Radionuclide angiocardiography: a comparison of first transit and gated blood pool methods

First-transit and gated blood-pool radionuclide angiocardiography are two fundamentally different methods for scintigraphic examination of the heart. Both are equally accurate methods of measuring left ventricular ejection fraction as shown by comparison with cineangiography (correlation coefficients range 0.84 t 0.95). Both methods demonstrate a high degree of reproducibility in the results obtained from repeated determinations of ejection fraction in the same patient (correlation coefficients range 0.93 to 0.95). Additionally, both methods enable assessment of segmental ventricular wall motion and volumes; while there is good agreement between scintigraphic and cineangiographic findings with respect to wall motion, quantification of volumes remains problematic. Shunt assessment and calculation of transit times can only be obtained with the first-transit method. Notable advantages of the blood-pool method are simplicity and the ability to obtain multiple repeated studies for several hours after a single injection of imaging agent. The major disadvantages of the blood pool method are the problem of chamber superimposition which substantially complicates the process of wall motion analysis and the temporal and spatial distortion of data inherent to the need for relatively long imaging times. The chief advantage of the first-transit method is temporal separation of right and left heart imaging. This allows easy and accurate assessment of ventricular wall motion from any view desired. Short acquisition time makes heart rate variation and patient motion less critical. The most notable disadvantages of the first-transit method are the necessity to inject at additional bolus of imaging agent for each study performed and the complexities of performing and processing the studies.