Restaging FDG-PET/CT scan in recurrent cutaneous SCC: Diagnostic performance and prognostic significance
BACKGROUND:There are no specific recommendations for FDG-PET/CT in assessing recurrent cutaneous squamous cell carcinoma (cSCC). OBJECTIVE:To evaluate FDG-PET/CT in recurrent cSCC. METHODS:FDG-PET/CT scans were retrospectively reviewed; sites of abnormal uptake were noted and correlated with biopsy/histopathology where available; follow-up imaging or clinical data in others. Comparison with available CT/MR was performed. Prognostic significance of PET/CT parameters was evaluated. PET/CT-based change in management was recorded. RESULTS:115 FDG-PET/CT scans were analyzed in 100 consecutive cSCC patients. Of these, 96 (84%) scans were positive for recurrence and 25 showed distant metastases. PET/CT detected unsuspected disease sites in 39/115 scans (34%): locoregional disease, 14; distant metastases, 11; both, 8; additional local cutaneous disease, 5; and second malignancy, 1. Comparison of 78 PET/CT scans with available CT/MR demonstrated 37 additional abnormalities on 23 PET/CT scans, predominantly including skin/subcutaneous lesions and nodes. PET/CT led to change in management in 28% of patients. On univariate/multivariate analysis, increased number of FDG-positive lesions and lung metastases on PET/CT were associated with increased risk of death/disease progression. LIMITATIONS/CONCLUSIONS:Retrospective study. CONCLUSIONS:FDG-PET/CT was sensitive in detecting recurrent disease in cSCC, led to change in management in 28% of patients, and proved to be of prognostic value.
Rosai-Dorfman Disease-Utility of 18F-FDG PET/CT for Initial Evaluation and Follow-up
BACKGROUND:The role of imaging in the management of Rosai-Dorfman disease (RDD), a rare non-Langerhans cell histiocytosis, is not clearly defined. We present an analysis of FDG PET/CT findings obtained for initial disease characterization, follow-up evaluation, and treatment planning for this disease. METHODS:From an institutional pathology database (2001-2018), we identified RDD patients who underwent FDG PET/CT scans either as part of clinical care or when done as part of clinical trials. For all scans, sites of abnormal FDG uptake were assessed, and SUVmax was measured. Comparison of PET/CT findings was made with anatomic (CT/MRI-based) imaging, where available. Instances of changing treatment based on PET/CT were recorded. RESULTS:We reviewed 109 FDG PET/CT scans in 27 patients with RDD. Five of 27 patients had only nodal/cutaneous disease, whereas 22 patients had extranodal disease, most commonly in bone (n = 9) and central nervous system (n = 7). PET/CT identified sites of active disease in 24 of 27 patients. All identified bone and extraskeletal lesions, except for a brain lesion in 1 patient, were FDG-avid. In 6 of 20 patients (30%) with available prior CT or MRI, PET/CT demonstrated additional RDD lesions (bones: n = 5, pleura: n = 1) that were not apparent on anatomic imaging; 3 of these lesions were outside the CT field of view, and 3 were not recognized on CT. Overall, 13 of 109 PET/CT scans led to a change in management, affecting 41% (11/27) of patients. CONCLUSION/CONCLUSIONS:FDG PET/CT was valuable in defining disease extent and optimizing treatment strategy in patients with RDD.
Reexamination of the chromium-51-labeled posttransfusion red blood cell recovery method
BACKGROUND:The chromium-51-labeled posttransfusion recovery (PTR) study has been the gold-standard test for assessing red blood cell (RBC) quality. Despite guiding RBC storage development for decades, it has several potential sources for error. METHODS:Four healthy adult volunteers each donated an autologous, leukoreduced RBC unit, aliquots were radiolabeled with technetium-99m after 1 and 6 weeks of storage, and then infused. Subjects were imaged by single-photon-emission computed tomography immediately and 4 hours after infusion. Additionally, from subjects described in a previously published study, adenosine triphosphate levels in transfusates infused into 52 healthy volunteers randomized to a single autologous, leukoreduced, RBC transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage were correlated with PTR and laboratory parameters of hemolysis. RESULTS:Evidence from one subject imaged after infusion of technetium-99m-labeled RBCs suggests that, in some individuals, RBCs may be temporarily sequestered in the liver and spleen immediately following transfusion and then subsequently released back into circulation; this could be one source of error leading to PTR results that may not accurately predict the true quantity of RBCs cleared by intra- and/or extravascular hemolysis. Indeed, adenosine triphosphate levels in the transfusates correlated more robustly with measures of extravascular hemolysis in vivo (e.g., serum iron, indirect bilirubin, non-transferrin-bound iron) than with PTR results or measures of intravascular hemolysis (e.g., plasma free hemoglobin). CONCLUSIONS:Sources of measurement error are inherent in the chromium-51 PTR method. Transfusion of an entire unlabeled RBC unit, followed by quantifying extravascular hemolysis markers, may more accurately measure true posttransfusion RBC recovery.
