MIBG and FDG PET Findings in a Patient With Malignant Pheochromocytoma: A Significant Discrepancy

Abstract

Radionuclide imaging has proven to be very useful when dealing with neuroendocrine tumors and several radiotracers are currently available. One of the most commonly used and widely accepted methods to image pheochromocytomas is I-131 metaiodobenzylguanidine (MIBG) scintigraphy. However, recent studies with positron emission tomography (PET) using 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in pheochromocytomas have shown that FDG PET imaging can be useful in those pheochromocytomas (usually malignant) that fail to accumulate MIBG. The therapeutic plan of malignant pheochromocytoma can include chemotherapy and/or a high dose of I-131 MIBG, so precise staging and characterization is mandatory for correct management and treatment.

Brown adipose tissue demonstrating intense FDG uptake in a patient with mediastinal pheochromocytoma

“…High FDG uptake and low MIBG uptake have been considered to indicate malignant pheochromocytomas in several reports [13,14]. Extra-adrenal pheochromocytomas have a higher incidence of malignancy than adrenal pheochromocytomas [15].…”

Malignant pheochromocytomas and paragangliomas: a diagnostic challenge

“…It has been repeatedly shown that 18F-FDG PET imaging may be useful in those malignant PCCs that fail to accumulate either 123I-MIBG [116] or 131I-MIBG [117,118]. One advantage of 18F-FDG in contrast to other tracers is that its uptake appears to be unrelated to the secretory status of the tumor.…”

Detection of metastatic lesions from malignant pheochromocytoma and paraganglioma with diffusion-weighted magnetic resonance imaging: comparison with 18F-FDG positron emission tomography and 123I-MIBG scintigraphy

“…Positron emission tomography with 2-[ 18 F]-fl uoro-2-deoxy-D-glucose (FDG-PET) has been used for the imaging of various neoplasms including adrenal tumor [6,7]. FDG-PET may also be useful for staging and assessing therapeutic response of malignant pheochromocytoma/paraganglioma [8,9], and this technique may depict some metastases which fail to accumulate MIBG [10]. A recent study using FDG-PET, 18 F-fl uorodopamine PET, MIBG, 111 Inpentetreotode, 99m Tc-methylene diphosphate scintigraphy indicated that FDG-PET was the preferable functional imaging modality for the localization of metastatic paraganglioma [11].…”