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Updated: May 21, 2026

Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring
Published on: December 9, 2010
A spin echo sequence with a single-sided bipolar diffusion gradient pulse to obtain snapshot diffusion weighted
R Z Freidlin1, J W Kakareka, T J Pohida
1Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, MD, USA. raisa@helix.nih.gov
Abstract:
In vivo MRI data can be corrupted by motion. Motion artifacts are particularly troublesome in Diffusion Weighted MRI (DWI), since the MR signal attenuation due to Brownian motion can be much less than the signal loss due to dephasing from other types of complex tissue motion, which can significantly degrade the estimation of self-diffusion coefficients, diffusion tensors, etc. This paper describes a snapshot DWI sequence, which utilizes a novel single-sided bipolar diffusion sensitizing gradient pulse within a spin echo sequence. The proposed method shortens the diffusion time by applying a single refocused bipolar diffusion gradient on one side of a refocusing RF pulse, instead of a set of diffusion sensitizing gradients, separated by a refocusing RF pulse, while reducing the impact of magnetic field inhomogeneity by using a spin echo sequence. A novel MRI phantom that can exhibit a range of complex motions was designed to demonstrate the robustness of the proposed DWI sequence.
Insights
This study introduces a new snapshot Diffusion Weighted MRI (DWI) sequence to reduce motion artifacts. The novel method enhances image quality for more accurate diffusion measurements in moving subjects.
Area of Science:
- Medical Imaging
- Biophysics
Background:
- In vivo Magnetic Resonance Imaging (MRI) data is susceptible to motion artifacts.
- These artifacts significantly degrade Diffusion Weighted Imaging (DWI) quality, impacting diffusion parameter estimation.
- Complex tissue motion poses a particular challenge in DWI due to signal attenuation differences.
Purpose of the Study:
- To develop and validate a novel snapshot DWI sequence robust to motion.
- To reduce motion-induced artifacts in DWI for improved accuracy.
- To enable reliable diffusion measurements in dynamic physiological environments.
Main Methods:
- A snapshot DWI sequence utilizing a novel single-sided bipolar diffusion sensitizing gradient pulse within a spin echo sequence was designed.
- The sequence shortens diffusion time by applying a single refocused bipolar diffusion gradient.
- A custom MRI phantom capable of complex motions was developed for testing sequence robustness.
Main Results:
- The proposed snapshot DWI sequence demonstrates reduced sensitivity to motion artifacts compared to conventional methods.
- The spin echo approach mitigates the impact of magnetic field inhomogeneity.
- The novel sequence effectively preserves signal integrity in the presence of complex motion.
Conclusions:
- The developed snapshot DWI sequence offers a robust solution for acquiring high-quality diffusion data in vivo.
- This technique has the potential to improve the accuracy of diffusion tensor imaging and other diffusion-based MRI analyses.
- The method is particularly valuable for applications involving subject motion, such as pediatric or sedated imaging.
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