Combining visual analytics and case-based reasoning for rupture risk assessment of intracranial aneurysms

Purpose Medical case-based reasoning solves problems by applying experience gained from the outcome of previous treatments of the same kind. Particularly for complex treatment decisions, for example, incidentally found intracranial aneurysms (IAs), it can support the medical expert. IAs bear the risk of rupture and may lead to subarachnoidal hemorrhages. Treatment needs to be considered carefully, since it may entail unnecessary complications for IAs with low rupture risk. With a rupture risk prediction based on previous cases, the treatment decision can be supported. Methods We present an interactive visual exploration tool for the case-based reasoning of IAs. In presence of a newaneurysm of interest, our application provides visual analytics techniques to identify the most similar cases with respect to morphology. The clinical expert can obtain the treatment, including the treatment outcome, for these cases and transfer it to the aneurysm of interest.Our application comprises a heatmap visualization, an adapted scatterplotmatrix and fully or partially directed graphs with a circle- or force-directed layout to guide the interactive selection process. To fit the demands of clinical applications, we further integrated an interactive identification of outlier cases as well as an interactive attribute selection for the similarity calculation. A questionnaire evaluation with six trained physicians was used. Result Our application allows for case-based reasoning of IAs based on a reference data set. Three classifiers summarize the rupture state of the most similar cases. Medical experts positively evaluated the application. Conclusion Our case-based reasoning application combined with visual analytic techniques allows for representation of similar IAs to support the clinician. The graphical representation was rated very useful and provides visual information of the similarity of the k most similar cases.Projekt DEAL 202

VICTORIA : VIrtual neck Curve and True Ostium Reconstruction of Intracranial Aneurysms

Purpose—For the status evaluation of intracranial aneurysms (IAs), morphological and hemodynamic parameters can provide valuable information. For their extraction, a separation of the aneurysm sac from its parent vessel is required that yields the neck curve and the ostium. However, manual and subjective neck curve and ostium definitions might lead to inaccurate IA assessments. Methods—The research project VICTORIA was initiated, allowing users to interactively define the neck curve of five segmented IA models using a web application. The submitted results were qualitatively and quantitatively compared to identify the minimum, median and maximum aneurysm surface area. Finally, image-based blood flow simulations were carried out to assess the effect of variable neck curve definitions on relevant flow- and shear-related parameters. Results—In total, 55 participants (20 physicians) from 18 countries participated in VICTORIA. For relatively simple aneurysms, a good agreement with respect to the neck curve definition was found. However, differences among the participants increased with increasing complexity of the aneurysm. Furthermore, it was observed that the majority of participants excluded any small arteries occurring in the vicinity of an aneurysm. This can lead to non-negligible deviations among the flow- and shear-related parameters, which need to be carefully evaluated, if quantitative analysis is desired. Finally, no differences between participants with medical and non-medical background could be observed. Conclusions—VICTORIAs findings reveal the complexity of aneurysm neck curve definition, especially for bifurcation aneurysms. Standardization appears to be mandatory for future sac-vessel-separations. For hemodynamic simulations a careful neck curve definition is crucial to avoid inaccuracies during the quantitative flow analysis.Projekt DEAL 202

Aseptic bone-flap resorption after cranioplasty - incidence and risk factors.

OBJECTIVE:One of the common complications occurring after cranioplasty (CP) is aseptic bone-flap resorption (ABFR). Reoperation necessary because of the development of ABFR can lead to unfavorable complications during subsequent surgery using a synthetic skull implant, and also necessarily leads to higher costs. The aim of this study is to identify prognostic factors that may help to predict the development of ABFR. METHODS:In this study, 303 CP surgeries performed between 2002 and 2017 were examined retrospectively to identify factors predicting the occurrence of ABFR. A number of these factors (e.g., time lapse between decompressive craniectomy (DC) and CP, bone-flap size, specific laboratory signs, and the reason for the original DC) were analyzed as possibly influencing the risk of developing ABFR. RESULTS:ABFR of an autologous bone flap that subsequently required a CP with synthetic skull implants occurred in 10 of 303 patients (3.0%). CP timing and patients' Karnofsky Performance Scores (KPS) (p = 0.008; p = 0.012) were identified as significant factors with an impact on the development of ABRF. Age did not reveal a significant value, but statistical analysis shows a clear trend. The younger the age, the more likely it was that an ABFR would develop. CONCLUSION:The risk of ABFR lessens the longer the period of time elapsed between DC and CP. Age does not reveal a significant value, but statistical analysis shows that there is a clear trend

