Multimodal Spectroscopy

Computational Brain Modelling

Our research focuses on the development of computational models of cerebral circulation and metabolism. These models integrate and simulate NIRS and MRS (magnetic resonance spectroscopy) measurements and contribute to the analysis of results from ongoing clinical experiments involving hypoxia ischaemia. Further information can be found on the Computational Brain Modelling group pages.

Multimodal Brain Spectroscopy (Ilias Tachtsidis, Tingting Zhu, Luke Dunne)

In order to specifically measure the absorption and scattering of light in tissue over a larger number of wavelengths in the near infrared region we have developed a new time resolved optical spectrometer.

Time resolved spectroscopy is performed by measuring the time-of-flight of photons as they travel through the tissue, if many photon are measured we can generate temporal point spread functions that provide information about the absorption and scattering of light in the tissue.

The system uses a supercontinuum laser and acousto-optic tunable filters allowing us to generate any combination of up to 16 wavelengths in the near infrared region and in a single measurement. The light is coupled to the tissue via two source fibres and detected by four photomultiplier tubes.

For further information you can have a look at I. Tachtsidis UCL Neuroscience Symposium poster [Poster Link] and ISCBFM Brain 2011 abstract [Abstract Link], A. Bainbridge ISMRM 2011 poster [poster link]

References:

Tachtsidis I., Bainbridge A., Faulkner S., Mahoney S., Price D., Thomas D., Cady E., Robertson N., Golay X. "Fusion of near-infrared and magnetic resonance spectroscopy delivers novel multimodal investigation of neonatal hypoxic-ischaemic brain injury.” Brain 2011, Barcelona, Spain, May 2011

Bainbridge A., Tachtsidis I., Faulkner S., Mahoney S., Price D., Thomas D., Cady E., Robertson N., Golay X. “Combined 1H MRS and Near-Infrared Spectroscopy Measurements of Cerebral Blood Volume, Oxygenation, Cytochrome Oxidase, and Intracellular Metabolites During Perinatal Hypoxia-Ischaemia” ISMRM 2011, Montreal, Canada, May 2011

Functional Activation (Tingting Zhu, Jabed F. Ahmed, Ilias Tachtsidis)

Measuring brain haemodynamics, oxygenation and metabolism during brain functional activation can offer information for brain neuronal activation and provide further insights into neurovascular coupling. We have adopted a multimodal approach that allow us to simultaneously measure: (1) the changes in brain tissue oxy- and deoxy-haemoglobin ([HbO2] [HHb]) and the redox changes in cytochrome-c-oxidase ([ox-redCCO] or [CtOx]), which is a marker of mitochondrial metabolism and (2) the changes in systemic physiology including blood pressure, heart rate and scalp blood flow. We have implemented a plethora of methodologies (SPM, ICA, Wavelets) to explore the crosstalk between systemic changes and NIRS signal changes during frontal lobe activation and have been recently reporting at the presence of false positives in NIRS frontal lobe functional activation studies.

For further information you can have a look at T. Zhu ISCBFM Brain 2011 poster [Poster Link] and A. Jelzow SPIE abstract [Abstract Link] and E. Kirilina ISMRM 2011 [Poster Link]

References:

E. Kirilina, A. Jelzow, R. Bruehl, A. Heine, M. Niessing, A. M. Jacobs, B. Ittermann, H. Wabnitz, R. Macdonald, and I. Tachtsidis "Physiological origin of systemic artifacts in functional near infrared spectroscopy as revealed by fMRI." ISMRM 2011, Montreal, Canada, May 2011

Jelzow A,Tachtsidis I,Kirilina E,Niessing M,Bruhl R,Wabnitz H,Heine A,Ittermann B,Macdonald R, “Simultaneous measurement of time-domain fNIRS and physiological signals during a cognitive task.” SPIE-INT SOC OPTICAL ENGINEERING, DIFFUSE OPTICAL IMAGING III, Volume 8088 (2011).