Application of High-Resolution C-Arm CT Combined with Streak Metal Artifact Removal Technology for the Stent-Assisted Embolization of Intracranial Aneurysms

Use of the Neuroform Atlas Stent or LVIS Jr Stent for Treatment of Unruptured Intracranial Aneurysms in Parent Arteries of <2 mm in Diameter: A Multicenter Experience

BACKGROUND AND PURPOSE

The Neuroform Atlas stent and the LVIS Jr stent are intracranial microstent systems for the treatment of wide-neck intracranial aneurysms. Hence, this study aimed to compare the efficacy and safety of the Neuroform Atlas stent and the LVIS Jr stent for the treatment of unruptured intracranial aneurysms in parent arteries of <2 mm in diameter.

MATERIALS AND METHODS

From March 2022 to April 2023, the clinical and imaging data of 135 patients with unruptured intracranial aneurysms treated with stent-assisted coiling using the Neuroform Atlas or LVIS Jr stent in parent arteries of <2 mm in diameter were retrospectively analyzed. Stent apposition was evaluated by high-resolution conebeam CT (HR-CBCT). Immediate aneurysm-embolization attenuation and occlusion at 6-month follow-up were evaluated using 2D DSA and the modified Raymond-Roy classification. Adverse events were recorded. Multivariate logistic regression analysis was undertaken to determine the independent factors affecting incomplete stent apposition.

RESULTS

One hundred thirty-five patients (135 aneurysms) underwent stent-assisted coiling (66 Neuroform Atlas stents and 69 LVIS Jr stents). Intraoperative HR-CBCT showed that 1 Neuroform Atlas stent and 11 LVIS Jr stents had incomplete stent apposition at the aneurysm neck (P <  .05). Perioperative complications occurred in 3 cases (2.22%). These comprised 2 cases of neurologic complications (1 case of distal intracranial vascular embolism and 1 case of cerebral parenchymal hemorrhage) and 1 case of severe postprocedural gastrointestinal hemorrhage. DSA follow-up showed 3 cases of aneurysm recurrence in the LVIS Jr group. Multivariate regression analysis showed that a stent angle of ≥75° (OR, 23.963; P = .005) or a parent artery diameter mismatch ratio of ≥1.25 (OR, 8.043; P = .037) were risk factors for incomplete stent apposition, especially for the LVIS Jr stent (OR, 20.297; P = .015).

CONCLUSIONS

The Neuroform Atlas stent and LVIS Jr stent are efficacious in the treatment of unruptured intracranial aneurysms in parent arteries of <2 mm in diameter. Apposition of the LVIS Jr stent was worse than in the Neuroform Atlas stent at the neck of some aneurysms.

Safety and Efficacy of LVIS Jr Stent-assisted Coiling of Intracranial Aneurysms in Small-diameter Parent Arteries : A Single-center Experience

OBJECTIVE

To investigate the safety and efficacy of LVIS Jr stent-assisted coiling (SAC) of intracranial aneurysms (IAs) in small-diameter parent arteries and determine the factors influencing incomplete aneurysm occlusion.

MATERIAL AND METHODS

Clinical and imaging data of 130 patients with IAs in small-diameter parent arteries that were treated with LVIS Jr SAC were retrospectively analyzed. Stent apposition was evaluated by high-resolution flat detector CT, and aneurysm embolization density was evaluated using 2D-DSA. Perioperative complications were recorded. Multivariate logistic regression analyses were performed to determine possible factors for incomplete aneurysm occlusion.

RESULTS

In this study, 130 patients (60 and 70 patients with ruptured and unruptured aneurysms, respectively) were successfully treated with LVIS Jr SAC. Immediate digital subtraction angiography (DSA) showed that the aneurysm occlusion was Raymond-Roy class I, II, IIIa, and IIIb in 93 (71.5%), 24 (18.5%), 8 (6.2%), and 5 (3.8%) cases, respectively. There were three cases of acute in-stent thrombosis and two cases of severe vasospasm observed during the perioperative period. The 6‑month follow-up angiograms indicated that complete aneurysm occlusion in 122 patients was 79.5% (97/122). Multivariate logistic regression analyses showed that an aneurysm size > 10.0 mm, parent artery mean diameter < 2.0 mm, and incomplete stent apposition at the aneurysm neck were possible risk factors for incomplete aneurysm occlusion.

CONCLUSION

The LVIS Jr SAC is effective for managing IAs in small-diameter parent arteries. An aneurysm size > 10.0 mm, parent artery mean diameter < 2.0 mm, and incomplete stent apposition at the aneurysm neck are possible risk factors for incomplete aneurysm occlusion.

