Formation and modulation of multi-pulse femtosecond laser-induced periodic surface structures by electromagnetic and partial differential equation simulations.

In order to demonstrate the formation of laser-induced periodic surface structures (LIPSS), simulations were performed to investigate the effect of multiple femtosecond laser pulses with different laser energy densities on a Ti6Al4V surface. In this work, a set of partial differential equations calculating the electron and lattice temperature variations, followed by coupling with an electric field, is used to analyze the evolution of the periodic surface structure induced by the interaction of the femtosecond laser with the material. As the number of pulses increases, the surface structure of the material changes from none to produce LIPSS structure and from low spatial frequency LIPSS (LSFL) structure to high spatial frequency LIPSS (HSFL) structure. In order to compare the results, single-point laser scanning ablation experiments were carried out at femtosecond laser energy. The experimental results are consistent with the simulation results.

Evidence of solidification crack propagation in pulsed laser welding of aluminum alloy.

It is difficult to collect the crack propagation signal under general continuous welding condition due to other signal interference of molten pool. In order to study the effect of residual stress on crack propagation, acoustic emission technology was successfully applied to monitor welding process according to the characteristics of pulsed laser welding. Crack free welding is achieved by reducing the pulse interval to limited the crack size of single pulse welding spot. The welding process was monitored synchronously by high speed photography and acoustic emission, the evidence of crack propagation after solidification of weld is successfully captured.

Evaluation of Quiescent-Interval Single-Shot Magnetic Resonance Angiography in Diabetic Patients With Critical Limb Ischemia Undergoing Digital Subtraction Angiography: Comparison With Contrast-Enhanced Magnetic Resonance Angiography With Calf Compression at 3.0 Tesla.

PURPOSE: To assess the diagnostic performance of quiescent-interval single-shot magnetic resonance angiography (QISS-MRA) at 3 tesla in diabetic patients with critical limb ischemia (CLI) vs contrast-enhanced MR angiography (CE-MRA) using digital subtraction angiography (DSA) as the standard of reference. METHOD: Thirty-seven consecutive diabetic patients (mean age 71.8±7.2 years; 30 men) with CLI (Fontaine stage III-IV) underwent QISS-MRA and CE-MRA with calf compression; DSA was the standard. Image quality (5-point Likert-type scale) and stenosis severity (5-point grading) for QISS-MRA and CE-MRA were evaluated by 2 blinded readers in 1147 and 654 vessel segments, respectively. Per-segment and per-region (pelvis, thigh, calf) sensitivity, specificity, positive predictive value, and negative predictive value were calculated. RESULTS: Image quality of QISS-MRA was lower compared with CE-MRA in the pelvic region (p<0.001 in both readers) and thigh region (p=0.033 in reader 1 and p=0.018 in reader 2), whereas in the calf region, the image quality of QISS-MRA was better than CE-MRA (p=0.009 in reader 1 and p=0.001 in reader 2). In segment-based analyses, there was no difference between QISS-MRA and CE-MRA in sensitivity [89.5% vs 90.3% in reader 1 (p=0.774) and 87.6% vs 90.6% in reader 2 (p=0.266)] or specificity [94.2% vs 92.9% in reader 1 (p=0.513) and 92.9% vs 92.9% in reader 2 (p>0.999)]. In region-based analyses, QISS-MRA and CE-MRA yielded similar sensitivity and specificity in all areas but the pelvic region for reader 2 (specificity 95.5% vs 84.8%, p=0.041). CONCLUSION: QISS-MRA performed very well in diabetic patients with CLI and was a good alternative for patients with contraindications to CE-MRA.

Morphological characteristics of chronic total occlusion: predictors of different strategies for long-segment femoral arterial occlusions.

