Objective: In interventional neuroradiology (INR), the evaluation of the peak skin dose (PSD) and lens dose is important because the patient radiation dose increases in cases in which the procedure is more difficult and complex. This study evaluated the radiation doses during INR procedures using a direct measurement system.

Methods: Radiation dose measurements during INR were performed in 332 patients with unruptured aneurysm (URAN), dural arteriovenous fistula (DAVF), and arteriovenous malformation (AVM). The PSD and bilateral lens doses were analyzed for each disease. The Pearson correlation test was used to determine whether the PSD and lens doses were linearly related to the reference air kerma (K_a,r).

Results: In all cases, the PSD and right and left lens doses were 2.36 ± 1.28 Gy, 114.2 ± 54.6 mGy, and 189.8 ± 160.3 mGy, respectively. The PSD and lens doses of the DAVF and AVM cases were significantly higher than those of the URAN case. The Pearson correlation test revealed statistically significant positive correlations between K_a,r and PSD, K_a,r and right lens dose, and K_a,r and left lens dose.

Conclusion: The characteristics of radiation dose in INR were clarified. Owing to the concern of increased radiation doses exceeding the threshold values in DAVF and AVM cases, protection from radiation is required. Simple regression analysis revealed the possibility of precisely predicting PSD using K_a,r.

Objective: To evaluate whether changes in the practice of mechanical thrombectomy could affect the clinical outcomes during the coronavirus disease (COVID-19) pandemic.

Methods: Patients who underwent mechanical thrombectomy from April 2019 to March 2021 for anterior circulation proximal large artery occlusion in our institute were divided into two groups of pre- and post-COVID-19, with April 2020 assumed to be the start of the COVID-19 era with the first declaration of a state of emergency. We compared patient characteristics, proportions of patient selection depending on rapid processing of perfusion and diffusion (RAPID) CT perfusion, outcomes including treatment variables such as time and reperfusion status, and patient independence at 3 months.

Results: Data for 112 patients (median age, 79 years; 44 females) were included in the analysis. A total of 50 patients were assigned to the pre-COVID-19 group (45%). More patients were selected with RAPID CT perfusion in the post-COVID-19 compared with the pre-COVID-19 (69% vs. 16%; P <0.001). Treatment details and clinical outcomes did not differ between the groups, including the door-to-puncture time (median [interquartile range], 66 [54–90] min vs. 74 [61–89] min; P = 0.15), proportions of significant reperfusion (82% vs. 87%; P = 0.60), and modified Rankin scale score of ≤2 at 3 months (46% vs. 45%; P >0.99). Multivariate logistic regression analysis for the clinical outcome of modified Rankin scale score of ≤2 at 3 months was performed and included the following factors: age, sex, the onset-to-door time, significant reperfusion, and pre- and post-COVID-19. The treatment period did not influence the outcomes (post-COVID-19 group, odds ratio, 0.79; 95% confidence interval, 0.34–1.85, P = 0.59).

Conclusion: In the setting of a limited access to emergency MRI during the COVID-19 pandemic, RAPID CT perfusion was performed significantly more often. Changes in the practice of mechanical thrombectomy with the protected code stroke did not bring the different level of treatment and clinical outcomes as before.

Objective: We report a case of additional carotid artery stenting (CAS) for plaque protrusion occurring after initial CAS for radiation-induced common carotid artery (CCA) stenosis.

Case Presentation: A 69-year-old man with a history of radiotherapy for laryngeal cancer presented to our hospital with sudden-onset right hemiparesis. Since vulnerable plaque of the left CCA was considered the embolic source for ischemic stroke, CAS was performed for left CCA stenosis. No perioperative complications were observed and the patient was discharged with a modified Rankin Scale score of 0. However, 1 month after CAS, cerebral embolism recurred. As protruding plaque was found on CTA, additional endovascular treatment was performed with intravascular ultrasonography. He was discharged without complications and showed a good outcome at 3 months.

Conclusion: In CCA stenosis after radiotherapy, accelerated arteriosclerosis may cause drug-resistant cerebral embolism and plaque protrusion after CAS, making determination of the treatment strategy difficult. Appropriate treatment options need to be based on individual underlying diseases and plaque instability.

Objective: Detection of acute arterial occlusion in an anomalous middle cerebral artery (MCA) is challenging in an emergency setting because of its rarity.