Correlation of Flow Diverter Malapposition at the Aneurysm Neck with Incomplete Aneurysm Occlusion in Patients with Small Intracranial Aneurysms: A Single-Center Experience

BACKGROUND AND PURPOSE

Flow diversion treatment repairs aneurysms by altering the hemodynamics of the aneurysmal sac and providing a scaffold for endothelial cell adhesion. The purpose of this study was to investigate the correlation of flow diverter (FD) malapposition at the aneurysm neck with incomplete occlusion of small intracranial aneurysms (IAs) and investigate other factors that are possibly related to incomplete occlusion.

MATERIALS AND METHODS

From January 2019 to June 2022, the clinical and imaging data for 153 patients (175 aneurysms) with unruptured small IAs treated with flow diversion were retrospectively analyzed. FD apposition at the aneurysm neck was evaluated by high-resolution conebeam CT (HR-CBCT), and the complete occlusion rate for aneurysms was judged according to the latest follow-up conventional angiography findings (≥6 months). Multivariate logistic regression analysis was used to determine factors associated with incomplete aneurysm occlusion.

RESULTS

In total, 159 FDs were implanted in 153 patients. HR-CBCT performed after the deployment revealed FD malapposition at the aneurysm neck in 18 cases. According to the latest follow-up angiograms (average: 9.47 ± 3.35 months), the complete aneurysm occlusion rate was 66.9%. The complete occlusion rates for incomplete and complete stent apposition at the neck were 38.9% (7/18) and 70.1% (110/157), respectively. The results of regression analysis showed that an aneurysm sac with branch vessels (OR, 2.937; P = .018), incomplete stent apposition at the aneurysm neck (OR, 3.561; P = .023), and a large aneurysm diameter (OR, 1.533; P = .028) were positive predictors of incomplete aneurysm occlusion.

CONCLUSIONS

An aneurysm sac with branch vessels, a large aneurysm diameter, and malapposition at the aneurysm neck significantly affect aneurysm repair after FD stent-only treatment for small IAs.

Clinical Efficiency of an Artificial Intelligence-Based 3D-Angiography for Visualization of Cerebral Aneurysm: Comparison with the Conventional Method

PURPOSE

Artificial intelligence (AI)-based three-dimensional angiography (3D-A) was reported to demonstrate visualization of cerebral vasculature equivalent to that of three-dimensional digital subtraction angiography (3D-DSA). However, the applicability and efficacy of the AI-based 3D‑A algorithm have not yet been investigated for 3D-DSA micro imaging. In this study, we evaluated the usefulness of the AI-based 3D‑A in 3D-DSA micro imaging.

MATERIALS AND METHODS

The 3D-DSA micro datasets of 20 consecutive patients with cerebral aneurysm (CA) were reconstructed with 3D-DSA and 3D‑A. Three reviewers compared 3D-DSA and 3D‑A in terms of qualitative parameters (degrees of visualization of CA and the anterior choroidal artery [AChA]) and quantitative parameters (aneurysm diameter, neck diameter, parent vessel diameter, and visible length of AChA).

RESULTS

Qualitative evaluation of diagnostic potential revealed that visualization of CA and the proximal to middle parts of the AChA with 3D‑A was equal to that with conventional 3D-DSA; in contrast, visualization of the distal part of the AChA was lower with 3D‑A than with 3D-DSA. Further, regarding quantitative evaluation, the aneurysm diameter, neck diameter, and parent vessel diameter were comparable between 3D‑A and 3D-DSA; in contrast, the visible length of the AChA was lower with 3D‑A than with 3D-DSA.

CONCLUSIONS

The AI-based 3D‑A technique is feasible and evaluable visualization of cerebral vasculature with respect to quantitative and qualitative parameters in 3D-DSA micro imaging. However, the 3D‑A technique offers lower visualization of such as the distal portion of the AChA than 3D-DSA.

Intraoperative cone-beam CT with metal artifact reduction for assessment of the electrode position and the intracranial structures during deep brain stimulation procedure

BACKGROUND

In deep brain stimulation (DBS) for Parkinson's disease (PD), the clinical outcome largely depends on the appropriate position of the electrode implanted in the targeted structure. In intraoperative cone-beam computed tomography (CT) performed for the evaluation of the electrode position, the metal artifact induced by the implanted electrode can prevent the precise localization of the electrode. Metal artifact reduction (MAR) techniques have been recently developed that can dramatically improve the visualization of objects by reducing metal artifacts after performing cone-beam CT. Hence, in this case series, we attempted to clarify the usefulness and accuracy of intraoperative cone-beam CT with MAR (intraCBCTwM) by comparing with both intraoperative cone-beam CT without MAR (intraCBCTwoM) and conventional postoperative CT (post-CT) for the assessment of the implanted electrode position and the intracranial structures during DBS procedures.

