Osman Ratib 1 Dynamic Image Acquisition Techniques 359
UCLA School of Medicine 2 Dynamic Analysis of Left Ventricular Function 360
2.1 Geometric Calculation of Changes in Cardiac Volumes • 2.2 Densitometric Calculation of Volumes • 2.3 Quantitative Evaluation of Regional Function • 2.4 Temporal Evaluation of Ventricular Wall Motion • 2.5 Dynamic Analysis of Myocardial Contraction
3 Quantitative Evaluation of Flow Motion 368
3.1 Two-Dimensional Color Doppler Ultrasound • 3.2 Velocity Encoded Cine-MRI
4 Conclusion 371
In diagnostic cardiac imaging, a large number of quantitative parameters that can be extracted from dynamic images are clinically relevant. Also in cardiology, almost all types of imaging modalities are used, and many of them tend to measure the same functional parameters in different ways. For example, cineangiograms, radionuclide ventriculography, ultrasound, and MRI can be used for the assessment of ventricular wall motion abnormalities. Coronary angiography, thallium scintigraphy, and positron emission tomography can be used to evaluate myocardial perfusion. Ultrasound, MRI, and fast CT can be used to visualize cardiac malformation, etc. Cardiac imaging procedures rely heavily on quantitative analysis techniques. Some of the quantitative measurement techniques used in different modalities are similar. For example: (1) A geometric estimate of ventricular size and ejection fraction can be applied to ultrasound, cineangiograms, radionuclide ventriculogram, and MRI images; (2) blood flow and coronary reserve can be evaluated from contrast coronary angiography, conventional scintigraphy, and PET using similar tracer kinetics models; and (3) the temporal behavior of regional ventricular wall motion can be analyzed from cineangiography, radionuclide ventriculography, and MRI using similar factorial and Fourier analysis techniques.
Since the heart is a moving organ, its mechanical function is evaluated using motion and temporal analysis techniques. The vital function of the heart is to mechanically push large volumes of blood through the vascular system; therefore, it is understandable that most quantitative analyses focus on the evaluation of its hemodynamic performance.
The first digital imaging modality used in cardiology was radionuclide imaging, where digital images were acquired and stored in digital acquisition systems. This led to the early development of image processing techniques directed toward the enhancement and quantitative evaluation of radionuclide images . All these early developments were focused on quantitative measurement of regional activity and ventricular function, overlooking problems associated with a rather poor spatial resolution. As radionuclide imaging techniques became more widely available, many new analysis methods were introduced, providing new approaches for quantitative assessment of abnormalities in cardiac function as well as myocardial perfusion. The improvement in diagnostic efficiency due to these analysis techniques was well demonstrated in clinical trials where they were compared to preexisting conventional methods [2,3]. New concepts in the assessment of ventricular function, such as the measurement of temporal changes in regional wall motion by Fourier phase analysis of radionuclide angiograms , led to a significant improvement in the detection of regional alterations in ventricular function.
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