Rare osteoarticular complications on [18F]FDG-PET/CT - following intravesical BCG immunotherapy for bladder cancer.

This case illustrates rare osteoarticular complications of Bacillus Calmette-Guérin (BCG) immunotherapy in a 55-year-old male with high-risk non-muscle-invasive bladder cancer (NMIBC). The patient was referred for 18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) to rule out bone metastases suspected on prior post-gadolinium magnetic resonance imaging (MRI). Although metastases were excluded, nearly symmetrical uptakes were detected in the costovertebral and costotransverse joints. Medical history revealed that the patient had been receiving intravesical instillations of BCG, the first-line therapy for high-risk NMIBC. The patient was diagnosed with reactive arthritis (ReA), a rare autoimmune complication of BCG, that was successfully treated with a nonsteroidal anti-inflammatory drug (NSAID).

Risk of Upstaging Due to Oncofertility Treatment Mimicking Pelvic Lymphoma on 18F-FDG PET/CT.

ABSTRACT: A 23-year-old woman with primary mediastinal large B-cell lymphoma was referred to 18F-FDG PET/CT for staging. Besides the large mediastinal FDG-avid tumor, another FDG-avid lesion with an SUV higher than expected in corpus luteum cysts was found in the pelvis, raising suspicion for tumor. However, gynecologic ultrasound and review of patient chart revealed history of oncofertility treatment with GNRH analog. This prior treatment was responsible for the intense 18F-FDG uptake within the left ovary, way above the SUV levels commonly associated with menstrual cycle. In this case, the disease was downgraded to stage II, resulting in a less aggressive treatment.

Assessing the Correlation Between 68Ga-PSMA-11 Renal PET Parameters and Renal Function Tests.

68Ga-prostate-specific membrane antigen (PSMA) ligands are used for prostate cancer but also show high renal cortical uptake. In this study, we aimed to assess whether there is any correlation between renal PSMA PET parameters and renal function tests using the images of prostate cancer patients. Methods: 68Ga-PSMA-11 PET/CT images of the patients with prostate cancer were retrospectively evaluated. The following PET parameters were obtained: SUVmax, SUVmean, SUVmax corrected for lean body weight, SUVmean corrected for lean body weight, volume, lean body weight--corrected total lesion glycolysis (TLGSUL), and counts of both kidneys, as well as SUVmean of the liver, blood pool, and spleen. Total TLGSUL, total volume, kidney-to-liver ratio, and kidney-to-blood pool ratio were calculated. Creatinine values were obtained, and glomerular filtration rate (GFR) was calculated using the "Modification of Diet in Renal Disease" formula. Statistical analysis was performed to understand whether there is a correlation between the above parameters and renal function tests. Results: Twenty-five patients were included in this study. GFR was significantly and positively correlated and creatinine was significantly and negatively correlated with the ratios of renal SUV to liver SUV and renal SUV to blood pool SUV. GFR was marginally positively correlated with renal SUVmean corrected for lean body weight, and creatinine was marginally negatively correlated with total TLGSUL Total renal parenchymal volume was significantly and directly (positively) associated with GFR and significantly and inversely (negatively) associated with creatinine. Conclusion: Renal 68Ga-PSMA uptake appears to be correlated with renal function tests. Our method of measuring approximate renal parenchymal volume on PET images appears to be reliable.

Liver: glucose metabolism and 18F-fluorodeoxyglucose PET findings in normal parenchyma and diseases.

Liver has a complex and unique energy metabolism and plays a major role in glucose homeostasis. Liver is the main control center for glycogenesis, glycogenolysis, glycolysis and gluconeogenesis which are essential to provide energy for other tissues. Liver meets its own energy need from various sources which is mainly glucose in the fed state and fatty acids in the fasting state. In this review article, we will mainly describe the glucose metabolism of the liver, effect of various factors on 18F-fluorodeoxyglucose (FDG) activity/uptake in the normal liver and 18F- FDG positron emission tomography (PET) uptake patterns in various malignant and benign liver pathologies. Brief information on metabolomics profiling analyses in liver disorders will also be provided.

Immune Checkpoint Inhibitor-Related Adverse Effects and 18F-FDG PET/CT Findings.

Immune checkpoint inhibitor (ICI) treatments activate T cells against tumors. Activated T cells attack not only the tumor but also healthy cells, causing an autoimmune reaction in various tissues. These immune-related adverse effects (IRAEs) cause 18F-FDG uptake in various tissues due to inflammation. It is important to recognize and report these findings on 18F-FDG PET/CT studies. 18F-FDG PET helps to determine the presence, location, and severity of IRAEs. In severe cases, ICI treatments are interrupted or suspended and antiinflammatory treatments are started. 18F-FDG uptake due to IRAEs may mimic metastases or disease progression. Their presence may also help in predicting response to treatment and have prognostic implications. In this review article, we provide basic information about ICI treatments, IRAEs, and 18F-FDG PET/CT findings.

Contrast between hypervascularized liver lesions and hepatic parenchyma: early dynamic PET versus contrast-enhanced CT.

