation was obtained in 31 patients. There were 27 metastatic and four nonmetastatic nodes (PPV 87.1 %). Metastatic nodes mostly presented with visual grade 3 (83.9 %), and SUV and size were 3.5 ± 4.3 and 5.6 ± 2.0 mm, respectively. Conclusion: F-FDG PET/CT has a high PPV for IMN metastasis in clinical stage III breast cancer, indicating the possibility of metastasis in IMNs with FDG uptake similar to/lower than that of the blood pool or small-sized nodes. [ABSTRACT FROM AUTHOR]

Purpose: Primary systemic anaplastic large cell lymphoma (ALCL) is divided into two entities according to the expression of anaplastic lymphoma kinase (ALK). We investigated 18F-fluorodeoxyglucose positron emission tomography ( 18F-FDG PET) findings in primary systemic ALCL according to ALK expression. Methods: Thirty-seven patients who had baseline PET before CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone)-based chemotherapy were enrolled. Among them, patients who underwent interim and/or post-therapy PET were further investigated for the treatment response and survival analysis. Baseline PET was analyzed visually and semi-quantitatively using peakSUV, and interim and post-therapy PETs were visually analyzed. Results: All cases were 18F-FDG-avid on baseline PET. The peakSUV of ALK-positive ALCL ( n = 16, 18.7 ± 10.5) was higher than that of ALK-negative ALCL ( n = 21, 10.0 ± 4.9) ( P = 0.006). In ALK-negative ALCL, complete response (CR) rate in negative-interim PET was higher than positive-interim PET (100 % vs 37.5 %, P = 0.02); however, there was no such difference in ALK-positive ALCL (100 % vs 75 %, P = 0.19). The 3-year progression-free survival (PFS) was not significantly different between ALK-positive and ALK-negative ALCL (72.7 % vs 47.6 %, P = 0.34). In ALK-negative ALCL, negative interim and post-therapy PET patients had better 3-year PFS than positive interim (83.3 % vs 25.0 %, P = 0.06) and post-therapy PET patients (70.0 % vs 20.0 %, P = 0.04). In contrast, ALK-positive ALCL had no such differences between PFS and PET results. Conclusions: On baseline PET, all cases showed 18F-FDG-avidity, and ALK expression was related to higher 18F-FDG uptake. ALK-positive patients tend to have better PFS than ALK-negative patients. Negative-interim PET was a good indicator of CR, and interim or post-therapy PET was helpful for predicting the prognosis only in the ALK-negative group. [ABSTRACT FROM AUTHOR]

Medical therapy for aortic stenosis (AS) remains an elusive goal. This study sought to establish whether evogliptin, a dipeptidyl peptidase-4 inhibitor, could reduce AS progression. A total of 228 patients (age 67 ± 11 years; 33% women) with AS were randomly assigned to receive placebo (n = 75), evogliptin 5 mg (n = 77), or evogliptin 10 mg (n = 76). The primary endpoint was the 96-week change in aortic valve calcium volume (AVCV) on computed tomography. Secondary endpoints included the 48-week change in active calcification volume measured using 18F-sodium fluoride positron emission tomography (18F-NaF PET). There were no significant differences in the 96-week changes in AVCV between evogliptin 5 mg and placebo (−5.27; 95% CI: −55.36 to 44.82; P = 0.84) or evogliptin 10 mg and placebo (−18.83; 95% CI: −32.43 to 70.10; P = 0.47). In the placebo group, the increase in AVCV between 48 weeks and 96 weeks was higher than that between baseline and 48 weeks (136 mm3; 95% CI: 108–163 vs 102 mm3; 95% CI: 75–129; P = 0.0485). This increasing trend in the second half of the study was suppressed in both evogliptin groups. The 48-week change in active calcification volume on 18F-NaF PET was significantly lower in both the evogliptin 5 mg (−1,325.6; 95% CI: −2,285.9 to −365.4; P = 0.008) and 10-mg groups (−1,582.2; 95% CI: −2,610.8 to −553.5; P = 0.0038) compared with the placebo group. This exploratory study did not demonstrate the protective effect of evogliptin on AV calcification. Favorable 18F-NaF PET results and possible suppression of aortic valve calcification with longer medication use in the evogliptin groups suggest the need for larger confirmatory trials. (A Multicenter, Double-blind, Placebo-controlled, Stratified-randomized, Parallel, Therapeutic Exploratory Clinical Study to Evaluate the Efficacy and Safety of DA-1229 in Patients With Calcific Aortic Valve Disease; NCT04055883) [ABSTRACT FROM AUTHOR]