OBJECTIVES: To investigate morphological characteristics used to predict recanalisation strategies in long-segment (>10 cm) femoral chronic total occlusion (LSF-CTO) angioplasty. METHODS: We retrospectively evaluated a range of morphological CTA and DSA features in patients who underwent recanalisation of LSF-CTO. The stage of CTO was classified into early (3-12 months) and late (>12 months) according to estimated duration. Characteristics including stump morphology, lesion length and calcification, proximal side branches, collaterals circulation, runoff vessels and concomitant arterial occlusion were used as predictors, and multivariate logistic regression analysis was performed to identify variables associated with late-stage CTO and retrograde technique. RESULTS: A total of 119 patients with 137 CTOs in 137 limbs were enrolled. Overall, successful recanalisation was achieved in 122 CTOs (89.1%). Flush occlusion [odds ratio (OR) 2.958; 95% confidence interval (CI) 1.172-7.465; p = 0.022], large collateral (OR 2.778; 95% CI 1.201-6.427; p = 0.017) and TransAtlantic Inter-Society Consensus II class D (TASC D) lesion (OR 1.743; 95% CI 1.019-2.981; p = 0.042) were predictors for late-stage CTO. Flush occlusion (OR 75.278; 95% CI 10.664-531.384; p < 0.001) and large collateral (OR 23.213; 95% CI 3.236-166.523; p = 0.002) were associated with high likelihood for retrograde approach. CONCLUSIONS: Flush occlusion and large collateral were associated with a CTO at late-stage which may require retrograde recanalisation. KEY POINTS: • CTO morphological characteristics help estimate lesion duration and optimise recanalisation strategies. • Flush occlusion and large collateral is associated with late-stage CTO and retrograde recanalisation. • Application of anterograde and retrograde recanalisation for long-segment femoral CTO is effective.

Correction to: Morphological characteristics of chronic total occlusion: predictors of different strategies for long-segment femoral arterial occlusions.

The original version of this article unfortunately contained mistakes. The legends to Figs. 2-4 were incorrectly interchanged. The correct versions are given below. The original article has been corrected.

Infrainguinal Endovascular Recanalization: Risk Factors for Arterial Thromboembolic Occlusions and Efficacy of Percutaneous Aspiration Thrombectomy.

PURPOSE: To investigate factors predictive of thromboembolic occlusions and evaluate the efficacy of percutaneous aspiration thrombectomy (PAT) for infrainguinal thromboembolic occlusions in patients undergoing endovascular recanalization (EVR). MATERIALS AND METHODS: In this single-center retrospective study, 23 patients who underwent PAT for thromboembolism during EVR and 237 patients who underwent successful EVR without thromboembolic occlusions (control group) were enrolled. Immediate posttreatment and follow-up outcomes between groups were compared. Multivariate analysis was performed to identify factors predictive of thromboembolic occlusions. Technical success of PAT was defined as achievement of < 30% residual stenosis and restoration of modified thrombolysis in myocardial infarction grade 3 flow. RESULTS: The technical success rate was 95.7% in the PAT group. After intervention, ankle brachial index (ABI), restoration of blood flow, and improvement in dorsal/plantar arterial pulse score showed no significant differences between the PAT and control groups. During follow-up, no significant differences were observed between groups in improvement of sustained ABI and maximum walking distance, ulcer healing, restenosis/occlusion and limb salvage rates, and pain relief in patients with critical ischemia. Stenosis greater than 90% with lesion occlusion (odds ratio, 12.891; 95% confidence interval, 1.676-99.161; P = .014) and intraluminal angioplasty (odds ratio, 18.423; 95% confidence interval, 2.408-140.942; P = .005) were associated with a high incidence of thromboembolism. CONCLUSIONS: Stenosis greater than 90% with lesion occlusion and intraluminal angioplasty may be factors predictive of thromboembolic occlusions. PAT is a safe and effective treatment for thromboembolism during infrainguinal arterial EVR.

Runoff detected by magnetic resonance angiography as an indicator for better recanalization outcomes in below-the-knee chronic total occlusions in diabetic patients.

