João Jorge

CSEM - Swiss Center for Electronics and Microtechnology

Objectives: The aim of this study was to demonstrate that eloquent cortex and epileptic-related hemodynamic changes can be safely and reliably detected using simultaneous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) recordings at ultra-high field (UHF) for clinical evaluation of patients with epilepsy. Materials and m...

Cerebrovascular reactivity (CVR) reflects the capacity of blood vessels to adjust their calibre in order to maintain a steady supply of brain perfusion, and it may provide a sensitive disease biomarker. Measurement of the blood oxygen level dependent (BOLD) response to a hypercapnia-inducing breath-hold (BH) task has been frequently used to map CVR...

Both electroencephalography (EEG) and functional Magnetic Resonance Imaging (fMRI) are non-invasive methods that show complementary aspects of human brain activity. Despite measuring different proxies of brain activity, both the measured blood-oxygenation (fMRI) and neurophysiological recordings (EEG) are indirectly coupled. The electrophysiologica...

Brain functional connectivity measured by resting-state fMRI varies over multiple time scales, and recurrent dynamic functional connectivity (dFC) states have been identified. These have been found to be associated with different cognitive and pathological states, with potential as disease biomarkers, but their neuronal underpinnings remain a matte...

Eye motion is a major confound for magnetic resonance imaging (MRI) in neuroscience or ophthalmology. Currently, solutions toward eye stabilisation include participants fixating or administration of paralytics/anaesthetics. We developed a novel MRI protocol for acquiring 3-dimensional images while the eye freely moves. Eye motion serves as the basi...

Eye motion is a major confound for magnetic resonance imaging (MRI) in neuroscience or ophthalmology. Currently, solutions toward eye stabilisation include participants fixating or administration of paralytics/anaesthetics. We developed a novel MRI protocol for acquiring 3-dimensional images while the eye freely moves. Eye motion serves as the basi...

Both electroencephalography (EEG) and functional Magnetic Resonance Imaging (fMRI) are non-invasive methods that show complementary aspects of human brain activity. Despite their differences in probing brain activity, both electrophysiology and BOLD signal can map the underlying functional connectivity structure at the whole brain scale at differen...

The central vein sign (CVS) is an efficient imaging biomarker for multiple sclerosis (MS) diagnosis, but its application in clinical routine is limited by inter‐rater variability and the expenditure of time associated with manual assessment. We describe a deep learning‐based prototype for automated assessment of the CVS in white matter MS lesions u...

Purpose: The thalamus is an important brain structure and neurosurgical target, but its constituting nuclei are challenging to image non-invasively. Recently, susceptibility-weighted imaging (SWI) at ultra-high field has shown promising capabilities for thalamic nuclei mapping. In this work, several methodological improvements were explored to enh...

Massed synchronised neuronal firing is detrimental to information processing. When networks of task-irrelevant neurons fire in unison, they mask the signal generated by task-critical neurons. On a macroscopic level, such synchronisation can contribute to alpha/beta (8-30Hz) oscillations. Reducing the amplitude of these oscillations, therefore, may...

Massed synchronised neuronal firing is detrimental to information processing. When networks of task-irrelevant neurons fire in unison, they mask the signal generated by task-critical neurons. On a macroscopic level, mass synchronisation of these neurons can contribute to the ubiquitous alpha/beta (8-30Hz) oscillations. Reductions in the amplitude o...

The temporal structure of self-generated cognition is a key attribute to the formation of a meaningful stream of consciousness. When at rest, our mind wanders from thought to thought in distinct mental states. Despite the marked importance of ongoing mental processes, it is challenging to capture and relate these states to specific cognitive conten...

The ventro-intermediate nucleus (Vim), as part of the motor thalamic nuclei, is a commonly used target in functional stereotactic neurosurgery for treatment of drug-resistant tremor. As it cannot be directly visualized on routinely used magnetic resonance imaging (MRI), its clinical targeting is performed using indirect methods. Recent literature s...

Electroencephalography (EEG) recordings performed in magnetic resonance imaging (MRI) scanners are affected by complex artifacts caused by heart function, often termed pulse artifacts (PAs). PAs can strongly compromise EEG data quality, and remain an open problem for EEG-fMRI. This study investigated the properties and mechanisms of PA variability...

Figure S1: The effect of the filter length and adaptability factor (λ) on A: the correlation between the original (gold standard, neuronal) and corrected signals and B: the ratio of the RMS amplitudes of the original and corrected signal. These plots show the average of each metric over all EEG channels using 2 mins 20 secs of neuronal data (from V...

Simultaneous EEG‐fMRI allows multiparametric characterisation of brain function, in principle enabling a more complete understanding of brain responses; unfortunately the hostile MRI environment severely reduces EEG data quality. Simply eliminating data segments containing gross motion artefacts [MAs] (generated by movement of the EEG system and he...

