| Popis: |
Computed tomography (CT) represents the optimum theoretical approach to x-ray imaging. This conclusion results from an awareness of CT's capacity to solve the fundamental limitation of all forms of x-ray imaging--the superimposition of anatomic structures. Because CT is potentially a fully three-dimensional method, this problem is addressed in a manner not subject to the risks, complications, and technical limitations of selective angiography, subtraction angiography, tomography, and other techniques. Ultrafast CT provides a broad spectrum of useful quantitative cardiac data during one minimally invasive procedure. Therefore, the optimism for cine CT imaging of the heart is well founded. Apart from the demonstration of anatomic structures in any reconstructed plane and in movie format, without the need for any form of electrocardiographic gating, this new generation of millisecond CT scanners offers a unique potential for measuring myocardial mechanics and perfusion. Myocardial integrity can be evaluated by measuring myocardial wall thickening, which is a sensitive indicator of blood flow. It can also be assessed by time-density changes derived from analyzing the passage of contrast medium through thin slices of myocardium. Feasibility studies have demonstrated that this should be possible in the clinical setting by use of fast CT scanning. The radiation exposure to the patient with cine CT is low and comparable to, or less than, that of conventional CT and 10-15% of that received during angiocardiography; therefore, it is not a practical limitation. Further clinical and research studies are needed to determine the future role of this exciting new modality in the diagnosis and management of patients with heart disease. |