PURPOSE: To compare the feasibility and efficacy of recanalizing below-the-knee (BTK) chronic total occlusions (CTOs) between patients with good or poor distal runoff based on magnetic resonance angiography (MRA) scans. METHODS: Two hundred long-segment BTK CTOs in 171 limbs of 113 diabetic patients (58 men; mean age 69.8±1.9 years) were divided into good distal runoff (GDR: 119 lesions, 98 limbs) or poor distal runoff groups (PDR: 81 lesions, 73 limbs) based on baseline MRA findings. After angioplasty, modified thrombolysis in myocardial ischemia (mTIMI) grades and ankle-brachial index (ABI) were used to assess immediate outcomes. Regularly scheduled duplex or MRA imaging was performed in follow-up. The restenosis and limb salvage rates were compared. RESULTS: The success rates were 93.3% and 87.7% in the GDR and PDR groups, respectively (p=0.21); subintimal angioplasty was more common in the PDR group (93.0% vs. 63.1%, p<0.01). Completion angiography indicated an mTIMI grade 3 blood flow in 71.2% lesions in the GDR patients and in 52.1% in the PDR (p=0.01) group. Improvement in the ABI was greater in the GDR limbs (p<0.001 vs. PDR). Mean imaging follow-up was 10.8±6.9 months in the GDR group and 11.1±6.6 months in the PDR group. Kaplan-Meier analysis showed a better restenosis-free rate in the GDR group (80.6% vs. 61.7%; p=0.02) at 12 months and for lesions with mTIMI grade 3 flow (p<0.01). At 24 months, Kaplan-Meier analysis revealed a better limb salvage rate in the GDR group (84.2% vs. 54.6%; p=0.02). CONCLUSION: Distal runoff detected using MRA could be a predictor for successful intraluminal recanalization, better distal tissue perfusion, improved long-term patency, and better limb salvage for patients with BTK CTOs.

Patency of runoff detected by MR angiography at 3.0 T with cuff-compression: a predictor of successful endovascular recanalization below the knee.

OBJECTIVES: Our aim was to assess the reliability of detecting distal runoff vessels using contrast-enhanced MR angiography (CE-MRA) that were occult on digital subtraction angiography (DSA) for predicting the outcome of endovascular recanalization (ER). METHODS: This retrospective analysis comprised 63 patients with diabetes (98 limbs) who underwent ER for infrapopliteal lesions. Before ER, they underwent CE-MRA and DSA for peripheral arterial disease; runoff vessels were detected with CE-MRA, but not with DSA. Immediate and follow-up postoperative outcomes were assessed. Univariate analysis was performed to identify variables associated with successful ER. RESULTS: Successful ER was achieved in 85.7 % of limbs, and runoff score was significantly lower than in failure limbs (5.1 ± 1.1 vs. 6.2 ± 1.3; P < 0.05). During follow-up, sustained ankle-brachial index (ABI) improvement was found in 76.6 % claudication patients, and walking distance improvement in 86.5 %; pain was relieved in 70.6 % of critical limb ischemia (CLI) limbs, ulceration healed in 81.3 %, and limb-salvage rate was 100 %. Restenosis/occlusion rate was higher for patients with CLI at 12 months (48.8 % vs. 96.3 % in claudication; P < 0.01). Runoff score was associated with a significantly higher likelihood of ER success (odds ratio = 4.096, 95 % confidence interval: 2.056-8.158; P < 0.001). CONCLUSION: Runoff vessels detected using CE-MRA could indicate immediate success and better outcome of ER for infrapopliteal occlusions. KEY POINTS: • 3-T MRA with cuff compression displayed distal below-the-knee (BTK) runoffs better than DSA • Detected runoffs indicate high recanalization rate and good clinical outcome • Runoff display provides potential opportunity to perform other backup recanalization strategies.

Nanosecond Laser Fabrication of Novel Micro-/Nanostructured Metal Surfaces: A Dual-Functional Supersurface Combining Antireflectivity and Superhydrophobic Properties.

