Pigmented villonodular synovitis: dedicated PET imaging findings.

Pigmented villonodular synovitis (PVNS) is an uncommon entity, which has the potential to cause severe pain. The gold standard for evaluation is MRI, and previous PET findings associated with PVNS have only been documented in the setting of concurrent malignancy. In the setting of recurrent disease, PET is being used to evaluate prebiological and postbiological treatment responses. Recurrent PVNS demonstrates greater hypermetabolic activity than previously documented, supporting the case as a potential mimic of malignant/metastatic disease. Post-treatment evaluations demonstrate decreased metabolic activity, which suggests response to treatment. This behaviour further supports the contention that there is a neoplastic origin to PVNS.

The hot rim sign on hepatobiliary scintigraphy (HIDA) with CT correlation.

An older male with multiple medical comorbidities presented to the emergency room after 3 days of worsening right upper quadrant pain. The patient had an elevated white blood cell count and mildly elevated liver functions. Initial ultrasound was equivocal and further imaging with CT scan was obtained. The CT scan was read as suggestive of cholecystitis, however a hepatobiliary scintigraphy (HIDA) scan was ordered for confirmation, as the patient was a poor operative candidate. The HIDA demonstrated no bile duct or small bowel activity on initial images or delays, however a classic 'hot rim' sign was present, confirming acute cholecystitis. The patient ultimately underwent percutaneous cholecystostomy with drainage for treatment where acute cholecystitis was confirmed. Upon retrospective review, the CT demonstrated hyperaemia surrounding the gallbladder fossa, which is the CT scan equivalent of a scintigraphic 'hot rim' sign. This is an uncommon example of a radiologic sign correlation between multiple imaging modalities.