Background: 18F-GP1 is a novel positron emission tomography (PET) tracer that targets glycoprotein IIb/IIIa receptors on activated platelets. The study objective was to explore the feasibility of directly imaging acute arterial thrombosis (AAT) with 18F-GP1 PET/computed tomography (PET/CT) and to quantitatively assess 18F-GP1 uptake. Safety, biodistribution, pharmacokinetics and metabolism were also evaluated.Methods: Adult patients who had signs or symptoms of AAT or had recently undergone arterial intervention or surgery within 14 days prior to 18F-GP1 PET/CT were eligible for inclusion. The AAT focus was demonstrated by conventional imaging within the 5 days prior to 18F-GP1 administration. Whole-body dynamic 18F-GP1 PET/CT images were acquired for up to 140 min after injection of 250 MBq of 18F-GP1. Venous plasma samples were analysed to determine 18F-GP1 clearance and metabolite formation.Results: Among the ten eligible patients assessed, underlying diseases were abdominal aortic aneurysm with endovascular repair (n = 6), bypass surgery and stent placement (n = 1), endarterectomy (n = 1), arterial dissection (n = 1) and acute cerebral infarction (n = 1). 18F-GP1 administration and PET/CT procedures were well tolerated, with no drug-related adverse events. All patients showed high initial 18F-GP1 uptake in the spleen, kidney and blood pool, followed by rapid clearance. Unmetabolised plasma 18F-GP1 levels peaked at 4 min post-injection and decreased over time until 120 min. The overall image quality was sufficient for diagnosis in all patients and AAT foci were detected in all participants. The 18F-GP1 uptake in AAT foci remained constant from 7 min after injection and began to separate from the blood pool after 20 min. The median standardised uptake value of AAT was 5.0 (range 2.4-7.9) at 120 min post-injection. The median ratio of standardised uptake value of AAT foci to the mean blood pool activity was 3.4 (range 2.0-6.3) at 120 min.Conclusions: 18F-GP1 is a safe and promising novel PET tracer for imaging AAT with a favourable biodistribution and pharmacokinetic profile.Trial registration: ClinicalTrials.gov identifier: NCT02864810, Registered August 3, 2016. [ABSTRACT FROM AUTHOR]

The cover image, by Won‐Beom Jung et al., is based on the Research Article Spatiotemporal microstructural white matter changes in diffusion tensor imaging after transient focal ischemic stroke in rats, DOI: 10.1002/nbm.3704. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflict of Interest: The authors have no financial conflicts of interest.

Purpose: The aim of this study was to generate deep learning-based regions of interest (ROIs) from equilibrium radionuclide angiography datasets for left ventricular ejection fraction (LVEF) measurement., Patients and Methods: Manually drawn ROIs (mROIs) on end-systolic and end-diastolic images were extracted from reports in a Picture Archiving and Communications System. To reduce observer variability, preprocessed ROIs (pROIs) were delineated using a 41% threshold of the maximal pixel counts of the extracted mROIs and were labeled as ground-truth. Background ROIs were automatically created using an algorithm to identify areas with minimum counts within specified probability areas around the end-systolic ROI. A 2-dimensional U-Net convolutional neural network architecture was trained to generate deep learning-based ROIs (dlROIs) from pROIs. The model's performance was evaluated using Lin's concordance correlation coefficient (CCC). Bland-Altman plots were used to assess bias and 95% limits of agreement., Results: A total of 41,462 scans (19,309 patients) were included. Strong concordance was found between LVEF measurements from dlROIs and pROIs (CCC = 85.6%; 95% confidence interval, 85.4%-85.9%), and between LVEF measurements from dlROIs and mROIs (CCC = 86.1%; 95% confidence interval, 85.8%-86.3%). In the Bland-Altman analysis, the mean differences and 95% limits of agreement of the LVEF measurements were -0.6% and -6.6% to 5.3%, respectively, for dlROIs and pROIs, and -0.4% and -6.3% to 5.4% for dlROIs and mROIs, respectively. In 37,537 scans (91%), the absolute LVEF difference between dlROIs and mROIs was <5%., Conclusions: Our 2-dimensional U-Net convolutional neural network architecture showed excellent performance in generating LV ROIs from equilibrium radionuclide angiography scans. It may enhance the convenience and reproducibility of LVEF measurements., Competing Interests: Conflicts of interest and sources of funding: none declared. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT; no. NRF-2020M2D9A1094074; 2021R1A2C3009056) and by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (HI18C2383)., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

