title: Semi-automatic carotid intraplaque hemorrhage detection and quantification on Magnetization-Prepared Rapid Acquisition Gradient-Echo (MP-RAGE) with optimized threshold selection.
abstract: Intraplaque hemorrhage (IPH) is associated with atherosclerosis progression and subsequent cardiovascular events. We sought to develop a semi-automatic method with an optimized threshold for carotid IPH detection and quantification on MP-RAGE images using matched histology as the gold standard.
  
  
  
  Fourteen patients scheduled for carotid endarterectomy underwent 3D MP-RAGE cardiovascular magnetic resonance (CMR) preoperatively. Presence and area of IPH were recorded using histology. Presence and area of IPH were also recorded on CMR based on intensity thresholding using three references for intensity normalization: the sternocleidomastoid muscle (SCM), the adjacent muscle and the automatically generated local median value. The optimized intensity thresholds were obtained by maximizing the Youden's index for IPH detection. Using leave-one-out cross validation, the sensitivity and specificity for IPH detection based on our proposed semi-automatic method and the agreement with histology on IPH area quantification were evaluated.
  
  
  
  The optimized intensity thresholds for IPH detection were 1.0 times the SCM intensity, 1.6 times the adjacent muscle intensity and 2.2 times the median intensity. Using the semi-automatic method with the optimized intensity threshold, the following IPH detection and quantification performance was obtained: sensitivities up to 59, 68 and 80 %; specificities up to 85, 74 and 79 %; Pearson's correlation coefficients (IPH area measurement) up to 0.76, 0.93 and 0.90, respectively, using SCM, the adjacent muscle and the local median value for intensity normalization, after heavily calcified and small IPH were excluded.
  
  
  
  A semi-automatic method with good performance on IPH detection and quantification can be obtained in MP-RAGE CMR, using an optimized intensity threshold comparing to the adjacent muscle. The automatically generated reference of local median value provides comparable performance and may be particularly useful for developing automatic classifiers. Use of the SCM intensity as reference is not recommended without coil sensitivity correction when surface coils are used.
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Liu
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Niranjan
authors.initials: N
authors.lastname: Balu
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Hippe
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Marina S
authors.initials: MS
authors.lastname: Ferguson
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Martinez-Malo
authors.affiliation: Walter Reed National Military Medical Center, Bethesda, MD, USA.
authors.forename: J Kevin
authors.initials: JK
authors.lastname: DeMarco
authors.affiliation: Michigan State University, East Lansing, MI, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Zhu
authors.affiliation: Tohoku University, Miyagi, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Ota
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Dongxiang
authors.initials: D
authors.lastname: Xu
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: William S
authors.initials: WS
authors.lastname: Kerwin
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hatsukami
authors.affiliation: University of Washington, Seattle, WA, USA. cyuan@uw.edu.
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001331:Automation; D001706:Biopsy; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000473:pathology; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006470:Hemorrhage / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D058226:Plaque, Atherosclerotic; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012015:Reference Standards; D015203:Reproducibility of Results
keywords: CMR; Carotid atherosclerosis; Intraplaque hemorrhage; MP-RAGE; Semi-automatic quantification; Threshold