Comparison of thallium redistribution with rest "reinjection" imaging for the detection of viable myocardium
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T P Rocco1, V Dilsizian, K A McKusick
1Department of Radiology, Massachusetts General Hospital, Boston 02114.
Insights
Rest reinjection imaging can reveal viable heart muscle in areas with persistent defects on delayed thallium scans. This method improves detection of myocardial ischemia, offering crucial insights for patient diagnosis.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Persistent perfusion defects on delayed thallium images may not always indicate non-viable myocardium.
- Assessing myocardial viability is crucial for guiding treatment decisions in patients with coronary artery disease.
Purpose of the Study:
- To evaluate the incidence of incomplete redistribution on conventional delayed thallium-201 myocardial perfusion imaging.
- To determine the utility of rest reinjection imaging in identifying viable myocardium in segments with fixed defects.
Main Methods:
- 41 patients with persistent perfusion defects on 3-4 hour delayed thallium images underwent rest reinjection with thallium-201.
- Myocardial images were analyzed qualitatively by experienced observers for redistribution.
- Coronary angiography was performed to correlate imaging findings with anatomical perfusion.
Main Results:
- A significant proportion (31%) of segments with persistent defects showed redistribution after rest reinjection.
- Rest reinjection imaging provided the sole evidence of ischemia in 9 patients.
- Redistribution after reinjection correlated with intact perfusion on coronary angiography in most cases.
Conclusions:
- Rest reinjection thallium imaging is valuable for detecting viable myocardium in segments with apparent fixed defects on delayed images.
- This technique enhances the diagnostic accuracy of myocardial perfusion imaging for identifying ischemia.
- Rest reinjection imaging can refine the assessment of myocardial viability and potentially alter patient management.
Abstract:
To determine the incidence of incomplete redistribution on conventional delayed thallium images, 41 patients with persistent perfusion defects on myocardial images recorded 3 to 4 hours after thallium injection during exercise were studied. At the conclusion of their delayed images the patients were reinjected at rest with approximately 1 mCi of thallium-201 and a third set of images was recorded. The images were presented at random in pairs (initial:delayed, initial:reinjection) to 2 experienced observers for qualitative scoring of 9 segments/patient. Of the 360 segments analyzed, concordance between the delayed and reinjected images occurred in 307 (85%). Of 141 segments that demonstrated a persistent perfusion abnormality on 3- to 4-hour delayed images, 44 (31%) were reassigned to a redistribution score after reinjection. In 9 patients, reinjection images provided the only evidence of ischemia from the scintigraphic data. In 13 of 14 vascular territories that demonstrated redistribution after reinjection, intact perfusion (either anterograde or via collaterals) was detected at coronary angiography. These data suggest that rest reinjection imaging may provide a means of detecting viable myocardium in segments that demonstrate a fixed perfusion abnormality on conventional 3- to 4-hour delayed thallium images.