title: Anatomical evaluation of CT-MRI combined femoral model.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Information and Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Korea. biomechanics.yslee@gmail.com
authors.forename: Yeon S
authors.initials: YS
authors.lastname: Lee
authors.forename: Jong K
authors.initials: JK
authors.lastname: Seon
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Shin
authors.forename: Gyu-Ha
authors.initials: GH
authors.lastname: Kim
authors.forename: Moongu
authors.initials: M
authors.lastname: Jeon
mesh_terms: D000818:Animals; D003198:Computer Simulation; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008953:Models, Anatomic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*