Luca Remonda

Background: Mixed-reality head-mounted display (MR-HMD) visualization and 3D-printed models may improve three-dimensional visualization in neurosurgical planning. Detailed, reproducible descriptions of the workflows, technical requirements, and practical limitations of these techniques in aneurysm clip ligation planning remain limited. Methods: Between February 2020 and June 2021, patient-specific MR-HMD visualizations and 3D-printed models were generated for 29 patients undergoing elective surgical clip ligation of intracranial aneurysms. CT and 3D rotational angiography were fused to create patient-specific holograms for MR-HMD visualization and 3D-printed models. All cases underwent standardized modality-specific processing. Preparation and manufacturing times as well as recorded workflow-related usability observations, technical advantages, and limitations were assessed. Results: The mean total preparation time (mean ± standard deviation, SD) was 40.6 ± 10.3 min for MR-HMD visualization and 108.8 ± 17.8 min for 3D-printed models, excluding printing, washing, and curing time. The average printing time for 3D-printed models was 894.9 ± 41.6 min. MR-HMD setup in the operating room averaged 7.0 ± 2.8 min. Identified limitations included manual hologram registration and repositioning after table or patient position changes, as well as the inability to track instruments or interact with the hologram. Conclusions: Both modalities could be integrated into a standardized patient-specific workflow and serve complementary functions. MR-HMD visualization supported flexible short-term visualization, whereas 3D-printed models provided a physical model for clip planning and patient education at the cost of longer preparation and production. These findings support a combined workflow in which modality selection is guided by clinical tasks and time constraints.

A transient ischemic attack (TIA) is a transient episode of neurological dysfunction without evidence of acute infarct demarcation on neuroimaging. The radiographic features of TIAs are uncertain, as since there is currently no perfect imaging method with which to differentiate a stroke from a TIA. We aimed to evaluate whether regional abnormalities are associated with TIA by identifying tissue with increased susceptibility (χ) values using quantitative susceptibility mapping (QSM). A total of 39 adults with clinical TIA symptoms (66 ± 12 years) and 39 age- and sex matched controls (65 ± 12 years) underwent MRI. Based on the QSM-maps, local susceptibility changes were tested for statistically significant differences between patients with TIA and healthy controls. The susceptibility maps of TIA patients showed that magnetic susceptibility differed from that of healthy volunteers, with the strongest effects observable in the right lingual gyrus (p < 0.001) and bilaterally in the caudal anterior cingulate (cACC, p < 0.01). TIA is often difficult to diagnose at the time of presentation in the emergency department, and QSM could show an association between regional QSM abnormalities and TIA.

Background: The endovascular approach has emerged as standard therapy for many intracranial aneurysms (IAs) to prevent hemorrhage, yet its long-term durability varies considerably. The aim of this study was to evaluate the safety and effectiveness of an initially deliberate endovascular approach regarding IA hemorrhage rates over a long-term follow-up period. Methods: This retrospective single-center study included all consecutive patients with endovascularly treated IAs who presented between January 2008 and December 2020 with a follow-up of at least 12 months. The primary endpoint was the proportion of patients with long-term IA hemorrhage rates and reperfusion. The secondary endpoint was treatment-related morbidity and mortality. Independent risk factors for IA reperfusion over the long term were analyzed using multivariate logistic regression. Results: Endovascular treatment was the therapy of choice for 333 patients with IAs, among whom 188 (57%) experienced rupture upon presentation. Complete coiling (Raymond I) was noted in 162 (49%) of the patients, with primary supportive devices being used in 51 (15%) patients. After a median (±SD) follow-up time of 34 ± 41 months (range 12–265 months), IA reperfusion was noted in 158 (47%), necessitating retreatment in 105 (32%) of the patients. Over the long term, hemorrhage was noted in four (1%) patients. Multivariate analysis revealed aneurysmal multilobarity (HR 1.8, 95%CI 1.2–2.7; p = 0.004) and a patient age of ≥50 years (HR 1.7, 95% CI 1.1–2.5, p = 0.01) as independent predictors of reperfusion over time. Intervention-related morbidity was noted in 16 (4.8%) patients, namely, thrombosis formation and contrast extravasation in 8 (2.4%) patients each, while no intervention-induced mortality was observed. Conclusion: In the long term, the hemorrhage rate in patients with IA with an initially more conservative endovascular approach is low. Therefore, a deliberate endovascular treatment approach might be justified.

