760 Correspondence

99mTc dimercaptosuccinic acid (DMSA) scan in urinary tract infection Sir, Dr Smellie et al, in their recent paper on 99mTc dimercapto-succinic (DMSA) scan in patients with established renal scarring, ' quoted a paper from this hospital.2 They failed to quote the principal findings of this paper, however, namely that a DMSA scan is the most accurate method of detecting renal scars in children 0-5 years old. In our paper we compared intravenous urograms, ultrasound, and a DMSA scan carried out over a six month period in 63 children known to have vesicoureteric reflux. A total of 60 children were found to have scarring on DMSA scans, 50 on ultrasound, and only 36 on intravenous urograms. The severity of the scarring was assessed and a highly significant difference was obtained for coupled comparisons of the three modalities-that is, between DMSA scanning and ultrasound, ultrasound and intravenous urography, and DMSA scanning and intravenous urography. None of the changes identified on a DMSA scan in this group was reversible indicating that the appearances were not the result of recent acute infection. The data were also assessed according to the age of the children, and the discriminating power between the techniques became less noticeable with increasing age. In our hands `mTc DMSA scanning is neither expensive nor time consuming (about £35 per examination). Reactions to DMSA are exceptional but there is still a definite morbidity and mortality associated with contrast media, even the non-ionic form. In our department scanning is carried out 1-5 hours after injection and takes 15-20 minutes. We never perform DMSA and diethylene-triamine pentacetic acid (DTPA) scans simultaneously. In this hospital the DMSA scan is used as the first line investigation of the renal tract in urinary tract infection. Intravenous urography is carried out only for assessment of possible structural abnormality, particularly before surgery. Reliance on intravenous urography and ultrasound, especially in those under 5 years old, will result in inadequate detection, treatment, and follow up of renal scarring