Assessment of salivary gland function after 177Lu-PSMA radioligand therapy: Current concepts in imaging and management
Prostate specific membrane antigen (PSMA) is a transmembrane protein that is highly expressed on prostate epithelial cells and is strongly upregulated in prostate cancer. Radioligand therapy using beta-emitting Lutetium-177 (177Lu)-labeled-PSMA-617, a radiolabeled small molecule, has gained attention as a novel targeted therapy for metastatic prostate cancer, given its high affinity and long tumor retention, and rapid blood pool clearance. In March 2022, the United States Food and Drug administration has granted approval to the targeted 177Lu-PSMA-617 therapy for treatment of patients with PSMA-positive metastatic castration resistant prostate cancer, who have been previously treated with an androgen-receptor pathway inhibitor and taxane-based chemotherapy. Studies have demonstrated the adverse effects of this treatment, mainly encountered due to radiation exposure to non-target tissues. Salivary glands show high PSMA-ligand uptake and receive increased radiation dose secondary to accumulation of 177Lu-PSMA-617. This predisposes the glands to radiation-mediated toxicity. The exact mechanism, scope and severity of radiation-mediated salivary gland toxicity are not well understood, however, the strategies for its prevention and treatment are under evaluation. This review will focus on the current knowledge about salivary gland impairment post 177Lu labeled PSMA-based radioligand therapies, diagnostic methodologies, and imaging with emphasis on salivary gland scintigraphy. The preventive strategies and known treatment options would also be briefly highlighted.
18F-FDG PET/CT for post-treatment surveillance imaging of patients with stage III Merkel cell carcinoma
To investigate diagnostic and prognostic value of 18F-FDG PET/CT for surveillance imaging in patients treated for Stage III Merkel cell carcinoma (MCC). Methods: This retrospective study included 61 consecutive stage III MCC patients, who were clinically asymptomatic and underwent surveillance FDG-PET/CT. Findings were correlated with either pathology and/or clinical/imaging follow-up. Median follow-up period was 4.8 years. Statistical analyses were performed. Results: FDG-PET/CT detected unsuspected recurrences in 33% patients (20/61) with lesion-based sensitivity, specificity, and accuracy of 92%, 93%, and 93%, respectively. MeanÂ±SD SUV for malignant and benign lesions was 7.5Â±3.9 and 3.8Â±2.0, respectively. Unknown distant metastases, as first recurrence site, were noted in 12 of 61 patients. Those with positive disease on FDG-PET/CT within one year of definitive treatment had relatively worse overall survival (p<0.0001). After adjustment on stage, risk of death increased with higher SUVmax (HR for one unit=1.17;P = 0.006) and with a higher number of positive lesions on FDG-PET/CT (HR for one additional lesion = 1.60;p<0.001). Conclusion: Post-definitive treatment surveillance FDG-PET/CT scan detects unsuspected recurrences and has prognostic value. Inclusion of FDG-PET/CT within the first 6 months after definitive treatment would be appropriate for surveillance and early detection of recurrence. Our data merits further studies to evaluate the prognostic implications.
18F-Fluciclovine Uptake in Thymoma Demonstrated on PET/MRI
A 68-year-old man with a history of prostate cancer post-primary treatment presented with rising prostate-specific antigen levels and was referred for F-fluciclovine PET/MRI to localize recurrent disease. PET/MRI revealed a solitary focus of uptake in a soft tissue nodule in the anterior mediastinum, which was resected and found to be a type B2 thymoma. F-fluciclovine uptake is mediated by amino acid transporters, primarily alanine-serine-cysteine transporter 2 and L-type amino acid transporter 1, previously demonstrated to be expressed on thymic carcinomas. This case highlights the possibility of overexpression of amino acid transporters in thymomas as well, rarely described before.
