Hemorrhagic Plaques in Mild Carotid Stenosis: The Risk of Stroke.

OBJECTIVES: Embolic ischemic strokes cause significant mortality and morbidity worldwide. It has been proposed that some of these strokes are due to unstable carotid plaques with intraplaque hemorrhage (IPH) but a low overall degree of stenosis. Our aim was to test a fat-saturated T1-weighted (T1WI) black-blood sequence on MRI for the detection of IPH in symptomatic individuals and to quantify the relation between IPH, severity of stenoses, and ischemic brain lesions. MATERIALS AND METHODS: Sixty-two patients were examined by 3T MRI. Sequences included brain diffusion-weighted imaging (DWI) as well as 3D turbo spin echo (TSE) fat-saturated black-blood T1 of the carotid bifurcations, to detect IPH as a focal intraplaque hyperintensity. Both carotid arteries were analyzed in each patient. The North American Symptomatic Carotid Endarterectomy Trial scale was used for quantification of stenosis degree. RESULTS: Thirty-six out of 62 patients (mean age, 74) showed brain ischemia on DWI. Fifteen of these 36 patients (42%) had associated ipsilateral IPH at the carotid bifurcation or the proximal internal carotid artery. Mean degree of stenosis in this group was 50%. In 21 patients with ischemia without IPH, the mean degree of stenosis was 44%. CONCLUSIONS: MRI with 3D TSE fat-saturated black-blood T1 technique is a safe, reliable, and noninvasive tool for the detection of IPH. A high percentage (42%) of ischemic events in patients with low- to moderate-degree stenosis were associated with IPH, an easily detectable imaging biomarker of plaque vulnerability. The ability to confirm IPH by MRI may help stratify patients into different risk and treatment groups in the future.

Neurovascular stent artifacts in 3D-TOF and 3D-PCMRI: Influence of stent design on flow measurement.

PURPOSE: The morphological and hemodynamic evaluations of neurovascular diseases treated with stents would benefit from noninvasive imaging techniques such as 3D time-of-flight MRI (3D-TOF) and 3D phase contrast MRI (3D-PCMRI). For this purpose, a comprehensive evaluation of the stent artifacts and their impact on the flow measurement is critical. METHODS: The artifacts of a representative sample of neurovascular stents were evaluated in vitro with 3D-TOF and 3D-PCMRI sequences. The dependency of the artifacts with respect to the orientation was analyzed for each stent design as well as the impact on the flow measurement accuracy. Furthermore, the 3D-PCMRI data of four patients carrying intracranial aneurysms treated with flow diverter stents were analyzed as illustrative examples. RESULTS: The stent artifacts were mainly confined to the stent lumen therefore indicating the leading role of shielding effect. The influence of the stent design and its orientation with respect to the transmitting MR coils were highlighted. The artifacts impacted the 3D-PCMRI velocities mainly in the low magnitude domains, which were discarded from the analysis ensuring reliable near-stent velocities. The feasibility of in-stent flow measurements was confirmed in vivo on two patients who showed strong correlation between flow and geometric features. In two other patients, the consistency of out-of-stent velocities was verified qualitatively through intra-aneurysmal streamlines except when susceptibility artifacts occurred. CONCLUSION: The present results motivate the conception of low inductance or nonconductive stent design. Furthermore, the feasibility of near-stent 3D-PCMRI measurements opens the door to clinical applications like the post-treatment follow-up of stenoses or intracranial aneurysms.

The Catch Mini stent retriever for mechanical thrombectomy in distal intracranial occlusions.

OBJECTIVE: Mechanical thrombectomy (MTB) is a treatment of reference for acute ischemic stroke due to large brain vessel occlusion but some concerns remain about its use in small distal branches. In the present study, we assessed the efficacy and the safety of distal MTB using the Catch Mini (CM) stent retriever. METHODS: We retrospectively reviewed a prospectively maintained database of all consecutive patients who underwent MTB for a distal intracranial occlusion with the Catch Mini device at our hospital. RESULTS: Forty-one patient underwent MTB for distal intracranial occlusions using the CM stent retriever. Good capillary reperfusion (TICT≥2b) was observed in 32 out of 41 patients (78%). Focal ischemia within the territory vascularized by the artery addressed by the CM was observed in 8 patients (19.5%). Post-procedural vasospasm was observed in 8 patients, all responding rapidly to vasodilatator administration. Two asymptomatic hemorrhages (4.9%) were noted on follow-up imaging (one patechial hemorrhage and one parenchymal hematoma) in patients with M2 occlusions. No vessel rupture were observed. Overall, good neurological outcome at three months (mRS≤2) was observed in 28 (out of 34 patients followed; 82.4%) of patients. CONCLUSIONS: Our single-center experience shows that the CM stent retriever is safe and effective for the recanalization of small diameter distal branches feeding eloquent brain areas.

