PET/CT in the Diagnosis and Workup of Sarcoidosis: Focus on Atypical Manifestations.

Sarcoidosis is a multisystem disease characterized by the formation of noncaseating granulomas. Lung and intrathoracic lymph nodes are classic sites of involvement; however, sarcoidosis can affect any site in the body. The clinical course is extremely variable, and the imaging features are diverse and dependent on the affected site, degree of inflammation, and treatment the patient receives. Atypical manifestations and imaging findings can make diagnosis and/or management challenging. In addition, assessment of treatment response can be difficult in the setting of chronic disease. Fluorine 18 fluorodeoxyglucose (FDG) PET/CT is sensitive for assessment of the inflammatory activity of sarcoidosis in any organ. Although FDG PET/CT is not included in the standard workup for sarcoidosis, there has been growing evidence that supports the value of this examination in guiding diagnosis and management. FDG PET/CT may be especially useful for assessing reversible granuloma, treatment response, disease extent, occult disease, and cardiac or osseous sarcoidosis, and determining the most suitable biopsy site. Capability to image the entire body during a single examination is advantageous in cases of systemic disease such as sarcoidosis. The authors review the use of FDG PET/CT, providing up-to-date evidence and describing various cases of sarcoidosis in which FDG PET/CT has an important role in diagnosis and/or management. They also discuss the usefulness of FDG PET/CT in cases of selective manifestations of sarcoidosis. ©RSNA, 2018.

68Ga-PSMA-11 PET/CT in Newly Diagnosed Prostate Adenocarcinoma.

INTRODUCTION: Prostate-specific membrane antigen (PSMA) ligand PET/CT is an emerging modality to detect the metastatic disease, especially in intermediate- and high-risk prostate cancer (PCa). In this study, we analyzed the contribution of Ga-PSMA-11 PET/CT in staging and therapy management of newly diagnosed PCa. MATERIALS AND METHODS: A total of 78 patients with biopsy-proven PCa who were referred for Ga-PSMA-11 PET/CT for primary staging were retrospectively analyzed. The patients were divided into risk groups according to the D'Amico risk stratification criteria. All of the patients had undergone pelvic MRI, and 65 patients had bone scintigraphy also. The findings of Ga-PSMA-11 PET/CT were compared with these conventional imaging (CI) methods for staging of the disease. The relations between SUVmax of the primary tumors and Gleason scores (GSs), prostate-specific antigen (PSA) levels, and metastatic extent of the disease were analyzed. RESULTS: Of 78 patients, 5 patients were in low-risk group, 18 patients were in intermediate-risk group, and 55 patients were in high-risk group. Metastatic disease was found in 40 (51.2%) of 78 patients in Ga-PSMA-11 PET/CT. Ten patients had regional lymph node metastases, and 30 patients had distant metastases. Ga-PSMA-11 PET/CT changed the staging in 44 (56.4%) of 78 patients compared with CI. There was significant difference between the SUVmax of the tumors with GSs of 6 and 7 compared with GSs of 8, 9, and 10 (P = 0.003). The SUVmax were significantly different between the patients with no metastasis (n = 38) and patients with regional lymph node metastases or distant metastases (n = 40; 16.1 ± 10.9, 28.7 ± 25.8, P = 0.003, respectively). There was significant difference between the SUVmax of patients with PSA level less than 10 ng/mL compared with patients with PSA level of 10 or greater and less than 20 ng/mL and PSA 20 ng/mL or greater (P = 0.009). A weak correlation between PSA and primary tumor SUVmax was also found (r = 0.21). CONCLUSIONS: Ga-PSMA-11 PET/CT is an important imaging modality for primary evaluation of newly diagnosed PCa changing the disease stage substantially. Also the SUVmax of the primary tumor has a relation with GS, metastatic extent of disease, and PSA levels defining the prognosis.