MDCT Coronary Angiography: Does the Benefit Justify Radiation Burden?
MDCT Coronary Angiography: Does the Benefit Justify Radiation Burden?
Recent technical developments in multi-detector computed tomography (MDCT), and particularly the introduction of 64-slice MDCT, have made the non-invasive imaging of coronary arteries a clinical reality. Beta blockers are used to decrease the heart rate to 65 bpm, sublingual glyceryl trinitrate (GTN) can be used to dilate the coronary arteries, and the patient is only required to breath-hold for a few seconds. Fast or irregular heart rates, extensive calcium blooming artefacts and patients with high body mass index (BMI) are the only limiting factors. The temporal resolution is faster with dual-source MDCT, reducing the need for beta blockers, and the 320-slice MDCT can image the heart in one heart beat.
MDCT coronary angiography (CTCA) has been shown to be highly accurate at detecting coronary artery disease (CAD) with more than 30 studies and several meta-analyses confirming excellent sensitivity and negative predictive value (NPV), when compared with invasive X-ray coronary angiography. This was confirmed in three multi-centre trials: Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography (ACCURACY) (n=230), Coronary Artery Evaluation Using 64-Row Multi-detector Computed Tomography Angiography (CORE-64) (n=291), and Meijboom et al. (n=360) (table 1). The positive predictive values (PPV) have generally been less impressive as the degree of coronary stenosis can appear more severe on MDCT than on invasive coronary angiography. This is the result of the calcium blooming artefacts and the fact that the extent of the positive remodelling of atherosclerosis in the vessel wall is not seen on invasive coronary angiography.
(Enlarge Image)
The excellent NPV has led MDCT to become the optimal test to rule out CAD in patients with low-to-moderate likelihood of disease. CTCA is also increasingly used as a second-line test to verify the findings of equivocal functional tests. There are prognostic data identifying increased risk of mortality in symptomatic patients with 50% left main stem or 70% proximal left anterior descending artery stenoses and confirming extremely low risk for patients with normal CTCA. MDCT is the method of choice for imaging anomalous coronary arteries and is also used to evaluate coronary artery bypass grafts, adult congenital heart disease, cardiac tumours and the pericardium.
Abstract and Introduction
Introduction
Recent technical developments in multi-detector computed tomography (MDCT), and particularly the introduction of 64-slice MDCT, have made the non-invasive imaging of coronary arteries a clinical reality. Beta blockers are used to decrease the heart rate to 65 bpm, sublingual glyceryl trinitrate (GTN) can be used to dilate the coronary arteries, and the patient is only required to breath-hold for a few seconds. Fast or irregular heart rates, extensive calcium blooming artefacts and patients with high body mass index (BMI) are the only limiting factors. The temporal resolution is faster with dual-source MDCT, reducing the need for beta blockers, and the 320-slice MDCT can image the heart in one heart beat.
MDCT coronary angiography (CTCA) has been shown to be highly accurate at detecting coronary artery disease (CAD) with more than 30 studies and several meta-analyses confirming excellent sensitivity and negative predictive value (NPV), when compared with invasive X-ray coronary angiography. This was confirmed in three multi-centre trials: Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography (ACCURACY) (n=230), Coronary Artery Evaluation Using 64-Row Multi-detector Computed Tomography Angiography (CORE-64) (n=291), and Meijboom et al. (n=360) (table 1). The positive predictive values (PPV) have generally been less impressive as the degree of coronary stenosis can appear more severe on MDCT than on invasive coronary angiography. This is the result of the calcium blooming artefacts and the fact that the extent of the positive remodelling of atherosclerosis in the vessel wall is not seen on invasive coronary angiography.
(Enlarge Image)
The excellent NPV has led MDCT to become the optimal test to rule out CAD in patients with low-to-moderate likelihood of disease. CTCA is also increasingly used as a second-line test to verify the findings of equivocal functional tests. There are prognostic data identifying increased risk of mortality in symptomatic patients with 50% left main stem or 70% proximal left anterior descending artery stenoses and confirming extremely low risk for patients with normal CTCA. MDCT is the method of choice for imaging anomalous coronary arteries and is also used to evaluate coronary artery bypass grafts, adult congenital heart disease, cardiac tumours and the pericardium.
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