Comparative study of 201Tl reinjection tomography and combined use of 13N-ammonia and 18F-fluorodeoxyglucose positron emission tomography for detection of viable myocardium

Objective: To compare the clinical value of 201Tl reinjection tomography and combined use of 13N-ammonia (NH3) regional myocardial perfusion and 18F-fluorodeoxyglucose (FDG) positron emission tomography transfer function and for the myocardium. Methods: The authors performed exercise 201Tl SPECT (Tl SPECT) on 20 patients with myocardial infarction and obtained standard 201Tl exercise-redistribution images. 201Tl was reinjected immediately after redistribution study, and the images were then acquired as also. The 20 patients also underwent PET imaging with 13N-NH3 and 18F-FDG (NH3-FDG PET) within one week of the above study. Vertical and horizontal long axis cuts were divided into nine segments, and uptakes of radioisotope were evaluated into four classes visually (Defect score, DS) (0:normal uptake, 3:severely reduced). Quantitative evaluation was performed on the vertical and horizontal long axis cuts of 201Tl redistribution, reinjection and FDG PET images using regions of interest. The relative myocardial 201Tl uptake and 18F-FDG uptake (% ID) were expressed as the percentage of this reference region accounted for of the maximal counts. Results: In 48 segments identified as viable by the NH3-FDG PET images, 45 (93.8%) segments were also identified as viable by the 201Tl redistribution imaging. Of 24 segments with severe irreversible defects on the 201Tl redistribution imaging, 87.5% of the segments were concordantly confirmed by 201Tl reinjection and NH3-FDG PET images with 37.5% identified as viable and 50% identified as scar. There was no significant difference in the average % ID, furthermore, regression analysis revealed a high positive correlation in the segmental % ID between 201Tl reinjection and FDG PET images in the 61 segments with myocardial infarction (r = 0.722). Conclusions: The results show that 201Tl reinjection tomography is of similar accuracy with NH3-FDG PET for detection of viable myocardium and possess important clinical practice value