(1) Background: Most intracranial aneurysms (IAs) can be treated either with microsurgical clipping or endovascular techniques. In a few cases, simultaneous treatment utilizing both modalities in a hybrid operation room may be favorable. This study analyzes the indication and benefits of a true hybrid approach (tHA) that combines simultaneous endovascular and microsurgical procedures for treatment of IAs in one session. (2) Methods: All patients receiving a true hybrid procedure between 2010 and 2022 in our institution were included. Demographic characteristics, neurological symptoms, pre-interventional treatments, angiographic findings, and postoperative clinical and radiological outcomes were analyzed. Results are discussed in the light of a systematic literature review on reported true hybrid procedures for IA treatment. (3) Results: In total, 10 tHAs were performed. Of these, coiling and concomitant decompressive craniectomy or hematoma evacuation was performed on six occasions. In two patients, multiple IAs were treated with different modalities during the same procedure. In two patients, intraoperative conditions did not allow for complete IA clipping, and the remnant was coiled in the same session. The review of the literature revealed nine papers comprising 58 IAs treated with a tHA. (4) Conclusions: The need for a tHA for IA treatment is rare and limited to highly selective cases. In our experience, tHAs have been most valuable in an emergency setting concerning ruptured IAs. Furthermore, tHAs may also be considered in patients with multiple aneurysms in different vascular territories.

Purpose: To evaluate the diagnostic accuracy of in situ postmortem multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) in the detection of primary traumatic extra‐axial hemorrhage.Materials and Methods: Thirty forensic neurotrauma cases and 10 nontraumatic controls who underwent both in situ postmortem cranial MSCT and MR imaging before autopsy were retrospectively reviewed. Both imaging modalities were analyzed in view of their accuracy, sensitivity, and specificity concerning the detection of extra‐axial hemorrhage. Statistical significance was calculated using the McNemar test. κ values for interobserver agreement were calculated for extra‐axial hemorrhage types and to quantify the agreement between both modalities as well as MRI, CT, and forensics, respectively.Results: Analysis of the detection of hemorrhagic localizations showed an accuracy, sensitivity, and specificity of 89%, 82%, and 92% using CT, and 90%, 83%, and 94% using MRI, respectively. MRI was more sensitive than CT in the detection of subarachnoid hemorrhagic localizations (P = 0.001), whereas no significant difference resulted from the detection of epidural and subdural hemorrhagic findings (P = 0.248 and P = 0.104, respectively). Interobserver agreement for all extra‐axial hemorrhage types was substantial (CT κ = 0.76; MRI κ = 0.77). The agreement of both modalitites was almost perfect (readers 1 and 2 κ = 0.88).Conclusion: CT and MRI are of comparable potential as forensic diagnostic tools for traumatic extra‐axial hemorrhage. Not only of forensic, but also of clinical interest is the observation that most thin blood layers escape the radiological evaluation. J. Magn. Reson. Imaging 2008;28:823–836.