Preserving Radiology Resident Education During the COVID-19 Pandemic: The Simulated Daily Readout
RATIONALE AND OBJECTIVES/OBJECTIVE:The educational value of the daily resident readout, a vital component of resident training, has been markedly diminished due to a significant decrease in imaging volume and case mix diversity. The goal of this study was to create a "simulated" daily readout (SDR) to restore the educational value of the daily readout. MATERIALS AND METHODS/METHODS:To create the SDR the following tasks were performed; selection of cases for a daily worklist for each resident rotation, comprising a combination of normal and abnormal cases; determination of the correct number of cases and the appropriate mix of imaging modalities for each worklist; development of an "educational" environment consisting of separate "instances" of both our Picture Archive Communication System and reporting systems; and the anonymization of all of the cases on the worklists. Surveys of both residents and faculty involved in the SDR were performed to assess its effectiveness. RESULTS:Thirty-two residents participated in the SDR. The daily worklists for the first 20 days of the SDR included 3682 cases. An average of 480 cases per day was dictated by the residents. Surveys of the residents and the faculty involved in the SDR demonstrated that both agreed that the SDR effectively mimics a resident's daily work on rotations and preserves resident education during the Coronavirus Disease 2019 crisis. CONCLUSION/CONCLUSIONS:The development of the SDR provided an effective method of preserving the educational value of the daily readout experience of radiology residents, despite severe decreases in imaging exam volume and case mix diversity during the Coronavirus Disease 2019 pandemic.
PET/CT for thyroid disorders
San Diego, CA : Plural Publishing, 
Clinical value of 18F-FDG-PET/CT in staging cutaneous squamous cell carcinoma
BACKGROUND:Cutaneous squamous cell carcinoma (cSCC) is the second most common skin malignancy. Computed tomography (CT) and/or MRI are commonly used for staging, however, the role of fluorine-18-fluorodeoxyglucose (F-FDG)-PET is not clearly established. In this study, we evaluated F-FDG-PET/CT imaging for initial staging of cSCC. PATIENTS AND METHODS/METHODS:F-FDG-PET/CT scans performed in patients with newly diagnosed cSCC were reviewed retrospectively. Images were visually assessed for lesions and F-FDG uptake [standardized uptake value (SUV)] in primary and secondary sites was measured. Suspected lesions on F-FDG-PET/CT were correlated with histopathology when available, follow-up imaging or clinical data in others. RESULTS:Twenty-three cSCC patients who underwent F-FDG-PET/CT at diagnosis were evaluated. Primary sites were in head/neck (n=21), chest (n=1), and foot (n=1). All patients had F-FDG-positive scans with a total of 51 F-FDG-positive lesions. All primary lesions (n=24) were F-FDG-positive (SUV: 2.3-22.8; mean 10.2), and additional 27 F-FDG-positive lesions, including 21 nodes, four cutaneous, one osseous and one lung lesion, were noted in 13 patients. Mean size of F-FDG-positive nodes was 0.9â€‰cm (range: 0.4-2.5â€‰cm), predominantly clinically impalpable. Pathology was available for 40/51 lesions; 31 sites positive for malignancy. SUV (meanÂ±SD) was 9.2Â±6.2 for malignant and 2.7Â±1.2 for benign lesions. Sensitivity, positive predictive value, and accuracy of F-FDG-PET/CT scan were 100, 77.5, and 77.5%, respectively. F-FDG detected seven additional lesions in three patients, compared to CT/MRI. Overall, staging F-FDG-PET/CT detected nine prior unknown lesions in five patients that were proven metastatic disease by histopathology or follow-up; F-FDG-PET/CT modified management in 5/23 (21.7%) patients. CONCLUSION/CONCLUSIONS:F-FDG-PET/CT has high sensitivity in the detection of cSCC lesions, including small cutaneous and nodal disease, and has a potential role in initial staging and management.
Enchondroma of Tibia as Potential False-positive Finding on 68Ga-DOTATOC PET/CT Scan [Case Report]
A 70-year-old man with a history of carcinoid tumor of small bowel was referred for Ga-DOTATOC study to evaluate the extent of disease. PET/CT scan revealed known metastatic disease in the liver, with other sites of involvement including pancreas, peritoneum, and bones. In addition, moderately intense uptake was noted in proximal right tibia and further correlation on CT showed metaphyseal lesion with "rings and arcs" calcification suggestive of enchondroma. This case highlights the possibility of overexpression of somatostatin receptors in enchondromas, which has been little explored in literature.