Compressed sensing velocity encoded phase contrast imaging: Monitoring skeletal muscle kinematics

Abstract

Purpose This study implements a compressed sensing (CS) 3‐directional velocity encoded phase contrast (VE‐PC) imaging for studying skeletal muscle kinematics within 40 s. Methods Independent variable density random sampling in the phase encoding direction for each temporal frame was implemented for various combinations of CS‐factors and views per segment. CS reconstruction was performed for the combined multicoil, temporal datasets using temporal Fourier transform followed by temporal principal component analysis sparsifying transformations. The method was tested on a flow phantom and in vivo, on velocity and strain rate of the medial gastrocnemius muscle of 11 subjects performing isometric contractions. Results For the flow phantom, velocity from 8 undersampled sequences matched very well with the flowmeter values over a range of velocities spanning in vivo muscle velocities. Bland‐Altman plots of the peak strain rate eigenvalues comparing 7 undersampled sequences was in good agreement with the reference (full k‐space) scan. CS‐factor of 4 combined with views per segment of 4 (scan times reduced by 4) yielded images with no visual artifacts allowing and yielded velocities and strain rate maps in the lower leg muscle in 40 s. Conclusion This study shows that a reduction in scan time of velocity encoded phase contrast imaging up to a factor of 4 is possible using the proposed CS reconstruction.

3D Muscle Deformation Mapping at Submaximal Isometric Contractions: Applications to Aging Muscle

“…The limitation of the velocity encoded MRI methods is the scan duration and the necessity for the subject to maintain consistent contractions for ∼70 cycles for imaging one slice. Recently, compressed sensing techniques combined with 2and 3-dimensional, 3-directional velocity encoded MRI with significant savings in times have been successfully implemented to study skeletal muscle kinematics (Mazzoli et al, 2018;Malis et al, 2020). Compressed sensing has been successfully integrated with MR imaging for reducing acquisition times and is a general approach for reconstructing a signal that has been sampled at frequencies well below the Nyquist frequency (Lustig et al, 2007).…”

Dynamic MRI of plantar flexion: A comprehensive repeatability study of electrical stimulation-gated muscle contraction standardized on evoked force

“…Although there have been many promising studies [10,11,[18][19][20][21][22], the reproducibility of PC imaging over spin tagging has been questioned [23]. The error of phase contrast sequence was reduced with the proper settings such as the phase encoding direction [24,25], but there has been no relevant study for motion guided by NMES.…”

“…existence of stiffness or atrophy [13]. Two parameters are mainly used for the final contractility evaluation: the strain [26] and the strain rate [13,19]. The strain is a tensorial quantity, which is defined as change of length per unit length in each spatial direction of a material under stress with respect to its length at rest.…”

“…The challenges of scanning standardization during voluntary contraction are the requirement for synchronization of the feedback loop with the MRI acquisition and the compliance of the subject with the exercise, which becomes even more important in case of patients [10][11][12][19][20][21]. An alternative is to use NMES for external controlled triggering.…”

Role of the Extracellular Matrix in Loss of Muscle Force With Age and Unloading Using Magnetic Resonance Imaging, Biochemical Analysis, and Computational Models

“…Frontiers in Physiology | www.frontiersin.org shear in the ECM and this is confirmed in the experimental studies (Sinha et al, 2018). Recent advances in fast sequences integrating compressed sensing with VE-PC acquisitions have enabled the study of the full 3D strain tensor at different %MVC at significantly lesser number of contraction cycles (Malis et al, 2019b(Malis et al, , 2020. It is anticipated that the ratio of shear to normal strains will decrease with increasing %MVC for aging subjects (compared to younger subjects) reflecting the decreased contribution of LTF in aging muscle.…”