Selected cases demonstrating the value of furosemide-primed 18F-FDG PET in identifying adrenal involvement

The adrenals are often a site of metastatic spread of cancer, and evaluation of the adrenals is important in assessing the extent of disease involvement in several malignancies. PET with 18F-FDG has been found extremely effective in detecting adrenal involvement not identified on CT or not meeting the CT size criteria for malignancy. However, evaluation of the adrenals and of retroperitoneal adenopathy or other pathologic conditions with 18F-FDG PET can be complicated at times by normal accumulation of the tracer in the uppermost renal calyx because of its somewhat posterior orientation, particularly when it is dilated. It is not infrequent for physicians to report doubt about adrenal involvement and to suggest that the PET findings be correlated with CT findings. This problem can often be circumvented clinically by administering intravenous furosemide (dosage adjusted according to body weight) to remove 18F-FDG activity from the renal pelvicalyceal system and by rescanning approximately 15-20 min later using 1-2 bed positions that include the renal area. We present 5 case vignettes, with representative illustrations, providing convincing evidence of the usefulness of this simple, noninvasive interventional procedure in ruling out suspected adrenal involvement that is otherwise difficult to assess, thereby obviating any further confirmation.