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Super selective arterial spin labeling technique in the assessment of blood supply from external carotid artery in Moyamoya Disease: comparison with digital subtraction angiography
Jing Yuan1, Jianxun Qu2, and Yaou Liu1

1Radiology Department, Beijing Tiantan Hospital, Capital Medical University, Beijing, China, 2MR Research, GE Healthcare, China, Beijing, China

Synopsis

Super selective arterial spin labeling (ssASL) is a MR territory perfusion technique based on arterial spin labeling. The efficacy of this technique to demonstrate the blood supply of external carotid artery (ECA) into the brain has not been studied. This study demonstrated ssASL was in good agreement with DSA, the gold standard for cerebral vessels, in the evaluation of preoperative ECA collaterals, superficial temporal artery to middle cerebral artery bypass and synangiosis-induced vessels in Moyamoya disease.

Introduction

Moyamoya disease (MMD) is a chronic cerebrovascular disease characterized by progressive stenosis of the terminal of internal carotid artery (ICA) and its main branches, accompanied by abundant collateral formation. Collateral status in MMD is important for the evaluation of the disease severity and prognosis. External carotid artery (ECA) is an important source of collaterals in MMD, mainly transdural collaterals from superficial temporal artery (STA) and middle meningeal artery (MMA). Super selective arterial spin labeling (ssASL) is a territory perfusion technique based on arterial spin labeling (ASL). This technique has been used in healthy subjects, steno-occlusive cerebral vascular disease to demonstrate perfusion territories of main cerebral vessels[1-3]. Recently, ssASL has been used in MMD to evaluate the collateral status and the STA to middle cerebral artery (MCA) bypass postoperatively. However, the efficacy of ssASL to demonstrate the blood supply of ECA into the brain has not been studied in MMD. In this work, we compare ssASL with digital subtraction angiography (DSA) in MMD to evaluate the agreement of ssASL with DSA to assess the blood supply of ECA.

Methods

One hundred and twenty diagnosed MMD patients were included in this study. SSASL and DSA examinations were performed within 7 days. SSASL was performed on a 3.0T whole body system (GE Discovery 750) equipped with an 8 channel head coil. TOF-MRA was acquired and used for locating the target arteries to be labeled. Bilateral ECA (at the main branch of STA and internal maxillary artery) and bilateral STA were individually labelled via super-selective scheme. The corresponding perfusion territory maps were acquired with 3D stack of spiral fast spin echo sequence and the parameters were as follows: labeling duration 1450ms, post labeling delay 2025ms, 4 arms, 512 points per arm, NEX 2, slice thickness 4mm. A circle labeling region of radius 20mm was used. DSA was performed using a biplane angiography. Bilateral ECA were studied at the level of the neck. Each vessel angiography was obtained in anterior-posterior projection and lateral projection. Blood supply from ECA on both image modalities were evaluated by two double-blind neuroradiologists. The results of both modalities were compared by Cohen’s ΔΈ statistic.

Results

Among 120 MMD patients, 10 were unilateral MMD, so there were 230 sides of MMD. Among them, there were 205 preoperative sides, 12 sides after STA to MCA bypass, and 13 sides after synangiosis. The intermodality agreement between ssASL and DSA in evaluation of preoperative ECA collaterals, the STA to MCA bypass and the synangiosis were κ=0.73, κ=0.75 and κ=0.73 separately. Generally, ssASL was in good agreement with DSA in diagnostic quality.

Discussion

Our study indicated ssASL was in good agreement with DSA, the gold standard for cerebral vessels, in the evaluation of preoperative ECA collaterals, STA to MCA bypass and synangiosis-induced vessels. Both DSA and ssASL are vessel selective and can demonstrate the blood supply of ECA into the brain. DSA achieved this by demonstrating the small collaterals from MMA and/or STA and the blood stain in capillary phase. ssASL achieved this by demonstrating the perfusion territory of ECA/STA inside the brain parenchyma. The advantage of DSA over ssASL is the ability to show the small collateral vessels. The advantage of ssASL over DSA is that the perfusion territory of ECA can be incorporated with the sectional anatomy.. The diagnostic difference between ssASL and DSA was that ssASL was not as sensitive as DSA to demonstrate ECA collaterals in less severe MMD. In general, higher Suzuki grades are associated with more severe ICA stenosis and more frequent ECA collateral formation. We observed in lower Suzuki grades, ssASL was not sensitive enough to demonstrate ECA collaterals due to low signal noise ratio. The agreement of ssASL with DSA increased with the increase of Suzuki grade.

Conclusion

ssASL technique can selectively demonstrate blood supply from ECA into the brain in MMD. The results of ssASL are comparable with DSA. As a non-invasive, non-radiation examination and no contrast medium is needed, ssASL is a promising technique in evaluation of MMD and may potentially reduce the times of DSA examination.

Acknowledgements

No acknowledgement found.

References

[1] Hartkamp NS, Petersen ET, De Vis JB, Bokkers RP, Hendrikse J. Mapping of cerebral perfusion territories using territorial arterial spin labeling: techniques and clinical application. NMR Biomed. 2013. 26(8): 901-12.

[2] Chng SM, Petersen ET, Zimine I, Sitoh YY, Lim CC, Golay X. Territorial arterial spin labeling in the assessment of collateral circulation: comparison with digital subtraction angiography. Stroke. 2008. 39(12): 3248-54.

[3] Dang Y, Wu B, Sun Y, et al. Quantitative assessment of external carotid artery territory supply with modified vessel-encoded arterial spin-labeling. AJNR Am J Neuroradiol. 2012. 33(7): 1380-6.

Figures

Figure 1 A case of MMD with ECA collaterals A) lateral view of DSA, capillary phase. Two areas of blood stain of ECA were demonstrated, one located in frontal area and the other located in parietal area. B) and C) lateral view of ssASL, labeling of ECA, incorporated with T1 images. B) ECA perfusion territory located in parietal area. C) ECA perfusion territory located in frontal area. The two perfusion territories were in agreement with DSA, but they were overlapped on DSA.

Figure 2 A case of MMD with collaterals of MMA, a branch of ECA A) Anterior-posterior view of DSA, late artery phase. Collaterals from right MMA were demonstrated, the blood supply areas were located on fontal area and temporal area. B) and C) coronal view of ssASL, labeling of right ECA, incorporated with T1 images. B) ECA perfusion territory located in temporal area. C) ECA perfusion territory located in frontal area. Labeling of right STA showed no perfusion territory inside the brain (images not shown), This result indicated the perfusion territory of right ECA was supplied by right MMA, not right STA.

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)
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