The research and applications in the field of micro/nano surface manufacturing are progressively shifting their focus toward multifunctional surfaces. In practical applications, objects often need to operate under demanding environmental conditions, and single-function surfaces have inherent limitations in terms of performance, adaptability, and longevity. In this paper, a micro-/nanolayered structural strategy with dual functions of ultrahigh antireflective properties and superhydrophobicity was created on the surface of titanium alloy by using nanosecond pulsed laser processing, and two structural modes of periodic honeycomb and lattice with controllable shapes were designed. In addition, the morphology and formation mechanism of multilevel micro-/nanostructures were investigated in depth, combining laser texturization and silanization of substrate microstructures. The effects of the micro-/nanostructured morphology on the reflection and wettability properties were evaluated with different pulse widths and lateral overlap index. This study also demonstrated that water droplets exhibit excellent bouncing and rolling behavior on superhydrophobic surfaces, further verifying the excellent hydrophobic properties of the prepared samples. Furthermore, in addressing the challenges of susceptibility to dust contamination and performance degradation in extreme environments associated with antireflective surfaces, a series of durability and mechanical stability tests were conducted on controllability periodic micro-/nanostructured surfaces. Successfully meeting this challenge will open up great potential and opportunities for significant improvements in equipment performance and stable operation under extreme operating conditions.

Near-Field-Regulated Ultrafast Laser Supra-Wavelength Structuring Directly on Ultrahard Metallic Glasses.

The ultrafast-laser-matter interactions enable "top-down" laser surface structuring, especially for materials difficult to process, with "bottom-up" self-organizing features. The subwavelength scenarios of laser-induced structuring are improved in defects and long-range order by applying positive/negative feedbacks. It is still hardly reported for supra-wavelength laser structuring more associated with complicated thermo/hydro-dynamics. For the first time to the knowledge, the near-field-regulated ultrafast-laser lithography of self-arrayed supra-wavelength micro/nano-pores directly on ultra-hard metallic glass is developed here. The plasmonic hot spots on pre-structures, as the positive feedback, clamped the lateral geometries (i.e., position, size). Simultaneously, it drilled and self-organized into micro/nano-pore arrays by photo-dynamic plasma ablation and Marangoni removal confined under specific femtosecond-laser irradiation, as the negative feedback. The mechanisms and finite element modeling of the multi-physical transduction (based on the two-temperature model), the far-field/near-field coupling, and the polarization dependence during laser-matter interactions are studied. Large-area micro/nano-pore arrays (centimeter scale or larger)  are manufactured with tunable periods (1-5 µm) and geometries (e.g., diameters of 500 nm-6 µm using 343, 515, and 1030 lasers, respectively). Consequently, the mid/far-infrared reflectivity at 2.5-6.5 µm iss decreased from ≈80% to ≈5%. The universality of multi-physical coupling and near-field enhancements makes this approach widely applicable, or even irreplaceable, in various applications.

Frequency and predictors of endoleaks and long-term patency after covered stent placement for the treatment of intracranial aneurysms: a prospective, non-randomised multicentre experience.

OBJECTIVE: We investigated immediate/late endoleaks and long-term patency following stent-graft placement for treatment of intracranial aneurysms located within the distal internal carotid artery (ICA) or vertebral artery (VA). METHODS: Forty-five aneurysms in 41 patients receiving covered stents in three centres were followed. Outcome measures included aneurysm occlusion rate, endoleaks, late in-stent stenosis rate, clinical improvement, neurological deficiencies and death. RESULTS: Total aneurysm exclusion was achieved in 69.2% (n = 27), with 30.8% (n = 12) experiencing immediate residual endoleaks. Angiographic follow-up (mean 43.5 ± 14.3 months) revealed that 87.2% (n = 34) were completely occluded with only 12.8% (n = 5) showing residual endoleaks. Predictors of immediate endoleaks in our patient group were stent number (P = 0.023) and stent diameter (P = 0.022), while predictors of late endoleaks in our patient group were stent diameter (P = 0.035) and stent angulation (P = 0.021). Late in-stent stenosis rates were 18.0 ± 13.3 and 29.0 ± 18.5% compared with the period immediately following implantation at 2- and 6-year follow-ups respectively. Smoking (P = 0.017) and stent angulation (P = 0.020) were predictors of late in-stent stenosis. CONCLUSION: Treating intracranial aneurysms with Willis stent-grafts has an acceptable immediate and late occlusion rate and long-term stented artery patency rate.

