Computed tomography of the heart: evaluation of anatomy and function

Diseases of the heart and blood vessels represent one of the most challenging problems for advanced diagnostic imaging systems. Computed tomographic scanning is potentially an ideal cardiac imaging modality since it is a cross-sectional imaging method with very high resolution. Currently available computed tomographic scanners have exposure speeds of 1 to 5 seconds, which are inadequate for the majority of cardiovascular imaging applications. Nevertheless, a variety of limited computed tomographic scanning techniques have been successfully performed in selected patient subgroups. These methods require the administration of contrast medium injected or infused into a peripheral vein, combined with either dynamic computed tomographic scanning or some form of electrocardiographic gated computed tomography. The newer conventional computed tomographic scanners can display anatomic structures in the heart and great vessels with considerable fidelity and provide not only cross-sectional displays but also, by means of computer manipulation, any selected reconstructed images in oblique, coronal or sagittal projections. Feasibility studies indicate improved accuracy of computed tomographic measurements of cardiac chamber volumes. Physiologic measurements include estimation of shunt flows and cardiac output and analysis of myocardial wall thickening. The full potential of computed tomography should be reached once fast, multiple slice, computed tomographic scanners using scanning electron beam techniques become available. The prototype CVCT (cine computed tomographic C-100 scanner) designed at the University of California, San Francisco, is now undergoing evaluation. This instrument images up to eight contiguous slices at the rate of 16 to 24 images/s. The computed tomographic scanner specifically designed for cardiac imaging should extend the utility of computed tomography in the evaluation of cardiac diseases and the study of cardiovascular physiology.