Physicians often order contrast-enhanced computed tomography (CT) to evaluate patients with suspected acute colonic diverticulitis, but studies suggest that intravenous contrast is unnecessary for this purpose. These researchers studied 110 consecutive patients with acute or subacute left-lower abdominal pain and suspected diverticulitis. Each patient underwent both low-dose unenhanced multidetector-row CT and standard-dose contrast-enhanced multidetector-row CT. Final diagnoses were based on clinical follow-up, surgical findings, and response to treatment.
Thirty-nine patients were ultimately diagnosed with diverticulitis. The interpretations of two radiologists were 100% sensitive and 99% specific with both low-dose unenhanced CT and standard-dose enhanced CT. A third radiologist and a gastroenterologist were slightly less accurate (sensitivities around 90% and specificities around 95%), but again, both the enhanced and unenhanced scans yielded similar results.
These findings suggest that low-dose unenhanced CT is satisfactory for diagnosing acute colonic diverticulitis. The low-dose scan used in this study exposed patients to 75% less radiation than the standard-dose scan. Moreover, because intravenous contrast appears to be unnecessary, clinicians can evaluate patients with renal impairment without having to worry about contrast-induced nephropathy.
Reference:
Tack D et al. Suspected acute colon diverticulitis: Imaging with low-dose unenhanced multi-detector row CT. Radiology 2005 Oct; 237:189-96.