title: Direct quantitative in vivo comparison of calcified atherosclerotic plaque on vascular MRI and CT by multimodality image registration.
abstract: OBJECTIVE
  To investigate direct volumetric in vivo correspondence of calcified atherosclerotic plaque lesions in MRI and CT images of the thoracic aorta by multimodality image registration and fusion.
  
  
  METHODS
  Twelve CT (11 noncontrast and one contrast) and MRI (TruFISP, contrast T1-weighted volumetric interpolated breath-hold examination (VIBE)) data sets were co-registered by approximate segmentation of the aorta and subsequent automatic co-registration by maximization of mutual information (MI). We quantitatively assessed 22 co-registered calcified plaque lesions on CT and MRI.
  
  
  RESULTS
  The three-dimensional registration consistency and accuracy were 1.74 +/- 1.3 mm, and 2.42 +/- 1.65 mm, respectively. The ratio of CT/MRI calcified plaque volume decreased asymptotically with MRI volume, and correlated with average CT lesion density (r = 0.72) for small lesions (<25 mm(3)). The average calcified plaque volume, circumferential extent, and maximal radial width by MRI were significantly smaller compared to CT (35%, 68%, and 53%, respectively; P < 0.05).
  
  
  CONCLUSIONS
  Software co-registration allowed precise, direct, and voxel-based comparison of calcified atherosclerotic plaque lesions imaged by MRI and CT. In comparison with co-registered MRI, overestimation of calcified plaque in aortic CT due to "blooming" correlates with the average lesion density for small plaques, and is greater for small plaques.
authors.affiliation: Division of Nuclear Medicine, Department of Imaging, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
authors.forename: Damini
authors.initials: D
authors.lastname: Dey
authors.forename: Piotr
authors.initials: P
authors.lastname: Slomka
authors.forename: Daisy
authors.initials: D
authors.lastname: Chien
authors.forename: David
authors.initials: D
authors.lastname: Fieno
authors.forename: Aiden
authors.initials: A
authors.lastname: Abidov
authors.forename: Rola
authors.initials: R
authors.lastname: Saouaf
authors.forename: Louise
authors.initials: L
authors.lastname: Thomson
authors.forename: John D
authors.initials: JD
authors.lastname: Friedman
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
mesh_terms: D000368:Aged; D000465:Algorithms; D001013:Aorta, Thoracic; D050197:Atherosclerosis / Q000000981:diagnostic imaging / Q000473:pathology*; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007472:Iohexol; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol