One-Minute Multi-contrast Echo Planar Brain MRI in Ischemic Stroke: A Retrospective Observational Study of Diagnostic Performance

Abstract

Background: Fast multi-contrast echo planar MRI (EPIMix) has comparable diagnostic performance to standard MRI for detecting brain pathology but its performance in detecting acute cerebral infarctions has not been determined.

Purpose: To assess the diagnostic performance of EPIMix for the detection of acute cerebral infarctions.

Study type: Retrospective observational cohort.

Population: One hundred and seventy-two consecutive patients with a clinical suspicion of non-hyperacute ischemic stroke (January 2018 to December 2019).

Field strength and sequence: 1.5 T or 3 T. EPIMix ((echo-planar based: diffusion weighted (DWI), T2*-weighted, T2-weighted, T2- and T1-fluid attenuated inversion recovery (FLAIR) images) vs. standard MRI: echo-planar DWI, echo-planar T2*-weighted or susceptibility weighted, turbo spin-echo T2-weighted, T2- and T1-FLAIR turbo spin-echo sequences.

Assessment: Three neuroradiologists rated EPIMix and standard MRI on two separate occasions. Incongruent assessments were resolved in consensus with the fourth reader. The ratings included the diagnostic category (acute infarct, normal, and other pathology). Congruent diagnoses together with consensus diagnoses served as the reference standard.

Statistical tests: The diagnostic performance of EPIMix and standard MRI against the reference standard was calculated by the area under the receiver operating characteristic curve (AUC) and compared by DeLong's test. Sensitivity and specificity were determined. Inter-rater agreements were evaluated by Fleiss's kappa.

Results: Of 172 patients (61 ± 16 years, 103 men), acute infarcts were present in 80/172 (47%), normal findings in 60/172 (35%), and other pathology in 32/172 (19%). Across readers, the AUCs were .94-.95 for EPIMix and .95-.99 for standard MRI, with overlapping 95% CI (P = .02-.18). Inter-rater agreement for EPIMix was 0.90 and for standard MRI was 0.93. The sensitivity for EPIMix and standard MRI was 88-91% and 91-98%, respectively, while the specificity was 98-100% and 98-99%, both with overlapping 95% CI.

Conclusion: Multi-contrast echo planar MRI showed a high but marginally lower diagnostic performance compared to standard MRI for the detection and characterization of acute brain infarct.

Level of evidence: 3 TECHNICAL EFFICACY: Stage 2.

Keywords: EPIMix; brain infarction; diagnostic performance; fast imaging; ischemic stroke; multi-contrast MRI.