Use of Multimodal Imaging for Thrombolysis-Eligible Stroke Patients Presenting to Hospitals in a Large Urban Region

Introduction: Advances in diagnostic imaging of stroke include the use of multimodal techniques, including noninvasive angiography to evaluate the intracranial and cervical vasculature as well as perfusion imaging. Despite increased adoption of these imaging techniques in academic medical centers, the current practice of multimodal imaging utilization among stroke patients in the community has remained largely uncharacterized. Methods: We quantified neuroimaging utilization in the ED among 1700 hyperacute stroke patients participating in the NIH Field Administration of Stroke Therapy Magnesium (FAST-MAG) study throughout Los Angeles and Orange Counties. Subjects were enrolled in the field <2 hours from symptom onset and transported to their usual care hospital, one of 58 centers throughout a single urban region. There was no recommendation as to what type of imaging should be utilized. Results: Of 1700 cases 1699 were imaged a median (IQR) of 92 (74-120) minutes after last known well time and 28 (19-40.75) minutes after ED arrival. The mean age was 71 (SD13) years old and the final diagnosis was cerebral ischemia in 73%, intracerebral hemorrhage in 23%, and mimic in 4%. Initial imaging scanner used in the ED was CT in a preponderance of cases (N=1612, 95%), with MRI in 88 cases (5%). Parenchymal CT scan was almost always performed without contrast and most commonly as the only study. However, CT angiography was obtained in 192 (11%) and perfusion CT in 91 (5.4%) cases in the first 24 hours. MRI imaging was universally obtained using diffusion-weighted images, 60% with MR angiography and 33% included perfusion imaging. Rates of multimodal (CTA and/or CTP) CT imaging utilization increased in the later years of the study from 4% in 2005-2006, 2% in 2007-2008, 8% in 2009-2010 and 26% in 2011-2012 (p for trend <0.001). There was no change in rates of multimodal MRI imaging as one academic medical center accounted for >80% of all studies. Conclusions: Among acute stroke patients presenting in the time window for TPA use, noncontrast CT was the most common initial imaging strategy in clinical practice in the 2005-2012 time period, though use of concomitant CTA grew to one-quarter of cases.