title: Relationship between the Carotid Plaque T1 Relaxation Time and the Plaque-to-Muscle Signal Intensity Ratio on Black-Blood Magnetic Resonance Imaging Scans.
abstract: BACKGROUND
  Black-blood magnetic resonance imaging (BB-MRI) is useful for the characterization and assessment of carotid artery plaques. The plaque-to-muscle signal intensity (SI) ratio (plaque/muscle ratio [PMR]) is used widely to evaluate plaques. However, the correlation between the PMR and the T1 relaxation time needs to be determined. We measured the T1 relaxation time of carotid plaques using T1 mapping and compared the results with the PMR on BB-MRI scans.
  
  
  METHODS
  Between April 2014 and July 2015, 20 patients with carotid artery stenosis were treated by carotid artery stenting. All patients underwent preoperative magnetic resonance plaque imaging. The ratio of the plaque SI to the sternocleidomastoid muscle was calculated on T1-weighted BB-MRI scans. T1 mapping was performed in the region where the vessel was narrowest using the inversion recovery technique. The T1 relaxation time was recorded to determine whether there was a correlation with the PMR.
  
  
  RESULTS
  The plaque T1 value was 577.3 ± 143.2 milliseconds; the PMR value obtained on BB-MRI scans was 1.23 ± .27. There was a statistically significant decrease in the T1 value as the PMR increased (P < .0001).
  
  
  CONCLUSIONS
  As the T1 relaxation time was well correlated with the PMR on BB-MRI scans, the evaluation of vulnerable plaques using the PMR was reliable and convenient.
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan. Electronic address: sangyouika@yahoo.co.jp.
authors: Ayumu
authors: A
authors: Eto
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Yoshimasa
authors: Y
authors: Kinoshita
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Yoshihisa
authors: Y
authors: Matsumoto
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Fumiaki
authors: F
authors: Kiyomi
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Minoru
authors: M
authors: Iko
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Kouhei
authors: K
authors: Nii
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Masanori
authors: M
authors: Tsutsumi
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Kimiya
authors: K
authors: Sakamoto
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Hiroshi
authors: H
authors: Aikawa
authors: Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan.
authors: Kiyoshi
authors: K
authors: Kazekawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017130:Angioplasty / Q000295:instrumentation; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000628:therapy; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009334:Neck Muscles / Q000000981:diagnostic imaging*; D058226:Plaque, Atherosclerotic; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D015607:Stents
keywords: Black-blood magnetic resonance imaging (BB-MRI); T1 mapping; T1 relaxation time; carotid plaque; plaque/muscle ratio (PMR)