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Session: Cardiac Diagnostics
Session starts: Friday 25 January, 10:30
Presentation starts: 10:45
Room: Lecture room 559

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John Klaessens (UMC Utrecht)
Herke Jan Noordmans (UMC Utrecht)
Martin Nelisse (UMC Utrecht)
Ruud Verdaasdonk (VUMC)

Abstract:
During clinical interventions objective and quantitative information of the tissue perfusion, oxygenation or temperature can be very useful for the surgical strategy. Spectral point measurements give limited information and affected areas can easily be missed, therefore imaging methods like hyper-spectral imaging and IR thermography1 are required to determine the tissue condition for large areas. We developed a hyper-spectral imaging system, based on a programmable LED light source (17 different wavelengths between 370 nm and 880 nm). The system was successfully validated under laboratory conditions on volunteers. Different algorithms to study the oxy- and deoxy-hemoglobin changes in tissue over time were developed and applied for different sets of wavelengths2. This multispectral imaging system and a thermo camera were applied during clinical interventions: Tissue flap transplantations (ENT), local anesthetic blocks and during open brain surgery (to resect the focus of epilepsy). The images covered an area of 20x20 cm. The measurements in clinical practice turned out to be more complicated compared to the laboratory experiment due to light fluctuations in the environment, movement of patient and limited field of view in operation room. Using self-written MultiSpec and Match software, light fluctuations and movements were corrected. Oxygenation concentration images could be calculated and combined with temperature images. During brain surgery, changes in oxygenation on the cortex can reveal the effect of an epileptic attack and slow brain waves can be seen running over the cortical surface. The effectivity of local anesthesia of a hand could be predicted in an early stage using the thermal camera and the reperfusion of transplanted skin flap could be imaged. The LED-based multispectral imaging system combined with thermal imaging provide complementary information on perfusion and oxygenation changes and are promising techniques for real-time diagnostics during clinical interventions. REFERENCES 1. E.F.Ring and K.Ammer, "Infrared thermal imaging in medicine,", Physiol Meas., vol. 33, pp. R33-R46, (2012/3). 2. J.H.G.M.Klaessens, H.J.Noordmans, R.de Roode, and R.M.Verdaasdonk, "Non-invasive skin oxygenation imaging using a multi-spectral camera system: effectiveness of various concentration algorithms applied on human skin,", SPIE BiOS Biomedical Optics, SPIE Vol: 7174, (2009/2/23).