A Concealed Intracranial Aneurysm Detected after Recanalization of an Occluded Vessel: A Case Report and Literature Review

Three-dimensional vessel wall imaging with 1.5-T MRI to visualize invisible occluded cerebral artery

BACKGROUND

Endovascular thrombectomy (EVT) is performed for acute ischemic stroke (AIS) caused by large vessel occlusion; therefore, preoperative visualization of the occluded invisible vessel course reduces complications and ensures success. Three-dimensional (3D) proton density-weighted (PDW) vessel wall imaging (VWI) using variable refocusing flip angle pulse-turbo spin-echo sequences (VRFA-TSE) with 3.0-T magnetic resonance imaging (MRI) can provide this information.

PURPOSE

To assess the effectiveness of 3D PDW-VWI using 1.5-T MRI without VRFA function.

MATERIAL AND METHODS

Five consecutive patients with AIS caused by large vessel occlusion underwent EVT in our institute. VWI with 1.5-T MRI using 3D PDW-fast spin echo (FSE) technique was added to conventional brain imaging.

RESULTS

PDW-FSE was successfully performed in all cases. 3D PDW-FSE was useful to visualize both the anterior and posterior circulations by clearly revealing invisible vessels but could not demonstrate the length and size of the clot in all five cases.

CONCLUSION

3D PDW-FSE with 1.5-T MRI without VRFA could clearly depict the course of the invisible occluded artery and might support favorable outcomes after EVT in patients with AIS.

Evaluation of Occluded Distal Vessels with Variable Flip-Angle 3-Dimensional Turbo Spin-Echo Magnetic Resonance Imaging Before Acute Mechanical Thrombectomy

OBJECTIVE

The aim of this study was to evaluate the course of occluded distal vessels before mechanical thrombectomy (MT) for acute large vessel occlusion (LVO) with non-contrast magnetic resonance imaging (MRI). The variable flip-angle three-dimensional turbo spin-echo (VRFA-3D-TSE) method was used to evaluate the course of occluded distal vessels quickly and clearly in acute LVO cases before MT.

METHODS

Patients with acute LVO who were indicated for MT between April 2021 and March 2022 were examined by the VRFA-3D-TSE method to evaluate the distal course of occluded vessels. We included internal carotid artery (ICA) occlusion, M1 occlusion of the middle cerebral artery, and basilar artery (BA) occlusion. Preoperative images were compared to the angiographic findings after recanalization or with follow-up magnetic resonance angiography, and the results were assessed by 2 endovascular treatment specialists as excellent, good, or poor imaging.

RESULTS

MT was performed in a total of 27 patients. There were 17 patients with intracranial occlusion of the ICA, M1, and BA. Occlusion was found in the intracranial ICA in 6 patients, the M1 in 7, and the BA in 4. VRFA-3D-TSE MRI was performed in all patients, and the imaging was rated (by the 2assessors) as excellent in 12 of 17 and 14 of 17 cases, good in 5 of 17 and 3 of 17 cases, and poor in 0 of 17 cases.

CONCLUSIONS

In patients with acute LVO, VRFA-3D-TSE MRI enabled rapid and good depiction of the course of occluded distal vessels before MT without the use of contrast medium.

Three-dimensional vessel wall MRI to characterize thrombus prior to endovascular thrombectomy for large vessel occlusion stroke

BACKGROUND AND PURPOSE

Endovascular thrombectomy (EVT) for acute ischemic stroke (AIS) caused by large vessel occlusion requires rapid and reliable imaging of the vessel course including the clot to reduce complications and ensure success. However, no method to acquire this information has been established.

METHODS

Six consecutive patients with AIS caused by large vessel occlusion underwent EVT in our institute. High-resolution vessel wall MRI was performed using three-dimensional (3D) variable refocusing flip angle pulse and turbo spin-echo sequences (VRFA-TSE) with the volume isotropic turbo spin-echo acquisition (VISTA) technique. This study evaluated the effectiveness of 3D proton density-weighted (PDW) VRFA-TSE (called PDW-VISTA) compared with T2-weighted (T2W) VRFA-TSE (called T2W-VISTA) to demonstrate the cerebral vessels including the occluded invisible lesion.

