RT Journal Article SR Electronic T1 Reproducibility of Renal Length Measurements with 99mTc-DSMA SPECT JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1632 OP 1635 VO 41 IS 10 A1 Eva Lin A1 Leonard P. Connolly A1 David Zurakowski A1 James DiCanzio A1 Laura Drubach A1 Karl Mitchell A1 Tracy Tetrault A1 Stephen P. Laffin A1 S. Ted Treves YR 2000 UL http://jnm.snmjournals.org/content/41/10/1632.abstract AB Renal length measurements are used in evaluating several abnormalities of the pediatric genitourinary tract. This study assesses reproducibility of renal length measurements obtained with 99mTc–dimercaptosuccinic acid (DMSA) SPECT. Methods: The lengths of 98 kidneys of 51 children (age range, 1–16 y; mean age, 5.4 y) who underwent 99mTc-DMSA SPECT were measured independently by 2 observers. Renal length was calculated by converting pixels between points at the superior and inferior renal margins on a summated coronal image to centimeters. Lengths were measured for kidneys as they appeared in situ and after realignment along their long axes. SPECT reconstruction, choice of display parameters, positioning of points used for measuring, and alignment were performed independently by each observer. Interobserver variability, interobserver correlation, and mean differences between observers' measurements (expressed as measurement of observer 2 − measurement of observer 1) were calculated. Results: Correlation between the observers' measurements was highly significant for both nonaligned and aligned studies (r = 0.95 and 0.97, respectively; both, P < 0.0001). Interobserver variability expressed as 1 SD was 3.6 mm for nonaligned studies and 2.8 mm for aligned studies. The mean difference between the 2 observers' measurements for nonaligned studies was 2.0 ± 4.8 mm (P < 0.0001) with a range of −11 to 14 mm. For aligned studies the mean difference between the 2 observers' measurements was −0.1 ± 4.0 mm (P = 0.88) with a range of −20 to 10 mm. Differences between observers were not dependent on absolute renal length (P = 0.68 for nonaligned studies; P = 0.40 for aligned studies). Conclusion: The variability in renal length measurements determined by 99mTc-DMSA SPECT is similar to that reported previously using sonography. Because the interobserver differences in renal length are similar to annual renal growth rates during childhood, caution should be applied when incorporating renal length measurements determined by 99mTc-DMSA SPECT into management algorithms. Additional studies are required to further establish interobserver variability, to assess intraobserver variability, and to evaluate means of improving standardization.