The kidneys are the primary route by which Tc-99m MDP is excreted, and they normally are well visualized on skeletal scintigraphy. On the anterior view of a skeletal scintigram, large calcified gallstones may attenuate gamma rays emitted by the kidneys, simulating a space-occupying lesion, but the renal appearance remains normal on the posterior view. It is important that attenuation by gallstones not be mistaken for renal pathology. A case is presented in which attenuation from a large gallstone mimics a focal area of decreased uptake in the upper pole of the right kidney.
*From the Department of Radiology, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, Ohio
†From the Department of Radiology, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio