Manifold‐based respiratory phase estimation enables motion and distortion correction of free‐breathing cardiac diffusion tensor MRI

• Published in: Magnetic resonance in medicine Vol. 87; no. 1; pp. 474 - 487
• Main Authors: Coll‐Font, Jaume, Chen, Shi, Eder, Robert, Fang, Yiling, Han, Qiao Joyce, Boomen, Maaike, Sosnovik, David E., Mekkaoui, Choukri, Nguyen, Christopher T.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.01.2022
• Subjects: Alignment; Anisotropy; Breathing; cardiac MRI; Compensation; Diffusion Magnetic Resonance Imaging; Diffusion Tensor Imaging; Diffusivity; Distortion; distortion correction; Echo-Planar Imaging; EKG; Electrocardiography; free‐breathing; Heart; Humans; Image acquisition; Laplacian eigenmaps; Magnetic resonance imaging; Mathematical analysis; Misalignment; Motion; Motion compensation; Parameters; Reproducibility of Results; Respiration; Retrospective Studies; Tensors; Ventricle; Laplacian eigenmaps; diffusion tensor imaging; free-breathing; distortion correction; cardiac MRI; motion compensation
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.28972

Purpose For in vivo cardiac DTI, breathing motion and B0 field inhomogeneities produce misalignment and geometric distortion in diffusion‐weighted (DW) images acquired with conventional single‐shot EPI. We propose using a dimensionality reduction method to retrospectively estimate the respiratory phase of DW images and facilitate both distortion correction (DisCo) and motion compensation. Methods Free‐breathing electrocardiogram‐triggered whole left‐ventricular cardiac DTI using a second‐order motion‐compensated spin echo EPI sequence and alternating directionality of phase encoding blips was performed on 11 healthy volunteers. The respiratory phase of each DW image was estimated after projecting the DW images into a 2D space with Laplacian eigenmaps. DisCo and motion compensation were applied to the respiratory sorted DW images. The results were compared against conventional breath‐held T2 half‐Fourier single shot turbo spin echo. Cardiac DTI parameters including fractional anisotropy, mean diffusivity, and helix angle transmurality were compared with and without DisCo. Results The left‐ventricular geometries after DisCo and motion compensation resulted in significantly improved alignment of DW images with T2 reference. DisCo reduced the distance between the left‐ventricular contours by 13.2% ± 19.2%, P < .05 (2.0 ± 0.4 for DisCo and 2.4 ± 0.5 mm for uncorrected). DisCo DTI parameter maps yielded no significant differences (mean diffusivity: 1.55 ± 0.13 × 10−3 mm2/s and 1.53 ± 0.13 × 10−3 mm2/s, P = .09; fractional anisotropy: 0.375 ± 0.041 and 0.379 ± 0.045, P = .11; helix angle transmurality: 1.00% ± 0.10°/% and 0.99% ± 0.12°/%, P = .44), although the orientation of individual tensors differed. Conclusion Retrospective respiratory phase estimation with LE‐based DisCo and motion compensation in free‐breathing cardiac DTI resulting in significantly reduced geometric distortion and improved alignment within and across slices.