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OBJECTIVE: This retrospective study evaluates the value of 68Ga-DOTATATE PET/CT in the diagnosis and localization of insulinomas, whether sporadic, malignant or MEN-1 associated insulinoma.
METHODS: The study included 43 patients, having clinical (symptomatic hypoglycemia) and/or laboratory suspicion of having insulinoma (72 h fasting test with serum insulin ≥18 pmol/L), with available pre-operative 68Ga-DOTATATE PET/CT and CE-CT, and diagnosed with insulinoma confirmed by post-operative histopathology. Preoperative imaging was retrospectively analyzed by two radiologists who were blinded to the final diagnosis and to the results of other imaging modalities. Histopathology of specimen was considered the reference standard, and head-to-head comparison of preoperative CE-CT and PET imaging findings. Findings were classified as true positive (TP), true negative (TN), false positive (FP), and false negative (FN) for each modality. Based on these results, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CE-CT, and 68Ga-DOTATATE PET/CT for the detection of insulinoma were calculated.
RESULTS: 43 patients (N = 43 patients, L = 56 lesions), out of these, 37 patients had benign sporadic insulinoma (N = 37, L = 42), only 3 patients had malignant sporadic insulinoma (N = 2, L = 9), and 3 patients had MEN-1 syndrome associated insulinoma (N = 3, L = 5). There was no significant statistical difference in sensitivity (P = 0.3058) and PPV (P = 0.5533) for insulinoma localization in the overall cohort with 68Ga-DOTATATE PET/CT (87.5 %, 90.74 %) compared to CE-CT (80.36 %, 93.75 %).
CONCLUSIONS: 68Ga-DOTATATE PET/CT is a non-invasive imaging modality that can identify most insulinomas. Still, it offers limited additional information when the tumor is localized by other anatomic imaging studies, so should be used as an adjunct when imaging studies fail to localize the tumor in insulinoma patients, especially when minimally invasive surgical is intended.

Background Intravenous prostate-specific membrane antigen (PSMA)-targeted radioligand therapy improves survival in men with metastatic castration-resistant prostate cancer. Yet, the impact of selective prostatic arterial administration on primary tumor uptake is unclear. Purpose To compare gallium 68 (68Ga)-PSMA-11 uptake using dynamic PET/CT in prostatic tumoral volumes of interest (VOIs) during intravenous and selective prostatic arterial infusions for individuals with untreated, high-risk prostate cancer. Materials and Methods In this prospective, intraindividual comparative study conducted at an academic medical center, five men aged 58, 61, 64, 66, and 68 years with treatment-naive prostate cancer were enrolled between January 2022 and February 2023 and underwent two dynamic 68Ga-PSMA-11 PET/CT examinations 1 week apart. During the first examination, the radiotracer was administered intravenously. During the second administration, the radiotracer was delivered into either the right or left prostatic artery through an angiographically placed microcatheter. The primary outcome was maximum standardized uptake value (SUVmax) in prostatic tumoral VOIs. The secondary outcomes included mean SUV (SUVmean) in prostatic tumoral VOIs and area under the SUVmean curves (AUC). Longitudinal mixed-effects models were used to compare dynamic SUVmax and SUVmean time-activity curves (TACs), and paired t tests were used for the remaining data. Results The mean SUVmax within tumoral VOIs was 14 (range, 3-43) for venous sessions and 938 (range, 460-1436) for arterial sessions (P = .008). The SUVmean within VOIs was greater during arterial sessions (P < .001) overall and 46-fold and 19-fold greater at peak uptake and final time points, respectively. The mean AUC was greater on arterial TACs than on venous TACs at 14600 SUV × min (range, 8353-20025 SUV × min) and 240 SUV × min (range, 69-622 SUV × min), respectively (P = .002). Conclusion Selective prostatic arterial infusion resulted in greater 68Ga-PSMA-11 tumoral SUV than intravenous infusion. Further study of local-regional, intra-arterial delivery of a PSMA-targeted theranostic agent is warranted in high-risk prostate cancer. ClinicalTrials.gov identifier: NCT04976257 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Civelek in this issue.

