Amir Samii

The estimation of rupture risk in Unruptured Intracranial Aneurysm (UIA) constitutes a major area of clinical interest due to the significant morbidity and mortality rates associated with aneurysm rupture. Classic clinical models based on factors such as size and location have demonstrated limited predictive accuracy, with small aneurysms being capable of rupture and larger ones remaining stable. Recent advances in Artificial Intelligence (AI) now allow the development of more sophisticated models that integrate both geometric and hemodynamic variables, including wall shear stress (WSS) and blood flow dynamics. While previous studies have examined these factors separately, our review specifically focuses on how they are combined within AI-based predictive models for unruptured intracranial aneurysms (UIAs). This integrated approach offers a more comprehensive and patient-specific risk assessment, going beyond traditional size-based methods. A wide array of machine learning (ML) and deep learning (DL) using SVMs (Support Vector Machine) and CNNs (Convolutional Neural Network) has demonstrated much better predictive accuracy than those attained by classical methods. Minimum necessary hemodynamic parameters including WSS and oscillatory shear index (OSI) were identified as critical indicators of rupture. Moreover, the review emphasized how CFD (Computational Fluid Dynamics) merged with AI in simulating patient-specific hemodynamics, outstanding progress having been achieved in the realm of risk assessment. Currently, there are promising developments in AI models for clinical practice, but large and good-quality datasets, along with interpretation of model predictions, remain challenges. More research would further refine these models toward improvement, with increased utility in a clinical setup to better aim at patient-specific risk assessment and optimization of treatment strategies for UIAs.

We conducted a two-center retrospective survey on standard MRI features including apparent diffusion coefficient mapping (ADC) of diffuse midline gliomas H3 K27M-mutant (DMG) compared to midline glioblastomas H3 K27M-wildtype (midGBM-H3wt). We identified 39 intracranial DMG and 18 midGBM-H3wt tumors. Samples were microscopically re-evaluated for microvascular proliferations and necrosis. Image analysis focused on location, peritumoral edema, degree of contrast enhancement and DWI features. Within DMG, MRI features between tumors with or without histomorphological GBM features were compared. DMG occurred in 15/39 samples from the thalamus (38%), in 23/39 samples from the brainstem (59%) and in 1/39 tumors involving primarily the cerebellum (2%). Edema was present in 3/39 DMG cases (8%) versus 78% in the control (midGBM-H3wt) group (p < 0.001). Contrast enhancement at the tumor rim was detected in 17/39 DMG (44%) versus 67% in control (p = 0.155), and necrosis in 24/39 (62%) versus 89% in control (p = 0.060). Strong contrast enhancement was observed in 15/39 DMG (38%) versus 56% in control (p = 0.262). Apparent diffusion coefficient (ADC) histogram analysis showed significantly higher skewness and kurtosis values in the DMG group compared to the controls (p = 0.0016/p = 0.002). Minimum relative ADC (rADC) values, as well as the 10th and 25th rADC-percentiles, were lower in DMGs with GBM features within the DMG group (p < 0.001/p = 0.012/p = 0.027). In conclusion, DMG cases exhibited markedly less edema than midGBM-H3wt, even if histomorphological malignancy was present. Histologically malignant DMGs and midGBM-H3wt more often displayed strong enhancement, as well as rim enhancement, than DMGs without histomorphological malignancy. DMGs showed higher skewness and kurtosis values on ADC-histogram analysis compared to midGBM-H3wt. Lower minimum rADC values in DMGs indicated malignant histomorphological features, likely representing a more complex tissue microstructure.

Background: About 6.2 million adults in Germany cannot read and write properly despite attending school for several years. They are considered to be functional illiterates (FI). Since the ability to read and write is crucial for being employed and socially accepted, we developed a special literacy training to overcome these deficits.Methods: In this study, we investigate training-related changes in intrinsic functional connectivity (iFC) at rest in a group of 20 FI and 20 adult normal readers using resting state functional magnetic resonance imaging (rsfMRI). We used independent component analysis (ICA) to define different networks.Results: Before training, the between group analysis showed increased iFC in FI in a left-fronto-parietal network (LFPN; anterior insula, medial frontal cortex, lateral and frontal parietal regions) and in the Basal Ganglia network (BGN: thalamus, caudate, putamen, pallidum, amygdala, supplementary motor cortex and cingulate gyrus). Furthermore, the Visual Network-1 (VN1; temporal occipital fusiform gyrus, lateral occipital cortex, occipital pole, lingual gyrus, thalamus) showed decreased iFC in FI. After training the FI group showed reversal of the “hyperconnectivity” in middle frontal gyrus and in the frontal orbital cortex and between supramarginal gyrus and the BGN. Furthermore, functional connectivity increased in FI VN1 (lateral occipital cortex, insular cortex). These changes in connectivity correlated with gains in reading speed and spelling accuracy.Conclusions: These findings show that poor reading and writing abilities are associated with abnormalities in iFC in several brain areas subserving cognitive processes important for reading. Intensive literacy training induces changes in the functional connectivity between and within neural networks important for literacy skills.

Background: Producing sounds by a musical instrument can lead to audiomotor coupling, i.e. the joint activation of the auditory and motor system, even when only one modality is probed. The sonification of otherwise mute movements by sounds based on kinematic parameters of the movement has been shown to improve motor performance and perception of movements.Results: Here we demonstrate in a group of healthy young non-athletes that congruently (sounds match visual movement kinematics) vs. incongruently (no match) sonified breaststroke movements of a human avatar lead to better perceptual judgement of small differences in movement velocity. Moreover, functional magnetic resonance imaging revealed enhanced activity in superior and medial posterior temporal regions including the superior temporal sulcus, known as an important multisensory integration site, as well as the insula bilaterally and the precentral gyrus on the right side. Functional connectivity analysis revealed pronounced connectivity of the STS with the basal ganglia and thalamus as well as frontal motor regions for the congruent stimuli. This was not seen to the same extent for the incongruent stimuli.Conclusions: We conclude that sonification of movements amplifies the activity of the human action observation system including subcortical structures of the motor loop. Sonification may thus be an important method to enhance training and therapy effects in sports science and neurological rehabilitation.

Skull base chondrosarcomas are rare tumors and individual experience with their management is limited. We present a series of such tumors treated at our institution. Particular attention was paid to their extension pattern, choice of surgical approach, and outcome. Twenty-five patients were operated consecutively over a period of 19 years. Their clinical presentation, radiological features, surgical treatment, early and late treatment outcome, as well as survival rate were analyzed. The most frequent initial symptom was abducent palsy. The typical bone destruction of the petrous apex was found in 83%. Chondrosarcomas extended in 92% to the posterior cranial fossa. Total number of surgeries was 39. The operative approach was tailored to each case. The retrosigmoid approach was used in 30.8%, the pterional in 23%, and the transethmoid in 15.4%. Total tumor removal was achieved in 19 of the surgeries. New neurological deficits immediately after surgery appeared in 33.3%. The perioperative mortality was 0%. The average Karnofsky performance score at last follow-up was 91%, and 5- and 10-year survival rates were 95%. Individually tailored approach in skull base chondrosarcomas allows radical removal with low morbidity rates and without mortality. Given the good long-term prognosis, surgical treatment should not deteriorate significantly patients’ quality of life.