Simultaneous assessment of myocardial function and perfusion

Abstract

The radionuclide techniques that may be used to assess function are listed in Table 1 [1, 2, 3]. Assessment of both myocardial function and perfusion in the past was done using two different radionuclides (for example, thallium-201 and technetium-99m pertechnetate) and two separate exercise studies [1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]. For a short period of time, thallium-201 and aurium-195m were simultaneously used for perfusion/function assessment but aurium-195m is no longer available for clinical use [4, 14]. Thallium-201 is injected 20 seconds before peak exercise and then, at peak exercise, radionuclide ventriculography is obtained with aurium-195m. The short half-life of aurium-195m (30.5 seconds) makes simultaneous dual isotope imaging possible and substantially reduces the radiation exposure from the isotope angiography. Narahara and associates [4] studied 24 subjects with coronary artery disease and 20 healthy volunteers, using such a dual technique. They were able to obtain high-quality first-pass angiograms in all patients. The exercise thallium images provided a sensitivity of 83% and a specificity of 95% suggesting that its diagnostic accuracy was not altered by simultaneous dual isotope imaging. The dual isotope technique permits simultaneous analysis of regional and global ventricular function in relation with regional thallium redistribution. Other short-lived isotopes, though available, have not received widespread interest or require specially designed gamma cameras such as tantalum-178. The methods available to assess both perfusion and function are summarized in table 2.