Comparative accuracy of lower limb bone geometry determined using MRI, CT, and direct bone 3D models

Abstract

Advancements in imaging and segmentation techniques mean that three dimensional (3D) modeling of bones is now increasingly used for preoperative planning and registration purposes. Computer tomography (CT) scans are commonly used due to their high bone-soft tissue contrast, however they expose subjects to radiation.Alternatively, magnetic resonance imaging (MRI) is radiation-free: however, geometric field distortion and poor bone contrast have been reported to degrade bone model validity compared to CT. The present study assessed the accuracy of 3D femur and tibia models created from "Black Bone" 3T MRI and high resolution CT scans taken from 12 intact cadaveric lower limbs by comparing them with scans of the defleshed and cleaned bones carried out using a high-resolution portable compact desktop 3D scanner (Model HDI COMPACT C210; Polyga). This scanner used structured light (SL) to capture 3D scans with an accuracy of up to 35 μm. Image segmentation created 3D models and for each bone the corresponding CT and MRI models were aligned with the SL model using the iterative closest point (ICP) algorithm and the differences between models calculated. Hausdorff distance was also determined. Compared to SL scans, the CT models had an ICP error of 0.82 ± 0.2 and 0.85 ± 0.2 mm for the tibia and femur respectively, whilst the MRI models had an error of 0.97 ± 0.2 and 0.98 ± 0.18 mm. A one-way analysis of variance found no significant difference in the Hausdorff distances or ICP values between the three scanning methods (p > .05). The black bone MRI method can provide accurate geometric measures of the femur and tibia that are comparable to those achieved with CT. Given the lack of ionizing radiation this has significant benefits for clinical populations and also potential for application in research settings.

Geometric accuracy of magnetic resonance imaging–derived virtual 3‐dimensional bone surface models of the mandible in comparison to computed tomography and cone beam computed tomography: A porcine cadaver study

“…Comparisons to an optical scan as a ground truth range from 0.15 to 0.85 mm for CT and 0.23 to 1.3 mm for MRI. [23][24][25][26][27] However, the results between the aforementioned studies are difficult to compare because of the inhomogeneous study settings, with differing imaging devices, imaging protocols with considerably varying resolutions, regions of interest, geometric measures, and segmentation techniques as well as the presence or absence of a ground truth.…”

“…This can be seen as a prerequisite for linking MR imaging to a digital workflow in CAS. 22 A few further cadaver studies reported on the accuracy of MRI-derived 3-dimensional models in comparison to CT for the lower extremities [23][24][25][26][27] but there are no data comparing MRI-derived surface models to those derived from CBCT.…”

Stochastic PCA-Based Bone Models from Inverse Transform Sampling: Proof of Concept for Mandibles and Proximal Femurs

“…In this context, the subject's geometry is generally obtained through reconstruction from Computed Tomography (CT) scans or Magnetic Resonance (MR) scans [1]. In all these cases, the 3D geometry can be built with very good accuracy, especially when detailed technical guidelines are followed [2,3].…”

Better precision of a new robotically assisted system for total knee arthroplasty compared to conventional techniques: A sawbone model study

“…This technique has potentially alleviated the complexity of TKA surgery and has improved both the reproducibility and accuracy of implant positioning 18 . For example, MAKO total knee robotic arm‐assisted surgery (Stryker) can improve the accuracy of bone resection 19 . Among these improvements, the mean difference from the plan for the anterior femoral cuts was 0.44 mm, with the mean difference for the distal femoral cuts being 0.38 mm and the mean difference for the tibial cuts being 0.37 mm 19 .…”

“…For example, MAKO total knee robotic arm‐assisted surgery (Stryker) can improve the accuracy of bone resection 19 . Among these improvements, the mean difference from the plan for the anterior femoral cuts was 0.44 mm, with the mean difference for the distal femoral cuts being 0.38 mm and the mean difference for the tibial cuts being 0.37 mm 19 . However, more robotic‐assisted TKA systems still need to be designed and developed.…”