OBJECTIVES: To detect hypervascularized liver lesions, early dynamic (ED) (18)F-FDG PET may be an alternative when contrast-enhanced (CE) imaging is infeasible. This retrospective pilot analysis compared contrast between such lesions and liver parenchyma, an important objective image quality variable, in ED PET versus CE CT. MATERIALS AND METHODS: Twenty-eight hypervascularized liver lesions detected by CE CT [21 (75%) hepatocellular carcinomas; mean (range) diameter 4.9 ± 3.5 (1-14) cm] in 20 patients were scanned with ED PET. Using regions of interest, maximum and mean lesional and parenchymal signals at baseline, arterial and venous phases were calculated for ED PET and CE CT. RESULTS: Lesional/parenchymal signal ratio was significantly higher (P < 0.005) with ED PET versus CE CT at the arterial phase and similar between the methods at the venous phase. CONCLUSION: In liver imaging, ED PET generates greater lesional-parenchymal contrast during the arterial phase than does CE CT; these observations should be formally, prospectively evaluated.

Multimodal evaluation of 2-D and 3-D ultrasound, computed tomography and magnetic resonance imaging in measurements of the thyroid volume using universally applicable cross-sectional imaging software: a phantom study.

A precise estimate of thyroid volume is necessary for making adequate therapeutic decisions and planning, as well as for monitoring therapy response. The goal of this study was to compare the precision of different volumetry methods. Thyroid-shaped phantoms were subjected to volumetry via 2-D and 3-D ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). The 3-D US scans were performed using sensor navigation and mechanical sweeping methods. Volumetry calculation ensued with the conventional ellipsoid model and the manual tracing method. The study confirmed the superiority of manual tracing with CT and MRI volumetry of the thyroid, but extended this knowledge also to the superiority of the 3-D US method, regardless of whether sensor navigation or mechanical sweeping is used. A novel aspect was successful use of the same universally applicable cross-imaging software for all modalities.

First experience with early dynamic (18)F-NaF-PET/CT in patients with chronic osteomyelitis.

OBJECTIVE: This study investigates whether early dynamic positron emission tomography/computed tomography (edPET/CT) using (18)F-sodium fluoride-((18)F-NaF) is feasible in depicting early phases of radiotracer distribution in patients with chronic osteomyelitis (COM). METHODS: A total of 12 ed(18)F-NaF-PET/CT examinations were performed on 11 consecutive patients (2 female, 9 male; age 53 ± 12 years) in list mode over 5 min starting with radiopharmaceutical injection before standard late (18)F-NaF-PET/CT. Eight consecutive time intervals (frames) were reconstructed for each patient: four 15 s, then four 60 s. Several volumes of interest (VOI) were selected, representing the affected area as well as different reference areas within the bone and soft tissue. Maximum and mean ed standardized uptake values (edSUVmax, edSUVmean, respectively) were calculated in each VOI during each frame to measure early fluoride influx and accumulation. Results were compared between affected and non-affected (contralateral) bones. RESULTS: Starting in the 31-45 s frame, the affected bone area showed significantly higher edSUVmax and edSUVmean compared to the healthy contralateral region. The affected bone areas also significantly differed from non-affected contralateral regions in conventional late (18)F-NaF-PET/CT. CONCLUSIONS: This pilot study suggests that, in patients with COM, ed(18)F-NaF -PET offers additional information about early radiotracer distribution to standard (18)F-NaF -PET/CT, similar to a three-phase bone scan. The results should be validated in larger trials which directly compare ed(18)F-NaF-PET to a three-phase bone scan.

Early dynamic 18F-FDG PET to detect hyperperfusion in hepatocellular carcinoma liver lesions.

UNLABELLED: In addition to angiographic data on vascularity and vascular access, demonstration of hepatocellular carcinoma (HCC) liver nodule hypervascularization is a prerequisite for certain intrahepatic antitumor therapies. Early dynamic (ED) (18)F-FDG PET/CT could serve this purpose when the current standard method, contrast-enhanced (CE) CT, or other CE morphologic imaging modalities are unsuitable. A recent study showed ED (18)F-FDG PET/CT efficacy in this setting but applied a larger-than-standard (18)F-FDG activity and an elaborate protocol likely to hinder routine use. We developed a simplified protocol using standard activities and easily generated visual and descriptive or quantitative endpoints. This pilot study assessed the ability of these endpoints to detect HCC hyperperfusion and, thereby, evaluated the suitability in of the protocol everyday practice. METHODS: Twenty-seven patients with 34 HCCs (diameter ≥ 1.5 cm) with hypervascularization on 3-phase CE CT underwent liver ED (18)F-FDG PET for 240 s, starting with (18)F-FDG (250-MBq bolus injection). Four frames at 15-s intervals, followed by 3 frames at 60-s intervals were reconstructed. Endpoints included focal tracer accumulation in the first 4 frames (60 s), subsequent focal washout, and visual and quantitative differences between tumor and liver regions of interest in maximum and mean ED standardized uptake value (ED SUVmax and ED SUVmean, respectively) 240-s time-activity curves. RESULTS: All 34 lesions were identified by early focal (18)F-FDG accumulation and faster time-to-peak ED SUVmax or ED SUVmean than in nontumor tissue. Tumor peak ED SUVmax and ED SUVmean exceeded liver levels in 85% and 53%, respectively, of lesions. Nadir tumor signal showed no consistent pattern relative to nontumor signal. HCC had a significantly shorter time to peak and significantly faster rate to peak for both ED SUVmax and ED SUVmean curves and a significantly higher peak ED SUVmax but not peak ED SUVmean than the liver. CONCLUSION: This pilot study provided proof of principle that our simplified ED (18)F-FDG PET/CT protocol includes endpoints that effectively detect HCC hypervascularization; this finding suggests that the protocol can be used routinely.