Cannabinoids in Glioblastoma Therapy: New Applications for Old Drugs

Glioblastoma (GBM) is the most malignant brain tumor and one of the deadliest types of solid cancer overall. Despite aggressive therapeutic approaches consisting of maximum safe surgical resection and radio-chemotherapy, more than 95% of GBM patients die within 5 years after diagnosis. Thus, there is still an urgent need to develop novel therapeutic strategies against this disease. Accumulating evidence indicates that cannabinoids have potent anti-tumor functions and might be used successfully in the treatment of GBM. This review article summarizes the latest findings on the molecular effects of cannabinoids on GBM, both in vitro and in (pre-) clinical studies in animal models and patients. The therapeutic effect of cannabinoids is based on reduction of tumor growth via inhibition of tumor proliferation and angiogenesis but also via induction of tumor cell death. Additionally, cannabinoids were shown to inhibit the invasiveness and the stem cell-like properties of GBM tumors. Recent phase II clinical trials indicated positive results regarding the survival of GBM patients upon cannabinoid treatment. Taken together these findings underline the importance of elucidating the full pharmacological effectiveness and the molecular mechanisms of the cannabinoid system in GBM pathophysiology

Theranostic applications of optical coherence tomography in neurosurgery?

In light of our own experiences, we value the existing literature to critically point out possible 'near' future applications of optical coherence tomography (OCT) as an intraoperative neurosurgical guidance tool. 'Pub Med', 'Cochrane Library', 'Crossref Metadata Search', and 'IEEE Xplore' databases as well as the search engine 'Google Scholar' were screened for 'optical coherence tomography + neurosurgery', 'optical coherence tomography + intraoperative imaging + neurosurgery', and 'microscope integrated optical coherence tomography + neurosurgery'. n = 51 articles related to the use of OCT as an imaging technique in the field of neurosurgery or neurosurgical research. n = 7 articles documented the intraoperative use of OCT in patients. n = 4 articles documented the use of microscope-integrated optical coherence tomography as a neurosurgical guidance tool. The Results demonstrate that OCT is the first imaging technique to study microanatomy in vivo. Postoperative analysis of intraoperative scans holds promise to enrich our physiological and pathophysiological understanding of the human brain. No data exists to prove that OCT-guided surgery minimizes perioperative morbidity or extends tumor resection. But results suggest that regular use of microscope-integrated OCT could increase security during certain critical microsurgical steps like, e.g., dural dissection at cavernous sinus, transtentorial approaches, or aneurysm clip placement. Endoscopy integration could aid surgery in regions which are not yet accessible to real-time imaging modalities like the ventricles or hypophysis. Theranostic instruments which combine OCT with laser ablation might gain importance in the emerging field of minimal invasive tumor surgery. OCT depicts vessel wall layers and its pathologies uniquely. Doppler OCT could further visualize blood flow in parallel. These abilities shed light on promising future applications in the field of vascular neurosurgery

Impact of acetylsalicylic acid in patients undergoing cerebral aneurysm surgery – should the neurosurgeon really worry about it?

There has been an increase in the use of acetylsalicylic acid (ASA, Aspirin®) among patients with stroke and heart disease as well as in aging populations as a means of primary prevention. The potentially life-threatening consequences of a postoperative hemorrhagic complication after neurosurgical operative procedures are well known. In the present study, we evaluate the risk of continued ASA use as it relates to postoperative hemorrhage and cardiopulmonary complications in patients undergoing cerebral aneurysm surgery. We retrospectively analyzed 200 consecutive clipping procedures performed between 2008 and 2018. Two different statistical models were applied. The first model consisted of two groups: (1) group with No ASA impact - patients who either did not use ASA at all as well as those who had stopped their use of the ASA medication in time (> = 7 days prior to operation); (2) group with ASA impact - all patients whose ASA use was not stopped in time. The second model consisted of three groups: (1) No ASA use; (2) Stopped ASA use (> = 7 days prior to operation); (3) Continued ASA use (did not stop or did not stop in time, <7 days prior to operation). Data collection included demographic information, surgical parameters, aneurysm characteristics, and all hemorrhagic/thromboembolic complications. A postoperative hemorrhage was defined as relevant if a consecutive operation for hematoma removal was necessary. An ASA effect has been assumed in 32 out of 200 performed operations. A postoperative hemorrhage occurred in one out these 32 patients (3.1%). A postoperative hemorrhage in patients without ASA impact was detected and treated in 5 out of 168 patients (3.0%). The difference was statistically not significant in either model (ASA impact group vs. No ASA impact group: OR = 1.0516 [0.1187; 9.3132], p = 1.000; RR = 1.0015 [0.9360; 1.0716]). Cardiopulmonary complications were significantly more frequent in the group with ASA impact than in the group without ASA impact (p = 0.030). In this study continued ASA use was not associated with an increased risk of a postoperative hemorrhage. However, cardiopulmonary complications were significantly more frequent in the ASA impact group than in the No ASA impact group. Thus, ASA might relatively safely be continued in patients with increased cardiovascular risk and cases of emergency cerebrovascular surgery

