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

A 78 Seconds Complete Brain MRI Examination in Ischemic Stroke: A Prospective Cohort Study

“…As DWI and T2* images were echo‐planar based with similar artifacts in both methods as previously reported 20 these artifacts did not cause differences in infarction detection comparing EPIMix and routine clinical MRI. This is in concordance with the previously reported similar diagnostic performance for infarctions in the posterior fossa for EPIMix compared to clinical MRI 21 . EPIMix had fewer motion artifacts than routine clinical MRI, probably due to the inherent motion‐robustness of the fast single‐shot echo‐planar technique.…”

NeuroMix—A single‐scan brain exam

“…In this work, we presented a new multicontrast sequence, NeuroMix, that includes the five most important contrasts for neuroimaging; T1w, T2w, T2*w, T2-FLAIR, and DWI. [15][16][17] Based on clinical experience from several hospitals with its predecessor, EPIMix, [25][26][27] NeuroMix has been developed as a standalone screening tool for brain MRI. Most importantly, the EPI readouts traditionally suffering from geometric distortions due to the low phase-encoding bandwidth were replaced by SSFSE readouts for the contrasts considered crucial for neurological screening: T2w and T2-FLAIR.…”

“…Recently, we presented EPIMix, 23,24 in which we combined a single‐shot EPI readout with different magnetization preparations, yielding a highly motion‐robust sequence acquiring the top‐five contrasts T1w, T2w, T2‐FLAIR, T2*w, and DWI in a little bit more than a minute. Several clinical studies have acknowledged that the quality of EPIMix is sufficient with only marginally lower diagnostic performance compared with conventional imaging 25–27 . The main clinical drawback for EPIMix was the inherent geometric distortions caused by the EPI readout, 25–27 which makes diagnosis near the skull base particularly problematic.…”

“…Several clinical studies have acknowledged that the quality of EPIMix is sufficient with only marginally lower diagnostic performance compared with conventional imaging. [25][26][27] The main clinical drawback for EPIMix was the inherent geometric distortions caused by the EPI readout, [25][26][27] which makes diagnosis near the skull base particularly problematic. The EPIMix method was therefore not sufficient to use as the only scan of a brain MRI screening protocol.…”

Combined acquisition of diffusion and T2*-weighted measurements using simultaneous multi-contrast magnetic resonance imaging

“…In these studies, T 2 *W images are acquired using gradient-recalled echo (GRE) sequences, such as FLASH [12,13] or single-shot, echo-planar imaging (ss-EPI) [14,15]. There are several publications showing that GRE-EPI for T 2 *W imaging is an appropriate choice for the detection of microbleeds in acute cerebral stroke [16][17][18][19][20], even at a relatively course base resolution [20,21]. Depending on the sequence type and protocol parameters, the scan times for these T 2 *W acquisitions range from tens of seconds to several minutes, with a corresponding variation in image quality and diagnostic value.…”