A 78-year-old female patient with a 5-year history of bradykinesia and tremor at rest of both upper limbs was referred to our Nuclear Medicine Department because of a rapid functional decline over 3 months with cognitive impairment, generalized myoclonus, and dependence for most basic daily activities. Brain SPECT with 148MBq (4 mCi) of I-123 FP-CIT and 740MBq (20 mCi) of Tc-99m ethylcysteinate dimer (thereafter Tc-99m ECD) was performed.

Objective Medullary thyroid carcinoma (MTC) is a rare malignancy. Location of residual, recurrent, or metastatic disease is crucial to treatment management and outcome. We aimed to evaluate the use of 18F-FDG PET/CT in localizing MTC foci in patients with biochemical relapse. Methods This is a retrospective cohort study. Review of 51 FDG PET/CT studies of 45 patients referred to restage MTC due to increased calcitonin (Ctn) and carcinoembryonic antigen (CEA) values at follow-up. FDG PET/CT diagnostic accuracy was determined through a patient-based analysis, using histology as criterion standard when available, or other imaging studies and clinical follow-up otherwise (mean, 4 years). Results There were 25 positive scans. Sensitivity, specificity, positive and negative predictive values, diagnostic accuracy, and positive likelihood ratio were 66.7%, 83.3%, 88.0%, 57.7%, 72.5%, and 4.0, respectively. Using a Ctn cutoff of 1000 pg/mL, sensitivity increased to 76.9%. There were significant differences of Ctn and CEA values between positive and negative FDG PET/CT (P < 0.05). Regarding true-positive studies, average SUVmax comparing locoregional and metastatic disease was at the limit of significance (P = 0.046). Conclusions PET/CT can be useful to restage patients with biochemical relapse of MTC, with a better performance in higher Ctn levels. Its high positive predictive value (88%) may impact in the therapeutic management, although its low negative predictive value (57.7%) makes strict follow-up mandatory in examinations without pathologic findings.

Background Uveal melanoma metastasizes to the liver. We aimed to explore the metabolic activity of liver metastases (LM) as a biomarker for survival. Methods We analyzed newly diagnosed patients with metastatic UM (MUM) with LM detected by liver‐directed imaging and had undergone a PET/CT at diagnosis. Findings 51 patients were identified between 2004 and 2019. Median age was 62 years, 41% male and 22% ECOG ≥1. LDH, ALP, and GGT were elevated in 49%, 37%, and 57% of patients. Median LM SUVmax was 8.5 (3–42.2). Same size lesions presented a wide range of metabolic activity. Median OS was 17.3 m (95% CI:10.6–23.9). Patients with SUVmax ≥8.5 had an OS of 9.4 m (95% CI:6.4–12.3), whereas patients with SUVmax <8.5 had an OS of 38.4 m (95% CI:21.4–55.5; p < 0.0001, HR = 2.9). We observed similar results when studying M1a disease separately. Multivariate analysis showed SUVmax as an independent prognostic factor for the whole population and those with M1a disease. Interpretation Increased metabolic activity of LM seems to be an independent predictor of survival. MUM is a heterogeneous disease and metabolic activity probably reflects a different intrinsic behavior.