Machi, Paolo

Abstract Background Three-dimensional visualization and quantitative analysis of cerebral arteries on 3DRA are central to endovascular treatment planning, device selection, and cerebrovascular research. Manual segmentation is time-consuming and operator-dependent, yet no open-source deep learning model has been prospectively validated for this task on 3DRA. Methods A nnUNet v2 model was trained for binary cerebral artery segmentation on 400 consecutive 3DRA acquisitions from three angiographic systems, comparing four configurations across architectures and loss functions. The best-performing configurations were prospectively validated on 40 patients using a dual approach: quantitative metrics (DSC, clDice, HD95, ASD, Precision, Recall), and blinded expert qualitative evaluation by two interventional neuroradiologists assessing 12 arterial segments, a global quality score, and clinical usability across 40 test cases. Results The ensemble model achieved median DSC 0.917, clDice 0.932, and HD95 1.494 mm. Global quality scores were significantly lower for nnUNet v2 than for expert segmentations (median 4 vs 5, p<0.001), but nnUNet v2 segmentations were rated clinically usable in 88–90% of cases versus 95–98% for expert segmentations, without significant difference on the binary usability criterion. A consistent proximal-to-distal quality gradient was identified, with comparable scores at proximal arteries and the largest differences at distal arterial segments. Conclusion nnUNet v2 with topology-aware training provides clinically usable cerebral artery segmentations on 3DRA, prospectively validated through both quantitative metrics and structured expert qualitative assessment, and represents a reproducible open-source foundation for endovascular and research applications.

Abstract Background Even for experienced operators, endovascular treatment of unruptured intracranial aneurysms involves intraoperative uncertainty that may lead to adjustments in strategy, prolong the procedure, and potentially cause inefficiency and device waste. This study aimed to evaluate whether pre-procedural testing (PPT) of endovascular treatment using patient-specific models was associated with increased operator confidence and perceived clinical utility, including improvements in procedural efficiency and reduced resource waste. Methods We enrolled a cohort of patients who underwent PPT before endovascular treatment for complex unruptured intracranial aneurysms and compared their outcomes with a control group treated without PPT. The primary outcome was the Training Fidelity Score, a composite of three operator-reported Likert items defined a priori. Secondary outcomes included perceived clinical utility, intraoperative strategy changes, procedural time, radiation exposure, device waste and safety. Results A total of 85 patients met the inclusion criteria (PPT=40; control=45). The Training Fidelity Score was high across the PPT group (median, 4.33/5). Perceived clinical utility was high and further increased significantly after the procedure. A significant reduction was observed in intraoperative strategy changes, with no changes recorded in the PPT group, compared to 6/45 in the control group (RR 0.09; p=0.027). Reductions in treatment time, radiation exposure and device waste were also noted. Conclusion PPT using patient-specific models was associated with increased operator confidence, fewer intraoperative strategy changes, improved procedural efficiency, and reduced device waste without compromising safety. These findings support its use in pre-interventional preparation, but require prospective multicenter validation.

Background The management of unruptured intracranial aneurysms (UIA) requires a balance between procedural risks and the potential benefit of rupture prevention. Objective The aim of this study is to evaluate the clinical and anatomical results of endovascular treatment for UIAs at our institution, to benchmark our practice and potential areas for improvement, and enable transparent communication with patients by providing accurate, evidence-based information. Methods We reviewed all patients treated for an UIA between January 2017 and July 2022. Patients were grouped according to treatment technique: simple or balloon-assisted coiling; stent-assisted coiling; or flow-diverter stent placement. Clinical outcomes included perioperative mortality, transient (<3 months), and permanent morbidity (>3 months). Anatomical results were graded with the Raymond-Roy or the O’Kelly-Marotta scales. Retreatment rates, length of hospitalization, readmissions, irradiation time, and total radiation dose were assessed. Results In total, 169 patients with 201 UIAs underwent 187 endovascular procedures without death, 1% permanent morbidity, 8% transient morbidity, and 4% retreatment. The treatment subgroups analysis shows an absence of permanent morbidity associated with flow-diverter stenting and stent-assisted coiling. Simple/balloon-assisted coiling suffered 2.6% permanent morbidity. Transient morbidity was observed in 9%, 9.5%, and 6.6% of flow-diverter stenting, stent-assisted coiling, and simple/balloon-assisted coiling, respectively. Conclusions In our hospital, about one in a hundred procedures caused lasting problems, while about one in 25 aneurysms needed a second treatment. These results reflect our case selection and multidisciplinary approach. Reporting them transparently helps patients understand what outcomes to expect at our hospital.

Background and Purpose Thrombectomy in distal, medium vessels is a topic of increasing interest. To date, there are few in vitro studies focused on performance of ≤5F catheters in medium vessels. The purpose of this study is to compare the performance of the 3F, 4F, and 5F MIVI Neuroscience Q Catheters versus Penumbra 3F, 4F, and MicroVention Sofia 5F Catheters. Methods Using in vitro methods, we assessed and compared the following parameters: aspiration flow rates, clot uncorking forces, impulse, and clot ingestion. For flow rate, each aspiration catheter was immersed in a cylindrical container. Flow rate at one second was used to calculate impulse. For clot uncorking force, the force required to disengage a catheter from a simulated clot was recorded. For ingestion, we measured time to ingest soft and medium stiffness synthetic clots. Results The measured flow rates without a stent retriever for the Q3, Q4, and Q5 catheters were 3.54 ml/s, 5.32 ml/s, and 6.87 ml/s. The measured flow rates without a stent retriever for the 3MAX, 4MAX, and 5F Sofia were 1.46 ml/s, 2.56 ml/s, and 1.73 ml/s. The impulse calculated for one second was 26 mNs for Q5 vs 9 mNs for Sofia 5, 35 mNs for Q4 vs 15 mNs for 4Max< and 35 mNs for Q3 vs 9 mNs for 3Max. The average system ingestion for Q was significantly faster than the competitive catheters. Conclusions The Q catheters demonstrated higher flow rates, higher uncorking force, and faster complete clot ingestion than competitive catheters.

Arterial spin labeling (ASL) has emerged as a promising noninvasive tool for the evaluation of both pediatric and adult arteriovenous malformations (AVMs). This paper reviews the advantages and challenges associated with the use of ASL in AVM assessment. An assessment of the diagnostic workup of AVMs and their variants in both adult and pediatric populations is proposed. Evaluation after treatments, whether endovascular or microsurgical, was similarly examined. ASL, with its endogenous tracer and favorable safety profile, offers functional assessment and arterial feeder identification. ASL has demonstrated strong performance in identifying feeder arteries and detecting arteriovenous shunting, although some studies report inferior performance compared with digital subtraction angiography (DSA) in delineating venous drainage. Challenges include uncertainties in sensitivity for specific AVM features. Detecting AVMs in challenging locations, such as the apical cranial convexity, is further complicated, demanding careful consideration due to the risk of underestimating total blood flow. Navigating these challenges, ASL provides a noninvasive avenue with undeniable merits, but a balanced approach considering its limitations is crucial. Larger-scale prospective studies are needed to comprehensively evaluate the diagnostic performance of ASL in AVM assessment.