title: In vivo 3D high-spatial-resolution MR imaging of intraplaque hemorrhage.
abstract: OBJECTIVE
  To apply magnetic resonance (MR) imaging of intraplaque hemorrhage (IPH), as compared with histologic analysis as the reference standard, to detect T1 hyperintense intraplaque signal and to test the hypothesis that T1 hyperintense material represents blood products (methemoglobin).
  
  
  METHODS
  Institutional review board approval and patient informed consent were obtained. Eleven patients undergoing carotid endarterectomy were examined with MR imaging of IPH, and MR images were assessed for T1 hyperintense intraplaque signal. A total of 160 images per patient were available for coregistration with corresponding histologic slices. Because of endarterectomy specimen size and degradation and processing artifacts, only 97 images were coregistered to corresponding histologic slices. A grid that consisted of 16 segments was overlaid on images for correlation of MR images and histologic slices. Only one of 16 segments was chosen randomly per slide and used in the analysis. Agreement between MR images and histologic slices was measured with the Cohen kappa statistic.
  
  
  RESULTS
  Strong agreement was seen between MR images and histologic slices, with T1-weighted high signal intensity corresponding to hemorrhagic material (kappa = 0.7-0.8). There was a low 2% false-negative rate for the detection of hemorrhage on the basis of T1-weighted hyperintensity (two of 97 measured segments). The results of diagnostic tests for T1 hyperintense detection of hemorrhage were as follows: sensitivity of 100%, specificity of 80%, positive predictive value of 70%, and negative predictive value of 100% for reader 1 and sensitivity of 94%, specificity of 88%, positive predictive value of 78%, and negative predictive value of 97% for reader 2.
  
  
  CONCLUSIONS
  With its high spatial resolution, MR imaging of IPH permits detection of plaque hemorrhage location, resulting in strong agreement between imaging and histologic findings.
authors.affiliation: Department of Medical Imaging, University of Toronto, Toronto, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Bitar
authors.forename: Alan R
authors.initials: AR
authors.lastname: Moody
authors.forename: General
authors.initials: G
authors.lastname: Leung
authors.forename: Sean
authors.initials: S
authors.lastname: Symons
authors.forename: Susan
authors.initials: S
authors.lastname: Crisp
authors.forename: Jagdish
authors.initials: J
authors.lastname: Butany
authors.forename: Corwyn
authors.initials: C
authors.lastname: Rowsell
authors.forename: Alexander
authors.initials: A
authors.lastname: Kiss
authors.forename: Andrew
authors.initials: A
authors.lastname: Nelson
authors.forename: Robert
authors.initials: R
authors.lastname: Maggisano
mesh_terms: D000368:Aged; D002340:Carotid Artery Diseases / Q000473:pathology*; D016893:Carotid Stenosis / Q000473:pathology; D016894:Endarterectomy, Carotid; D005188:False Negative Reactions; D006470:Hemorrhage / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008706:Methemoglobin / Q000032:analysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D008706:Methemoglobin