[Ultrafast computed tomography and measurement of the left ventricular volume]

Ultrafast computed tomography is a method of acquiring cardiac tomographic images 8 mm thick of high resolution in a very short time (about 50 ms). It is particularly well adapted to evaluation of the anatomy and quantification of the volume of the left ventricle. Acquisition of the image is initiated by the R wave of the electrocardiogram. Short axis or long axis views of the heart may be recorded. There are usually 12 short axis tomographic cuts from the apex to the base and for each there are 13 acquisitions in the RR cycle at 58 ms intervals. The half circulation time must be determined beforehand as 50 cc of contrast medium have to be injected peripherally to visualise the cardiac chambers. The contrast medium enhances the endocardium and papillary muscle borders enabling semi-automatic contour tracings. End diastole and end systole are easily determined from the 13 acquisitions in the cardiac cycle, and the wall motion of the left ventricle can be analysed using a cineloop facility. Akinesia, dyskinesia and even wall thickness can be determined. After tracing the endocardial contour, the microprocessor calculates the surface of the enclosed area, and the volume of this simple cylinder can be derived by multiplication of the thickness of each slice. The total volume at each of the 13 instances is obtained by summation. End diastolic, end systolic volumes and ejection fraction can thereby be determined. Left ventricular mass may also be evaluated by tracing the epicardial border.(ABSTRACT TRUNCATED AT 250 WORDS)