Feasibility of Combining Perforating Artery Imaging and Whole Brain Vessel Wall Imaging at 7T
Zihao Zhang1,2, Qi Yang3,4, Zhaoyang Fan3, Xianchang Zhang1,2, Yujiao Yang4, Jing An5, Zhentao Zuo1, and Rong Xue1,6

1State Key Laboratory of Brain and Cognitive Science, Beijing MR Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, People's Republic of, 2Graduate School, University of Chinese Academy of Sciences, Beijing, China, People's Republic of, 3Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, 4Xuanwu Hospital, Beijing, China, People's Republic of, 5Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China, People's Republic of, 6Beijing Institute for Brain Disorders, Beijing, China, People's Republic of


In this study, we improved TOF-MRA and T1w-SPACE to a higher resolution for imaging perforating arteries and intracranial vessel walls at 7T. With the combination of the two techniques, we are for the first time able to depict the position of perforators and the vessel wall lesion in patients with ICAD. Small changes within the vessel wall may be revealed, and the certainty of the diagnosis may become better established, enabling better therapeutic management.


Intracranial vessel wall and its pathology can be depicted with 7T vessel wall magnetic resonance imaging. However, no study has been performed to investigate the combination of perforating artery imaging1 and vessel wall imaging2 in one image setting at 7T. We attempted to assess perforating arteries and atherosclerotic lesions using high-resolution TOF-MRA and whole brain vessel wall imaging, and to evaluate the association between image findings and clinical courses of stroke.

Material and Methods

14 volunteers and 6 patients with ICAD were recruited in the IRB approved study with informed consent. The diagnosis of ICAD was listed in Table 1. All the images were acquired on a whole-body 7T MR system (Siemens Healthcare, Erlangen, Germany) equipped with a Nova 32-channel head coil. All the patients underwent TOF-MRA, 3D T1-weighted (T1w) SPACE, 2D T1w and T2-weighted (T2w) TSE imaging. Post-contrast T1w-SPACE was applied on patient 6.

For TOF-MRA, the parameters were optimized to visualize the perforators from MCA: FA=24°, TR=26ms, TE=15ms, voxel=0.25x0.25x0.25mm3, FOV=210x164x32mm3, GRAPPA=3, time of acquisition (TA)=9:23min. An inversion recovery (IR) prepared 3D-SPACE sequence was applied for T1w vessel wall imaging: time of inversion (TI)=1100ms, TR=2100ms, TE=13ms, voxel=0.53x0.53x0.53mm3, FOV=128x170x170mm3, GRAPPA=3, TA=10:22min. The same parameters were used in post-contrast T1w-SPACE. In 2D vessel wall imaging, a multi-slice Turbo Spin Echo (TSE) was positioned perpendicular to the MCA where the stenosis or occlusion was observed in TOF-MRA or T1w-SPACE: TR=1800ms/TE=13ms for T1w, TR=3000ms/TE=52ms for T2w, voxel=0.35x0.35x2.00mm3.


In all the healthy volunteers, the optimized high-resolution TOF-MRA managed to image perforating arteries arising from MCA. A typical Maximal Intensity Projection (MIP) image is given in Fig. 1. To evaluate the quality of T1w-SPACE in whole-brain vessel wall imaging, the SNR and CNR of vessel walls are calculated in several main intracranial arteries. The results are listed in Table 2. The typical images of MCA and PCA are shown in Fig. 2, in which the profile of vessel wall is illustrated.

The images of patient 2, 3 and 6 are presented here as the examples in clinical scanning (respectively in Fig. 3, 4 and 5). In all the patients, TOF-MRA was able to visualize multiple perforators. The reconstruction of 3D SPACE images was flexible to present the status of vessel wall in any desired direction. The fusion of TOF-MRA and vessel wall images provided an efficient way to estimate the risk of MCA stenosis or occlusion.


The experiments on healthy volunteers ensured the performance of high-resolution TOF-MRA on the visualization of perforating arteries. In T1w-SPACE vessel wall imaging, the SNR and CNR of vessel walls were high enough for clinical diagnosis. The high resolution of isotropic 0.53mm produced sharp profiles in MCA and PCA, which was beneficial to identify vessel walls from the CSF surrounded. The low signal in the lumen indicated that the flow signal was well suppressed.

With the higher attainable SNR at 7 T, it became possible to perform isotropic high-resolution vessel wall imaging with a whole brain coverage. This made it possible to reconstruct each artery with a different course in different orientations. Besides, combining the imaging of perforating arteries and vessel wall allows to distinguish the subtypes of patients with ischemic stroke, such as TOAST classification. In the current study, both the plaques and perforators in symptomatic ICAD patients can be readily depicted. The developments and optimization of vessel wall imaging protocols at 7T may help us find disease-specific key imaging findings of the intracranial arterial walls in stroke patients.


We demonstrated that high-resolution TOF-MRA for perforating artery imaging and T1w-SPACE for whole brain vessel wall imaging are feasible at 7T. With the use of intracranial vessel wall imaging and the perforator artery imaging, small changes within the vessel wall may be revealed, and the certainty of the diagnosis may become better established, enabling better therapeutic management.


The work is supported in part by Chinese MOST grant (2012CB825500), CAS grants (XDB02010001 and XDB02050001), AHA-15SDG25710441 and NIH-NHLBI 2R01HL096119.


1. Harada T, Sato Y, Nanba T, et al. High-Resolution MR Angiography at 7T: Detection of Perforating Arteries of the Anterior Communicating and Distal Middle Cerebral Arteries. In: Proceedings of the 22th Annual Meeting of the ISMRM, Milan, Italy. ; 2014. p. 1411.

2. Yang Q, Song H, Zhang H, Ling F, Chung Y-C, Zhang L, Fan Z, Liu X, Li K, Li D. Intracranial Vessel Wall MR Registry. In: Proceedings of the 23th Annual Meeting of the ISMRM, Toronto, Canada. ; 2015. p. 0664.


Fig. 1. The MIP image of high-resolution TOF-MRA in a healthy volunteer. Perforators arising from bilateral MCA are pointed by the yellow arrows.

Fig. 2. The section view of the right MCA and left PCA in a healthy volunteer. The right plots are the profiles of the extracted lines in the sagittal views.

Fig. 3. 30yo male patient with atherosclerotic stenosis. The yellow arrow indicates the perforator arising from the location of stenosis in left MCA. Eccentric vessel wall thickening is found in both 3D and 2D images.

Fig. 4. 50yo male patient with thrombotic occlusion. The yellow arrow indicates the perforators at the proximal position of occlusion. The red arrow indicates the hyperintensity signal of thrombus.

Fig. 5. 42yo male patient with severe atherosclerotic stenosis. A bundle of perforating arteries at the distal end of stenosis is clearly shown in TOF-MRA (yellow arrow). The fusion view of pre- and post-contrast T1w-SPACE indicate the location of focus (white arrow), where the section view demonstrate eccentric enhancement after contrast agent management.

Table 1. Basic information of the patients.

Table 2. The statistics of SNR and CNR of vessel wall on healthy volunteers (denoted by mean ± standard deviation).

Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)