Nuclear renal imaging in acute pyelonephritis

Patients with acute pyelonephritis may present with a spectrum of clinical signs and symptoms. There are few noninvasive diagnostic studies, however, to confirm or exclude this diagnosis. A small number of patients, generally those with severe disease, will demonstrate radiographic changes on excretory urography, but the lack of sensitivity of the IVP in early, acute pyelonephritis is well documented. Several radionuclide techniques have been proposed to assist in the earlier detection of this clinical problem including imaging with Mercury-197 chlormerodrin, Gallium-67 citrate, Technetium-99m glucoheptonate, Technetium-99m DMSA, and, more recently, Indium-111 labeled white blood cells. The success of the renal cortical imaging agents as well as those which localize in infection are described in this report. There appears to be a complimentary role for the cortical imaging agents and the radiopharmaceuticals which localize in bacterial infection. Cortical agents offer the advantage of specific assessment of functioning renal tissue and a convenient, rapid method for following the response to treatment in a noninvasive manner. A pattern is described which may be diagnostic; correlation with Gallium-67 citrate or Indium-111 WBCs may increase the probability of infection as the cause for the cortical abnormality. The measurement of differential renal function using cortical agents provides additional information to assist the clinician in predicting the late effects of infection. Improved sensitivity and specificity, and a reproducible method for following the response to therapy in patients with acute pyelonephritis are the advantages of the techniques described.