IMAGING OF PHEOCHROMOCYTOMA IN 2 DOGS USING p-[18F] FLUOROBENZYLGUANIDINE

p-18F]Fluorobenzylguanidine (18F]PFBG) is a norepinephrine analog that has been developed as a positron emission tomography (PET) imaging radiopharmaceutical. Myocardial sympathetic innervation, neuroendocrine structures, and tumors can be noninvasively imaged with 18F]PFBG. In this study, the uptake characteristics of 18F]PFBG were investigated in 2 dogs with a spontaneous pheochromocytoma. The extent of the pheochromocytoma was well documented in both dogs on the PET study. The standardized uptake values within the pheochromocytomas were greater than 25 by 10 min, and were 37 and 50 by 45 min in each dog. A third dog that was suspected to have an adrenal mass was also studied. In this dog, the 18F]PFBG study was normal. Surgical exploration and adrenal biopsy confirmed the 15F]PFBG imaging findings in both dogs. In each dog, there was rapid blood-pool clearance (within 10 min after intravenous administration of the 18F]PFBG), with high uptake specific within the myocardium and adrenal medulla. The results indicate that 18F]PFBG may be useful for imaging canine pheochromocytomas and aid in differentiating adrenal masses.