201-Thallium (Tl) and (99m)Tc-sestamibi (SM) present different biological properties and kinetics, suggesting a complementary evaluation of mitochondrial and cell membrane functions with subsequent implications regarding myocardial injury mapping. To verify the usefulness of a dual isotopic approach in Q infarcted patients, 30 subjects were submitted at rest, within 5 days, to SM imaging, 4h-delayed Tl scans and echocardiography (ECHO). Left ventricle segmental uptake and wall motion were graded on a 3 points scale (0=absent to 2=normal) and compared on the basis of an 11 segments model.
Results and discussion: 1) The analysis of SM normal segments demonstrated a strong concordance (97%) with Tl and ECHO, suggesting that both mitochondrial and cell membrane functions are preserved; 2) 49% of SM graded 0 segments were scored 1 by Tl and ECHO, suggesting a worse impairment of mitochondrial function with respect to cell membrane function; 3) approximately 55% of segments showing a reduced MIBI uptake were found normal using Tl, then an impaired mitochondrial but a normal cell membrane function could be hypothesized. 4) Tl provided a better estimation of the effective infarction size with respect to SM.
Conclusions: The SM and Tl dual approach, allowing scintigraphic mapping of myocardial injury, seems to provide a useful tool for a complete evaluation of infarcted patients.