Magnetic Resonance Characterization of Pheochromocytomas in the Abdomen and Pelvis: Imaging Findings in 18 Surgically Proven Cases

Purpose: To study the magnetic resonance imaging characteristics of adrenal and extra-adrenal pheochromocytomas in the abdomen and pelvis. Methods: We retrospectively reviewed 18 cases of pathologically proven cases of pheochromocytomas in the abdomen and pelvis. These patients have undergone magnetic resonance imaging evaluation before surgery. The study population included 10 men and 7 women (age range, 19-68 years; mean, 38 years). A consensus review of the magnetic resonance images was performed by 2 blinded expert observers. A qualitative evaluation was completed, and the tumors were classified by anatomical location, shape, T2 signal, contrast enhancement, and signal dropout on chemical shift pulse sequences. Results: On T2-weighted images, most lesions demonstrated mild to moderate increased signal intensity (SI) (n = 12), 5 lesions demonstrated a markedly increased SI, and only 1 lesion demonstrated an isointense SI on T2-weighted images. Five lesions demonstrated marked postcontrast enhancement. Three lesions demonstrated moderate enhancement, and 5 lesions demonstrated mild postcontrast enhancement. The pattern of enhancement was variable: 4 salt and pepper, 4 homogeneous, 3 heterogeneous, and 2 target with central necrosis and hemorrhage. None of the lesions contained significant amount of intracellular lipid, as no lesions demonstrated greater than 16.5% signal dropout on out-of-phase compared with in-phase pulse sequences.