Variability in the interpretation of DMSA scintigraphy after urine infection

Full text: This study investigated the extent of and potential reasons for interpretation disagreement of 99mTc-DMSA scans after urine infection in children. Methods: 441 scans were selected from children with first urine infection (UTI) from 1993-1995. 294 scans were performed at a median time of seven days after UTI and 147 in children free from infection over one year follow-up. Two nuclear medicine physicians independently reported according to whether renal abnormality was present or absent and used the four level grading system described by Goldraich: grade 1-no more than two cortical defects; grade 2 -more than 2 defects; grade 3-diffuse reduction in uptake with or without defects; grade 4 -shrunken kidney <10% function. Indices for variability used were the percentage of agreement and kappa statistic, expressed as a percentage. For the grading scale used, both measures were weighted with integers representing the number of categories from perfect agreement. Disagreement was analysed for children, kidneys and kidney zones. Results: There was agreement in 86 per cent (kappa 69%) for the normal-abnormal DMSA scan dichotomy, the weighted agreement was 94 per cent (kappa 82%) for the grading scale. Disagreement of DMSA scan interpretation ≥ two grades was present in three cases (0.7%). The same level of agreement was present for the patient, kidney and kidney zones comparisons. Agreement was not influenced by age or the timing of scintigraphy after urine infection. Conclusion: Two experienced physicians showed good agreement in the interpretation DMSA scintigraphy in children after urine infection and using the grading system of Goldraich