title: Renal stones on portal venous phase contrast-enhanced CT: does intravenous contrast interfere with detection?
abstract: OBJECTIVE
  To determine the sensitivity of portal venous phase contrast-enhanced CT for the detection of renal stones.
  
  
  METHODS
  This retrospective study included 97 CT examinations of the abdomen without and with intravenous contrast, including 85 (87.6%) examinations with at least one renal stone on the "gold standard" noncontrast images, as scored by a single radiologist. Three other radiologists each independently reviewed only the contrast-enhanced images from all 97 examinations and recorded all renal stones. Reviewer sensitivity for stones was categorized by stone diameter. Reviewer sensitivity and specificity for stone disease were also calculated on a per-kidney basis.
  
  
  RESULTS
  The 97 cases included a total of 238 stones ≥1 mm, with a mean (±SD) of 1.2 ± 1.9 stones per kidney and a stone diameter of 3.5 ± 3.0 mm. Pooling data for the three reviewers, sensitivity for all stones was 81%; sensitivity for stones ≥2, ≥3, ≥4, and ≥5 mm was 88%, 95%, 99%, and 98%, respectively. Sensitivity for stone disease on a per-kidney basis was 94% when considering all stones; when considering only stones ≥2, ≥3, and ≥4 mm, sensitivity was 96%, 99%, and 100%, respectively. Specificity for stone disease on a per-kidney basis was 98% overall, 99% when considering only stones ≥2 mm, and 100% when considering only stones ≥3 mm.
  
  
  CONCLUSIONS
  Contrast-enhanced CT is highly sensitive for the detection of renal stones ≥3 mm in diameter and less sensitive for smaller stones. In cases where the clinical diagnosis is uncertain and performance of a CT examination is being contemplated, intravenous contrast utilization would allow assessment for stone disease while also optimizing evaluation for other conditions.
authors: Department of Radiology, Albert Einstein College of Medicine and Montefiore Medical Center, 111 E 210th St, Bronx, NY, 10467, USA, rdym@montefiore.org.
authors: R Joshua
authors: RJ
authors: Dym
authors: Dameon R
authors: DR
authors: Duncan
authors: Michael
authors: M
authors: Spektor
authors: Hillel W
authors: HW
authors: Cohen
authors: Meir H
authors: MH
authors: Scheinfeld
mesh_terms: D061605:Administration, Intravenous; D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011169:Portal Vein; D011856:Radiographic Image Enhancement / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media