Hybrid Machine-Learning-Based Prediction Model for the Peak Dilation Angle of Rock Discontinuities.

The peak dilation angle is an important mechanical feature of rock discontinuities, which is significant in assessing the mechanical behaviour of rock masses. Previous studies have shown that the efficiency and accuracy of traditional experimental methods and analytical models in determining the shear dilation angle are not completely satisfactory. Machine learning methods are popular due to their efficient prediction of outcomes for multiple influencing factors. In this paper, a novel hybrid machine learning model is proposed for predicting the peak dilation angle. The model incorporates support vector regression (SVR) techniques as the primary prediction tools, augmented with the grid search optimization algorithm to enhance prediction performance and optimize hyperparameters. The proposed model was employed on eighty-nine datasets with six input variables encompassing morphology and mechanical property parameters. Comparative analysis is conducted between the proposed model, the original SVR model, and existing analytical models. The results show that the proposed model surpasses both the original SVR model and analytical models, with a coefficient of determination (R2) of 0.917 and a mean absolute percentage error (MAPE) of 4.5%. Additionally, the study also reveals that normal stress is the most influential mechanical property parameter affecting the peak dilation angle. Consequently, the proposed model was shown to be effective in predicting the peak dilation angle of rock discontinuities.

Laser Welding Penetration Monitoring Based on Time-Frequency Characterization of Acoustic Emission and CNN-LSTM Hybrid Network.

In-process penetration monitoring of the pulsed laser welding process remains a great challenge for achieving uniform and reproducible products due to the highly complex nature of the keyhole dynamics within the intense laser-metal interactions. The main purpose of this study is to investigate the feasibility of acoustic emission (AE) measurement for penetration monitoring based on acoustic wave characteristics and deep learning. Firstly, a series of laser welding experiments on aluminum alloys were conducted using high-speed photography and AE techniques. This allowed us to in-situ visualize the complete keyhole dynamics and elucidate the generation mechanism of acoustic waves originating from pressure fluctuations at the keyhole wall. Then, an adaptive time-frequency technique namely VMD (Variational Mode Decomposition) was proposed to characterize the acoustic energy distribution among the nine subsignals with low-frequency and high-frequency components under different welding penetrations. Lastly, a novel hybrid model combing CNN (Convolutional Neural Network) and LSTM (Long Short Term Memory) was designed to deeply mine the spatial and temporal acoustic features from the extracted frequency components. Extensive experiments demonstrate that our proposed approach yields a remarkable classification performance with a test accuracy of 99.8% and a standard deviation of 0.21, which obtains a high recognition rate. This work is a new paradigm in the digitization and intelligence of the laser welding process and contributes to an alternative way of developing an efficient end-to-end penetration monitoring system.

Corrigendum: Bio-high entropy alloys: Progress, challenges, and opportunities.

[This corrects the article DOI: 10.3389/fbioe.2022.977282.].

Bio-high entropy alloys: Progress, challenges, and opportunities.

With the continuous progress and development in biomedicine, metallic biomedical materials have attracted significant attention from researchers. Due to the low compatibility of traditional metal implant materials with the human body, it is urgent to develop new biomaterials with excellent mechanical properties and appropriate biocompatibility to solve the adverse reactions caused by long-term implantation. High entropy alloys (HEAs) are nearly equimolar alloys of five or more elements, with huge compositional design space and excellent mechanical properties. In contrast, biological high-entropy alloys (Bio-HEAs) are expected to be a new bio-alloy for biomedicine due to their excellent biocompatibility and tunable mechanical properties. This review summarizes the composition system of Bio-HEAs in recent years, introduces their biocompatibility and mechanical properties of human bone adaptation, and finally puts forward the following suggestions for the development direction of Bio-HEAs: to improve the theory and simulation studies of Bio-HEAs composition design, to quantify the influence of composition, process, post-treatment on the performance of Bio-HEAs, to focus on the loss of Bio-HEAs under actual service conditions, and it is hoped that the clinical application of the new medical alloy Bio-HEAs can be realized as soon as possible.

