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Quantitative and continuous measurement of cerebral blood flow by a thermal method

Wei, Datong
http://rave.ohiolink.edu/etdc/view?acc_num=case1060354210

Abstract Details

1993, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
A thermal perfusion system is developed to measure cerebral blood flow continuously and quantitatively, with thermistors placed on brain surface to minimize tissue damage. Heat transfer models for tissue and self-heated thermistor are used to compare sensitivity, resolution and dynamic response under different operating modes and boundary conditions. Simulation results indicate that large perfusion sensitivity requires large thermistor while fast dynamic response calls for small thermistor. Adiabatic condition at the tissue-environment interface can maximize perfusion sensitivity and minimize thermal interference. Theoretical framework for optimal probe and system design based on measurement requirements has been established through the steady-state relations between thermal output and perfusion. The system, with lock-in amplifiers and a thermistor for reference temperature, can detect temperature signal of 0.001°C caused by perfusion changes while accommodating baseline temperature variations on the order of 0.1°C. The perfusion sensitivity and dynamic response are tested in vitro and in vivo. Noise analysis indicates that thermal fluctuations in tissue and environment are much larger than electrical noise and are the major error source. Perfusion changes associated with arterial blood pressure changes caused by bolus norepinephrine injections are used to validate the system output during continuous heating. In vivo evaluation demonstrates that the dynamic response is adequate to follow transient perfusion changes before autoregulation and perfusion cycling around 0.1 Hz. A partial analytical solution of the heat transfer model is developed, resulting consistent relations between transient and continuous heating modes. Model parameters including perfusion are estimated by nonlinear least-squares fitting from the temperature response during transient heating. A calibration coefficient is obtained from the estimated parameters without varying perfusion at different levels. Continuous perfusion changes can be quantified from the thermal output during continuous heating using the calibration coefficient. Estimated perfusion resolution of the system is about 1 mL/100g-min. Practical procedures to estimate the frequency response of thermal system have been developed for the first time. Animal experiments show that perfusion estimates from the thermal and the quantitative autoradiographic techniques are correlated. CO2 reactivity test demonstrates the sensitivity of the quantitative procedure of the thermal method to perfusion changes
Gerald Saidel (Advisor)
211 p.
Engineering, Biomedical
Cerebral blood flow, measurement; Thermal method

Recommended Citations

Citations

  • Wei, D. (1993). Quantitative and continuous measurement of cerebral blood flow by a thermal method [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1060354210

    APA Style (7th edition)

  • Wei, Datong. Quantitative and continuous measurement of cerebral blood flow by a thermal method. 1993. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1060354210.

    MLA Style (8th edition)

  • Wei, Datong. "Quantitative and continuous measurement of cerebral blood flow by a thermal method." Doctoral dissertation, Case Western Reserve University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1060354210

    Chicago Manual of Style (17th edition)

case1060354210
484
© 1993, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.