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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: 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.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: 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.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