Differences of renal parenchymal attenuation for acutely obstructed and unobstructed kidneys on unenhanced helical CT: a useful secondary sign?
OBJECTIVE
The purpose of this study was to ascertain whether the difference in attenuation frequently noted on unenhanced helical CT scans between a patient's acutely obstructed kidney and the unobstructed kidney is a reliable secondary sign of acute renal obstruction.


CONCLUSIONS
In 95% of patients with acute renal obstruction, the affected kidney was less dense than the unobstructed kidney. When visually detected by radiologists using CT, this difference in density was at least two standard deviations above normal, making it a reliable secondary sign for acute obstruction.
Department of Radiology, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287, USA.
C S
CS
Georgiades
C J
CJ
Moore
D P
DP
Smith
D000208:Acute Disease; D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging*; D007089:Image Enhancement; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging*