Intraoperative integration of multimodal imaging to improve neuronavigation: a technical note

Role of Virtual iMRI in Glioblastoma Surgery: Advantages, Limitations, and Correlation with iCT and Brain Shift

Background: Elastic image fusion (EIF) using an intraoperative CT (iCT) scan may enhance neuronavigation accuracy and compensate for brain shift. Objective: To evaluate the safety and reliability of the EIF algorithm (Virtual iMRI Cranial 4.5, Brainlab AG, Munich Germany, for the identification of residual tumour in glioblastoma surgery. Moreover, the impact of brain shift on software reliability is assessed. Methods: This ambispective study included 80 patients with a diagnosis of glioblastoma. Pre-operative MRI was elastically fused with an intraoperative CT scan (BodyTom; Samsung-Neurologica, Danvers, MA, USA) acquired at the end of the resection. Diagnostic specificity and the sensitivity of each tool was determined. The impact of brain shift on residual tumour was statistically analysed. An analysis of accuracy was performed through Target Registration Error (TRE) measurement after rigid image fusion (RIF) and EIF. A qualitative evaluation of each Virtual MRI image (VMRI) was performed. Results: VMRI identified residual tumour in 26/80 patients (32.5%), confirmed by post-operative MRI (true positive). Of these, 5 cases were left intentionally due to DES-positive responses, 8 cases underwent near maximal or subtotal resection, and 13 cases were not detected by iCT. However, in the other 27/80 cases (33.8%), VMRI reported residual tumour that was present neither on iCT nor on post-operative MRI (false positive). i-CT showed a sensitivity of 56% and specificity of 100%; VMRI demonstrated a sensitivity of 100% and specificity of 50%. Spearman correlation analysis showed a moderate correlation between pre-operative volume and VMRI tumour residual. Moreover, tumour involving insula or infiltrating more than one lobe displayed higher median values (p = 0.023) of virtual residual tumour. A statistically significant reduction towards lower TRE values after EIF was observed for test structures. Conclusions: Virtual iMRI was proven to be a feasible option to detect residual tumour. Its integration within a multimodal imaging protocol may provide neurosurgeons with intraoperatively updated imaging.

CTA-based 3D virtual model for preoperative simulation and intraoperative neuronavigation in the surgical treatment of distal anterior cerebral artery aneurysms

OBJECTIVE

This study aims to assess the efficacy and limitations of Computed Tomography Angiography (CTA)-based 3D virtual models for preoperative simulation and intraoperative neuronavigation in the surgical treatment of Distal Anterior Cerebral Artery (DACA) Aneurysms.

METHODS

A retrospective observational study was conducted, analyzing patients who underwent surgical clipping of DACA aneurysms via an interhemispheric approach from 2016 to 2022. Outcomes measured included qualitative analyses of 3D reconstructions against actual intraoperative anatomy, neuronavigator accuracy, 6-month modified Rankin Scale (mRS), complete exclusion rates, and surgical complications. Patient demographics, clinical characteristics, surgical timing, and intraoperative data were meticulously documented for analysis.

RESULTS

Fifteen patients were included in the study, with a mean age of 52 years. The mean Hunt-Hess score at admission was 2.2, encompassing 2 unruptured and 13 ruptured aneurysms. Intraoperative anatomical visualization perfectly matched the preoperative 3D model in 13 cases, with discrepancies in two. Neuronavigation demonstrated a mean accuracy of 1.76 mm, remaining consistent in 14 patients, and accurately tracking the planned trajectory. Postoperative complications occurred in 26.5 % of patients, including two fatalities, with no navigation-related complications. Incomplete aneurysm occlusion was observed in one case. The mean mRS score at 6 months was 2.46.

CONCLUSIONS

The employment of 3D CTA for preoperative simulation and intraoperative neuronavigation holds significant potential in enhancing the surgical management of DACA aneurysms. Despite some discrepancies and technical limitations, the overall precision of preoperative simulations and the strategic value of intraoperative neuronavigation highlight their utility in improving surgical outcomes.

Combination of Tractography, Intraoperative Computed Tomography and 5-Aminolevulinic Acid Fluorescence in Stereotactic Brain Biopsies: A Case Series

Stereotactic needle biopsy (SNB) may be performed to collect tissue samples from lesions not amenable to open surgery. Integration of tractography, intraoperative imaging and fluorescence has been applied to reduce risk of complications and confirm the adequacy of bioptic specimens. Clinical and radiological data from patients who underwent stereotactic needle biopsy with the use of intraoperative CT, tractography and 5-aminolevulinic acid (5-ALA) fluorescence in a single Hospital were retrospectively reviewed to evaluate the accuracy and safety of the procedure. Seven patients were included in the study, and all the collected specimens showed red fluorescence. In six of them, the final histopathological diagnosis was grade 4 glioblastoma IDH-wt and in the other case it was Diffuse large B-Cell Lymphoma. The integration of tractography, intraoperative CT and 5-ALA as an intraoperative marker of diagnostic samples may be suggested in biopsies of suspect gliomas and lymphomas. The cost-effectiveness of the procedure should be evaluated in future studies.