Purpose: To improve current classification schemes of esthesioneuroblastoma by detailed analysis of imaging findings and to correlate tumor extent with recurrence and survival rates. Material/Methods: Over a period of 15 years (1989 to 2004), 15 patients (9 men, 6 women; 16 to 77 yrs; mean age, 52.4 yrs) were operated for esthesioneuroblastoma. Twelve patients had preoperative MR imaging; in 3 cases, CT was performed. All imaging studies were retrospectively evaluated for exact delineation of tumor boundaries and assessment of structures infiltrated by the tumor. A grading scheme was developed that rated infiltration from one point (e.g., nasalcavity) to five points (e.g., dural infiltration) for 23 anatomic structures. A total of 76 points was possible. Results: The mean tumor infiltration rating was 45.5 points. Although all tumors were classified as Grade 4 in conventional classification schemes, our grading system provided a finer differentiation; the range was 25 to 68 points. Tumor recurrence was markedly earlier in cases with > 50 points. Conclusion: Current grading schemes for esthesioneuroblastoma are not sufficiently detailed. Infiltration of surrounding structures alone does not necessarily mean that a tumor is inoperable; only a large degree of infiltration into surrounding structures does markedly reduce the recurrence-free interval.

Introduction: Embolization is an established endovascular neuroradiologic technique for preoperative devascularization of tumors and vascular malformation. Patients with vascular or tumorous lesions of the skull base that have an unusual extent or location and in particular cases that have undergone previous unsuccessful treatment represent a major challenge, as “classic” approaches often cannot be used. Material and Methods: Over a period of 12 years, more than 100 patients with tumors and vascular lesions were treated using endovascular therapy in our institution in combination with skull base surgery. Rare and impressive cases managed in close cooperation with skull base surgery and neuroradiology, as well the recommendation of a joint therapeutic concept to be utilized in such cases, will be described. Results: We describe the pretherapeutic evaluation by imaging techniques (CT and MRI) of uncommon complex skull base tumors and vascular lesions and the angiographic work-up. The arterial supply and venous drainage, feeding arteries, the angioarchitecture of the vascular lesions, and arterioarterial anastomoses are shown. We will discuss how to avoid dangers and complications associated with vascular lesion embolization including visual loss, cranial nerve palsies, and stroke. The close cooperation of skull base surgery and interventional neuroradiology with a joint therapeutic concept will be discussed. Conclusions: Owing to the recent continuous advances in interventional neuroradiologic techniques, it is possible to contribute to the treatment of uncommon complex skull base tumor and vascular lesions in close cooperation between skull base surgery and neuroradiology with a joint therapeutic concept.

Background— The aim of this study was to determine the clinical and radiological outcome of acute stroke patients who had no vessel occlusion on arteriography and to define predictors of clinical outcome. Methods— We analyzed clinical and radiological data of stroke patients whose arteriography performed within 6 hours of symptom onset did not visualize any vessel occlusion. Results— Twenty-eight of 283 consecutive patients (10%) who underwent arteriography with the intention to perform intraarterial thrombolysis did not show any arterial occlusion. Their median baseline National Institutes of Health Stroke Scale (NIHSS) score was 7. Time from symptom onset to arteriography ranged from 115 to 315 minutes; on average, it was 226 minutes. Presumed stroke cause was cardiac embolism in 11 patients (39%), small artery disease in 6 (21%), coronary angiography in 1 (4%), and undetermined in 10 patients (36%). After 3 months, modified Rankin Scale score (mRS) was ≤2 in 21 patients (75%), indicating a favorable outcome. Six patients (21%) had a poor outcome (mRS 3 or 4) and 1 patient (4%) had a myocardial infarction and died. Twenty-seven patients had follow-up brain imaging. It was normal in 5, showed a lacunar lesion in 8, a striatocapsular infarct in 2, a small or medium-sized anterior circulation infarct in 6, multiple small anterior circulation infarcts in 2, and multiple posterior circulation infarcts in 4. No predictors of clinical outcome were identified. Conclusions— Most acute stroke patients with normal early arteriography show infarcts on brain imaging; however, clinical outcome is usually favorable.

Summary: A recently developed neck-bridging device (TriSpan; Target Therapeutics/Boston Scientific, Fremont, CA) was used to prevent coil migration into the internal carotid artery during transvenous occlusion of a high-flow, large-tear carotid cavernous fistula.