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Simpleware Case Study: Verification of Three-Dimensional Computed Tomography Bone Density Measures
Overview
Osteoporosis is a growing concern as the population ages, leading to increased risk of fractures and surgical complications. To make informed treatment decisions and identify patients who are prone to bone density related issues, surgeons need to know the bone quality of their patients before surgery. However, the current methods of bone density analysis, such as 2D Hounsfield unit or intraoperative thumb test, are not very reliable or accurate.
This study aimed to develop a preoperative method to measure the local cancellous bone mineral density (BMD) of the proximal humerus from CT data. Simpleware software allowed researchers to use three dimensional regions of interest to be more precise and consistent than the existing methods.
Highlights
- Preoperative method to measure local cancellous bone mineral density of the proximal humerus using CT data
- Measurement verified through accuracy analysis of standard CT scans using µCT data
- Simpleware software allowed confirmation of spatial location of bone densities (reliability), and of accurate extraction of bone density features from clinical CT scans
Reference
Ritter, D., et al., 2024. Preoperative 3D Computed Tomography Bone Density Measures Provide Objective Bone Quality Classifications for Stemless Anatomic Total Shoulder Arthroplasty, J Shoulder Elbow Surg, S1058-2746(23)00887-X.
Thanks to
"We used Simpleware software in this work to verify automatically analyzed bone density data of the humeral bone with a 3D visualized reconstruction using standard CT and in- vitro µCT scans. This allowed us to verify the reproducibility of the spatial humeral mapping as well as the accuracy of the standard clinical scan, to use these variables in larger cohorts."
Daniel Ritter, Research Engineer, Arthrex
Image Acquisition
30 cadaveric humeri were scanned with a voxel size of 78 0.6mm (120 kVp and 80 mA) in a clinical CT scanner (Siemens SOMATOM Definition AS+, Siemens Healthcare GmbH) with gray scale values converted into BMD [mgHA/cm3] values using the manufacturer’s density phantoms. Additional microCT (µCT) (Phoenix v/tome/x s micro-CT scanner, Waygate Technologies) scans with a voxel resolution of 50μm and a phantom-calibrated 82 gray scale in BMD [mgHA/cm3] were used as a reference to assess the accuracy of the density analyses.
Analysis Method
Illustration of the analysis method to verify 3D CT bone density measures.
Accuracy analysis was carried out in standard CT scans of a phantom calibrated cohort (n=30) using µCT data. Reliability analysis was conducted using an automated image processing script for density analyses.
Accuracy and reliability were assessed using intraclass correlation coefficients (ICCs) of the clinical CT data and the image processing script versus the µCT data and Simpleware-tooled analysis. A two-way random effects analysis for single measures was carried out, and reliability was applied to a context of the consistency of a single measure of a single rater/method. ICCs greater than 0.75 were considered to be excellent, ICCs of 0.40 to 0.75 were considered to indicate moderate reliability, and ICCs for less than 0.40 as indicating poor reliability.
For tooled analysis, Simpleware software was used to reconstruct the clinical CT and µCT scans, and to globally segment the humerus, identify global regions of interest (ROIs), and implantation-relevant ROIs. Scores and other variables were also obtained from the scanned data. The workflow was then run with an automated algorithm, and density measurements collected based on the global and implantation-relevant ROIs, as well as scores and variables.
Global ROI segmentation in clinical CT and µCT scans using Synopsys Simpleware.
Visualization of 'normal' vs. 'weak' areas of bone density in a standard clinical CT (top) and µCT (bottom) scan.
Results and Conclusions
Results comparing the reliability of the scripted method vs. the tooled approach for both clinical CT and µCT found good-to-excellent agreement between the two methods. Simpleware software enabled confirmation of the spatial location of bone densities, demonstrating reliability. In addition, the software allowed confirmation of accurate extraction of bone density features from standard phantom-calibrated clinical CT scans.
Intraclass correlation coefficients.
Learn More
Application of these methods in a retrospective evaluation of a clinical cohort was performed based on these reliability and accuracy analyses to develop prediction models for reviewing surgical vs. density-based decisions. See Ritter et. al., Preoperative 3D Computed Tomography Bone Density Measures Provide Objective Bone Quality Classifications for Stemless Anatomic Total Shoulder Arthroplasty for further details.
Any Questions?
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