Anatomical evaluation of CT-MRI combined femoral model

Yeon S Lee¹ , Jong K Seon² , Vladimir I Shin¹ , Gyu-Ha Kim³ and Moongu Jeon¹

¹School of Information and Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Korea

²Center for Joint Disease, Chonnam National University Hwasun Hospital, Hwasun-gun, Jeonnam, Korea

³Division of Automotive & Mechanical Engineering, Nambu University, Gwangju, Korea

author email corresponding author email

BioMedical Engineering OnLine 2008, 7:6doi:10.1186/1475-925X-7-6


Published:	30 January 2008

Abstract

Background

Both CT and MRI are complementary to each other in that CT can produce a distinct contour of bones, and MRI can show the shape of both ligaments and bones. It will be ideal to build a CT-MRI combined model to take advantage of complementary information of each modality. This study evaluated the accuracy of the combined femoral model in terms of anatomical inspection.

Methods

Six normal porcine femora (180 ± 10 days, 3 lefts and 3 rights) with ball markers were scanned by CT and MRI. The 3D/3D registration was performed by two methods, i.e. the landmark-based 3 points-to-3 points and the surface matching using the iterative closest point (ICP) algorithm. The matching accuracy of the combined model was evaluated with statistical global deviation and locally measure anatomical contour-based deviation. Statistical analysis to assess any significant difference between accuracies of those two methods was performed using univariate repeated measures ANOVA with the Turkey post hoc test.

Results

This study revealed that the local 2D contour-based measurement of matching deviation was 0.5 ± 0.3 mm in the femoral condyle, and in the middle femoral shaft. The global 3D contour matching deviation of the landmark-based matching was 1.1 ± 0.3 mm, but local 2D contour deviation through anatomical inspection was much larger as much as 3.0 ± 1.8 mm.

Conclusion

Even with human-factor derived errors accumulated from segmentation of MRI images, and limited image quality, the matching accuracy of CT-&-MRI combined 3D models was 0.5 ± 0.3 mm in terms of local anatomical inspection.