Comparison of cartilage and bone morphological models of the ankle joint derived from different medical imaging technologies

Abstract

Background: Accurate geometrical models of bones and cartilage are necessary in biomechanical modelling of human joints, and in planning and designing of joint replacements. Image-based subjectspecific model development requires image segmentation, spatial filtering and 3-dimensional rendering. This is usually based on computed tomography (CT) for bone models, on magnetic resonance imaging (MRI) for cartilage models. This process has been reported extensively in the past, but no studies have ever compared the accuracy and quality of these models when obtained also by merging different imaging modalities.The scope of the present work is to provide this comparative analysis in order to identify optimal imaging modality and registration techniques for producing 3-dimensional bone and cartilage models of the ankle joint.Methods: One cadaveric leg was instrumented with multimodal markers and scanned using five different imaging modalities: a standard, a dual-energy and a cone-beam CT (CBCT) device, and a 1.5 and 3.0 Tesla MRI devices. Bone, cartilage, and combined bone and cartilage models were produced from each of these imaging modalities, and registered in space according to matching model surfaces or to corresponding marker centres. To assess the quality in overall model reconstruction, distance map analyses were performed and the difference between model surfaces obtained from the different imaging modalities and registration techniques was measured. Results:The registration between models worked better with model surface matching than corresponding marker positions, particularly with MRI. The best bone models were obtained with the CBCT. Models with cartilage were defined better with the 3.0 Tesla than the 1.5 Tesla. For the combined bone and cartilage models, the colour maps and the numerical results from distance map analysis (DMA) showed that the smallest distances and the largest homogeneity were obtained from the CBCT and the 3.0 T MRI via model surface registration.Conclusions: These observations are important in producing accurate bone and cartilage models from medical imaging and relevant for applications such as designing of custom-made ankle replacements or, more in general, of implants for total as well as focal joint replacements.

An Anatomical-Based Subject-Specific Model of In-Vivo Knee Joint 3D Kinematics From Medical Imaging

“…For instance, fiducial points were used in this study for MRI-CT registration, since they are standard, simple, and applied in many clinical procedures, in particular when aligning bony landmarks. However, many other techniques have been proposed, like mutual information and iterative-closest-point techniques [31,33]. The use of fiducial points for MRI-CT registration showed a good accuracy in a previous investigation [31], with a mean distance between corresponding surfaces lower than 2 mm, consistent with the accuracy of the medical imaging techniques used in the present study.…”

“…However, many other techniques have been proposed, like mutual information and iterative-closest-point techniques [31,33]. The use of fiducial points for MRI-CT registration showed a good accuracy in a previous investigation [31], with a mean distance between corresponding surfaces lower than 2 mm, consistent with the accuracy of the medical imaging techniques used in the present study. Since one of the scopes of geometry optimization is to limit the influence of both the segmentation and registration inaccuracies, the effect of a different registration technique on the results is believed to be small.…”

“…3D bone surfaces of the proximal and distal femur, proximal tibia, patella and malleoli were obtained from the CT. A second 3D representation of anatomical surfaces also featuring cartilage of the femur and tibia, and the attachment areas of each ligament involved in the kinematic model was obtained from MRI. Performances and accuracy assessment of the whole procedure of morphological reconstruction using the adopted imaging acquisition devices were reported in a recent study [31].…”

Weight-bearing CT Technology in Musculoskeletal Pathologies of the Lower Limbs: Techniques, Initial Applications, and Preliminary Combinations with Gait-Analysis Measurements at the Istituto Ortopedico Rizzoli

“…Among the general issues for CBCT scans, there is also the limited field of measurement; in several of these devices, large-size feet cannot be scanned entirely. In that case, the area of major interest, for example the rearfoot or the forefoot, can be targeted, or both areas can be taken in two successive scans and then merged by shape matching or other spatial registration techniques, 30 with or without common technical or anatomical references. Computerbased 3D models of the bones are clearly necessary, and these can be obtained today only by time-consuming 3D reconstructions via segmentation of DICOM files; however, freeware software and robust modern tools can now facilitate this critical work.…”

Angular and linear measurements of adult flexible flatfoot via weight-bearing CT scans and 3D bone reconstruction tools

“…These modern CBCT devices can provide 3D scans in weight-bearing, which is particularly valuable for foot and ankle studies 20 – 24 . This new feature adds to the demonstrated relatively low radiation, high spatial resolution, and convenient ergonomy and post-processing 13 , 25 – 29 , making this technology fundamental nowadays in many clinical studies 6 , 7 , 10 , 12 – 16 , 20 – 23 , 26 – 28 , 30 . The load can be modulated from case to case, ranging from standard single- or double-leg up-right postures to other postural conditions with the leg under determined and controlled positions 13 .…”