Utility of Repeat Cerebrovascular Imaging among Hospitalized Stroke Patients

The purpose of this study is to evaluate the frequency and clinical utility of repeat cerebrovascular imaging with computed tomography angiography (CTA) of the head after contrast-enhanced magnetic resonance angiography (CE-MRA) of the head in acute stroke patients.

All stroke patients admitted to 2 academic medical centers from January 1, 2012 through December 31, 2014 were identified as part of prospective radiology database if they underwent CE-MRA of the head followed by subsequent CTA of the head within 7 days. Two vascular neurologists blinded to CTA results retrospectively reviewed medical records including documented indications for imaging studies and clinical changes in patients to determine necessity of CTA.

Of 1355 acute stroke patients who underwent CE-MRA of the head, 195 (14%) patients underwent subsequent CTA of the head within 7 days, including 33 patients with nondiagnostic CE-MRA because of motion artifact. Of the remaining 162 (12%) patients, 69 (43%) were considered to have an unnecessary CTA of the head. Multivariable logistic regression analysis identified (1) absence of new neurologic examination changes [OR 7.29; 95% CI 1.92-27.63] and (2) same documented indication for both studies [OR 6.47; 95% CI 3.04-13.78] as significant predictors of an unnecessary CTA. Changes in clinical management after CTA were significantly more common in necessary CTAs compared with studies determined to be unnecessary (42% versus 7%, P < .0001).

The utility of repeat cerebrovascular imaging with CTA of the head following a diagnostic CE-MRA is low when there is no change in neurologic examination or when ordered for the same indication.