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Keywords:
Vascular, CNS, Neuroradiology brain, MR, MR-Angiography, Imaging sequences, Arteriosclerosis, Ischaemia / Infarction
Authors:
L. Chen, Q. Liu, X. Tian, Q. Zhan, C. Ma, Y. Jiang, W. Peng, B. Tian, J.-P. Lu; Shanghai/CN
DOI:
10.1594/ecr2016/C-0430
Methods and materials
Subjects
Ten patients (eight males,
two females,
mean age 61 years) with >30% stenosis as identified by conventional MRA were recruited.
This study was approved by the local institutional review board and written informed consent was obtained from each subject.
MRI Protocols
All imaging was performed on a 3T MR system using a standard 20-channal phased-array head/neck coil.
All patients underwent repeated MRI scan sessions of basilar artery vessel wall with two protocols: 3D time of flight (TOF) and 2D T2 weighted turbo spin echo (T2W TSE).
After the first scan,
the patient was got out from the scanner for a short rest and the coil was removed,
then the patient was repositioned for the second scan.
The following parameters were used for 3D TOF protocol: Repetition time (TR) /Echo time (TE) = 21 ms/3.4 ms,
Field of view (FOV) = 180 mm × 200 mm,
matrix = 330 × 384,
thickness = 0.7 mm,
and average = 1,
and parameters for 2D T2W TSE were TR/TE = 2890 ms/46 ms,
FOV = 100 mm × 100 mm,
matrix = 256 × 256,
thickness =2 mm,
Turbo factor = 20,
and number of averages = 2.
Image analysis
Outer wall areas,
inner wall areas and lumen areas of cross-sectional T2 weighted images with plaques were traced manually by an experienced observer (Figure 1).
PA,
SR and PPB were quantitatively evaluated on T2W images,
PA= inner wall area - lumen area,
SR = 1- plaque area/ inner wall area,
PPB = plaque area/outer wall area.
To test the intraobserver reproducibility,
the observer measured BA plaque at another time point that were separated by a 2 weeks interval to avoid any recall bias.
Fig. 1: Example of lumen and wall boundaries for quantitative analysis of the T2W image.
Statistical analysis
Agreement between repeated measurements was quantified through intraclass correlation coefficient (ICC) and coefficient of variation (CV).
The mean differences between repeated measurements against the mean value of repeated measurements were analyzed with Bland-Altman plots.