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High-resolution diffusion imaging using phase-corrected segmented echo-planar imaging
S Brockstedt1, J R Moore, C Thomsen
1Department of Diagnostic Radiology, Lund University Hospital, Sweden. Sara.Brockstedt@drad.lu.se
Abstract:
Diffusion magnetic resonance imaging (MRI) was performed with a high-resolution segmented echo-planar imaging technique, which provided images with substantially less susceptibility artifacts than images obtained with single-shot echo-planar imaging (EPI). Diffusion imaging performed with any multishot pulse sequence is inherently sensitive to motion artifacts and in order to reduce motion artifacts, the presented method utilizes navigator echo phase corrections, performed after a one-dimensional Fourier transform along the frequency-encoding direction. Navigator echo phases were fitted to a straight line prior to phase correction to avoid errors from internal motion. In vivo imaging was performed using electro cardiographic (ECG) triggering. Apparent diffusion coefficient (ADC) maps were calculated on a pixel-by-pixel basis using up to seven diffusion sensitivities, ranging from b = 0 to 1129 x 10(6) s/m(2).
Insights
This study introduces a new diffusion MRI technique using segmented echo-planar imaging and navigator echo phase corrections. This method significantly reduces motion and susceptibility artifacts, improving image quality for apparent diffusion coefficient mapping.
Area of Science:
- Medical Imaging
- Neuroimaging
- Biophysics
Background:
- Diffusion magnetic resonance imaging (dMRI) is crucial for assessing tissue microstructure.
- Susceptibility and motion artifacts commonly degrade dMRI quality, particularly with echo-planar imaging (EPI).
- Reducing these artifacts is essential for accurate quantitative analysis, such as apparent diffusion coefficient (ADC) mapping.
Purpose of the Study:
- To develop and evaluate a high-resolution segmented EPI technique for dMRI.
- To minimize susceptibility artifacts compared to single-shot EPI.
- To implement navigator echo phase corrections for reducing motion artifacts in multishot dMRI sequences.
Main Methods:
- High-resolution segmented echo-planar imaging (EPI) was employed.
- Navigator echo phase corrections were applied after 1D Fourier transform.
- Navigator echo phases were linearly fitted to correct for internal motion.
- In vivo imaging utilized electrocardiographic (ECG) triggering.
- Apparent diffusion coefficient (ADC) maps were calculated using multiple b-values (0-1129 x 10^6 s/m^2).
Main Results:
- The segmented EPI technique yielded images with substantially fewer susceptibility artifacts than single-shot EPI.
- Navigator echo phase corrections effectively reduced motion artifacts inherent in multishot sequences.
- The method allowed for robust pixel-by-pixel calculation of ADC maps.
Conclusions:
- The proposed high-resolution segmented EPI technique with navigator echo phase correction is effective in reducing artifacts in diffusion MRI.
- This advancement improves image quality and reliability for quantitative ADC mapping.
- The technique holds promise for enhanced diagnostic capabilities in various clinical applications.