We aimed to explore whether the imaging of antiporter system x C - of immune cells with (4 S )-4-(3- 18 F-fluoropropyl)-l-glutamate ( 18 F-FSPG) PET can assess inflammatory bowel disease (IBD) activity in murine models and patients (NCT03546868). Methods: 18 F-FSPG PET imaging was performed to assess IBD activity in mice with dextran sulfate sodium-induced and adoptive T-cell transfer-induced IBD and a cohort of 20 patients at a tertiary care center in South Korea. Immunohistochemical analysis of system x C - and cell surface markers was also studied. Results: Mice with experimental IBD showed increased intestinal 18 F-FSPG uptake and xCT expression in cells positive (+) for CD11c, F4/80, and CD3 in the lamina propria, increases positively associated with clinical and pathologic disease activity. 18 F-FSPG PET studies in patients, most of whom were clinically in remission or had mildly active IBD, showed that PET imaging was sufficiently accurate in diagnosing endoscopically active IBD and remission in patients and bowel segments. 18 F-FSPG PET correctly identified all 9 patients with superficial or deep ulcers. Quantitative intestinal 18 F-FSPG uptake was strongly associated with endoscopic indices of IBD activity. The number of CD68 + xCT + and CD3 + xCT + cells in 22 bowel segments from patients with ulcerative colitis and the number of CD68 + xCT + cells in 7 bowel segments from patients with Crohn disease showed a significant positive association with endoscopic indices of IBD activity. Conclusion: The assessment of system x C - in immune cells may provide diagnostic information on the immune responses responsible for chronic active inflammation in IBD. 18 F-FSPG PET imaging of system x C - activity may noninvasively assess the IBD activity., (© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)

Purpose: (4S)-4-(3-[ 18 F]Fluoropropyl)- L -glutamic acid ( 18 F-FSPG) is a radiopharmaceutical for PET imaging of system x C - activity, which can be upregulated in prostate cancer. We present data on the first evaluation of patients with newly diagnosed or recurrent prostate cancer with this radiopharmaceutical., Experimental Design: Ten patients with primary and 10 patients with recurrent prostate cancer were enrolled in this prospective multicenter study. After injection of 300 MBq of 18 F-FSPG, three whole-body PET/CT scans were obtained. Visual analysis was compared with step-section histopathology when available as well as other imaging studies and clinical outcomes. Metabolic parameters were measured semiquantitatively. Expression levels of xCT and CD44 were evaluated by IHC for patients with available tissue samples., Results: 18 F-FSPG PET showed high tumor-to-background ratios with a relatively high tumor detection rate on a per-patient (89%) and per-lobe (87%) basis. The sensitivity was slightly higher with imaging at 105 minutes in comparison with 60 minutes. The maximum standardized uptake values (SUV max ) for cancer was significantly higher than both normal ( P < 0.005) and benign pathology ( P = 0.011), while there was no significant difference between normal and benign pathology ( P = 0.120). In the setting of recurrence, agreement with standard imaging was demonstrated in 7 of 9 patients (78%) and 13 of 18 lesions (72%), and revealed true local recurrence in a discordant case. 18 F-FSPG accumulation showed moderate correlation with CD44 expression., Conclusions: 18 F-FSPG is a promising tumor imaging agent for PET that seems to have favorable biodistribution and high cancer detection rate in patients with prostate cancer. Further studies are warranted to determine the diagnostic value for both initial staging and recurrence, and how it compares with other investigational radiotracers and conventional imaging modalities., (©2020 American Association for Cancer Research.)