RESULTS

PDW-VISTA and T2W-VISTA were successfully performed in all cases. PDW-VISTA was more useful to visualize the anterior circulation than T2W-VISTA by clearly revealing invisible vessels, whereas PDW-VISTA and T2W-VISTA had similar findings in the posterior circulation. The vessel courses shown by 3D PDW-VISTA imaging before treatment and digital subtraction angiography after treatment showed good agreement in all cases. Furthermore, 3D PDW-VISTA imaging demonstrated the length and size of the clot.

CONCLUSIONS

PDW-VISTA imaging was found to more clearly depict the cerebral vessels including occluded lesion than T2W-VISTA imaging. Findings of thrombus size and length were important for correctly placing the stent retriever and securing safety during the procedure.

Mechanical thrombectomy for acute fetal posterior cerebral artery occlusion with a hidden unruptured cerebral aneurysm: illustrative case

BACKGROUND

Fetal posterior cerebral artery occlusion is rare and often presents with severe neurological symptoms. Although acute recanalization therapy is commonly used for cerebral vessel occlusion, unruptured cerebral aneurysms can be hidden distal to the occluded vessels.

OBSERVATIONS

An 87-year-old man presented with consciousness disturbance and right hemiparesis. The authors diagnosed left fetal posterior cerebral artery occlusion and performed mechanical thrombectomy. A stent retriever was deployed from the middle cerebral artery M1 segment across the mural thrombus of the internal carotid artery. After the first pass, the fetal posterior cerebral artery remained occluded, with confirmation of a contrast effect around the thrombus. Because the anatomical course of the fetal posterior cerebral artery was unidentified, the procedure was stopped. At 1-week recovery, magnetic resonance imaging revealed complete recanalization and a fetal posterior cerebral artery aneurysm hidden within the occluded site. Blood flow was directed to the aneurysm, and the thrombus within the aneurysm simultaneously occluded the fetal posterior cerebral artery.

LESSONS

To avoid critical complications following mechanical thrombectomy for fetal posterior cerebral artery occlusion, hidden aneurysms should be suspected when a “fried egg–like” contrast effect is observed around the thrombus.

Telerobotic neurovascular interventions with magnetic manipulation

Advances in robotic technology have been adopted in various subspecialties of both open and minimally invasive surgery, offering benefits such as enhanced surgical precision and accuracy with reduced fatigue of the surgeon. Despite the advantages, robotic applications to endovascular neurosurgery have remained largely unexplored because of technical challenges such as the miniaturization of robotic devices that can reach the complex and tortuous vasculature of the brain. Although some commercial systems enable robotic manipulation of conventional guidewires for coronary and peripheral vascular interventions, they remain unsuited for neurovascular applications because of the considerably smaller and more tortuous anatomy of cerebral arteries. Here, we present a teleoperated robotic neurointerventional platform based on magnetic manipulation. Our system consists of a magnetically controlled guidewire, a robot arm with an actuating magnet to steer the guidewire, a set of motorized linear drives to advance or retract the guidewire and a microcatheter, and a remote-control console to operate the system under real-time fluoroscopy. We demonstrate our system's capability to navigate narrow and winding pathways both in vitro with realistic neurovascular phantoms representing the human anatomy and in vivo in the porcine brachial artery with accentuated tortuosity for preclinical evaluation. We further demonstrate telerobotically assisted therapeutic procedures including coil embolization and clot retrieval thrombectomy for treating cerebral aneurysms and ischemic stroke, respectively. Our system could enable safer and quicker access to hard-to-reach lesions while minimizing the radiation exposure to physicians and open the possibility of remote procedural services to address challenges in current stroke systems of care.

