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The imaging of myocardial perfusion with 81mKr during coronary arteriography
Insights
This study explored using Krypton-81m (81mKr) for myocardial perfusion imaging during coronary arteriography. 81mKr effectively visualizes blood flow, aiding in assessing coronary artery stenosis and collateral circulation with minimal radiation exposure.
Area of Science:
- Cardiovascular Imaging
- Nuclear Cardiology
- Radiopharmacology
Background:
- Coronary arteriography can be ambiguous in assessing stenosis significance.
- Evaluating tissue perfusion and collateral flow is crucial for understanding coronary artery disease.
- Previous methods lacked real-time perfusion assessment during interventions.
Purpose of the Study:
- To investigate the utility of Krypton-81m (81mKr) for myocardial perfusion imaging during coronary arteriography.
- To assess the impact of coronary artery stenosis on regional blood flow and collateral circulation.
- To evaluate the feasibility of repeated imaging with low radiation risk for intervention assessment.
Main Methods:
- Development of a sterile Rubidium-81-Krypton-81m (81Rb-81mKr) generator.
- Utilized fast, intermittent 3-ml 81mKr-dextrose bolus injections to mitigate streaming artifacts.
- Performed imaging in 13 patients using a mobile scintillation camera and digital imaging system.
- Calculated coronary blood flow using the inert gas washout technique.
Main Results:
- Demonstrated good correlation (r = 0.91) between 81mKr and 133Xe for coronary blood flow determination.
- Perfusion images obtained with 81mKr correlated well with coronary angiograms.
- Identified total coronary occlusions as perfusion defects and showed a two-fold increase in myocardial flow in normal arteries during pacing.
Conclusions:
- 81mKr is a valuable tool for myocardial perfusion imaging during coronary arteriography, clarifying stenosis significance.
- The technique allows for separate evaluation of collateral flow contributions from individual coronary arteries.
- Low radiation risk enables repeated studies for intervention evaluation and dynamic assessment of myocardial blood flow changes.
Abstract:
The use of 81mKr was investigated for imaging myocardial perfusion during coronary arteriography using conventional catheters. When the significance of stenosis judged by arteriography is unclear, the effect on tissue perfusion can be established and the contribution to collateral flow by each artery separately evaluated. The distribution of 81mKr, due to its 13-s half-life, represents regional blood flow. In order to evaluate interventions, studies can be repeated at a low radiation risk to patients. A sterile pyrogen-free 81Rb-81Kr generator was developed. With slow infusion, inadequate mixing and streaming takes place due to laminar flow in coronary arteries. Fast intermittent 3-ml 81Kr-dextrose bolus injections convincingly eliminated streaming artefacts. Imaging was performed in 13 patients with a mobile scintillation camera and digital imaging system. Blood flow was calculated using the inert gas washout technique. There was good correlation (r = 0.91) between coronary blood flow determinations using 81mKr and 133Xe respectively. The perfusion images correlated well with the coronary angiograms. Total coronary arterial occlusions as demonstrated by arteriography were all shown as perfusion defects during rest. During atrial pacing myocardial flow was increased two-fold in normal coronary arteries and to a lesser extent in arteries with significant disease. The most critical lesion in a branch of a left coronary artery leads to a redistribution of perfusion during pacing.