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Magnetic resonance angiography of the aortic arch
J P Carpenter1, G A Holland, M A Golden
1Department of Surgery, University of Pennsylvania School of Medicine, USA.
Abstract:
Duplex ultrasound and magnetic resonance angiographic (MRA) studies are the principal noninvasive methods for evaluation of extracranial occlusive disease in patients at risk for stroke, but each has limited ability to diagnose aortic arch and arch vessel disease. Recent favorable reports of the nonnephrotoxic contrast agent Gadolinium (Gd) being used to enhance MRA images of the abdominal aorta prompted us to examine its utility for the aortic arch vessels. Prospectively, 28 patients with suspected carotid or arch vessel disease were imaged by contrast arteriographic examination and MRA + Gd of the aortic arch within 30 days of each other. One (for contrast arteriograms) or two (for MRA) blinded readers measured stenoses with the contrast arteriograms as the standard. A total of 196 arch vessels containing 58 stenoses and four occlusions (by arteriogram) were examined with each method. Interobserver agreement for interpretation of MRA studies was substantial (kappa = 0.68). MRA detected all anatomic anomalies (e.g., bovine arch). The correlation of MRA with arteriographic scans for arch vessel stenoses > 50% was sensitivity, 73% (readers 1 and 2); specificity, 98% (reader 1), 89% (reader 2); positive predictive value, 73% (reader 1), 89% (reader 2); negative predictive value, 98% (readers 1 and 2); accuracy, 97% (reader 1), 98% (reader 2). MRA + Gd is an accurate new noninvasive imaging method for detection of significant aortic arch disease. In its current state of development, however, it cannot obviate the need for contrast arteriographic examination.
Insights
Gadolinium-enhanced magnetic resonance angiography (MRA) is an accurate noninvasive tool for detecting significant aortic arch disease, showing high accuracy in identifying stenoses and anomalies. However, it does not yet replace traditional contrast arteriography.
Area of Science:
- Vascular Imaging
- Radiology
- Cardiovascular Disease
Background:
- Duplex ultrasound and MRA are primary noninvasive methods for extracranial occlusive disease.
- These methods have limitations in diagnosing aortic arch and arch vessel disease.
- Gadolinium (Gd) enhancement shows promise for MRA of the abdominal aorta.
Purpose of the Study:
- To evaluate the utility of Gadolinium-enhanced MRA (MRA + Gd) for imaging aortic arch vessels.
- To assess the accuracy of MRA + Gd in detecting significant aortic arch disease compared to contrast arteriography.
Main Methods:
- Prospective study of 28 patients with suspected carotid or arch vessel disease.
- Patients underwent contrast arteriography and MRA + Gd of the aortic arch within 30 days.
- Two blinded readers evaluated MRA studies, with contrast arteriograms serving as the standard.
Main Results:
- MRA + Gd detected all anatomic anomalies, including bovine arch.
- For stenoses > 50%, MRA + Gd demonstrated high accuracy (97-98%) and specificity (89-98%).
- Sensitivity was 73%, and positive predictive value was 73-89% for detecting stenoses.
Conclusions:
- MRA + Gd is an accurate noninvasive imaging method for significant aortic arch disease.
- The technique shows substantial interobserver agreement for interpretation.
- Currently, MRA + Gd cannot fully replace contrast arteriographic examination.