Clinical Usefulness of Preoperative MCA Anatomical Scanning MRI in Thrombectomy Therapy for Acute Anterior Circulation Vessel Occlusion

Objective

The aim of the present study was to evaluate the usefulness of the T2-weighted three-dimensional sequence method, known as "basi-parallel anatomical scanning (BPAS)-magnetic resonance imaging (MRI)," in demonstrating the running course of the obstructed middle cerebral artery (MCA) before acute mechanical thrombectomy.

Methods

Patients whose M1 part and internal carotid artery (ICA) were occluded on preprocedural MRA, but well demonstrated on MCA anatomical scanning (MAS)-MRI were enrolled in this study. The MAS-MR images for patients in whom thrombectomy was performed were compared with the post-thrombectomy angiography. We compared the running course of the C1-M2 bifurcation on MAS-MRI and angiography after thrombectomy, and the results were classified into 3 groups (Excellent, Good, and Poor).

Results

A total of 13 patients (range: 54-89) were enrolled, among whom 12 underwent thrombectomy. We compared MAS-MRI and post-thrombectomy angiography in 10. On comparison between MAS-MRI and post-procedural angiography, visualization was excellent in six (60%) patients. The mean age was 75.7 years, ranging from 54 to 89, and 6 were males. 3 patients had ICA occlusion and seven had MCA occlusion.

Conclusion

MAS-MRI was considered useful to clarify the running course of the MCA before acute mechanical thrombectomy.

Safety of antithrombotic therapy for patients with acute ischemic stroke harboring unruptured intracranial aneurysm

Background The safety of antithrombotic therapy for patients with acute ischemic stroke harboring unruptured intracranial aneurysms remains unclear. Aims This study was performed to determine whether treatment with antiplatelets, anticoagulants, or intravenous thrombolytic agents is safe for patients with acute ischemic stroke and unruptured intracranial aneurysms. Methods Among 9149 patients with acute ischemic stroke enrolled in the Fukuoka Stroke Registry from June 2007 to December 2014, 8857 patients with data on cerebrovascular imaging and three-month outcomes were included in this study. The frequency of adverse events, including intracranial hemorrhage, symptomatic intracranial hemorrhage, and in-hospital mortality, was compared between patients with and without unruptured intracranial aneurysms. The risk of a poor functional outcome (modified Rankin scale score of ≥3) at three months after stroke onset was estimated after adjusting for confounding factors by logistic regression analysis. Results Unruptured intracranial aneurysms were identified in 412 (4.7%) patients, and the mean diameter was 4.1 ± 3.2 mm. There was no significant difference in the frequency of any adverse events between patients with and without unruptured intracranial aneurysms among the overall patients or patients receiving antiplatelets, anticoagulants, or intravenous thrombolytic agents. The odds ratios of a poor functional outcome were not significantly higher in the presence of unruptured intracranial aneurysms, even in patients undergoing antiplatelet therapy, anticoagulation therapy, or intravenous thrombolysis. Conclusions These findings suggest that unruptured intracranial aneurysms are not associated with increased risks of adverse events or poor functional outcomes even after antithrombotic therapy for acute ischemic stroke. However, accumulation of cases is required to verify these findings.

A Direct Aspiration First Pass Technique for Mechanical Thrombectomy in the Setting of a Suspected Cerebral Aneurysm

There is little guidance in the literature on which thrombectomy technique is preferred in patients with acute ischemic stroke and concomitant aneurysms. Here, we present the case of a 58-year-old female with an acute ischemic stroke requiring emergent thrombectomy that was complicated by the presence of multiple, nonruptured intracranial aneurysms. Imaging confirmed an occlusion of the right middle cerebral artery and multiple nonruptured intracranial aneurysms. The patient was administered intravenous recombinant tissue plasminogen activator and the thrombus was aspirated via a direct aspiration first pass technique (ADAPT). Her symptoms improved significantly postoperatively with a consequent National Institutes of Health Stroke Scale (NIHSS) score of 0. The purpose of this case report is to give an overview and compare various techniques that can help guide the physician for safe, early revascularization while reducing recanalization time in patients having an ischemic stroke who also harbor intracranial aneurysms.