June 27, 2010

Helical CT for Urolithiasis

A coronal-reformatted CT image (without IV contrast) shows an obstructing right ureterovesical junction (UVJ) stone (arrow), causing hydroureteronephrosis. There is enlargement of the right kidney with perinephric stranding (arrowheads) as a result.

  • Urolithiasis incidence in the U.S. and Europe approximately 0.1% - 0.4% of population
  • Male to female ratio = 3:1
  • Peak age during third to fifth decade of life
  • Recurrence rate about 75% during 20 years
Detection Rates by Various Imaging Methods
  • Conventional radiography 50-70%
  • Intravenous urography (IVU) 70-90%
  • Ultrasound 50-60%
  • Normal-dose CT: sensitivity 94-100%, specificity 97%
  • Low-dose CT: sensitivity 95%, specificity 95%
Advantages of CT over IVU
  • Shorter examination time
  • Avoid cost and complications of IV contrast
  • Greater sensitivity for stone detection
  • Higher potential for detection of abnormalities unrelated to stone disease
  • Study directly compared low-dose (<>
  • Meta-analysis of 7 studies of low-dose CT in 1061 patients showing 95% sensitivity and specificity for stone diagnosis
1. Liu W, Esler SJ, Kenny BJ, et al. Low-dose nonenhanced helical CT of renal colic: assessment of ureteric stone detection and measurement of effective dose equivalent. Radiology 2000;215:51-54.
2. Niemann T, Kollmann T, Bongartz G. Diagnostic performance of low-dose CT for the detection of urolithiasis: a meta-analysis. AJR 2008;191:396-401.

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