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Updated: Aug 5, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
Quantification of Viable Myocardium in Multivessel Coronary Disease: Effects of the Redistribution Time after
Helber1, Müller-Schauenburg, Hoffmeister
1Medizinische Klinik Abt. III, Eberhard-Karls-Universität, Tübingen, Germany
Insights
Reinjection of thallium-201 (201Tl) helps detect viable heart muscle. A 2-hour redistribution time after reinjection accurately quantifies perfusion defects in multivessel coronary artery disease patients, matching postoperative results.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Myocardial perfusion imaging with thallium-201 (201Tl) is crucial for assessing coronary artery disease.
- Accurate quantification of perfusion defects is essential for treatment planning, especially in patients with multivessel disease and impaired left ventricular function.
Purpose of the Study:
- To prospectively evaluate the impact of redistribution time after 201Tl reinjection on the definitive quantification of perfusion defect size.
- To compare post-reinjection defect sizes with pre-operative and post-operative assessments in patients undergoing coronary artery bypass grafting.
Main Methods:
- Thirty patients with multivessel coronary artery disease and impaired left ventricular function were studied preoperatively.
- 201Tl-chloride (80-90 MBq) was administered, followed by exercise and a 3-hour rest imaging. A reinjection dose (40-50 MBq) was given, with imaging at 10 minutes, 2 hours, and 20 hours post-reinjection.
- Perfusion defect size was quantified as a percentage of left ventricular myocardium and compared across different time points and with postoperative findings.
Main Results:
- Perfusion defect sizes decreased over time post-reinjection: post-stress (27%), 3-hour rest (17%), 10-min post-reinjection (12%), 2-hour post-reinjection (9%), and 20-hour post-reinjection (7%).
- A significant reduction in defect size (p < 0.05) was observed at 2 and 20 hours post-reinjection compared to the 3-hour rest study.
- At 2 hours post-reinjection, 15/30 patients showed a ≥50% reduction in defect size, with sizes matching postoperative assessments (10%).
Conclusions:
- The redistribution time after 201Tl reinjection is critical for accurately determining the definitive perfusion defect size versus viable myocardium.
- A 2-hour redistribution delay post-reinjection provides the most accurate assessment, correlating well with postoperative defect sizes.
- Extended redistribution times beyond 2 hours did not offer significant additional advantages in defect size reduction.
Abstract:
Reinjection of 201Tl is used for improved detection of viable myocardium. Prospectively the effect of the redistribution time after injection for the quantification of the definitive perfusion defect size in multivessel coronary heart disease and severely impaired left ventricular function was examined. Thirty patients were included preoperatively before CABG. The study was performed with 80-90 MBq 201Tl-Cl and reinjection (40-50 MBq). Imaging was performed after an exercise test and 3 hours afterwards. Thereafter, the reinjection dose was given and repeated studies were performed 10 minutes, 2 hours, and 20 hours later. Defect sizes were compared with the 3-hour rest-study without reinjection. Imaging studies were repeated postoperatively. The defect size was expressed as % of left ventricular total myocardium. Perfusion defect sizes were as follows: post-stress study (27%), 3 hour rest-study (17%), post-reinjection-10 min (12%), 2 hours (9%), and 20 hours (7%). Compared with the 3 hour rest-study, the perfusion defect was reduced only in 7/30 patients in the study immediately after reinjection. In the delayed studies, defect sizes were markedly smaller (p < 0.05) both in studies 2 hours and 20 hours after reinjection. In 15/30 patients there was a marked reduction of 50% of defect sizes in the study 2 hours post-reinjection vs the 3 hour rest-study. The residual defects at 2 hours after reinjection were identical to the postoperative defect sizes (10%). Further prolongation of the redistribution time to 20 horus caused an additional small reduction in defect size only in two patients compared with the 2-hour post-reinjection images (n.s.). Using a marker as 201Tl with redistribution characteristics, the redistribution time after reinjection is of utmost importance to correctly identify the definitive size of the perfusion defect vs viable myocardium in patients with multivessel disease. A delay of 2 hours for redistribution after the reinjection most correctly corresponds to the postop defect size; a longer redistribution time did not provide additional advantages.
