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Anatomical evaluation of CT-MRI combined femoral model.

Lee YS, Seon JK, Shin VI, Kim GH, Jeon M - Biomed Eng Online (2008)

Bottom Line: 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.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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Information and Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Korea. biomechanics.yslee@gmail.com

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.

Show MeSH
The 3 points-to-3 points matching and the surface-to-surface matching. The 3 points-to-3 points matching was executed by registration the center points of reconstructed CT-derived ball markers to their corresponding center points of reconstructed MRI-derived ball markers. The surface-to-surface matching was executed by 3D/3D surface registration using the ICP algorithm.
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Figure 3: The 3 points-to-3 points matching and the surface-to-surface matching. The 3 points-to-3 points matching was executed by registration the center points of reconstructed CT-derived ball markers to their corresponding center points of reconstructed MRI-derived ball markers. The surface-to-surface matching was executed by 3D/3D surface registration using the ICP algorithm.

Mentions: Landmark-based matching, generally known as a gold standard matching method for checking accuracy, was executed. The landmarks (center points) of three CT-derived ball models were matched to their corresponding MRI-derived ball models, referred here as the 3 points-to-3 points method (Fig. 3). Because the landmarks and CT-derived model were linked, the reference landmarks reconstructed from CT images were also transferred along the same path as the femoral model. First, the 1st point of the CT-derived model was moved to the its corresponding 1st point of the MRI-derived model. Second, the vector passing the 1st and 2nd points of the CT-derived model was aligned along the vector passing the 1st and 2nd points of the MRI-derived model. Finally, the plane determined by the 1st, 2nd, and 3rd points of the CT-derived model was placed on the plane determined by the 1st, 2nd, and 3rd points of the MRI-derived model.


Anatomical evaluation of CT-MRI combined femoral model.

Lee YS, Seon JK, Shin VI, Kim GH, Jeon M - Biomed Eng Online (2008)

The 3 points-to-3 points matching and the surface-to-surface matching. The 3 points-to-3 points matching was executed by registration the center points of reconstructed CT-derived ball markers to their corresponding center points of reconstructed MRI-derived ball markers. The surface-to-surface matching was executed by 3D/3D surface registration using the ICP algorithm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2265715&req=5

Figure 3: The 3 points-to-3 points matching and the surface-to-surface matching. The 3 points-to-3 points matching was executed by registration the center points of reconstructed CT-derived ball markers to their corresponding center points of reconstructed MRI-derived ball markers. The surface-to-surface matching was executed by 3D/3D surface registration using the ICP algorithm.
Mentions: Landmark-based matching, generally known as a gold standard matching method for checking accuracy, was executed. The landmarks (center points) of three CT-derived ball models were matched to their corresponding MRI-derived ball models, referred here as the 3 points-to-3 points method (Fig. 3). Because the landmarks and CT-derived model were linked, the reference landmarks reconstructed from CT images were also transferred along the same path as the femoral model. First, the 1st point of the CT-derived model was moved to the its corresponding 1st point of the MRI-derived model. Second, the vector passing the 1st and 2nd points of the CT-derived model was aligned along the vector passing the 1st and 2nd points of the MRI-derived model. Finally, the plane determined by the 1st, 2nd, and 3rd points of the CT-derived model was placed on the plane determined by the 1st, 2nd, and 3rd points of the MRI-derived model.

Bottom Line: 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.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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Information and Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Korea. biomechanics.yslee@gmail.com

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.

Show MeSH