title: Characterization of carotid artery plaque components on magnetic resonance imaging using signal intensity of the phantom as a reference.
abstract: OBJECTIVE
  To evaluate the properties of plaque by the use of magnetic resonance imaging (MRI), it is necessary to use a material with stable signal intensity (eg, muscle or submandibular gland) as a reference. However, there may be differences between individuals. Therefore, we used a small phantom set on the circumference of the neck as a reference. The signal intensity ratio (SIR) methods using the phantom as a reference were reviewed for discrimination of the properties of plaque in the carotid artery.
  
  
  METHODS
  Three phantoms (phantom 1: water; phantom 2: 5 μmol gadopentetate dimeglumine; and phantom 3: 2.5 μmol gadopentetate dimeglumine) were set around the neck. SIR was calculated for each region of interest and compared according to pathological grade.
  
  
  RESULTS
  The method using a phantom as a reference reduced the standard deviations of tissue ratios to 0.16 from 0.27 in comparison with the method using muscle and showed a close correlation with pathological grade. In addition, the agreement rates with pathological grade and grades from each SIR using signal intensity of the phantom as a reference were higher than using signal intensity of the muscle as a reference to 0.86 from 0.63 for two-dimensional images and to 0.86 from 0.71 for three-dimensional images.
  
  
  CONCLUSIONS
  The method described here reduced error compared to the method using muscle as a reference, and the results were closely correlated with pathological grade.
authors.affiliation: Graduate School, Gunma Prefectural College of Health Sciences, 323-1, Kamioki-machi, Maebashi, Gunma, Japan; Department of Radiology, Kyoto City Hospital, Kyoto, Japan. Electronic address: a-ogura@mbox.kyoto-inet.or.jp.
authors.forename: Akio
authors.initials: A
authors.lastname: Ogura
authors.forename: Katsumi
authors.initials: K
authors.lastname: Hayakawa
authors.forename: Fumie
authors.initials: F
authors.lastname: Maeda
authors.forename: Mariko
authors.initials: M
authors.lastname: Kajihara
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Takatsu
authors.forename: Ken'ichiro
authors.initials: K
authors.lastname: Yamamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002339:Carotid Arteries / Q000473:pathology*; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D058226:Plaque, Atherosclerotic / Q000175:diagnosis* / Q000473:pathology; D014867:Water
chemical_list: D014867:Water; D019786:Gadolinium DTPA
keywords: Plaque; carotid artery; characterization of plaque; phantom signal