Reliability of DMSA for the diagnosis of renal parenchymal abnormality in children

The objective of this study was to evaluate the variability of technetium-9 9m dimercaptosuccinic acid (DMSA) scintigraphy interpretation by four nucle ar medicine physicians for the diagnosis of renal parenchymal abnormality i n children, and to compare variability among three different DMSA methods i n clinical use: planar alone, single-photon emission tomography (SPET) alon e, and planar with SPET. One hundred consecutive DMSA studies were independ ently interpreted 3 times by four participating nuclear medicine specialist s from different departments and in random order. All scans were classified by the presence or absence of renal parenchymal abnormality using the modi fied four-level grading system of Goldraich. Indices of agreement were the percentage of agreement and the kappa statistic. Disagreement was analysed using children, kidneys and kidney zones (three zones per kidney). Using pa tients as the unit of analysis, agreement for planar and planar with SPET m ethods was 87%-88% (kappa 0.74) for the normal-abnormal scan classification . The corresponding agreement value for the SPET alone method was 78% (kapp a 0.56). Similarly, substantial disagreement (disagreement greater than or equal to2 categories) occurred in 2.5% and 1.3% of comparisons between obse rvers for planar alone and planar with SPET, respectively, but in 5.2% of c omparisons for SPET alone. These results did not vary appreciably whether i nterpretation of patients, kidneys or kidney zones was compared. It is conc luded that the four experienced nuclear medicine physicians showed substant ial agreement in the interpretation of planar alone and planar with SPET DM SA scintigraphic images. Interpretation of SPET DMSA images, without planar images, was significantly more variable than interpretation using the two other methods, disagreement occurring in mote than 20% of comparisons. SPET DMSA scintigraphy, when used without planar images, does not provide a fir m basis for clinical decision making in the care of children who may have r enal damage. There is no apparent benefit of reduced variability from the e xtra provision of SPET data to nuclear medicine physicians who already have planar images.