TY - JOUR T1 - The effect of alternate background and kidney regions of interest and use of geometric mean versus posterior images on the computation of differential renal function with MAG-3 JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 2089 LP - 2089 VL - 52 IS - supplement 1 AU - Mark Ahlman AU - W. Rowlett AU - David Springle AU - Ryan Parker AU - Kenneth Spicer AU - Leonie Gordon Y1 - 2011/05/01 UR - http://jnm.snmjournals.org/content/52/supplement_1/2089.abstract N2 - 2089 Objectives To determine if there are significant changes in differential renal function (DRF) which may change clinical decision making when: 1. Two different types of background regions of interest (ROIs) or two types of kidney ROIs are drawn on geometric mean (GM) images from MAG-3 renal scans. 2. GM data is used as opposed to posterior image (PI) acquisition. Methods Twenty eight MAG-3 renal scans performed on 27 patients (average age of 50) were retrospectively analyzed. DRF was computed on each study using four separate techniques: GM data from: (1) perirenal background ROI and kidney ROI including the renal pelvis; (2) perirenal background ROI and kidney ROI excluding the renal pelvis; (3) inferolateral background ROI (excluding liver/spleen) and kidney ROI including the renal pelvis. PI data from: (4) perirenal background ROI and kidney ROI excluding the renal pelvis. These four data sets were compared against each other and mean differences in differential renal function were determined. Statistical analysis using a paired t-test for means was used to determine the significance of these differences to 95% confidence. Results Comparison of pelvic inclusion versus exclusion in the kidney ROI (1 vs. 2) yielded a mean difference = 2.02%; 95% CI 0.83 to 3.21; p = 0.002. Comparison of background ROIs (1 vs. 3) produced a mean difference = 4.15%; 95% CI -6.83 to -1.47; p = 0.004. GM versus PI (2 vs. 4) yielded a mean difference = -0.30%; 95% CI -2.22 to 1.63; p = 0.75. Conclusions This study reveals that when GM images are used to determine DRF, the location of the background ROIs as well as the inclusion/exclusion of the renal pelvis from the kidney ROI can play a statistically significant role in the determination of differential renal function. When the renal pelvis is excluded, we found no significant difference in DRF when PI data is used versus GM data ER -