Case Presentation: We report an 81-year-old woman who presented with acute occlusion of a duplicated middle cerebral artery (DMCA). Although the absence of the superior trunk of the left MCA was identified on preoperative imaging, initial angiography showed no typical sign of the occluded vessel. Repeated angiography eventually revealed retrograde arterial flow parallel to the other visible MCA trunk, which raised the possibility of a DMCA. The occlusion occurred at the origin of the DMCA originating from the internal carotid artery terminus, which obscured its presence. Mechanical thrombectomy was performed and achieved complete recanalization. The DMCA had two trunks of approximately equal size. The patient completely recovered within 90 days.

Conclusion: Comprehensive knowledge of cerebrovascular anomalies is essential to identify the occluded branch faster and accurately and to avoid thrombectomy-related complications in endovascular recanalization therapy. Relevant DMCA anatomy and tips for identifying an occluded DMCA are discussed.

Objective: We describe a rare case report of micro-arteriovenous malformation (micro-AVM) treated by the endovascular approach in addition with literature review.

Case Presentation: A 12-year-old boy presenting with a spontaneous intracerebral hematoma in the left occipital lobe underwent conventional diagnostic workups. The results of initial catheter angiography were considered to be equivocal as the AVM. Superselective angiography (SA) demonstrated a micro or small AVM (single feeder and single drainer type) with an aneurysmal dilatation. Immediate transarterial embolization (TAE) might fail to occlude the whole of nidus area completely, and subsequently, we switched to the surgical exploration of AVM lesion. Intraoperative findings demonstrated that the whole of AVM lesion had already been occluded completely, indicating the complete occlusion by TAE only. Pathological findings of the surgical specimen showed an aneurysmal dilatation was a venous aneurysm with vulnerable vascular wall structure, which was certainly the source of bleeding. Based on the above results, the retrospective revaluation of superselective angiogram permitted us to understand that the nidus of AVM was micro nidus type and TAE had resulted in the complete nidus occlusion.

Conclusion: SA is the most useful diagnostic modality to clarify the angioarchitecture of micro-AVM and AVM-related aneurysms. If SA is successfully performed and relatively safe TAE is expected to be possible, the subsequent attempt to do curative embolization as a first-line treatment may be worthy of consideration. However, the surgical procedure should be fully reserved for the possible incomplete obliteration and hemorrhagic complications.

Objective: We describe a patient treated with transarterial Onyx embolization for a tentorial dural arteriovenous fistula (DAVF) who presented with hemifacial spasm (HFS).

Case Presentation: A 56-year-old man suffered from right blepharospasm for 4 years, and the symptom gradually spread to the right side of his face with oculo-oral synkinesis. MRI of the brain revealed abnormal multiple flow voids at the surface of brainstem and cerebellar hemisphere. MRA (time of flight) and spoiled gradient recalled echo-revealed abnormal vessels at the posterior fossa indicated arteriovenous shunting. 3D-MRI fusion images showed that a dilated vein was in contact with the root exit zone (REZ) of the right facial nerve. The right carotid angiography displayed a complex tentorial DAVF on the right side. There were multiple feeding vessels drained to the tentorial sinus at the point where the inferior cerebellar vermian vein met, and severe venous congestion was noted. We diagnosed a tentorial DAVF and thought that this was responsible for the right HFS. We used neuroendovascular treatment for this lesion. After transarterial Onyx embolization, his right HFS diminished. MRI after treatment showed that the vein in contact with the REZ of the right facial nerve had shrank.

Conclusion: We experienced a rare case of HFS associated with a DAVF. Our case supports that transarterial Onyx embolization can treat HFS associated with a tentorial DAVF. It is the first description of successful treatment that could be confirmed through postoperative MRI.

Objective: It is often difficult and has a potential risk of vessel injury to navigate a catheter or a microcatheter through the difficult types of aortic arches and through an occluded segment of the intracranial arteries under fluoroscopic guidance alone. Herein, we demonstrate a supportive technique of virtual fluoroscopic imaging from a data of non-contrast CT for a case of thrombectomy for acute occlusion of the right middle cerebral artery (MCA).

Case Presentation: An 85-year-old woman was transferred to our hospital with complaints of left-sided paralysis, dysarthria, and aphasia. CT revealed a hyperdense MCA sign, suggesting acute right MCA occlusion. CT showed bovine type of aortic arch too. Subsequently, mechanical thrombectomy was performed with the right brachial approach. A guiding catheter and a microcatheter system were successfully navigated into the target lesion under virtual fluoroscopic imaging guidance, and then thrombolysis in cerebral infarction (TICI) 3 recanalization was obtained in puncture-to-recanalization time of 37 minutes.

Conclusion: Virtual fluoroscopic images helped us to perform thrombectomy in a case of acute MCA occlusion, which provided anatomical information on the artery distal to the occlusion site, and were useful in determining the direction of the wire guidance.