Comparison of Scintigraphy vs Ultrasound in the Measurement of Renal Size
Objective: To determine the accuracy of scintigraphic measurement of renal size as compared to ultrasonography.
Methods: A total of 43 kidneys from 34 patients were assessed retrospectively. Each kidney was measured from the superior pole to the inferior pole using ultrasound and MAG3 renal scintigraphic methods. The pairs of renal length measurements obtained from each modality were analysed statistically using the Pearson correlation co-efficient and paired t-test to determine whether there was any difference and/or correlation between them.
Results: The mean renal lengths obtained via ultrasound and scintigraphy were 11.8 and 10.8 respectively. Paired t-testing of 43 pairs of renal sizes resulted in a t-score of 5.063 (p<0.001), demonstrating a strongly significant difference in measurement of renal size between the two modalities. A Pearson correlation coefficient of +0.673 (p<0.001) suggests a definite correlation between the sets of values. MAG3 renal scintigraphic measurement of renal length significantly under-estimates the value compared to that of ultrasonography.
Conclusions: Scintigraphic measurement of renal length was shown to differ from ultrasound dimensions with the values significantly underestimating the true renal size (assuming ultrasound to be the gold standard). Renal sizes were shown with high statistical probability to correlate by producing consistently smaller measurements.