Subacute vessel wall imaging at 7-T MRI in post-thrombectomy stroke patients

Abstract

PurposeReports from 3-T vessel wall MRI imaging have shown contrast enhancement following thrombectomy for acute stroke, suggesting potential intimal damage. Comparisons have shown higher SNR and more lesions detected by vessel wall imaging when using 7 T compared with 3 T. The aim of this study was to investigate the vessel walls after stent retriever thrombectomy using high-resolution vessel wall imaging at 7 T.MethodsSeven patients with acute stroke caused by occlusion of the distal internal carotid artery (T-occlusion), or proximal medial cerebral artery, and treated by stent retriever thrombectomy with complete recanalization were included and examined by 7-T MRI within 2 days. The MRI protocol included a high-resolution black blood sequence with prospective motion correction (iMOCO), acquired before and after contrast injection. Flow measurements were performed in the treated and untreated M1 segments.ResultsAll subjects completed the MRI examination. Image quality was independently rated as excellent by two neuroradiologists for all cases, and the level of motion artifacts did not impair diagnostic quality, despite severe motion in some cases. Contrast enhancement correlated with the deployment location of the stent retrievers. Flow data showed complete restoration of flow after treatment.ConclusionVessel wall imaging with prospective motion correction can be performed in patients following thrombectomy with excellent imaging quality at 7 T. We show that vessel wall contrast enhancement is the normal post-operative state and corresponds to the deployment location of the stent retriever.Electronic supplementary materialThe online version of this article (10.1007/s00234-019-02242-9) contains supplementary material, which is available to authorized users.

High-resolution vessel wall imaging after mechanical thrombectomy

“…Previous studies have shown that increased contrast enhancement of vessels after MT occurs after intimal injury. 6,17 Truong et al analysed the pattern of wall enhancement with 7T MRI on seven patients who underwent MT. 17 Vessel wall enhancement in all cases correlated with the deployment zone of the stentriever rather than the location of the thrombus.…”

“…6,17 Truong et al analysed the pattern of wall enhancement with 7T MRI on seven patients who underwent MT. 17 Vessel wall enhancement in all cases correlated with the deployment zone of the stentriever rather than the location of the thrombus. The manipulation of target vessels by MT devices produces intimal injury, but the extent of this injury is unknown and the impact on different layers of the arterial wall is unclear.…”

A high resolution scanning electron microscopy analysis of intracranial thrombi embedded along the stent retrievers

“…The advantages of endovascular treatment are beyond doubt, as MTB improves recanalization rates in AIS patients and decreases associated morbidity and mortality 29 , 30 . It is becoming recognized that the use of stent retrievers is associated with vascular injury 31 – 34 . It is therefore not surprising to find in our study remnants of vascular tissue attached to the extracted thrombi.…”

Accuracy investigations for volumetric head‐motion navigators with and without EPI at 7 T

“…We chose to exclude movements with a rotation parameter > 10 • from our analysis, as we observed many outlying points for these big movements, which would drive the linear fitting, and therefore dominate the analysis unreasonable much compared with their relevance. Such big rotations are rarely seen, even with highly uncooperative patients, 21,22 and are also difficult to correct with retrospective corrections, as large gaps in k-space occur with sub-Nyquist sampling. 23 With prospective correction there is typically a limit to how large rotation angles can be corrected in real time, to not pose too conservative limits on the gradient strength and slew rate in the starting position.…”