Objective: Renal cortical scintigraphy with (99m)Tc dimer captosuccinic acid (DMSA) is the standard method to detect acute pyelonephritis and cortical scarring. Different acquisition methods have been used: planar parallel-hole or pinhole collimation and single photon emission tomography (SPECT). Publications support the superiority of each; few comparative studies have been reported, with mixed results. We have compared planar parallel-hole cortical scintigraphy and dual-head SPECT for detection of cortical defects.
Materials and methods: Forty patients (37 children, 3 adults; 9 male, 31 female) were imaged 3 hours after injection of (99m)Tc-DMSA with dual-head SPECT and planar imaging (posterior, left, and right posterior oblique views with a parallel-hole collimator). For each patient, planar and SPECT images were evaluated at different sittings, in random order, by three independent observers. Twelve cortical segments were scored as normal or reduced uptake. The linear correlation coefficient for the number of abnormal segments detected between readers, techniques, and segments was calculated.
Results: No significant difference was seen in the average number of abnormal segments detected by planar versus SPECT imaging; 2.1 for planar imaging and 2.2 for SPECT (p = 0.84, two-tailed). For all observers, the average correlation coefficient for SPECT alone, planar imaging alone, and between techniques (SPECT vs planar imaging) was high (r = 0.93-0.94). Applying nonparametric Spearman's rank analysis, the average correlation remained high (r = 0.70-0.75). Correlation between readers, techniques, and segments for methods and readers was also good (r = 0.69-0.77).
Conclusion: (99m)Tc-DMSA renal cortical imaging using dual-head SPECT offers no statistically significant diagnostic advantage over planar imaging for detection of cortical defects.