Additional Non-contrast CT to Portal Venous Phase is not Relevant for Patients referred for Colonic Diverticulitis or...

To evaluate the usefulness of unenhanced CT added to the portal venous phase in the diagnostic accuracy of acute colonic diverticulitis/sigmoiditis.

Between January 1st and December 31st, 2020, all consecutive adult patients referred to the radiology department for clinical suspicion of acute colonic diverticulitis/sigmoiditis were retrospectively screened. To be included, patients must have undergone a CT with both unenhanced (UCT) and contrast-enhanced portal venous phase CT (CECT). CT examinations were assessed for features of diverticulitis, complications, differential diagnosis and incidental findings using UCT + CECT association, medical management, and follow-up as the reference. Radiation doses were recorded on our image archiving system and assessed.

Of the 114 patients included (mean age was 67±18 years; 60% were female), 46 had acute colonic diverticulitis/sigmoiditis. No diagnosis of sigmoiditis/diverticulitis, complication or differential diagnosis was missed with the CECT alone. Apart from diverticulitis, only one 2 mm meatal urinary microlithiasis was missed with no impact on patient management. The confidence level in diagnosis was not increased by UCT. The average DLP of CECT was 450 mGy.cm, and 382 mGy.cm for UCT. The use of a single-phase CECT acquisition allowed a reduction of 45.9% of the irradiation.

Unenhanced CT is not necessary for patients addressed with clinical suspicion of acute colonic diverticulitis/sigmoiditis, and CECT alone protocol must be used.