Radioactive Gases in the Evaluation of Left Ventricular Function
The hydrodynamic performance of heart chambers can be noninvasively investigated by quantitative evaluation of tracer dilution curves. The application of nuclear medical procedures to cardiac dynamic measurements must begin with two fundamental decisions concerning the radiotracer and the detection system, chosen to measure the desired cardiac parameter with the greatest sensitivity. After these choices have been made, the statistical quality of the data will dictate the level of refinement that is justified in the quantitative modeling of the heart as a pump. In particular, the measurement of atrial and ventricular ejection fractions and detection of valvular insufficiencies stand apart from most nuclear medical procedures due to the severe demands placed on spatial and temporal resolution. Accurate diagnosis can hinge on seeing count-rate differences of several percent in successive 10 cm2 × 10 msec image slices, suggesting that observed data rates from the heart alone should be of the order of 1 MHz. The fundamental tracer/ detector choices determine how far short of this ideal a practical procedure will fall.
KeywordsCatheter Dioxide Catalysis Radionuclide Convolution
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