Research in the DOIT Lab
Research activities in our group range from basic theoretical analyses to experimental studies, from instrumentation development to practical applications in vitro and in vivo, from new methods of data collection to new approaches of data analysis, all the way to pilot clinical applications. Click on a research activity listed below to learn more about our work within the domain.
Diffusion theory: continuous-wave (CW), frequency domain (FD), and time domain (TD)
Light propagation in biological tissue can be described as the diffusion of photons that experience absorption and scattering events.
Photon-density waves
Intensity-modulated light launches strongly damped waves of optical energy into tissue.
Absolute optical measurements with multi-distance FD-NIRS data
The slopes of the amplitude and phase of photon-density waves yield robust measurements of absorption and scattering properties of tissue.
Novel data types in FD-NIRS
Different combinations of DC intensity, AC amplitude, and phase enrich the data space of FD-NIRS.
Monte Carlo simulations for solving the radiative transfer equation
Stochastic approaches such as Monte Carlo simulations are powerful tools for the solution of the radiative transfer equation.
Basic concept of dual slopes
A special combination of two sources and two detectors yields dual-slope data that self-calibrate for instrumental factors.
From going bananas to going nuts
Dual-slope data feature regions of sensitivity that are nut-shaped rather than banana-shaped as typical for single-distance data.
Dual-slope broadband spectroscopy
The self-calibrated nature of dual-slope data lends itself to broadband absorption spectroscopy.
Spectrophotometry of turbid media in a cuvette
Dual-ratio methods extend the dual-slope approach to the optical characterization of turbid media in a standard cuvette.
Finger pulse oximetry
Dual-slope FD NIRS methods are applied to pulsatile hemodynamic measurements for pulse oximetry.
Dual-slope imaging
Specially designed source-detector arrays allow for imaging applications based on dual-slope data.
Non-invasive optical sensing of the brain
Cerebral hemodynamics can be measured non-invasively by placing light sources and optical detectors on the scalp.
Depth sensitivity of FD-NIRS signals from two-layered media
Theoretical analyses of FD-NIRS data from two-layered media provide indications on their sensitivity to superficial and deep tissue.
Dual-slope FD-NIRS during visual stimulation
The cerebral hemodynamic response to brain activation is efficiently measured with dual-slope data.
The general idea of CHS
Coherent hemodynamics spectroscopy is based on cerebral hemodynamics that are associated with a specific physiological process.
The CHS cerebrovascular model
The CHS model treats the cerebral microvasculature as a linear time-invariant system.
CHS measurements of capillary transit time and cerebral autoregulation
Cerebral blood flow and its autoregulation in response to blood pressure fluctuations can be measured with CHS.
Depth dependence of coherent [Hb] and [HbO2] oscillations
Data interpreted with the CHS model indicate that hemodynamics in the scalp are driven by blood volume and in the brain by blood flow.
![[HbT] in the forearm during venous occlusion.](/bme/sites/g/files/lrezom551/files/styles/large/public/2024-09/fantini-vascular-occlusions-1160x468.png?itok=_42Bj0c3)
Blood flow and oxygen consumption with vascular occlusions
The rates of blood accumulation and blood desaturation during vascular occlusion yield measures of blood flow and oxygen consumption.
Role of adipose tissue and bone tissue
In addition to adipose tissue, also bone tissue may impact non-invasive optical measurements of skeletal muscle.