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Comparison between thallium-201 and technetium-99m methoxyisobutyl isonitrile defect size in single-photon emission
J C Maublant1, X Marcaggi, J R Lusson
1Department of Nuclear Medicine, Centre Jean Perrin, Clermont, France.
Insights
Technetium-99m-methoxyisobutyl isonitrile (MIBI) and thallium-201 (TI-201) SPECT imaging show high reproducibility for myocardial defect size. MIBI demonstrates smaller defect sizes compared to TI-201 in patients with coronary artery disease during exercise and redistribution.
Area of Science:
- Nuclear Cardiology
- Cardiovascular Imaging
- Medical Diagnostics
Background:
- Myocardial perfusion imaging is crucial for diagnosing coronary artery disease.
- Thallium-201 (TI-201) and technetium-99m-methoxyisobutyl isonitrile (MIBI) are common radiotracers used in SPECT.
- Comparing the accuracy and reproducibility of these tracers is essential for clinical practice.
Purpose of the Study:
- To compare the defect size measurements between TI-201 and MIBI in patients undergoing myocardial perfusion SPECT.
- To assess the reproducibility of defect size measurements for both TI-201 and MIBI.
- To evaluate potential differences in defect sizes between tracers in patients with myocardial infarction versus coronary artery disease.
Main Methods:
- Single-photon emission computed tomographic (SPECT) imaging was performed on 30 patients using both TI-201 and MIBI.
- One group of 15 patients with myocardial infarction was studied at rest.
- Another group of 15 patients with coronary artery disease underwent exercise TI-201 imaging and rest/exercise MIBI imaging.
Main Results:
- Both TI-201 and MIBI demonstrated high reproducibility in defect size measurements (r = 0.978 for TI-201, r = 0.981 for MIBI).
- Patients with coronary artery disease showed significantly smaller defect sizes with MIBI compared to TI-201 during exercise and redistribution (p < 0.05).
- No significant difference in defect size was observed between the tracers in patients with myocardial infarction studied at rest.
Conclusions:
- MIBI and TI-201 SPECT imaging are highly reproducible methods for assessing myocardial defect size.
- MIBI may underestimate defect size compared to TI-201 in patients with coronary artery disease under stress conditions.
- The findings suggest that MIBI can be a reliable alternative to TI-201, with careful consideration of potential differences in defect quantification.
Abstract:
Defect size on myocardial tomograms was measured in 30 patients who underwent 2 separate studies, 1 with thallium-201 (TI-201), the other with technetium-99m-methoxyisobutyl isonitrile (MIBI). A group of 15 patients with myocardial infarction was studied at rest and received both tracers on the same day. The other 15 patients had documented coronary artery disease. They were were given injections of TI-201 at peak exercise and underwent imaging immediately after exercise and again 4 hours later. They then received a dose of MIBI for imaging at rest. A week later they underwent a second exercise test with the same work load and received a second dose of MIBI. Defect size on single-photon emission computed tomographic images was measured and repeated twice. Results were expressed in percentage of the volume of the whole myocardium. Reproducibility of the defect size measurement was high for TI-201 (r = 0.978; SEE = 1.59) as well as for MIBI (r = 0.981; SEE = 0.80). In patients with coronary artery disease the mean size of the defects was significantly larger with TI-201 than with MIBI at exercise (6.7 +/- 5.2 vs 4.6 +/- 5.2%, respectively, p less than 0.05) and at redistribution (5.1 +/- 4.4 vs 2.8 +/- 3.2%, respectively, p less than 0.05), where no difference was seen in patients with myocardial infarction studied only at rest (11.2 +/- 10.4 vs 12.0 +/- 11.5%, respectively, p = not significant). Smaller MIBI defect sizes, when compared with TI-201, in the exercise and redistribution studies were not due to technical artefacts since there was no difference when they were compared at rest.