Current status of mechanical thrombectomy for acute stroke treatment.

Acute ischemic stroke is a morbid and disabling medical condition with a significant social and economic impact throughout the world. Intravenous thrombolysis (IVT) has been the first line treatment for patients presenting up to 4.5 hours after symptom onset for many years. Endovascular stroke treatment has been used successfully as rescue therapy after failed IVT; in patients with contraindications to rtPA or presenting outside the 4.5-hour window. The effectiveness of IVT is high for distal thrombi but significantly lower for proximal occlusions. Endovascular treatment has been revolutionized by the evolution from intra-arterial thrombolysis and first generation mechanical devices to the current generation of stent retrievers and aspiration systems with large bore catheters. These devices have been associated with excellent revascularization, improved clinical outcomes, shorter procedure times and reduced device and procedure related complications. We report the current literature, clinical standards and perspectives on mechanical thrombectomy in acute ischemic stroke.

Vascular Imaging Techniques of the Spinal Cord.

The various imaging techniques used to depict vascular lesions of the spinal cord are described in this article with particular emphasis on magnetic resonance imaging (MRI), vascular sequences, and advantages of high-field MRI. Technical vascular protocols are discussed in computed tomography, MRI, and conventional angiography. The diverse magnetic resonance angiography protocols are presented as well as their findings, specificities, and pitfalls. A review of the vascular anatomy and the most common pathologies analyzed by magnetic resonance angiography and conventional angiography is described.

CO2BOLD assessment of moyamoya syndrome: Validation with single photon emission computed tomography and positron emission tomography imaging.

AIM: To compare the assessment of cerebrovascular reserve (CVR) using CO2BOLD magnetic resonance imaging (MRI) vs positron emission tomography (PET) and single photon emission computed tomography (SPECT) as reference standard. METHODS: Ten consecutive patients (8 women, mean age of 41 ± 26 years) with moyamoya syndrome underwent 14 pre-surgical evaluations for external-internal carotid artery bypass surgery. CVR was assessed using CO2BOLD and PET (4)/SPECT (11) with a maximum interval of 36 d, and evaluated by two experienced neuroradiologists. RESULTS: The inter-rater agreement was 0.81 for SPECT (excellent), 0.43 for PET (fair) and 0.7 for CO2BOLD (good). In 9/14 cases, there was a correspondence between CO2BOLD and PET/SPECT. In 4/14 cases, CVR was over-estimated in CO2BOLD, while in 1/14 case, CVR was underestimated in CO2BOLD. The sensitivity of CO2BOLD was 86% and a specificity of 43%. CONCLUSION: CO2BOLD can be used for pre-surgical assessment of CVR in patients with moyamoya syndrome and combines the advantages of absent irradiation, high availability of MRI and assessment of brain parenchyma, cerebral vessels and surrogate CVR in one stop.

New Pipeline Flex device: initial experience and technical nuances.

BACKGROUND: Flow diverter stents (FDS) have been described as a breakthrough in the treatment of intracranial aneurysms. Of the various flow diverter models, the Pipeline device has been the main approved and used device, with established and good long-term results. OBJECTIVE: To present the first series of patients treated with its new version, the Pipeline Flex device. This has kept the same device design and configuration but redesigned and completely modified the delivery system. METHODS: In this technical report, we include 10 consecutive patients harboring 12 saccular aneurysms of the anterior circulation. We report the main changes on the system, immediate results, and technical nuances with illustrative cases. RESULTS: We implanted 12 devices, including 11 Pipeline Flex and one Pipeline device. We used the old version in one case that required a second layer with a short length not available in the Pipeline Flex size range. All attempts at treatment were successful and no device was discharged or removed. Recovery was required or used in half of the cases with good or excellent performance, except in one case that presented with multiple proximal loops and tight curves. We had two transitory events without ischemic lesions on MRI that recovered 1 and 4 h after all patients were discharged home asymptomatic. CONCLUSIONS: Pipeline Flex represents a major advance in FDS technology. The redesigned system has significantly improved the deployment of the Pipeline stent, by enabling the operator to resheath the device. It has the potential to continue revolutionizing the endovascular approach for intracranial aneurysms.