Variability in interpretation of static renal scintigraphy findings

Abstract

Background. Static renal scintigraphy with 99mTc-DMSA is a sensitive method for evaluation of any reduction of cortical mass function. There is not enough reliable references in the literature on scintigraphic reports in terms of objectivity and standardization. The aim of this paper was to assess the differences in interpretation of routine renal scintigraphic findings by nuclear medicine specialists from various institutions (interobserver variability). Methods. Both interobserver variability and agreement in the interpretation were evaluated in two groups. Six observers from four different institutions (group A), and three observers from the same institution (group B) interpreted independently 60 static renal scintigraphy findings obtained by analogous imaging using x-ray films in four standard projections. Using at least two options, seven parameters of renal scintigraphy protocols were analyzed: size (1), uptake (2), outlines (3), scars (4), focal changes (5), relative function (6), and conclusions (7). Results. The interpretations of scintigraphic findings were in accordance in items 1 to 7 within the group A: 62, 42.5, 45, 9, 47, 52, and 34 percent respectively, and within the group B: 72, 55, 59, 22, 62, 60, and 41 percent, respectively. The conformity was more significant in the findings observed in group B as opposed to group A, which was statistically highly significant, especially for the category of scars (p<0.01). Significant variability was also observed by six observers in all the parameters of scintigraphic protocol, especially, again, in the scars analysis (p<0.01). Conclusion. Insignificant degree of accordance, especially in the assessment of scars necessitates the standardization of criteria and terminology in order to interpret the renal scintigraphy with more accuracy and objectivity.