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Updated: May 15, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Clinical evaluation of single-shot and readout-segmented diffusion-weighted imaging in stroke patients at 3 T
John Morelli1, David Porter, Fei Ai
1Scott & White Memorial Hospital/Texas A&M Health Sciences Center, Radiology, Temple, TX, USA.
Background:
Diffusion-weighted imaging (DWI) magnetic resonance imaging (MRI) is most commonly performed utilizing a single-shot echo-planar imaging technique (ss-EPI). Susceptibility artifact and image blur are severe when this sequence is utilized at 3 T.
Purpose:
To evaluate a readout-segmented approach to DWI MR in comparison with single-shot echo planar imaging for brain MRI.
Material And Methods:
Eleven healthy volunteers and 14 patients with acute and early subacute infarctions underwent DWI MR examinations at 1.5 and 3T with ss-EPI and readout-segmented echo-planar (rs-EPI) DWI at equal nominal spatial resolutions. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) calculations were made, and two blinded readers ranked the scans in terms of high signal intensity bulk susceptibility artifact, spatial distortions, image blur, overall preference, and motion artifact.
Results:
SNR and CNR were greatest with rs-EPI (8.1 ± 0.2 SNR vs. 6.0 ± 0.2; P <10(-4) at 3T). Spatial distortions were greater with single-shot (0.23 ± 0.03 at 3T; P <0.001) than with rs-EPI (0.12 ± 0.02 at 3T). Combined with blur and artifact reduction, this resulted in a qualitative preference for the readout-segmented scans overall.
Conclusion:
Substantial image quality improvements are possible with readout-segmented vs. single-shot EPI - the current clinical standard for DWI - regardless of field strength (1.5 or 3 T). This results in improved image quality secondary to greater real spatial resolution and reduced artifacts from susceptibility in MR imaging of the brain.
Insights
Readout-segmented echo-planar (rs-EPI) DWI significantly improves brain MRI quality compared to single-shot EPI. This advanced technique reduces artifacts and enhances spatial resolution, offering better diagnostic clarity at both 1.5 T and 3 T.
Area of Science:
- Medical Imaging
- Radiology
- Neuroimaging
Background:
- Diffusion-weighted imaging (DWI) is crucial for brain MRI.
- Single-shot echo-planar imaging (ss-EPI) is the standard DWI technique.
- ss-EPI at 3 T suffers from severe susceptibility artifact and image blur.
Purpose of the Study:
- To compare readout-segmented EPI (rs-EPI) with ss-EPI for brain DWI.
- To evaluate DWI MR performance at 1.5 T and 3 T.
Main Methods:
- 11 healthy volunteers and 14 patients underwent DWI MR at 1.5 T and 3 T.
- Scans were acquired using both ss-EPI and rs-EPI techniques at equal nominal spatial resolutions.
- Quantitative SNR/CNR and qualitative reader assessments of artifacts and image quality were performed.
Main Results:
- rs-EPI demonstrated significantly higher SNR and CNR compared to ss-EPI at 3 T.
- rs-EPI showed reduced spatial distortions compared to ss-EPI at 3 T.
- Readers preferred rs-EPI scans due to reduced blur and artifact, leading to better overall image quality.
Conclusions:
- rs-EPI offers substantial image quality improvements over ss-EPI for brain DWI.
- These improvements are evident at both 1.5 T and 3 T field strengths.
- rs-EPI provides greater real spatial resolution and reduced susceptibility artifacts, enhancing MR imaging of the brain.
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