Stereotactic placement of dual lumen catheter system for continuous drainage, irrigation, and intraventricular antibiotic therapy for treatment of brain abscess with ventriculitis - A case report and literature review

Background

Cerebral abscesses complicated by ventriculitis present significant treatment challenges, often associated with high morbidity and mortality. Traditional management approaches, including systemic antibiotic therapy and external ventricular drainage (EVD), face limitations due to the blood-brain barrier and risks of catheter-related complications. This report discusses a case where the dual-lumen catheter system, an innovative neurosurgical tool integrating continuous irrigation with drainage, was employed.

Case Description

A patient presented with a cerebral abscess ruptured into the ventricle, leading to ventriculitis. Conventional treatment options were limited due to the abscess's deep and eloquent location and the associated risk of complications from standard EVD. The dual lumen system was chosen for its ability to provide continuous irrigation and drainage, effectively addressing issues of catheter blockage and enhancing localized antibiotic delivery. The system was used to create a single stereotactic tract for simultaneous treatment of the abscess and ventriculitis. This approach allowed for a more controlled and effective treatment process, resulting in rapid resolution of the conditions without chronic hydrocephalus development or further complications.

Conclusion

The use of the dual lumen system represented a significant advancement in this case, addressing the limitations of conventional treatments. Its ability to maintain intracranial pressure within optimal limits while providing localized, continuous treatment was pivotal. This case highlights the potential of the dual lumen catheter in managing complex neurosurgical infections and underscores the need for further research to establish its efficacy in broader clinical applications.

Multi-modal medical Transformers: A meta-analysis for medical image segmentation in oncology

Multi-modal medical image segmentation is a crucial task in oncology that enables the precise localization and quantification of tumors. The aim of this work is to present a meta-analysis of the use of multi-modal medical Transformers for medical image segmentation in oncology, specifically focusing on multi-parametric MR brain tumor segmentation (BraTS2021), and head and neck tumor segmentation using PET-CT images (HECKTOR2021). The multi-modal medical Transformer architectures presented in this work exploit the idea of modality interaction schemes based on visio-linguistic representations: (i) single-stream, where modalities are jointly processed by one Transformer encoder, and (ii) multiple-stream, where the inputs are encoded separately before being jointly modeled. A total of fourteen multi-modal architectures are evaluated using different ranking strategies based on dice similarity coefficient (DSC) and average symmetric surface distance (ASSD) metrics. In addition, cost indicators such as the number of trainable parameters and the number of multiply-accumulate operations (MACs) are reported. The results demonstrate that multi-path hybrid CNN-Transformer-based models improve segmentation accuracy when compared to traditional methods, but come at the cost of increased computation time and potentially larger model size.

Minimally invasive ultrasound-assisted evacuation of Spontaneous Supratentorial Intracerebral hemorrhages: Retrospective observational single-cohort study

OBJECTIVE

To assess safety and efficacy of minimally invasive evacuation of Spontaneous Supratentorial Intracerebral Hemorrhage (SSICH) by means of tailored minicraniotomies and intraoperative ultrasound (iUS) assistance.

METHODS

Retrospective analysis of 55 patients who underwent microsurgical evacuation of SSICH using minicraniotomy and iUS assistance, between January 2015 and January 2022. Surgical complications, mortality rate, recurrent bleeding, percentage of hematoma evacuation and reliability of iUS were collected and investigated. The clinical outcomes were measured by the modified Rankin Scale (mRS) at 6 months. Subgroup analysis was performed to assess the differences between the pre-operative GCS (3-9 versus 10-14), the residual hematoma volume (<10ml versus >10ml) and the location (deep versus lobar).

RESULTS

3 patients had an unfavourable outcome owing to surgery. The 6-month overall mortality accounted for 10,9%. Symptomatic recurrent bleeding occurred in 3 cases. 2 patients (3.6%) developed brain swelling treated with decompressive hemicraniectomy. With reference to clinical outcome, 39 patients (70,9%) had a good functional outcome (GFO) and the average 6-month mRS was 2,75±1,97. Hematoma volume decreased from 54,2±12,8mL pre-evacuation (range 30-95mL) to 11,1±12,5mL post-evacuation (range 0-35mL), with an average reduction of 78,15%±16,4% (P < 0.001). iUS was reliable to correctly check hematoma evacuation during the procedure in 46 patients (83.6%). Pre-operative GCS>9 and residual hematoma <10ml were found to be associated with higher probability to have GFO (P < 0.01).

CONCLUSIONS

Evacuation of SSICH using minicraniotomy with iUS assistance is a straightforward, affordable, and reproducible technique. Its safety and efficacy profiles appear consistent with other published studies.