Brain biopsy in patients with CLIPPERS syndrome : why and when? A case report and literature review

CLIPPERS (chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids) is an inflammatory disorder of the central nervous system (CNS), predominantly involving the brainstem with a characteristic magnetic resonance imaging (MRI) appearance and clinical and radiological responsiveness to glucocorticosteroids. Yet diagnostic biomarkers are missing and other immune-mediated, (para-) infectious and malignant causes mimic CLIPPERS-like MRI presentations. We report the case of a 51-yearold male patient with CLIPPERS who repeatedly responded well to high-dose corticosteroids. After 7 months, however, treatment failed, and he had a biopsy-confirmed diagnosis of a CNS B-cell lymphoma. Clinical and MRI signs of CLIPPERS include a wide spectrum of differential diagnoses which often arise only later during the course of disease. Similar to the case presented here, delayed diagnosis and specific therapy may contribute to an unfavorable outcome. Hence, we propose that in the absence of other diagnostic markers, brain biopsy should be performed as early as possible in CLIPPERS patients.Transformationsvertra

VR-based training of craniotomy for intracranial aneurysm surgery

Purpose!#!Intracranial aneurysms can be treated micro-surgically. This procedure involves an appropriate head position of the patient and a proper craniotomy. These steps enable a proper access, facilitating the subsequent steps. To train the access planning process, we propose a VR-based training system.!##!Method!#!We designed and implemented an immersive VR access simulation, where the user is surrounded by a virtual operating room, including medical equipment and virtual staff. The patient's head can be positioned via hand rotation and an arbitrary craniotomy contour can be drawn. The chosen access can be evaluated by exposing the aneurysm using a microscopic view.!##!Results!#!The evaluation of the simulation took place in three stages: testing the simulation using the think-aloud method, conducting a survey and examining the precision of drawing the contour. Although there are differences between the virtual interactions and their counterparts in reality, the participants liked the immersion and felt present in the operating room. The calculated surface dice similarity coefficient, Hausdorff distance and feedback of the participants show that the difficulty of drawing the craniotomy is appropriate.!##!Conclusion!#!The presented training simulation for head positioning and access planning benefits from the immersive environment. Thus, it is an appropriate training for novice neurosurgeons and medical students with the goal to improve anatomical understanding and to become aware of the importance of the right craniotomy hole

Combining visual analytics and case-based reasoning for rupture risk assessment of intracranial aneurysms

Purpose!#!Medical case-based reasoning solves problems by applying experience gained from the outcome of previous treatments of the same kind. Particularly for complex treatment decisions, for example, incidentally found intracranial aneurysms (IAs), it can support the medical expert. IAs bear the risk of rupture and may lead to subarachnoidal hemorrhages. Treatment needs to be considered carefully, since it may entail unnecessary complications for IAs with low rupture risk. With a rupture risk prediction based on previous cases, the treatment decision can be supported.!##!Methods!#!We present an interactive visual exploration tool for the case-based reasoning of IAs. In presence of a new aneurysm of interest, our application provides visual analytics techniques to identify the most similar cases with respect to morphology. The clinical expert can obtain the treatment, including the treatment outcome, for these cases and transfer it to the aneurysm of interest. Our application comprises a heatmap visualization, an adapted scatterplot matrix and fully or partially directed graphs with a circle- or force-directed layout to guide the interactive selection process. To fit the demands of clinical applications, we further integrated an interactive identification of outlier cases as well as an interactive attribute selection for the similarity calculation. A questionnaire evaluation with six trained physicians was used.!##!Result!#!Our application allows for case-based reasoning of IAs based on a reference data set. Three classifiers summarize the rupture state of the most similar cases. Medical experts positively evaluated the application.!##!Conclusion!#!Our case-based reasoning application combined with visual analytic techniques allows for representation of similar IAs to support the clinician. The graphical representation was rated very useful and provides visual information of the similarity of the k most similar cases