Pathophysiological correlates of thallium-201 myocardial uptake in experimental infarction

Abstract

The pathophysiological correlates of thallium-201 (201TI) myocardial uptake were studied in a 24-hour-old closed-chest canine infarct model. Reduction in regional 201Tl uptake correlated well with the magnitude of tissue creatine phosphokinase depletion and microsphere estimates of transmural blood flow. In low flow endocardial regions 201Tl occasionally under-estimated the magnitude of flow reduction. Even slight reductions of 201Tl uptake (less than 0.86 of normal) were associated with histopathological and histochemical evidence of necrosis.

Super-normal retention in hibernating myocardium: an ex-vivo study using the failing human heart

“…flows of the control segments was significantly higher than in myocardium supplied by the patent coronary artery w x w x 201 32 . DiCola et al 33 observed that Tl uptake in very low flow endocardial regions tends to overestimate the relative regional flow assessed by means of the microsphere technique. Although these authors suggested that the disproportionately high 86 Rb or 201 Tl content at very low flows was very probably due to the inverse relationship between flow and extraction, they did not provide any explanation for the higher tracer uptake in peri-ischemic w x segments with only a slightly reduced flow 32,33 .…”

Potential value of thallium-201 scintigraphy as a means of selecting patients for the coronary care unit.

“…This is not surprising since thallium-201 uptake in the myocardium reflects regional myocardial perfusion (Strauss et al,. 1975;DiCola et al, 1977) and the integrity of the Na+K+-ATPase system (Britten and Blank, 1968;Adolph et al, 1976;Gelbart etal., 1976). This lack of specificity is not necessarily a disadvantage, since both myocardial infarction and unstable angina provide indications for coronary care unit admission.…”

Myocardial imaging with extractable cations and inert tracers: The effects of flow and metabolism

“…There is an inverse relationship between flow and extraction and a dissociation between these two determinants with hypoxia, glucose and insulin, digitalis, propranolol, diuretics and catecholamines (8,9,13,14,17,22,26). It is also interesting that a number of studies have shown that the reg-ional myocardial distribution of 201n can be closely correlated with metabolic changes such as the regional myocardial depletion of creatine kinase (10,23,33).…”

“…The physical properties of these indicators have been investigated, and 201 11 has recently emerged as the radionuclide of choice (4,8). The biological properties of this tracer are complex and they influence the interpretation of changes in the distribution of activity in the heart seen in clinical practice (10,27).…”