Combination of noninvasive neurovascular imaging modalities in stroke patients: patterns of use and impact on need for digital subtraction angiography.

BACKGROUND The diagnostic work-up of acute stroke relies on the use of proper imaging studies. We sought to determine the use of a combination of 2 noninvasive tests, namely magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) in diagnosing vascular lesions and the necessity for a subsequent digital subtraction angiography (DSA) for the definitive diagnosis. METHODS Patients admitted to 2 comprehensive stroke centers between January 2008 and July 2010 who had an equivocal initial noninvasive test were reviewed. The proportions of patients who underwent CTA and MRA in combination and those who required additional DSA for definitive diagnosis were determined. The diagnostic yield and impact on management in patients with CTA and MRA combination was compared with patients who underwent CTA and MRA followed by DSA. RESULTS Among a total of 1063 patients (mean age ± SD 63 ± 16), 384 (36%) underwent >1 vascular imaging study. There was no difference in the rates of cardiovascular risk factors and stroke subtype between different combination groups. The agreement between CTA and MRA was high (concordance 81%). Among the 164 patients who underwent both CTA and MRA, a DSA was required for resolution/confirmation in only 27 (16%) patients. Among these 27, DSA findings changed the clinical decision-making in 22 (82%) patients (11 stenotic severities and 11 diagnoses of arteriovenous fistula, aneurysm, or dissection). CONCLUSIONS In our experience, a combination of CTA and MRA was frequently used in patients in whom the initial noninvasive imaging was determined insufficient. The combination of findings from CTA and MRA were considered adequate in a large portion of patients resulting in a lower requirement for DSA and higher treatment impact from DSA.