Is the indicator dilution theory really the adequate base of many blood flow measurement techniques?

1997 ◽  
Vol 24 (12) ◽  
pp. 1889-1898 ◽  
Author(s):  
P.-A. Doriot ◽  
P.-A. Dorsaz ◽  
L. Dorsaz ◽  
W. J. Rutishauser
Keyword(s):  
Blood Flow ◽  
Flow Measurement ◽  
Measurement Techniques ◽  
Indicator Dilution ◽  
Blood Flow Measurement ◽  
Indicator Dilution Theory ◽  
Dilution Theory

Feasibility Study of Time-Intensity-Based Blood Flow Measurements Using Deconvolution

2001 ◽  
Vol 23 (2) ◽  
pp. 90-105 ◽  
Author(s):  
Chih-Kuang Yeh ◽  
Sheng-Wuei Wang ◽  
Pai-Chi Li
Keyword(s):  
Blood Flow ◽  
Contrast Agent ◽  
Contrast Agents ◽  
Indicator Dilution ◽  
Time Constants ◽  
Lti System ◽  
Mixing Chamber ◽  
Indicator Dilution Theory ◽  
Deconvolution Techniques ◽  
Dilution Theory

Ultrasonic contrast agents have been used to enhance the acoustic backscattered intensity of blood and to assist the assessment of blood flow parameters. One example is the time-intensity method based on the indicator-dilution theory. In this case, a mixing chamber model can be employed to describe the concentration of the contrast agent as a function of time. By measuring the time intensities at both the input and output of the blood mixing chamber, blood flow information can be obtained if proper deconvolution techniques are applied. Note that most deconvolution techniques assume a linear and time invariant (LTI) system for the mixing of the contrast agent with blood. In this paper, the hypothesis that a blood mixing chamber is an LTI system was tested. Several aspects were studied. One aspect was the linear relationship between the concentration of the contrast agent and the backscattered intensity. The other aspect was the dependence of the derived time constants on the concentration. The concept of an effective mixing volume was also introduced and evaluated. Finally, the input and the output time constants were measured and compared to theory under the LTI assumption. Extensive experiments were performed. Two in vitro flow models were constructed and two contrast agents were used. Results indicated that the LTI assumption does not hold and quantitative flow estimation is generally not possible. Nonetheless, the indicator-dilution theory can still be applied if only relative measurements of the flow rate are required.

A review of ocular blood flow measurement techniques

2000 ◽  
Vol 24 (3) ◽  
pp. 401-409 ◽  
Author(s):  
Drora Zarfati ◽  
Alon Harris ◽  
Hanna J. Garzozi ◽  
Miriam Zacish ◽  
Larry Kagemann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Measurement ◽  
Measurement Techniques ◽  
Ocular Blood Flow ◽  
Blood Flow Measurement

MEASUREMENT OF BLOOD FLOW WITH FREELY DIFFUSIBLE INDICATORS AS INERT GASES, ANTIPYRINE, LABELLED WATER AND RUBIDIUM

1972 ◽  
Vol 68 (2_Supplb) ◽  
pp. S95-S111 ◽  
Author(s):  
Niels A. Lassen ◽  
Ole Andrée Larsen
Keyword(s):  
Blood Flow ◽  
Flow Measurement ◽  
Capillary Wall ◽  
Inert Gases ◽  
Tissue Blood Flow ◽  
Blood Flow Measurement

ABSTRACT Indicators which freely cross the capillary wall can be used for measurement of tissue blood flow in many different ways. Basically one can distinguish two categories of methods, viz. the ones where the indicator enters the tissue via the inflowing blood and the ones where the indicator is deposited locally in the tissue. The most important methods are briefly described with special emphasis on the theory of blood flow measurement.

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