Journal of Neuroradiology最新文献

Background and Purpose

Intracranial aneurysms are more common in women than in men. Some anatomical variants of the circle of Willis (CoW) are associated with a higher risk of developing intracranial aneurysms. We hypothesized that variations of the CoW are sex dependent which may partly explain why intracranial aneurysms are more common in women. We systematically reviewed and meta-analyzed the literature to compare the presence of anatomical variations of the CoW between women and men in the general population.

Material and Methods

A systematic search in Pubmed and EMBASE using predefined criteria, following the PRISMA guidelines was performed. The presence of different CoW anatomical variants and a complete CoW was compared between women and men using an inverse variance weighted random effects meta-analysis to calculate relative risks (RR) with 95% confidence intervals (95% CIs).

Results

Fourteen studies were included reporting on 5478 healthy participants (2511 women, 2967 men). Bilateral fetal type posterior cerebral arteries (RR 2.79; 95%CI 1.65–4.72, I²=0%), and a complete CoW (RR 1.24, 95%CI 1.13–1.36; I²=0%) were more prevalent in women than in men. The variants absence or hypoplasia of one of the anterior cerebral arteries (RR 0.58, 95%CI 0.38–0.88, I²=57%) and hypoplasia or absence of both posterior communicating arteries (RR 0.79, 95%CI 0.71–0.87, I²=0%) were more prevalent in men.

Conclusions

Several anatomical variations of the CoW are sex dependent, with some variants being more common in women while others in men. Future research should assess how these sex-specific CoW variants relate to the sex-specific occurrence of intracranial aneurysms.

Background

Mechanical thrombectomy for acute ischemic stroke is effective and includes different technical approaches. Operators use direct aspiration, a stent retriever, or a combination of both. Direct aspiration can be performed with various catheters of different sizes depending on the diameter of the occluded vessel.

Purpose

We studied the relationship between the catheter diameter in regards to the occluded vessel diameter and the rate of successful recanalization.

Materials and methods

We conducted a retrospective, monocentric study on a series of consecutive patients treated with mechanical thrombectomy. For each procedure, we extracted each attempt that used direct aspiration and rated the attempt as successful or unsuccessful. We also measured the occluded artery diameter and calculated the ratio between the occluded artery and the aspiration catheter diameters. We tested the association between the diameter ratio and the recanalization status. We also performed inter-rater agreement for the arterial diameter measurement between three interventional neuroradiologists.

Results

We included 119 patients with 201 attempts of direct aspiration. A higher diameter ratio was associated with a higher recanalization rate. The analysis in terciles showed that the odds of success were 4.80 higher when the ratio was >0.71 vs <0.54 (p < 0.01). Inter-rater agreement showed near-perfect intraclass correlation with 0.93 (0.91–0.94) consistency and 0.92 (0.90–0.94) absolute agreement.

Conclusions

We demonstrated an association between higher recanalization and a diameter of ratio >0.71 between the aspiration catheter and the occluded artery. These results could guide intraoperative decisions regarding the appropriate selection of aspiration catheters during mechanical thrombectomy increasing the rate of successful recanalisation. A larger study could provide additional data to further specify the optimal ratio.

In acute ischemic stroke, the composition of the occlusive clot can be associated with the underlying pathophysiology and the response to treatment. For these reasons, it is important to characterize the clot composition from clinical scans. We examine the ability of 3T and 7T MRI to distinguish the composition of in vitro clots, using quantitative T₁ and T₂*, alternatively R₂*, mapping. When comparing the two field strengths, we found a tradeoff between sensitivity for clot composition and confidence in the clot depiction associated with spatial resolution. The loss of sensitivity at 7T can be mitigated by combining the T₁ and T₂* signals.

Purpose

In the endovascular era, postcoiling recanalization of cerebral aneurysms is occurring with greater frequency. Repeat coiling is usually done to prevent rebleeding, although long-term outcomes of re-embolization have yet to be adequately investigated. The present study was undertaken to assess clinical and radiographic outcomes of re-embolization in recanalized aneurysms, focusing on procedural safety, efficacy, and durability.

Method

In this retrospective review, we examined 308 patients with 310 recurrent aneurysms. All lesions were re-coiled, once major recanalization (after initial coil embolization) was established. Medical records and radiologic data amassed during extended follow-up were then subject to review. Cox proportional hazards regression analysis was undertaken to identify risk factors for subsequent recurrence.

Result

During a lengthy follow-up (mean, 40.2 ± 33.0 months), major recanalization developed again in 87 aneurysms (28.1%). Multivariable Cox regression analysis linked re-recanalization to initial saccular neck width (p=.003) and autosomal dominant polycystic kidney disease (ADPKD; p<.001). Stent implantation (p=.038) and successful occlusion at second coiling (p=.012) were protective against later recanalization in this setting. The more recent the second embolization was performed, the lower the risk of further recurrence (p=.023). Procedure-related complications included asymptomatic thromboembolism (n = 9), transient ischemic neurologic deficits (n = 2), procedural bleeding (n = 1), and coil migration (n = 1), but there were no residual effects or deaths.

Conclusion

Repeat coil embolization is a safe therapeutic option for recanalized cerebral aneurysms. Wide-necked status and ADPKD emerged as risks for subsequent recanalization, whereas successful occlusion and stent implantation seemed to reduce the likelihood of recurrence after re-embolization procedures.

