Abstract

ABSTRACT:
BACKGROUND:
About 2-3% of the population experiences an attack of acute ureteric colic during their lifetime,
and 67%-95% caused by ureteric calculi. Magnetic Resonance Imaging (MRI) can rapidly
demonstrate both the presence and the level of ureteric obstruction.]
OBJECTIVE:
To study the diagnostic accuracy of MRI (alone and in combination with plain abdominal
radiograph) in detecting acute ureteric calculus obstruction compared to unenhanced Computed
Tomography (CT).
PATIENTS AND METHODS:
A cross sectional comparative study was conducted on a total of 48 patients suspected to have
acute ureteric calculus obstruction, at the radiology department in AL-Imamain AL-Kadhemain
Medical city, during the period from March to November 2015. Patients underwent MRU then
unenhanced abdominal CT, and plain abdominal radiograph. The sensitivity, specificity, positive
predictive value, negative predictive value and overall accuracy of MRU findings were obtained in
comparison to CT findings regarding ureteric dilatation and its level, stone detection and perirenal
fluid and fat stranding.
RESULTS:
Of the 48 patients imaged with both CT and MRU, 4 of them showed no evidence of obstruction
on any imaging modality, and 44 of them had a final diagnosis of acute calculus ureteric
obstruction. Regarding the detection of ureteric dilatation in MRU, in comparison to CT, the
sensitivity = 100%, specificity = 80%, the positive predictive value (97.72%), the negative
predicative value (100%), and overall accuracy (97.9%). The detection of ureteric stone by MRU
(when combined with plain abdominal radiograph) in comparison to CT, the sensitivity = 95.45%,
specificity = 100%, the positive predictive value (100%), the negative predicative value (66.66%),
and over all accuracy (95.8%). The detection of peri-renal fluid by MRU in comparison to CT, the
sensitivity = 96.66%, specificity = 72.22%, positive predictive value (85.29%), the negative
predicative value (92.85%), and overall accuracy (87.5%).
CONCLUSION:
MRI when combined with plain abdominal radiograph was nearly as accurate as unenhanced spiral
CT in acute calculus ureteric obstruction. Also the MRI was more sensitive than unenhanced CT
in detecting the secondary signs of upper urinary tract obstruction, as perirenal fluid.