The presence of a vein inside white matter lesions was recently proposed as an imaging biomarker that can help in the differential diagnosis of Multiple Sclerosis (MS), potentially reducing the challenging clinical-radiological gap. Here, we propose a prototype based on ensembling small 3D convolutional networks to classify perivenular (P+) and non...

When at rest, our mind wanders from thought to thought in distinct mental states. Despite the marked importance of ongoing mental processes, it is challenging to capture and relate these states to specific cognitive contents. In this work, we employed ultra-high field functional magnetic resonance imaging (fMRI) and high-density electroencephalogra...

BACKGROUND AND PURPOSE Surgery is the first choice therapeutic approach in case of drug‐resistant epilepsy. Unfortunately, up to 43% of patients referred for presurgical assessment do not have a lesion detectable by routine 3T magnetic resonance imaging (MRI) (MRI‐negative), although most of them likely have an underlying epileptogenic lesion. Thus...

External stimuli and tasks often elicit negative BOLD responses in various brain regions, and growing experimental evidence supports that these phenomena are functionally meaningful. In this work, the high sensitivity available at 7T was explored to map and characterize both positive (PBRs) and negative BOLD responses (NBRs) to visual checkerboard...

The ventro-intermediate nucleus (Vim), as the others thalamic subparts, cannot be directly visualized by current standard magnetic resonance imaging (MRI), in daily clinical practice. Hence, for treatment of tremor in functional neurosurgery, where the commonly used target is the Vim, the targeting procedure is done indirectly. We present a novel d...

Purpose: Physiological noise often dominates the blood-oxygen level-dependent (BOLD) signal fluctuations in high-field functional MRI (fMRI) data. Therefore, to optimize fMRI protocols, it becomes crucial to investigate how physiological signal fluctuations impact various acquisition and reconstruction schemes at different acquisition speeds. In p...

Purpose: To develop a novel approach for head motion and B0 field monitoring based on tracking discrete off-resonance markers with three spokes (trackDOTS). Methods: Small markers filled with acetic acid were built and attached to a head cap. Marker positions and phase were tracked with fast MR navigators (DotNavs) consisting of three off-resona...

Simultaneous EEG-fMRI using SMS-EPI was performed at 7T on a human volunteer, during resting-state and an eyes-open/closed paradigm. The functional sensitivity of each modality, and their integration, was investigated. In this first report on EEG-fMRI at 7T using SMS-EPI, eyes-open/closed responses and resting-state networks were robustly detected...

The enhanced BOLD sensitivity available at 7T can bring significant advantages for EEG-fMRI studies, and the use of accelerated fMRI sequences such as SMS-EPI could further boost sensitivity. This work investigated whether SMS-EPI can be safely acquired with EEG at 7T, and whether the resulting sensitivity is favorable for combined EEG-fMRI approac...

The ballistocardiogram (BCG) artefact is currently one of the most challenging in the EEG acquired concurrently with fMRI, with correction invariably yielding residual artefacts and/or deterioration of the physiological signals of interest. In this paper, we propose a family of methods whereby the EEG is decomposed using Independent Component Analy...

Objectives: To compare physiological noise contributions in cerebellar and cerebral regions of interest in high-resolution functional magnetic resonance imaging (fMRI) data acquired at 7T, to estimate the need for physiological noise removal in cerebellar fMRI. Materials and methods: Signal fluctuations in high resolution (1 mm isotropic) 7T fMR...

In this study, a three-dimensional finite element (FE) model based on the specific anatomy of a patient presenting a femoroacetabular impingement of the 'cam'-type is developed. The FE meshes of the structures of interest are obtained from arthrographic magnetic resonance images. All soft tissues are considered linear elastic and isotropic, and the...

High-field magnetic resonance imaging (MRI) systems allow for critical improvements in image signal-to-noise ratio (SNR), potentially leading to higher sensitivity and spatial resolution for functional MRI (fMRI). 3D segmented echo volumar imaging (EVI) has recently been proposed for high resolution fMRI at ultra-high fields. It provides higher ima...

Magnetic resonance arthrography (MRa) is an imaging modality designed to diagnose problems within a diathrodial joint of the human body such as the knee or the hip with the aid of a contrast agent. In fact, magnetic resonance imaging (MRI) without arthrography is of limited value when the detection of abnormalities is sought. The arthrography invol...

The conflict known as femoro-acetabular impingement depends on an abnormal morphological relation between the femoral head and the acetabular cavity. The "Cam" type impingement is due to the presence of a non-spherical portion of the femoral head, usually located at the antero-superior quadrant of the region of transition with the anatomical neck....