Percutaneous transluminal angioplasty (PTA) and stenting have been used for the treatment of internal carotid artery (ICA) stenosis over the past two decades. A systematic review was performed to understand the efficacy of PTA and/or stenting for petrous and cavernous ICA stenosis. In total, 151 patients (mean age 64.9) met criteria for analysis, 117 (77.5%%) were male and 34 (22.5%) were female. Of the 151 patients, 35 of them (23.2%) had PTA, and 116 (76.8%) had endovascular stenting. Twenty-two patients had periprocedural complications. There was no significant difference in the complication rates between the PTA (14.3%) and stent (14.7%) groups. Distal embolism was the most common periprocedural complication. Average clinical follow up for 146 patients was 27.3 months. Eleven patients (7.5%) out of 146 had retreatment.

The treatment of petrous and cavernous ICA with PTA and stenting has relatively significant procedure related complication rates and adequate long-term patency.

Purpose

Traditional flow diverters (FDs) for treating aneurysms at the fetal posterior communicating artery are unsatisfactory. Surpass Streamline is a novel FD with different mesh characteristics; however, the outcomes for such aneurysms remain unclear. This study aimed to compare hemodynamic alterations induced by Surpass Streamline, Pipeline Flex, and Tubridge devices and explore possible strategies for aneurysms at the fetal posterior communicating artery.

Methods

Two simulated aneurysms (Case 1, Case 2) were constructed from digital subtraction angiography (DSA). The three FDs were virtually deployed, and hemodynamic analysis based on computational fluid dynamics was performed. Hemodynamic parameters, including the sac-averaged velocity magnitude (Velocity), high-flow volume (HFV), and wall shear stress (WSS), were compared between each FD and the untreated model (control). Surpass Streamline was performed in real life for two aneurysms and the clinical outcomes were collected for analysis.

Results

Compared to the control, the Surpass resulted in the most significant reduction in flow. In Case 1, the Velocity, HFV, and WSS were reduced by 51.6%, 78.1%, and 64.3%, respectively. In Case 2, the Velocity, HFV, and WSS were reduced by 48.0%, 81.1%, and 65.3%, respectively. Tubridge showed slightly larger changes in hemodynamic parameters than Pipeline. In addition, our analysis suggested that metal coverage was correlated with the WSS, Velocity, and HFV. The postoperative DSA showed that the aneurysm was nearly occluded in Case 1 and decreased in Case 2.

Conclusion

Compared to that with the Pipeline and Tubridge, the Surpass resulted in the greatest reduction in hemodynamic parameters and might be effective for aneurysms at the fetal posterior communicating artery. Virtual FD deployment and computational fluid dynamics analysis may be used to predict the treatment outcomes.

Background and purpose

Diffuse low-grade gliomas (DLGG) are characterized by a slow and continuous growth and always evolve towards an aggressive grade. Accurate prediction of the malignant transformation is essential as it requires immediate therapeutic intervention. One of its most precise predictors is the velocity of diameter expansion (VDE). Currently, the VDE is estimated either by linear measurements or by manual delineation of the DLGG on T2 FLAIR acquisitions. However, because of the DLGG's infiltrative nature and its blurred contours, manual measures are challenging and variable, even for experts. Therefore we propose an automated segmentation algorithm using a 2D nnU-Net, to 1) gain time and 2) standardize VDE assessment.

Materials and Methods

The 2D nnU-Net was trained on 318 acquisitions (T2 FLAIR & 3DT1 longitudinal follow-up of 30 patients, including pre- & post-surgery acquisitions, different scanners, vendors, imaging parameters…). Automated vs. manual segmentation performance was evaluated on 167 acquisitions, and its clinical interest was validated by quantifying the amount of manual correction required after automated segmentation of 98 novel acquisitions.

Results

Automated segmentation showed a good performance with a mean Dice Similarity Coefficient (DSC) of 0.82±0.13 with manual segmentation and a substantial concordance between VDE calculations. Major manual corrections (i.e., DSC<0.7) were necessary only in 3/98 cases and 81% of the cases had a DSC>0.9.

Conclusion

The proposed automated segmentation algorithm can successfully segment DLGG on highly variable MRI data. Although manual corrections are sometimes necessary, it provides a reliable, standardized and time-winning support for VDE extraction to asses DLGG growth.

The increasing use of embolization devices with suboptimal radio-opacity to treat intracranial aneurysm underscores the need for advanced imaging techniques to characterize device-vessel interactions more accurately. Contrast-diluted cone-beam CT is commonly used in neurointervention but requires additional technical refinements to improve endovascular treatment assessment. In this technical note, we describe the virtual dilution cone beam CT (VDCBCT), a technique that synthetizes non-contrast and contrast-enhanced CBCT images to virtually dilute iodinated contrast agents, thereby facilitating a more accurate assessment of embolization device apposition.

Through a set of intracranial aneurysms treated with different embolization devices, we describe the VDCBCT protocol and its usefulness for device apposition confidence.

VDCBCT may enhance the global understanding of neurovascular embolization treatments by providing improved visualization of target vessels and low-radio-opacity embolization devices, obviating the need for contrast dilution.