Tractography of Porcine Meniscus Microstructure Using High-Resolution Diffusion Magnetic Resonance Imaging

Abstract

To noninvasively evaluate the three-dimensional collagen fiber architecture of porcine meniscus using diffusion MRI, meniscal specimens were scanned using a 3D diffusion-weighted spin-echo pulse sequence at 7.0 T. The collagen fiber alignment was revealed in each voxel and the complex 3D collagen network was visualized for the entire meniscus using tractography. The proposed automatic segmentation methods divided the whole meniscus to different zones (Red-Red, Red-White, and White-White) and different parts (anterior, body, and posterior). The diffusion tensor imaging (DTI) metrics were quantified based on the segmentation results. The heatmap was generated to investigate the connections among different regions of meniscus. Strong zonal-dependent diffusion properties were demonstrated by DTI metrics. The fractional anisotropy (FA) value increased from 0.13 (White-White zone) to 0.26 (Red-Red zone) and the radial diffusivity (RD) value changed from 1.0 × 10-3 mm2/s (White-White zone) to 0.7 × 10-3 mm2/s (Red-Red zone). Coexistence of both radial and circumferential collagen fibers in the meniscus was evident by diffusion tractography. Weak connections were found between White-White zone and Red-Red zone in each part of the meniscus. The anterior part and posterior part were less connected, while the body part showed high connections to both anterior part and posterior part. The tractography based on diffusion MRI may provide a complementary method to study the integrity of meniscus and nondestructively visualize the 3D collagen fiber architecture.

Applications of Diffusion‐Weighted MRI to the Musculoskeletal System

“…DTI provided objective biomarkers to assess graft healing following ACL reconstruction to guide the time of return to sports 77–79 . The zonal‐dependent DTI metrics (FA, MD, axial, and transversal diffusivity) of the porcine meniscus have been recently reported using a 3D DW‐SE sequence 80 . The complex collagen fiber architecture of the entire meniscus can be resolved by diffusion tractography 24,80 …”

“…[77][78][79] The zonal-dependent DTI metrics (FA, MD, axial, and transversal diffusivity) of the porcine meniscus have been recently reported using a 3D DW-SE sequence. 80 The complex collagen fiber architecture of the entire meniscus can be resolved by diffusion tractography. 24,80 Figure 10 summarizes the DWI studies in the ligament, tendon, and meniscus.…”

“…80 The complex collagen fiber architecture of the entire meniscus can be resolved by diffusion tractography. 24,80 Figure 10 summarizes the DWI studies in the ligament, tendon, and meniscus. Both FA and MD values are strongly dependent on the b-values in the tendon.…”

Natural biopolymer scaffold for meniscus tissue engineering

“…The collagen fibers in the main body of the meniscus are arranged in circular patterns, allowing pressure loads to be distributed, while the surface and middle of the meniscus are radially distributed to resist longitudinal tears caused by external forces (Beaupré et al, 1986). Radial fibers are also present in the deeper regions of the meniscus, where they hold the circumferential fibers in place and maintain structural integrity (Shen et al, 2022). In the white-white region, collagen is composed of only Col II (60%) and Col I (40%) (Fox et al, 2012;Bansal et al, 2020).…”

High angular resolution diffusion imaging (HARDI) of porcine menisci: a comparison of diffusion tensor imaging and generalized q-sampling imaging

“…Diffusion MRI (dMRI) allows for the quantification of water diffusion properties and the assessment of directional anisotropy in soft tissues ( 21 , 22 ). Recently, diffusion tensor imaging (DTI) and tractography have been performed to visualize the 3D collagen fiber network of the meniscus ( 23 ). However, a significant limitation of DTI is that only a single fiber orientation can be calculated within each imaging voxel ( 21 , 24 ).…”