OBJECTIVE: Although the diagnostic accuracy of 18F-fluorodeoxyglucose - positron emission tomography/computed tomography (18F-FDG-PET/CT) for breast cancer (BC) has been well studied, few studies have evaluated the impact of 18F-FDG-PET/CT on BC patient care. This study aimed to investigate restaging and 18F-FDG-PET/CT-induced changes in clinical decision-making in patients with BC.
METHODS: We retrospectively evaluated 18F-FDG-PET/CT-scans performed for BC-related indications in a prospectively collected consecutive cohort of adult patients at Skane University Hospital, Sweden. Patients with all BC stages were included and divided into three groups based on the indication for 18F-FDG-PET/CT: Group A (primary staging), Group B (response evaluation), and Group C (recurrence). The impact of 18F-FDG-PET/CT-scans on clinical management was categorized as no change, minor change (e.g. modification of treatment plans), or major change (e.g. shift from curative to palliative treatment intention).
RESULTS: A total of 376 scans (151 patients) were included: Group A 9.3% (35 of 376 scans), Group B 77.4% (291 of 376 scans), and Group C 13.3% (50 of 376 scans). Significant stage migration, predominantly upstaging, occurred in Group A (45.7%) and Group C (28.0%). Changes in clinical management were observed in 120 scans (31.9%), of which 66 were major and 54 were minor. The largest proportion of 18F-FDG-PET/CT-induced management changes were observed in Group A (57.1%), most commonly a shift from curative to palliative treatment intention due to upstaging.
CONCLUSIONS: Our study indicates the clinical utility of 18F-FDG-PET/CT in BC restaging and changes in clinical management; the latter observed in approximately one-third of all cases.

OBJECTIVE: Therapeutic hypothermia (TH) is widely acknowledged as one of the interventions for preventing hypoxic ischemic brain injury in comatose patients following cardiac arrest (CA). Despite its recognized efficacy, recent debates have questioned its effectiveness. This preclinical study evaluated the impact of TH on brain glucose metabolism, utilizing fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) in a rat model of CA.
METHODS: Asphyxia CA was induced in Sprague-Dawley rats using vecuronium. Brain PET images using 18F-FDG were obtained from 21 CA rats, who were randomized to receive either TH or no intervention. Of these, 9 rats in the TH group received hypothermia under general anesthesia and mechanical ventilation for eight hours, while the remaining 12 rats in the non-TH group were observed without intervention. We conducted regional and voxel-based analyses of standardized uptake values relative to the pons (SUVRpons) to compare the two groups.
RESULTS: Survival rates were identical in both the TH and non-TH groups (67%). There was no discernible difference in the SUVRpons across the brain cortical regions between the groups. However, in a subgroup analysis of the rats that did not survive (n = 7), those in the TH group (n = 3) displayed significantly higher SUVRpons values across most cortical regions compared to those in the non-TH group (n = 4), with statistical significance after false-discovery rate correction (p < 0.05).
CONCLUSIONS: The enhancement in SUVRpons due to TH intervention was only observed in the cortical regions of rats with severe encephalopathy that subsequently died. These findings suggest that the beneficial effects of TH on brain glucose metabolism in this asphyxia CA model may be confined to cases of severe ischemic encephalopathy.

Purpose: 68Ga-labeled fibroblast activation protein inhibitor (FAPI) is a novel PET tracer with great potential for staging pancreatic cancer. Data on locally advanced or recurrent disease is sparse, especially on tracer uptake before and after high dose chemoradiotherapy (CRT). The aim of this study was to evaluate [68Ga]Ga-FAPI-46 PET/CT staging in this setting. Methods: Twenty-seven patients with locally recurrent or locally advanced pancreatic adenocarcinoma (LRPAC n = 15, LAPAC n = 12) in stable disease or partial remission after chemotherapy underwent FAPI PET/CT and received consolidation CRT in stage M0 with follow-up FAPI PET/CT every three months until systemic progression. Quantitative PET parameters SUVmax, SUVmean, FAPI-derived tumor volume and total lesion FAPI-uptake were measured in baseline and follow-up PET/CT scans. Contrast-enhanced CT (ceCT) and PET/CT data were evaluated blinded and staged according to TNM classification. Results: FAPI PET/CT modified staging compared to ceCT alone in 23 of 27 patients in baseline, resulting in major treatment alterations in 52% of all patients (30%: target volume adjustment due to N downstaging, 15%: switch to palliative systemic chemotherapy only due to diffuse metastases, 7%: abortion of radiotherapy due to other reasons). Regarding follow-up scans, major treatment alterations after performing FAPI PET/CT were noted in eleven of 24 follow-up scans (46%) with switch to systemic chemotherapy or best supportive care due to M upstaging and ablative radiotherapy of distant lymph node and oligometastasis. Unexpectedly, in more than 90 % of the follow-up scans, radiotherapy did not induce local fibrosis related FAPI uptake. During the first follow-up, all quantitative PET metrics decreased, and irradiated lesions showed significantly lower FAPI uptake in locally controlled disease (SUVmax p = 0.047, SUVmean p = 0.0092) compared to local failure. Conclusion: Compared to ceCT, FAPI PET/CT led to major therapeutic alterations in patients with LRPAC and LAPAC prior to and after radiotherapy, which might help identify patients benefiting from adjustments in every treatment stage. FAPI PET/CT should be considered a useful diagnostic tool in LRPAC or LAPAC before and after CRT.

