DMSA renal scans in adults with acute pyelonephritis

The 99mTc-DMSA scan is accepted as the most sensitive imaging modality for detecting areas of renal parenchymal scarring. More recently the DMSA scan has also been shown to be of value in imaging areas of renal parenchymal involvement in both children and adults with acute pyelonephritis. We assessed the acute DMSA scan findings in a consecutive series of 81 patients hospitalized with acute pyelonephritis. Acute pyelonephritis was diagnosed if the patient had a fever of > 37.8 degrees C, loin pain or tenderness and infected urine (99% Escherichia coli). Patients had a blood culture taken (8 positive), as well as a hematological (leukocytosis 75%) and biochemical screen, C-reactive protein (CRP) (increased in 57 of 66 [86%]) and urinary tract ultrasonography. If the initial DMSA scan was abnormal it was repeated after three months and in some instances again at six months. If persisting defects were noted an intravenous urogram was then undertaken. Of the 81 patients, 37 (46%) had an abnormality on the DMSA scan. Nineteen had a single defect, 12 multifocal defects, five features suggestive of pre-existing renal parenchymal scarring (all later shown to have reflux nephropathy) and one a shrunken kidney. Those patients with an abnormal scan had a higher CRP concentration than those with a normal scan. Of the 31 patients who had either a focal or multifocal defect on their initial DMSA scan there was adequate follow-up on 24 patients. In 18 of these the defects had resolved by six months (usually within three months), while of the remainder, three were shown to have reflux nephropathy, one had a large single renal cyst and another an area of parenchymal calcification. Fifty-three of 76 patients (70%) had normal ultrasonography. In adults with acute pyelonephritis, the DMSA scan may prove to be the most useful renal imaging procedure.