Validation of a simple gamma camera method using minimal transit times to measure left ventricular ejection fraction

Left ventricular ejection fraction (LVEF) is one of the most important parameters of cardiac function. In contrast to the invasive X-ray catheter technique, nuclear medicine procedures allow the determination of LVEF at rest (LAO equilibrium technique and RAO first-pass technique = FP) and under a physical work load (LAO equilibrium stress technique). Another nuclear medical technique was developed as a simple bedside procedure by the Institute for Nuclear Research in Juelich, Federal Republic of Germany. In this technique 50 to 100 MBq unprocessed 99Tcm pertechnetate or 113Inm (available in every minor nuclear medical unit) are injected as a bolus into an antecubital vein. With an all purpose gamma camera interfaced to a normal minicomputer, 300 pictures are taken at a rate of 10 per second. Later these data can be processed and the minimal cardiac transit times (MTT) can be determined using a semi-automatic computer program. The measurement of different cardiac MTTs quantifies the function of different segments of the cardiopulmonary tract. MTT measurements are of value in the assessment of different pathological conditions such as heart failure, coronaropathy, valvular diseases and also primary pulmonary diseases. The Juelich group also showed that a LVEF calculated from MTT data correlates well with LVEF measured by X-ray catheter technique. In a study using the stored data of 81 patients in random sequence we calculated EF measured by MTT (anterior projection) immediately prior to determination of LVEF using FP (30 deg. LAO). Calculation of EF by FP has been a routine procedure in our institute for more than ten years. A good correlation between the two techniques was found. As previously published, it has been found that LVEF calculated by FP correlates well with catheter techniques. It is the aim of this work to show that the use of MTT is a simple, inexpensive and reliable method to measure left ventricular ejection fraction. (author). 9 refs