title: Multiplanar Reformations in the Measurement of Renal Length on CT: Is It Plain Which Plane to Use?
abstract: OBJECTIVE
  The objective of this study was to determine the accuracy of renal measurement on CT in multiple imaging planes.
  
  
  METHODS
  In this study, three board-certified radiologists retrospectively measured 110 kidneys on CT in 55 consecutive patients. Five measurement methods were used: axial, coronal single image, coronal multiimage, sagittal single image, and sagittal multiimage. The coronal database was sent to a postprocessing workstation, and each radiologist performed a maximum renal measurement using a best off-axis plane that was our reference standard. An ANOVA test with repeated measures and posthoc Bonferroni corrected t tests were performed.
  
  
  RESULTS
  The mean differences (± standard error) compared with the reference standard method were as follows: axial, 7.7 ± 0.7 mm; coronal single image, 13.1 ± 1.4 mm; coronal multiimage, 6.4 ± 0.8 mm; sagittal single image, 6.4 ± 0.6 mm; and sagittal multiimage, 2.8 ± 0.3 mm. The reference standard measurement was larger (p < 0.001), whereas the coronal single-image measurement (p ≤ 0.006) was smaller than all other methods. The sagittal multiimage (p ≤ 0.005) was statistically significantly different from all other methods. There were no statistically significant differences among the axial, coronal multiimage, and sagittal single-image methods (p ≥ 0.088).
  
  
  CONCLUSIONS
  The single-image coronal method is the least accurate, with an error of approximately 13 mm. The axial, multiimage coronal, and single-image sagittal methods underestimate renal size by approximately 6-8 mm. Multiimage sagittal is the most accurate method for measuring kidneys with an error of approximately 3 mm.
authors.affiliation: 1 Department of Radiology, San Antonio Military Medical Center, 3851 Roger Brooke Dr, #3600, San Antonio, TX 78234.|2 Department of Radiology, Uniformed Services University of the Health Sciences, Bethesda, MD.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lisanti
authors.affiliation: 1 Department of Radiology, San Antonio Military Medical Center, 3851 Roger Brooke Dr, #3600, San Antonio, TX 78234.
authors.forename: David J
authors.initials: DJ
authors.lastname: Oettel
authors.affiliation: 3 Department of Radiology, Stony Brook University Medical Center, Stony Brook, NY.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Reiter
authors.affiliation: 1 Department of Radiology, San Antonio Military Medical Center, 3851 Roger Brooke Dr, #3600, San Antonio, TX 78234.|2 Department of Radiology, Uniformed Services University of the Health Sciences, Bethesda, MD.
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Schwope
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D007479:Iopamidol; D007668:Kidney / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012015:Reference Standards; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; D007479:Iopamidol
keywords: multiplanar reformations; renal CT; renal length; renal size