METHODS

Between November 2019 and December 2020, 10 patients with PD who underwent DBS at our institution were recruited, and the images of 9 patients (bilateral: n = 8, unilateral: n = 1) were analyzed. The artifact index (AI) in intraCBCTwM or intraCBCTwoM, and conventional post-CT were retrospectively assessed using the standard deviation of the region-of-interest around the implanted electrodes and background noise. Additionally, the Euclidean distances gap of electrode tip based on post-CT in each fusion image was compared between intraCBCTwM and intraCBCTwoM.

RESULTS

The AI was significantly lower in intraCBCTwM than in intraCBCTwoM (P < 0.01). The mean Euclidean distance between the tip of the electrode in intraCBCTwM and in post-CT was significantly shorter compared to that in intraCBCTwoM (P < 0.05).

CONCLUSIONS

The results reported here suggest that intraCBCTwM is a more useful and accurate method than intraCBCTwoM to assess the implanted electrode position and intracranial structures during DBS.

Efficacy of 3D-Printed Titanium Mesh-Type Patient-Specific Implant for Cranioplasty

Objective

Autologous bone grafting for cranioplasty is associated with a high infection rate and bone absorption. Synthetic implant materials for cranioplasty have been developed. In this study, we evaluated the efficacy of titanium mesh-type patient-specific implants (PSIs) for patients with skull defects using the dice similarity coefficient (DSC), clinical outcomes, and artifacts caused by implants.

Methods

This retrospective study included 40 patients who underwent cranioplasty with a titanium mesh PSI at our institution. Based on preoperative and postoperative computed tomography scans, we calculated DSC and artifacts.

Results

The calculated DSC of 40 patients was 0.75, and the noise was 13.89% higher in the region of interest (ROI) near the implanted side (average, 7.64 hounsfield unit [HU]±2.62) than in the normal bone (average, 6.72 HU±2.35). However, the image signal-to-noise ratio did not significantly differ between the ROI near the implanted side (4.77±1.78) and normal bone (4.97±1.88). The patients showed no significant perioperative complications that required a secondary operation.

Conclusion

Titanium mesh-type PSIs for cranioplasty have excellent DSC values with lower artifacts and complication rates.

Application of High-Resolution Flat Detector Computed Tomography in Stent Implantation for Intracranial Atherosclerotic Stenosis

Objective

To evaluate the utility of high-resolution flat-detector computed tomography (HR-FDCT) compared with conventional flat-detector computed tomography (FDCT) for stent placement in symptomatic intracranial atherosclerotic stenosis (ICAS).

Methods

We retrospectively reviewed the clinical data of 116 patients with symptomatic ICAS who underwent stent implantation. Images were acquired using conventional FDCT [voxel size = 0.43 mm (isotropic)] and HR-FDCT [voxel size = 0.15 mm (isotropic)]. Immediately after stent deployment, dual-volume three-dimensional (3D) fusion images were obtained from 3D digital subtraction angiography (DSA) and HR-FDCT. The image quality for stent visualization was graded from 0 to 2 (0: not able to assess; 1: limited, but able to assess; 2: clear visualization), and the stent-expansion status (“full,” “under-expanded” or “poor apposition”) was recorded.

Results

A total of 116 patients with symptomatic ICAS were treated successfully using 116 stents (58 Neuroform^TM EZ, 42 Enterprise^TM, and 16 Apollo^TM). The mean pre-stent stenosis was 80.5 ± 6.4%, which improved to 20.8 ± 6.9% after stenting. Compared with FDCT, HR-FDCT improved visualization of the fine structures of the stent to improve the image quality that significantly (mean score: 1.63 ± 0.60 vs. 0.41 ± 0.59, P < 0.001). In 19 patients, stent under-expansion (n = 11) or poor apposition (n = 8) was identified by HR-FDCT but not by conventional FDCT. After balloon dilatation, stent malapposition was shown to have improved on HR-FDCT. None of the 19 patients with stent malapposition experienced short-term complications during hospitalization or had in-stent stenosis at 6-month follow-up.

Conclusion

High-resolution flat-detector computed tomography (HR-FDCT) improves visualization of the fine structures of intracranial stents deployed for symptomatic ICAS compared with that visualized using conventional FDCT. High-resolution flat-detector computed tomography improves assessment of stent deployment and could reduce the risk of complications.