Biocompatibility of micro/nano structures on the surface of Ti6Al4V and Ti-based bulk metallic glasses induced by femtosecond laser.

Femtosecond laser surface modification has been proved to be a versatile technology to create various functional materials by modifying solid surface properties. An interesting experimental phenomenon is found by exposing a Ti6Al4V alloy and Ti-based metallic glass to femtosecond laser irradiation. The research results show that the femtosecond laser induces different micro-nano structures on the surfaces of Ti6Al4V alloy and Ti-based metallic glass. Spherical structure and LIPSS (Laser-induced periodic surface structures) can be formed on the surface of Ti6Al4V alloy after femtosecond laser irradiation. On the surface of Ti-based metallic glass, LIPSS, SWPSS (Super-wavelength periodic surface structure) and neatly arranged microholes structures can be found. Under the same laser parameters, the micro-nano structures showed different evolution trends on the Ti6Al4V alloy and Ti-based metallic glass surfaces. The difference in surface structure between Ti6Al4V alloy and Ti-based metallic glass is since amorphous materials have no crystal lattice and a fixed melting temperature. In addition, there are differences in the biocompatibility of different surface structures. The size and distance of the micro-pits on the surface of different structures determine the ability of cells to adhesion, proliferate and differentiate. This conclusion has important significance for the application of Ti6Al4V alloy and Ti-based metallic glass in the field of biomedicine.

Synergistic function of Au NPs/GeO2 nanozymes with enhanced peroxidase-like activity and SERS effect to detect choline iodide.

A novel Au NPs/GeO2 nanozymes are developed as Surface-Enhanced Raman Scattering (SERS) substrates with the promising prospect for detection ChI. Herein, it is discovered that both Au NPs and GeO2 nanozymes have peroxidase-like activity, catalyzing colorless 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue TMBox. Interestingly, compared with single Au NPs or GeO2 nanozymes, the Au NPs/GeO2 nanozymes show stronger peroxidase-like activity, and significantly ameliorated SERS signal of TMBox. The mentioned two enhancements are ascribed to a positive synergistic function of Au NPs/GeO2 nanozymes. Surprisingly, choline iodide (ChI) can inhibit the positive synergy in Au NPs/GeO2 nanozymes, and slow down the reaction of TMB-H2O2-Au NPs/GeO2 system. On this foundation, a new Au NPs/GeO2 SERS technique with high sensitivity, label-free detection method of choline iodide (ChI) is established, suggesting that Au NPs/GeO2 nanozymes have the potential application of water environment.

Endovascular reconstruction with the Willis covered stent for the treatment of large or giant intracranial aneurysms.

BACKGROUND: The purpose of this study was to evaluate the feasibility, safety and efficacy of endovascular treatment of large or giant intracranial aneurysms with the Willis covered stent. METHODS: Nineteen patients, each with a large or giant intracranial aneurysm, were treated with the Willis covered stent. Of these 19 aneurysms, 6 were giant and 13 were large; 18 were located in the cranial internal carotid artery and 1 in the vertebral artery. Results of the procedure, technical events and complications were recorded. Clinical and imaging follow-ups were performed at 3 and 6-12 months after the procedure. RESULTS: Placement of Willis covered stent was successful in all patients. Complete aneurysm exclusion was achieved in 13 of the 19 aneurysms immediately after the procedure. No mortality or morbidity developed during the treatment or the follow-up period. During the follow-up period, complete aneurysm exclusion was achieved in 18 of the 19 patients; 11 aneurysms were totally involuted, 3 decreased to 25% of the original diameter, 4 decreased to 50% and 1 remained unchanged. Nine patients experienced full recovery, 9 improved and 1 was unchanged. No obvious in-stent stenosis was noted. CONCLUSIONS: Endovascular treatment of large or giant intracranial aneurysm with the Willis covered stent is feasible, safe and efficacious in selected cases. Endoleak is a frequent issue after initial covered stent placement, but can be eliminated or dramatically reduced to minimal endoleak by additional covered stent placement and/or balloon reinflation. Minor endoleak is likely to spontaneously resolve over time.