Background CT performed for various clinical indications has the potential to predict cardiometabolic diseases. However, the predictive ability of individual CT parameters remains underexplored. Purpose To evaluate the ability of automated CT-derived markers to predict diabetes and associated cardiometabolic comorbidities. Materials and Methods This retrospective study included Korean adults (age ≥ 25 years) who underwent health screening with fluorine 18 fluorodeoxyglucose PET/CT between January 2012 and December 2015. Fully automated CT markers included visceral and subcutaneous fat, muscle, bone density, liver fat, all normalized to height (in meters squared), and aortic calcification. Predictive performance was assessed with area under the receiver operating characteristic curve (AUC) and Harrell C-index in the cross-sectional and survival analyses, respectively. Results The cross-sectional and cohort analyses included 32166 (mean age, 45 years ± 6 [SD], 28833 men) and 27 298 adults (mean age, 44 years ± 5 [SD], 24 820 men), respectively. Diabetes prevalence and incidence was 6% at baseline and 9% during the 7.3-year median follow-up, respectively. Visceral fat index showed the highest predictive performance for prevalent and incident diabetes, yielding AUC of 0.70 (95% CI: 0.68, 0.71) for men and 0.82 (95% CI: 0.78, 0.85) for women and C-index of 0.68 (95% CI: 0.67, 0.69) for men and 0.82 (95% CI: 0.77, 0.86) for women, respectively. Combining visceral fat, muscle area, liver fat fraction, and aortic calcification improved predictive performance, yielding C-indexes of 0.69 (95% CI: 0.68, 0.71) for men and 0.83 (95% CI: 0.78, 0.87) for women. The AUC for visceral fat index in identifying metabolic syndrome was 0.81 (95% CI: 0.80, 0.81) for men and 0.90 (95% CI: 0.88, 0.91) for women. CT-derived markers also identified US-diagnosed fatty liver, coronary artery calcium scores greater than 100, sarcopenia, and osteoporosis, with AUCs ranging from 0.80 to 0.95. Conclusion Automated multiorgan CT analysis identified individuals at high risk of diabetes and other cardiometabolic comorbidities. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Pickhardt in this issue.

UNASSIGNED: Primary hyperparathyroidism (PHPT) is the third most common endocrine disease. With parathyroidectomy, a cure rate of over 95% at initial surgery is reported. Localization of the abnormal parathyroid gland is critical for the operation to be successful. The aim of this study is to analyze data of patients with single gland disease (SGD) and positive concordant localization imaging undergoing minimally invasive parathyroidectomy (MIP) and intraoperative parathyroid hormone monitoring (IOPTH) to evaluate if IOPTH is still justified in patients with localized SGD.
UNASSIGNED: A retrospective database analysis of all minimally invasive operations with IOPTH for PHPT and positive concordant localization in ultrasound (US) and 99mTc-sestamibi scintigraphy (MIBI) between 2016-2021. When both US and MIBI were negative, patients underwent either choline or methionine PET-CT. The patients were also analyzed a second time without applying IOPTH.
UNASSIGNED: In total, 198 patients were included in the study. The sensitivity of US, MIBI and PET-CT was 96%, 94% and 100%, respectively. Positive predictive value was 88%, 89% and 94% with US, MIBI and PET-CT, respectively. IOPTH was true positive in 185 (93.4%) patients. In 13 (6.6%) patients, no adequate IOPTH decline was observed after localizing and extirpating the assumed enlarged parathyroid gland. Without IOPTH, the cure rate decreased from 195 (98.5%) to 182 (92%) patients and the rate of persisting disease increased from 2 (1.0%) to 15 (7.5%) patients.
UNASSIGNED: Discontinuing IOPTH significantly increases the persistence rate by a factor of 7.5 in patients with concordantly localized adenoma. Therefore, IOPTH appears to remain necessary even for this group of patients.

UNASSIGNED: Amyloidosis is a protein misfolding disorder characterized by the extracellular deposition of insoluble amyloid fibrils, derived from abnormally folded proteins. These fibrils disrupt tissue structure and function, leading to organ dysfunction. The condition encompasses various subtypes, each associated with distinct precursor proteins and clinical manifestations. 99mTc-PYP scintigraphy is used widely and holds significant importance for diagnosis. 68Ga-FAPI is also a promising radiotracer for various diseases. To our knowledge, this is the first case of a patient with hereditary transthyretin amyloidosis with cardiac involvement, which FAPI PET showed diffuse increased myocardial uptake.

UNASSIGNED: Atypical spindle cell/pleomorphic lipomatous tumor is categorized as a benign lipomatous tumor, but various MRI findings pose accurate diagnostic challenges. In our case, both MRI and PET/CT scans indicated the possibility of atypical lipomatous tumor/well-differentiated liposarcoma or dedifferentiated liposarcoma. Needle biopsy suggested benign to low-grade malignancy; hence, we opted for the wide resection. The final diagnosis of atypical spindle cell/pleomorphic lipomatous tumor was confirmed through histopathology analysis, including immunohistochemistry and fluorescence in situ hybridization. Since achieving an accurate diagnosis solely through imaging can be challenging, histopathology remains essential.