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Magnetic resonance imaging during dobutamine stress in coronary artery disease
D J Pennell1, S R Underwood, C C Manzara
1Magnetic Resonance Unit, Royal Brompton National Heart and Lung Hospital, London, United Kingdom.
Insights
Dobutamine stress magnetic resonance imaging (MRI) effectively detects coronary artery disease (CAD) by inducing wall motion abnormalities. This method shows high agreement with thallium tomography for identifying myocardial ischemia in CAD patients.
Area of Science:
- Cardiovascular Imaging
- Diagnostic Cardiology
- Medical Imaging Techniques
Background:
- Cine magnetic resonance imaging (MRI) assesses regional ventricular function but is limited during dynamic exercise.
- Assessing ventricular function in patients with coronary artery disease (CAD) during stress is crucial.
- Previous limitations in dynamic exercise imaging necessitated alternative stress induction methods.
Purpose of the Study:
- To evaluate the efficacy of dobutamine stress MRI in detecting inducible wall motion abnormalities in patients with suspected CAD.
- To compare dobutamine MRI findings with dobutamine thallium emission tomography and coronary arteriography.
- To assess the safety and tolerability of dobutamine infusion for stress MRI.
Main Methods:
- Dobutamine infusion was administered to 25 patients presenting with exertional chest pain and abnormal exercise electrocardiograms.
- Regional ventricular function was assessed using cine MRI during dobutamine stress.
- Myocardial perfusion was evaluated using dobutamine thallium emission tomography, and coronary arteriography was performed for comparison.
Main Results:
- Dobutamine MRI identified reversible wall motion abnormalities in 91% of patients with significant CAD (20 out of 22).
- There was high agreement between dobutamine MRI and thallium tomography in identifying ischemic segments (90-96% agreement).
- Dobutamine infusion was generally well-tolerated, with mild side effects and no significant limitations to the procedure.
Conclusions:
- Dobutamine stress MRI is a valuable tool for assessing regional ventricular function and detecting myocardial ischemia in patients with CAD.
- The technique demonstrates high sensitivity and specificity, comparable to established methods like thallium tomography.
- Dobutamine's short half-life makes it suitable for stress imaging, potentially offering advantages over dipyridamole for provoking wall motion abnormalities in CAD.
Abstract:
Cine magnetic resonance imaging (MRI) provides a tomographic method of assessing regional ventricular function in any desired plane. It has not been possible to obtain adequate images during dynamic exercise, and this has limited its value in patients with coronary artery disease (CAD). Therefore, an infusion of dobutamine was used to study 25 patients with exertional chest pain and abnormal exercise electrocardiograms. Areas of abnormal wall motion were compared with areas of abnormal myocardial perfusion imaged by dobutamine thallium emission tomography and with coronary arteriography. Twenty-two patients had significant CAD. Twenty-one (96%) of these patients had reversible myocardial ischemia shown by dobutamine thallium tomography, and 20 (91%) had reversible wall motion abnormalities shown by dobutamine MRI. Comparison of abnormal segments of perfusion and wall motion showed 96% agreement at rest, 90% agreement during stress, and 91% agreement for the assessment of functional reversibility. The normalized magnetic resonance signal intensity of the ischemic segments showed a small but significant reduction when compared with that of normal segments (-67 units [9.2%]; p less than 0.05). Dobutamine infusion was well-tolerated, despite causing chest discomfort in 24 patients (96%). Nine patients (36%) developed a minor dysrhythmia that was usually ventricular premature complexes, but this did not limit infusion, and other side effects were mild. The short plasma half-life of dobutamine makes it ideal as a stress agent for imaging techniques (such as MRI), and these results suggest that it is more effective in the provocation of wall motion abnormalities than is dipyridamole in patients with CAD.