Comparison of Outcomes of Ischemic Stroke Initially Imaged With Cranial Computed Tomography Alone vs Computed Tomography Plus Magnetic Resonance Imaging

ACR Appropriateness Criteria® Cerebrovascular Diseases-Stroke and Stroke-Related Conditions

Cerebrovascular disease encompasses a vast array of conditions. The imaging recommendations for stroke-related conditions involving noninflammatory steno-occlusive arterial and venous cerebrovascular disease including carotid stenosis, carotid dissection, intracranial large vessel occlusion, and cerebral venous sinus thrombosis are encompassed by this document. Additional imaging recommendations regarding complications of these conditions including intraparenchymal hemorrhage and completed ischemic strokes are also discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Moving From CT to MRI Paradigm in Acute Ischemic Stroke: Feasibility, Effects on Stroke Diagnosis and Long-Term Outcomes

BACKGROUND

The relative value of computed tomography (CT) and magnetic resonance imaging (MRI) in acute ischemic stroke (AIS) is debated. In May 2018, our center transitioned from using CT to MRI as first-line imaging for AIS. This retrospective study aims to assess the effects of this paradigm change on diagnosis and disability outcomes.

METHODS

We compared all consecutive patients with confirmed diagnosis of AIS admitted to our center during the MRI-period (May 2018-August 2022) and an identical number of patients from the preceding CT-period (December 2012-April 2018). Univariable and multivariable analyses were performed to evaluate outcomes, including the number and delay of imaging exams, the rate of missed strokes, stroke mimics treated with thrombolysis, undetermined stroke mechanisms, length of hospitalization, and 3-month disability.

RESULTS

The median age of the 2972 included patients was 76 years (interquartile range, 65-84), and 46% were female. In the MRI-period, 80% underwent MRI as first acute imaging. The proportion of patients requiring a second acute imaging modality for diagnostic ± revascularization reasons increased from 2.1% to 5% (Punadj <0.05), but it decreased in the subacute phase from 79.0% to 60.1% (Padj <0.05). In thrombolysis candidates, there was a 2-minute increase in door-to-imaging delay (Padj <0.05). The rates of initially missed AIS diagnosis was similar (3.8% versus 4.4%, Padj=0.32) and thrombolysis in stroke mimics decreased by half (8.6% versus 4.3%; Padj <0.05). Rates of unidentified stroke mechanism at hospital discharge were similar (22.8% versus 28.1%; Padj=0.99). The length of hospitalization decreased from 9 (interquartile range, 6-14) to 7 (interquartile range, 4-12) days (Padj=0.62). Disability at 3 months was similar (common adjusted odds ratio for favorable Rankin shift, 0.98 [95% CI, 0.71-1.36]; Padj=0.91), as well as mortality and symptomatic intracranial hemorrhage.

CONCLUSIONS

A paradigm shift from CT to MRI as first-line imaging for AIS seems feasible in a comprehensive stroke center, with a minimally increased delay to imaging in thrombolysis candidates. MRI was associated with reduced thrombolysis rates of stroke mimics and subacute neuroimaging needs.