Jonas B Fischer

• Doctor of Philosophy
• formerly at ICFO Institute of Photonic Sciences

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit of novel methods to explore brain health and function. While the first report focused on neurophotonic tools mostly applicable to animal studies, here, we highlight optical spectroscopy and imaging methods relevant to noninvasive hu...

Intracranial pressure (ICP) is an important parameter to monitor in several neuropathologies. However, because current clinically accepted methods are invasive, its monitoring is limited to patients in critical conditions. On the other side, there are other less critical conditions where ICP monitoring could still be useful, thus there is a need to...

The COVID-19 pandemic led to widespread mandates requiring the wearing of face masks, which led to debates on their benefits and possible adverse effects. To that end, the physiological effects at the systemic and at the brain level are of interest. We have investigated the effect of commonly available face masks (FFP2 and surgical) on cerebral hem...

Significance A shortcoming of the routine clinical use of diffuse optics (DO) in the injured head has been that the results from commercial near-infrared spectroscopy-based devices are not reproducible, often give physiologically invalid values, and differ among systems. Besides the limitations due to the physics of continuous-wave light sources, o...

Background: Red blood cells transfusions (RBCT) are utilized to restore normal values of hemoglobin concentration and hematocrit percentage in anemic patients. As expected, RBCT often leads to local and global alteration of blood flow (BF) and blood/tissue oxygenation which could have local deleterious consequences. This complicates its use and its...

This paper explores the analysis of the waveform of pulsatile signals obtained through time-resolved spectroscopy and diffuse correlation spectroscopy measures of the brain, for the potential application of identifying changes in intracranial compliance.

Hyperventilation (HV) can lower intracranial pressure to prevent secondary injuries in traumatic brain injury patients. Hybrid diffuse optics can detect misery perfusion, precursor of ischemia, to help guiding personalized therapy during HV. 22/27 measurement sessions (18 patients) showed MP risk.

Cerebral autoregulation (CAR) assessment in traumatic brain injury during hyperventilation can be multimodally assessed by hybrid diffuse optical device combined with physiological parameters. Results indicate a heterogeneous and complex response in CAR indices.

Chronological and evolutive study of the impact of perihematomal edema in patients with intracerebral hemorrhage using a hybrid diffuse optical device combining DCS and TRS.

Hybrid diffuse optics was utilized to monitor infants born with severe congenital heart defects during cardiac surgery. We have characterized the cerebral hemdoynamics and oxygen metabolism during the cannulation and the initiation of the cardiopulmonary bypass (CPB).

Alterations in microvascular cerebral blood flow, oxygenation and metabolism measured by diffuse optical spectroscopies, provide insights into intracranial pressure alterations.

A new hybrid convolutional and recurrent neural network model, trained on data acquired by fast diffuse correlation spectroscopy (DCS) from children and adults with different pathologies is proposed to estimate intracranial pressure from cerebral blood flow time-traces.

[This corrects the article DOI: 10.1117/1.NPh.9.4.045005.].

Hyperventilation (HV) therapy uses vasoconstriction to reduce intracranial pressure (ICP) by reducing cerebral blood volume. However, as HV also lowers cerebral blood flow (CBF), it may provoke misery perfusion (MP) where the decrease in CBF is coupled with increased oxygen extraction fraction (OEF). MP may rapidly lead to the exhaustion of brain e...

Significance: Benign external hydrocephalus (BEH) is considered a self-limiting pathology with a good prognosis. However, some children present a pathological intracranial pressure (ICP) characterized by quantitative and qualitative alterations (the so-called B-waves) that can lead to neurological sequelae. Aim: Our purpose was to evaluate wheth...

We present a study investigating the effect of non-medical face masks (FFP2 and surgical) on cerebral hemodynamics measured by transcranial hybrid diffuse optics, and on systemic physiology in 13 healthy adults (age: 23-33 years).

In a study by Law and colleagues recently published in Neuroimage, the authors reported that wearing a surgical mask during an fMRI scan leads to a statistically significant subject-specific change (30%) in the baseline BOLD level in gray matter, although the response to a sensory-motor task was unaffected. An average increase in end-tidal CO2 of 7...

Over the recent years, a typical implementation of diffuse correlation spectroscopy (DCS) instrumentation has been adapted widely. However, there are no detailed and accepted recipes for designing such instrumentation to meet pre-defined signal-to-noise ratio (SNR) and precision targets. These require specific attention due to the subtleties of the...

Intracranial pressure (ICP) is an important parameter to monitor in several neuropathologies. However, because current clinically accepted methods are invasive, its monitoring is limited to patients in critical conditions. On the other side, there are other less critical conditions where ICP monitoring could still be useful, thus there is a need to...

The precision of diffuse correlation spectroscopy (DCS) measurements was evaluated for varying instrumental and experimental parameters to provide recipes for making practical choices when designing devices.

A new hybrid diffuse optical platform was developed with fast, time-resolved and correlation spectroscopied. We present the device and results from an on-going clinical trial to evaluate hemodynamic and metabolic biomarkers for guiding acute ischemic stroke management.

We present a proof-of-principle of a method for non-invasive estimation of intracranial pressure in infants and adults based on the pulsatile cerebral blood flow measured by diffuse correlation spectroscopy and employing a recurrent neural network.