Increased prognostic value of combined myocardial perfusion SPECT Imaging and the quantification of lung TI-201 uptake
Abstrakt
Purpose: The authors wanted to identify those patients assessed by exercise SPECT in whom the quantification of lung TI-201 uptake helps to evaluate disease prognosis. Methods: One hundred forty-nine patients (114 men, 35 women; 74 after myocardial infarction [MI]; mean age, 54 +/- 9 years) underwent exercise TI-201 SPECT.
The SPECT patterns were divided into normal (n = 45), fixed defects (n = 29), and inducible ischemia (n 75). Anterior planar imaging was performed before SPECT acquisition to calculate the lung-to-heart ratio (L;H).
Results: During an average follow-up of 20 +/- 9 months, eight patients had died of cardiac causes and 13 patients experienced nonfatal MIs. Among the 45 patients with normal perfusion, no cardiac event was observed and the L:H ratio was not helpful for risk stratification.
In 29 patients with fixed defects, four cardiac deaths occurred (all in patients with L:H ratios >0.5; annual event rate, 21.1% for L:H ratios >0.5 compared with 0% for L:H ratios 0.5 compared with 13% for L:H ratios <0.5; P = NS). Conclusions: These findings suggest a benign prognosis in patients with normal SPECT (regardless of the L:H ratio).
Conversely, all patients with ischemia are at high risk for future cardiac events. Quantification of the TI-201 lung uptake seems to be valuable in evaluations of disease prognosis, especially in patients with fixed defects.