Can Multidirectional DWI Improve Low-Field MRI Detection of Acute Ischemic Stroke?

Researchers have demonstrated that a multidirectional diffusion-weighted imaging (DWI) sequence on portable low-field magnetic resonance imaging (MRI) may significantly improve sensitivity for detecting small ischemic stroke lesions in comparison to conventional single-direction DWI, a finding with meaningful implications for triage in the emergency department.

For the prospective study, recently published in Stroke: Vascular and Interventional Neurology, researchers compared multidirectional diffusion-weighted imaging (DWI) and single-direction imaging with low-field MRI (Swoop system, Hyperfine) in a 95-patient cohort. The cohort included 62 cases of confirmed acute ischemic stroke, according to the study.

The study authors found that multidirectional DWI achieved a 95 percent positive predictive value (PPV) for differentiating acute ischemic stroke and stroke mimics in comparison to 78.2 percent for single-direction DWI. In a recent interview with Diagnostic Imaging, W. Taylor Kmberly, M.D., Ph.D., a senior author of the study, emphasized the utility of multidirectional DWI in detecting smaller ischemic lesions.

“The key takeaway is that we were able to detect ischemic stroke lesions that were about .4 or .5 CCs in volume or, if you were to measure it in a single dimension, we could measure down to 2.8 millimeters. So these are very small lesions, and we were able to do so with the multi-direction DWI sequence. With a single direction (imaging), the limit of sensitivity was more in the range of 1, 2 or 3 CCs,” pointed out Dr. Kimberly, chief of the Division of Neurocritical Care in the Department of Neurology at Mass General Brigham, and professor of neurology at Harvard Medical School.

Dr. Kimberly said the increased capability of the multi-directional DWI with a portable low-field MRI device to identify smaller ischemic lesions could facilitate more timely triage decisions for patients with mild neurological symptoms or transient neurological symptoms. He added that patients with transient ischemic attack (TIA) or mild stroke now account for nearly half of patients with strokes or stroke-like symptoms.

“That's one area where we think this technology can make a big difference is in that emergency room environment, helping with the triage, and, frankly, doing it even faster, because patients come right to the scanner or the scanner comes to the patient. There's less of a wait to get that scan and help make those important triage decisions,” emphasized Dr. Kimberly.

(Editor’s note: For related content, see “FDA Clears Updated Software for Faster Low-Field MRI Brain Scans,” “Neuroradiology Insights on the Updated AHA/ASA Guideline for Management of Acute Ischemic Stroke” and “Can AI Foundation Models Bolster the Amount of Imaging Data Obtained from Brain MRI?: An Interview with Benjamin Kann, MD.”)

Reference

1. Sorby-Adams A, Pinter NK, Demopoulos A, et al. Enhanced detection of acute ischemic stroke with low-field MRI. Stroke Vasc Interv Neurol. 2026 Jan 21;6(2):e002110. doi: 10.1161/SVIN.125.002110. eCollection 2026 Mar.