Brain diffusion MRI with multiplexed sensitivity encoding for reduced distortion in a pediatric patient population

Jens Johansson; Kerstin Lagerstrand; Liz Ivarsson; Pär-Arne Svensson; Hanna Hebelka; Stephan E Maier

doi:10.1016/j.mri.2022.01.003

Brain diffusion MRI with multiplexed sensitivity encoding for reduced distortion in a pediatric patient population

Magn Reson Imaging. 2022 Apr:87:97-103. doi: 10.1016/j.mri.2022.01.003. Epub 2022 Jan 7.

Authors

Jens Johansson¹, Kerstin Lagerstrand², Liz Ivarsson³, Pär-Arne Svensson³, Hanna Hebelka⁴, Stephan E Maier⁵

Affiliations

¹ Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. Electronic address: Jens.johansson@gu.se.
² Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.
³ Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
⁴ Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden; Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
⁵ Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.

PMID: 34999160
DOI: 10.1016/j.mri.2022.01.003

Abstract

Background: Diffusion-weighted imaging (DWI) is a valuable tool for routine imaging of the pediatric brain. However, the commonly used single-shot (ss) echo-planar imaging (EPI) DWI sequence is prone to geometric distortions and T₂*-blurring. This study aimed to investigate in a pediatric population the benefits of using multiplexed sensitivity-encoding (MUSE) without and with reversed polarity gradients (RPG) instead.

Methods: This retrospective study compared image quality, geometric distortions, and diffusion values between three different approaches for DWI (ssEPI, MUSE, and RPG-MUSE) in 14 patients (median age = 4 (0.6-15) years, 11 males). Distortion levels were quantified and compared in two brain regions, i.e., the brain stem and the temporal lobes, using the Dice Coefficient and the Hausdorff Distance, with T₂-weighted images as reference. Expected geometrical distortion was further evaluated by comparing the effective echo spacing between the DWI sequences. Apparent diffusion coefficient (ADC) values were determined in the genu of the corpus callosum and the optic nerves. Two raters graded overall image quality and image distortions on a Likert scale.

Results: Distortion levels assessed with Dice coefficient and Hausdorff distance were significantly lower for MUSE (p < 0.05) and RPG-MUSE (p < 0.01) compared to ssEPI. No significant difference in ADC values was observed between methods. The RPG-MUSE method was graded by one rater as significantly higher in overall image quality than ssEPI (p < 0.05) and by both raters as significantly lower in levels of image distortions than both MUSE (p < 0.05) and ssEPI (p < 0.05). These results were in agreement with the reduced effective echo spacing was that was attained with MUSE and RPG-MUSE.

Conclusion: For imaging of the pediatric brain, MUSE and even more so RPG-MUSE offers both improved geometric fidelity and image quality compared to ssEPI.

Keywords: Diffusion-weighted imaging; Echo-planar imaging; Geometric distortion; Multiplexed sensitivity-encoding; Pediatric brain; Reverse polarity gradients.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brain / diagnostic imaging
Child
Child, Preschool
Diffusion Magnetic Resonance Imaging* / methods
Echo-Planar Imaging* / methods
Humans
Magnetic Resonance Imaging
Male
Retrospective Studies