Treatment of traumatic internal carotid artery pseudoaneurysms with the Willis covered stent: a prospective study.

PURPOSE: To evaluate the efficacy of the Willis covered stent in the treatment of traumatic pseudoaneurysms of the internal carotid artery (ICA). MATERIALS: Thirty-eight patients with traumatic head and neck injury underwent angiography. We evaluated 14 delayed pseudoaneurysms in 13 patients who underwent angiography after treatment with the Willis covered stent. Prospective data on the technical success, initial and final angiographic results, mortality, morbidity, and final clinical outcome were analyzed immediately after the procedure, at the time of discharge from the hospital, at 3 months, 6 months, and 12 months after the procedures, and yearly thereafter. RESULTS: The Willis covered stent placement was successful in all 14 pseudoaneurysms. The initial angiographic results showed complete exclusion in 9 patients with 10 aneurysms (71.4% [95% confidence interval {CI}: 44-98%]) and incomplete exclusion in 4 patients. The angiographic follow-up (mean, 15 months [95% CI: 9-20 months]; range, 3-36 months) findings exhibited a complete exclusion in 12 patients with 13 aneurysms (92.9% [95% CI: 77-108%]) and an incomplete exclusion in 1 patient and maintained patency of the ICA in all patients. The clinical follow-up (mean, 20 months [95% CI: 14-27 months]) findings demonstrated full recovery (11 patients), symptom improvement (1 patient), or no change in the symptoms (1 patient). No procedure-related complications or deaths occurred during follow-up. CONCLUSION: Treatment with the Willis covered stent provides a viable approach for patients with traumatic pseudoaneurysms of the ICA, maintaining patency of the ICA and thus leading to excellent clinical results. An expanded clinical experiences and a larger sample are needed.

Treatment of complex ruptured anterior communicating arterial aneurysms by endovascular coil embolisation of the anterior communicating artery.

PURPOSE: The current study evaluates the feasibility and safety of coil embolisation of the anterior communicating artery (ACoA) for the treatment of complicated anterior communicating arterial aneurysms (ACoAAs). METHODS AND MATERIALS: Five patients presented with a subarachnoid haemorrhage caused by a ruptured ACoAA. The ACoAA morphologies were well defined by three-dimensional digital subtraction angiography (3D-DSA) and magnetic resonance angiography (MRA). Two of the ACoAAs were tiny (<3 mm in diameter), and the remaining three ACoAAs were small (3-5 mm in diameter). All of the aneurysms were localised to the ACoA. The projection of the aneurysm dome was defined as being oriented superiorly or posteriorly in all five aneurysms. We performed a superselective catheterisation of each aneurysm, and we subsequently performed coil embolisation with balloon, stent or microcatheter assistance. Angiography and clinical follow-up occurred 3-6 months after the procedure. Clinical follow-up data were collected and retrospectively analysed, and patient responses were categorised as fully recovered, improved, unchanged or aggravated. RESULTS: All five patients with ACoAA were treated successfully using coil embolisation. In three patients, both the aneurysm sac and the ACoA were embolised using coils, and in two patients, only the ACoA was embolised. Acute angiography showed occlusion of the aneurysm and ACoA. Follow-up angiography confirmed complete occlusion of the aneurysm sac, and no ACoAA recurrence was detected in any of the patients. In clinical follow-up visits, none of the patients had haemorrhaged or had a stroke. CONCLUSION: Combined coil embolism of the aneurysm sac and the ACoA could be a feasible and safe method for the treatment of complicated ACoAAs without bilateral aplasia of the A1 segment.