Lei Zhang1, Jun Wu2, Lijie Ren3, Tingting Wang2, Xin Liu1, and Yiu-Cho Chung1
1Paul C. Lauterbur Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academic of Sciences, Shenzhen, China, People's Republic of, 2Neurology, Peking University Shenzhen Hospital, Shenzhen, China, People's Republic of, 3Neurology, Shenzhen Second People’s Hospital, Shenzhen, China, People's Republic of
Synopsis
In this study, we evaluated multi-contrast three dimensional (3D) high resolution black blood vessel wall
imaging technique for joint intra- and extracranial artery wall imaging in 8 stroke patients. The new techniques covered both the intra- and
extracranial segments in one scan. T1w, T2w scans were performed. MPRAGE was included when hemmorrhage was suspected. 8 plaques were identified. Two of them had high signal in all three sequences, suggestive of intraplaque hemorrhage. The 3D multi-contrast large
coverage black blood techniques would be a promising tool to the study on the
association between atherosclerotic plaques and ischemic stroke.Introduction
Intracranial and extracranial atherosclerotic disease are two important
causes for ischemic stroke [1,2]. Multi-contrast intracranial vessel wall imaging can detect
atherosclerotic plaque and identify its various components [3]. However, the
two dimensional techniques commonly used severely limit the vascular territory
that can be examined. High resolution three dimension imaging covering both the
head and neck has been proposed for vessel wall imaging of intra- and
extracranial arteries [4]. Multi-contrast imaging of arterial walls at these two regions would allow the comparison of signal characteristics of plaques
in the two vascular territories. This study evaluates the use of multi-contrast
high resolution three dimensional vessel wall imaging of intra- and
extracranial arteries in stroke patients.
Methods
Sequences: T1 weighted and T2 weighted SPACE (T1w-SPACE, T2w-SPACE [5]) were used.
Both sequences used the DANTE preparation module [6] for the suppression of blood
signal and slow moving CSF [7]. A coil set consisting of an 8-element carotid
coil and 24 element head coil was custom designed for simultaneous head and
neck imaging [8]. The sequence and coil set implementations were based on a 3T
MRI system (TIM TRIO, Siemens, Erlangen).
Patient study: All experiments
were performed on the same 3T system.The study was IRB approved, and informed
consents were obtained from all subjects before the MR examination. 7 patients
(4 Females, 27~66 years old, average 45 years old) diagnosed with recent
ischemic stroke or TIA were recruited. After localization, the patient was
scanned using standard protocols for brain infarction (T1, T2, FLAIR, DWI). T1w-SPACE
and T2w-SPACE were then scanned. If high signal was detected in T1w-SPACE,
MPRAGE was used to help identify intraplaque hemorrhage or fresh thrombus [9]. Imaging
parameters common to both SPACE sequences were: FOV=212mm×159mm×40mm; NEX=1.4; base matrix=336, 72 slices, GRAPPA rate 2. Specific
parameters for T1w-SPACE were: TR/TE=1140ms/23ms; ETL=35; scan time=7m36s. T2w-SPACE
specific parameters were: TR/TE=2500ms/105ms; ETL=69; scan time=8m20s. DANTE related
parameters were: flip angle=8o, gradient strength=20mT/m, gradient
duration=1.5ms, the number of pulses for T1w-SPACE and T2w-SPACE were 150 and
250 respectively. Imaging parameters for MPRAGE were: matrix size = 256×256; 160 slices; voxel size = 0.7mm×0.7mm ×0.7mm; flip angle = 10o, TR/TE=1700ms/5.04ms, inversion
recovery time = 800ms, scan time = 5m54s.
Results
One
patient was excluded due to poor image quality. 8 plaques were found from the 6
patients. The signal characteristics of these plaques were summarized in table
1. The two cases in Figure 1 and 2 demonstrated the value of multi-contrast
imaging in identifying the properties of plaques. The plaques appeared bright in
MPRAGE, suggestive of intraplaque hemorrhage. Figure 3 showed a plaque located
at carotid artery and the plaque signal appeared isointense in both T1w and T2w
sequence.
Discussion
In this
study, we evaluated a three dimension high resolution multi-contrast image
technique for simultaneous imaging of intra- and extracranial arterial wall. Mossa-Basha M et al. [10] related hyperintensity in T2w images
primarily to intracranial arterial diseases. It was interesting to noted here that
hemorrhage/flesh thrombus could be hyperintense in T1, T2 weighted images as
well as in MPRAGE. No contrast was used in this study due to time constraints
of the study. Simultaneous imaging of intra- and extracranial arteries is
important from the scan time viewpoint as time savings multiply with the number
of contrasts used. The approach also allows better understanding of the signal
properties of plaques in the two different vascular territories under different
contrast at the same settings.
Acknowledgements
This work is funded by grants no. 2013CB733800/2013CB733803, 81470077, 81301216, JCYJ20140417113430589 and JSGG20141020103440414.References
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