Multi-Rigid Image Segmentation and Registration for the Analysis of Joint Motion From Three-Dimensional Magnetic Resonance Imaging

Abstract

We report an image segmentation and registration method for studying joint morphology and kinematics from in vivo magnetic resonance imaging (MRI) scans and its application to the analysis of foot and ankle joint motion. Using an MRI-compatible positioning device, a foot was scanned in a single neutral and seven other positions ranging from maximum plantar flexion, inversion, and internal rotation to maximum dorsiflexion, eversion, and external rotation. A segmentation method combining graph cuts and level set was developed. In the subsequent registration step, a separate rigid body transformation for each bone was obtained by registering the neutral position dataset to each of the other ones, which produced an accurate description of the motion between them. The segmentation algorithm allowed a user to interactively delineate 14 foot bones in the neutral position volume in less than 30 min total (user and computer processing unit [CPU]) time. Registration to the seven other positions took approximately 10 additional minutes of user time and 5.25 h of CPU time. For validation, our results were compared with those obtained from 3DViewnix, a semiautomatic segmentation program. We achieved excellent agreement, with volume overlap ratios greater than 88% for all bones excluding the intermediate cuneiform and the lesser metatarsals. For the registration of the neutral scan to the seven other positions, the average overlap ratio is 94.25%, while the minimum overlap ratio is 89.49% for the tibia between the neutral position and position 1, which might be due to different fields of view (FOV). To process a single foot in eight positions, our tool requires only minimal user interaction time (less than 30 min total), a level of improvement that has the potential to make joint motion analysis from MRI practical in research and clinical applications.

Hind‐ and midfoot bone morphology varies with foot type and sex

“…CTs were obtained using a Phillips Mx8000‐IDT 16 scanner with an in‐plane resolution of 512 × 512, a slice spacing varying between 0.75 and 1.0 mm, and an in‐plane pixel size between 0.9629 and 0.9766 mm . The hind‐ and midfoot bones were segmented from the scans using Multi‐Rigid, an in‐house validated segmentation tool, to yield 3D surface models of the calcaneus, talus, navicular, and cuboid. One foot from each subject (left or right) was randomly chosen for this analysis.…”

Talonavicular joint coverage and bone morphology between different foot types

“…The bones of the foot were segmented into 3D computer models using Multi‐Rigid , a custom software package (Fig. ) . The TNJ surface on both the talus and navicular was selected from the CT data with Blender, an open source 3D graphics program.…”

“…1). 18 The TNJ surface on both the talus and navicular was selected from the CT data with Blender, an open source 3D graphics program. Since cartilage is invisible on CT, we manually selected the relevant bone surfaces.…”

First Ray Kinematics in Women With Rheumatoid Arthritis and Bunion Deformity: A Gait Simulation Imaging Study

“…The control group was sampled in the previous studies by Glasoe et al (see publications for details []). Use of previously collected data was necessary because of the high cost of imaging, and because of the time investment required to digitally reconstruct image data ().…”