Localization of acute pyelonephritis in pyrexia of unknown origin using FDG PET/CT.

Objectives: Acute pyelonephritis presents with high-grade fever, dysuria, flank pain, leukocytosis, and microscopic hematuria. Urine culture aids in the diagnosis of this infection. It can be complicated or uncomplicated.

Pericardial sarcoidosis presenting as PUO diagnosed on FDG PET CT scan.

Pyrexia of unknown origin (PUO) is a common problem in day-to-day practice. FDG PET CT is an established investigation that aids in identifying the cause of PUO. Due to its high sensitivity PET detects an occult hypermetabolic focus in the body where CT helps in anatomical localization, vascularity, enhancement characteristics of the lesion detected on PET.

False-positive FDG PET CT Scan in Vertebral Hemangioma.

FDG PET CT scan is considered to be a sensitive tool to detect skeletal metastasis in known malignancies. However, it's high sensitivity and low specificity may account for false positive diagnosis in cases of trauma, infection, inflammation and other benign conditions. Skeletal hemangioma is one of the common benign conditions which are typically ametabolic on FDG PET CT with no uptake on bone scan.