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Purpose: 18F-Fluciclovine PET imaging has been increasingly used in the restaging of prostate cancer patients with biochemical recurrence (BCR); however, its clinical utility in patients with low prostate-specific antigen (PSA) levels following primary radiation therapy has not been well-studied. This study aims to determine the detection rate and diagnostic accuracy of 18F-fluciclovine PET and the patterns of prostate cancer recurrence in patients with rising PSA after initial radiation therapy, particularly in patients with PSA levels below the accepted Phoenix definition of BCR (PSA nadir +2 ng/mL). Methods: This retrospective study included patients from two tertiary institutions who underwent 18F-fluciclovine PET scans for elevated PSA level following initial external beam radiation therapy, brachytherapy, and/or proton therapy. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to determine the diagnostic accuracy of 18F-fluciclovine PET and associations of PSA kinetic parameters with 18F-fluciclovine PET outcome. Results: One hundred patients were included in this study. The overall detection rate on a patient-level was 79% (79/100). 18F-Fluciclovine PET was positive in 62% (23/37) of cases with PSA below the Phoenix criteria. The positive predictive value of 18F-fluciclovine PET was 89% (95% CI: 80–94%). In patients with PSA below the Phoenix criteria, the PSA velocity had the highest predictive value of 18F-fluciclovine PET outcome. PSA doubling time (PSADT) and PSA velocity were associated with the presence of extra-pelvic metastatic disease. Conclusion: 18F-Fluciclovine PET can identify recurrent disease at low PSA level and PSA rise below accepted Phoenix criteria in patients with suspected BCR after primary radiation therapy, particularly in patients with low PSADT or high PSA velocity. In patients with low PSADT or high PSA velocity, there is an increased probability of extra-pelvic metastases. Therefore, these patients are more likely to benefit from PET/CT or PET/MRI than pelvic MRI alone. [ABSTRACT FROM AUTHOR]

Recent experience with radionuclide imaging has provided the clinician with several techniques to noninvasively detect and locate sources of gastrointestinal hemorrhage. These tests can be rapidly performed and often in an ICU setting. One method used Tc-99m sulfur colloid which, in an animal model, has been shown to detect acute bleeding at rates as low as 0.1 ml/min. However, because the tracer remains in the blood for a short period of time, it may be suboptimal for identifying patients with intermittent bleeding. Tc-99m red cells is a tracer that remains within the blood and permits detection of both acute and intermittent bleeding. With tagged red cells, sites of bleeding from both the upper and lower gastrointestinal tract can be found. Both of these techniques can provide important information in the patient with suspected active gastrointestinal bleeding and aid the clinician in more effective management including the use of invasive diagnostic and therapeutic techniques. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 20-year-old woman with T-cell lymphobastic lymphoma who came for a 1 month follow up PET/CT scan after completing a chemotherapy regimen. Topics discussed include the steroid prednisone having abruptly been stopped 1 day prior to the scan, the patient presenting to the emergency department less than 24 hours after the scan complaining of muscle weakness and nausea, and being diagnosed with acute adrenal crisis.

Rationale: A definitive dietary preparation recommendation is not possible based on literature in achievement of myocardial suppression for diagnosis of cardiac sarcoidosis (CS) with 18 F-FDG PET/CT. Our goal is to compare three different dietary preparations in achievement of the best myocardial suppression and CS diagnosis. Methods: We retrospectively reviewed and compared three dietary preparations used at our institution. Three different diets were applied from 03/2014 to 12/2019. 24-h ketogenic diet with overnight fasting ( n = 94); 18h-fasting ( n = 44); 72-h daytime ketogenic diet with 3-day overnight fasting ( n = 98). The interpretation of initial reports was recorded, and an independent radiologist (observer) retrospectively re-evaluated each case regarding CS diagnosis (Negative, Positive, Indeterminant) and myocardial suppression (Complete, Failed, Partial). Interobserver agreement was analyzed. We measured MaxSUV from bloodpool, liver, and the most suppressed normal myocardium. Results: We identified superior myocardial suppression with the 72-h preparation indicated by a higher bloodpool/myocardium and liver/myocardium ratios (P<0.001). Myocardial suppression rates for 72-h ketogenic diet, 24-h ketogenic diet and 18-h fasting preparations are as follows; Complete myocardial suppression: 96.9%/68.1%/52.3%, Failed myocardial suppression: 0%/23.4%/25%, Partial myocardial suppression: 3.1%/8.5%/22.7%) (P<0.001). The 72-hour preparation had significantly fewer "indeterminant" and "positive" exams. CS diagnosis rates for 72-h ketogenic diet, 24-h ketogenic diet and 18-h fasting preparations are as follows; Negative: 82.7%/52.1%/27.3%, Indeterminant: 2.0%/24.5%/40.9%, Positive: 15.3%/23.4%/31.8% (P<0.001). High agreement was present with the observer and the report (κ=0.88) Conclusion: A 72-h daytime ketogenic diet with 3-day overnight fasting, achieved substantially superior myocardial suppression versus 24-h ketogenic diet with overnight fasting and 18h-fasting using 18 F-FDG PET/CT. This 72-h preparation results in significantly fewer "indeterminant" and potentially "false positive" CS results., (Copyright © 2021 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)