title: CT-based assessment of renal function impairment in patients with acute unilateral ureteral obstruction by urinary stones.
abstract: OBJECTIVE
  The purpose of our study was to evaluate computed tomography (CT) imaging factors related to renal function impairment in patients with acute unilateral ureteral obstruction by urinary stones.
  
  
  METHODS
  The study included 94 patients who had acute unilateral ureteral obstruction due to a urinary stone and a normal contralateral kidney. We retrospectively investigated the serum creatinine (SCr) levels immediately prior to CT examination and at least 1 week after treatment. CT examinations were performed using a CT urography protocol, including pre- and post-contrast images. The 67 patients with a SCr change of less than 0.3 mg/dL constituted group A. The other 27 patients with a SCr decrease of more than 0.3 mg/dL constituted group B. To evaluate factors related to renal function impairment, differences in CT imaging factors between the two groups, including the cortical and medullary density, renal and pelvic anteroposterior diameter, and perinephric fluid, were statistically analyzed.
  
  
  RESULTS
  The SCr immediately prior to CT examination significantly differed between the two groups. The follow-up SCr after resolution did not significantly differ between the two groups. The difference in the mean cortical and medullary HU on the nephrographic phase between the obstructed kidney and normal kidney was higher in group B than in group A (27.1 ± 23.1 and 69.4 ± 59.1 vs. 5.7 ± 8.8 and 31.8 ± 34.8; p < 0.001 and p = 0.004, respectively). The cut-off point for the difference in the mean cortical HU on the nephrographic phase between the obstructed kidney and normal kidney for renal function impairment was 15 HU, as determined by a receiver operating characteristic curve analysis.
  
  
  CONCLUSIONS
  Patients with significantly impaired renal function due to an acute unilateral ureteral obstruction may show a decreased nephrogram of the affected kidney and a significant difference in the HU on the nephrographic phase between the obstructed and normal kidney.
authors: Department of Radiology, Dong-A University College of Medicine, Dongdaesin-dong 3(sam)ga, Seo-gu, Busan, 602-715, South Korea.
authors: Dong Won
authors: DW
authors: Kim
authors: Department of Radiology, Dong-A University College of Medicine, Dongdaesin-dong 3(sam)ga, Seo-gu, Busan, 602-715, South Korea. kimdw@dau.ac.kr.
authors: Seong Kuk
authors: SK
authors: Yoon
authors: Department of Radiology, Dong-A University College of Medicine, Dongdaesin-dong 3(sam)ga, Seo-gu, Busan, 602-715, South Korea.
authors: Dong-Ho
authors: DH
authors: Ha
authors: Department of Radiology, Dong-A University College of Medicine, Dongdaesin-dong 3(sam)ga, Seo-gu, Busan, 602-715, South Korea.
authors: Myong Jin
authors: MJ
authors: Kang
authors: Department of Radiology, Dong-A University College of Medicine, Dongdaesin-dong 3(sam)ga, Seo-gu, Busan, 602-715, South Korea.
authors: Jin Hwa
authors: JH
authors: Lee
authors: Department of Radiology, Dong-A University College of Medicine, Dongdaesin-dong 3(sam)ga, Seo-gu, Busan, 602-715, South Korea.
authors: Sunseob
authors: S
authors: Choi
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging* / Q000209:etiology*; D014545:Urinary Calculi / Q000150:complications* / Q000000981:diagnostic imaging*; D055815:Young Adult
chemical_list: D003287:Contrast Media
keywords: Hydronephrosis; Kidney; Multidetector computed tomography; Renal insufficiency; Ureteral calculi