Trascallosal bilateral transforaminal resection of a solid partially calcified colloid cyst: 2D operative video

BACKGROUND

Colloid cysts are benign lesions of the roof of the third ventricle, often diagnosed incidentally; sometimes they can cause hydrocephalus due to obstruction of the foramina of Monroe. Symptomatic cysts could be resected either microsurgically (transcallosal or transcortical) or endoscopically. Although both strategies are effective and have advantages and disadvantages, there is no consensus on the choice of the optimal approach. Transcallosal resection, although more invasive than endoscopy, allows adequate bimanual manipulation of the cyst and is associated with high rates of complete resection, the use of neuronavigator and intraoperative ultrasound optimizes surgical trajectory and improves safety of the procedure with complication rates comparable to endoscopy. Endoscopy is less invasive but complete resection of solid cysts can be challenging.

CASE DESCRIPTION

In Video 1, we show resection of a solid partially calcified colloid cyst using a transcallosal bilateral transforaminal approach to anterior third ventricle male, 65 years old; headache and mild memory impairment for 6 months; admitted at our emergency department because of a brief loss of consciousness. Neurologic examination was normal. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a colloid cyst at the level of anterior third of the third ventricle (1.5 cm in diameter) with hypointense appearance in T2 sequences suggesting a solid calcific component. The ventricular system was enlarged. Colloid cyst risk score 3/5 (diameter >0.7 cm, headache, risk zone I) considered an intermediate-risk subgroup according to Alford et al. On this basis, we proposed the surgical treatment. We chose a transcallosal microsurgical resection. The patient gave consent for the procedure. A preoperative planning with a computer-generated 3D model is performed to simulate the approach. Craniotomy, interhemispheric dissection, and callosotomy were planned with the neuronavigator and with the aid of intraoperative ultrasound to optimize the trajectory and perform a limited and tailored callosotomy. The 1.5 cm callosotomy allows to approach both lateral ventricles, the cyst was progressively dissected working bilaterally through both foramina of Monroe without injuries of the fornices. Resection at term is complete. Postoperative MRI and CT scan confirmed complete excision without complications; the patient was discharged after a week in good neurological condition with complete regression of headache.

CONCLUSION

Microscopic transcallosal resection of the colloid cyst of the third ventricle allows for complete resection with low complication rates. The use of preoperative 3D planning and integrated neuronavigation with intraoperative ultrasound helps to reduce invasiveness.

Vertical Hemispherotomy: Contribution of Advanced Three-Dimensional Modeling for Presurgical Planning and Training

Vertical hemispherotomy is an effective treatment for many drug-resistant encephalopathies with unilateral involvement. One of the main factors influencing positive surgical results and long-term seizure freedom is the quality of disconnection. For this reason, perfect anatomical awareness is mandatory during each step of the procedure. Although previous groups attempted to reproduce the surgical anatomy through schematic representations, cadaveric dissections, and intraoperative photographs and videos, a comprehensive understanding of the approach may still be difficult, especially for less experienced neurosurgeons. In this work, we reported the application of advanced technology for three-dimensional (3D) modeling and visualization of the main neurova-scular structures during vertical hemispherotomy procedures. In the first part of the study, we built a detailed 3D model of the main structures and landmarks involved during each disconnection phase. In the second part, we discussed the adjunctive value of augmented reality systems for the management of the most challenging etiologies, such as hemimegalencephaly and post-ischemic encephalopathy. We demonstrated the contribution of advanced 3D modeling and visualization to enhance the quality of anatomical representation and interaction between the operator and model according to a surgical perspective, optimizing the quality of presurgical planning, intraoperative orientation, and educational training.

Single thalamic localization of brain toxoplasmosis mimicking brain tumors: Radiological and clinical findings

Background:

Cerebral toxoplasmosis is a relatively rare disorder that usually affects immunocompromised patients. The most common scenario occurs among human immunodeficiency virus (HIV)-positive patients. In those patients, toxoplasmosis is the most frequent cause of expansive brain lesion and continues to cause elevated morbidity and mortality. In typical cases of toxoplasmosis, both computed tomography and magnetic resonance imaging reveal single/ multiple nodular or ring-enhancing lesions with surrounding edema. Nevertheless, cases of cerebral toxoplasmosis with atypical radiological features have been reported. Diagnosis can be obtained by finding organisms in the cerebrospinal fluid or in stereotactic biopsy samples of the brain lesion. If untreated, cerebral toxoplasmosis is uniformly fatal, so prompt diagnosis is mandatory. A prompt diagnosis is necessary, as untreated cerebral toxoplasmosis is uniformly fatal.

Case Description:

We discuss imaging and clinical findings of a patient – not aware of being HIV-positive – with a solitary atypical brain localization of toxoplasmosis mimicking a brain tumor.

Conclusion:

Although relatively uncommon, neurosurgeons should be aware of the potential occurrence of cerebral toxoplasmosis. High index of suspicion is needed for timely diagnosis and prompt initiation of therapy.