title: Patients with acute flank pain: comparison of MR urography with unenhanced helical CT.
abstract: OBJECTIVE
  To compare unenhanced helical computed tomography (CT) and magnetic resonance (MR) urography, by using T2-weighted and contrast material-enhanced T1-weighted imaging to examine patients with acute flank pain, with reference to excretory urography and final clinical diagnosis.
  
  
  METHODS
  Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine-enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results.
  
  
  RESULTS
  At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P <.001) and 0.75 (P <.001) and at MR urography, 0.49 (P =.005) and 0.51 (P =.004).
  
  
  CONCLUSIONS
  In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Finland. mazen.sudah@pkshp.fi
authors.forename: Mazen
authors.initials: M
authors.lastname: Sudah
authors.forename: Ritva L
authors.initials: RL
authors.lastname: Vanninen
authors.forename: Kaarina
authors.initials: K
authors.lastname: Partanen
authors.forename: Sakari
authors.initials: S
authors.lastname: Kainulainen
authors.forename: Auli
authors.initials: A
authors.lastname: Malinen
authors.forename: Antero
authors.initials: A
authors.lastname: Heino
authors.forename: Martti
authors.initials: M
authors.lastname: Ala-Opas
mesh_terms: D000208:Acute Disease; D005260:Female; D021501:Flank Pain / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014567:Urography / Q000379:methods