Variations on calculating left-ventricular volume with the radionuclide count-based method

Radionuclide left ventricular volume determination. Influence of scattered radiation and surrounding activity

Radionuclide measurements of left ventricular volumes, ejection fractions and stroke volumes were performed by an equilibrium technique in nine patients using left anterior oblique projection and individual depth correction. Phantom studies were made in order to evaluate attenuation and scattering of the radiation. It was found that a simple depth correction factor, k(d) = e mu d, can be used under certain conditions. However, the determination of left ventricular volume by radionuclide techniques is not a truly absolute method. The depth correction factor to be used is dependent on the condition of measuring and evaluation, for instance how the region of interest for the left ventricle is selected. Therefore, this method should be carefully standardized, evaluated and compared to other techniques. Stroke volume measured by radionuclide and dye-dilution technique showed a correlation coefficient of 0.76 (nine patients) at rest and 0.77 (seven patients) at work. This method can be easily performed during routine ejection fraction determination and can thus be useful in clinical studies.

Assessment of a procedure for left ventricle volumetry

A three-step radiographic procedure is described for the determination of left ventricle volumes, based on one lateral and two angled single plane images. The first angled image is taken to yield a minimally foreshortened LV image and the second image, at the same angle, is taken of a calibration sphere. Five sources of operator-related, or 'input', error are analysed, two of which are normally removable. The remaining three input errors are assessed using a commercial digital subtraction angiography system and comparisons with the analysis are given. A summary result is that relative errors in end-systolic and end-diastolic LV volumes, as well as cardiac output, should normally be less than 13% under reasonable operator care. The input errors should not contribute to errors in calculated ejection fractions.