Unenhanced versus multiphase MDCT in patients with hematuria, flank pain, and a negative ultrasound.
OBJECTIVE
To compare the impact of unenhanced and contrast-enhanced multi-detector computed tomography (MDCT) for the detection of urinary stones and urinary obstruction in patients with suspected renal colic.


METHODS
95 patients with suspected renal colic underwent a three-phase MDCT for evaluation of the urinary tract. The unenhanced scan and the multiphase examination were reviewed retrospectively by two radiologists for the characterization of urinary stones and signs of obstruction. Results of unenhanced MDCT were compared with those obtained during the second review of the entire multiphase examination.


RESULTS
Overall diagnosis of urinary stones revealed an accuracy of 97.0% for unenhanced, and 98.9% for multiphase MDCT with a significant difference between both protocols (mixed-effects logistic regression: odds ratio 3.3; p=0.019). With 3 versus 15 false positive ratings, multiphase MDCT was superior to unenhanced MDCT for the diagnosis of urinary stones. There was no significant difference in detecting signs of obstruction. Inter-reader agreement for overall stone detection was excellent on both unenhanced (kappa 0.84) and multiphase (kappa 0.88) MDCT.


CONCLUSIONS
Contrast-enhanced multiphase MDCT offers distinct advantages compared to an unenhanced approach for the assessment of urinary stone disease, and therefore should be considered as a complementary examination for patients with inconclusive findings.
Institute of Diagnostic Radiology, Department of Medical Radiology, University Hospital of Zurich, and Biostatistics Unit, Institute of Social and Preventive Medicine, University of Zurich, Raemistrasse 100, 8006 Zurich, Switzerland. t-krauss@gmx.de
T
T
Krauss
T
T
Frauenfelder
R T
RT
Strebel
J
J
Birzele
H
H
Scheffel
B
B
Seifert
B
B
Marincek
G W
GW
Goerres
D003287:Contrast Media; D005260:Female; D021501:Flank Pain / Q000000981:diagnostic imaging*; D006417:Hematuria / Q000000981:diagnostic imaging*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted; D056844:Renal Colic / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids; D014463:Ultrasonography; D052878:Urolithiasis / Q000000981:diagnostic imaging*
D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol