IDENTIFICATION OF VIABLE MYOCARDIUM BY TL -201 SCINTIGRAPHY - A COMPARISON OF METHODS

The present study was undertaken to compare four different imaging app roaches to evaluate uptake defect Tl-201 reversibility. 24 infarcted p atients underwent standard stress/redistribution Tl-201 imaging (R1). Then, after reinjection of 37 MBq of Tl-204, patients were re-imaged e ither after 15 min (R2) 24 h later (R3). A separate rest study (R4) fo llowing a new tracer injection was done within 2-3 days. Planar images were obtained in the standard three views and subdivided into 216 seg ments for qualitative analysis based on a visual score. A semiquantita tive analysis based upon circumferential profiles was also applied. A stress defect was found in 127 segments (58.7%). By visual inspection reperfusion was considered to occur in 32.3%, 41.7%, 33.0% and 49.6% o f the cases with R1, R2, R3, and R4, respectively. The semiquantitativ e method showed a high reperfusion only with R1 (62%), while the other procedures proved less effective. No improvement was found with R4. S ix patients (25%) showed myocardial viability that was not detected wi th the early reinjection technique.