Cardiac Imaging - Technical Advances in MDCT Compared with Conventional X-ray Angiography

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Abstract

Coronary artery disease (CAD) represents the major cause of morbidity and mortality in Western populations. The prime diagnostic tool that allowed the development of rational treatment techniques for this disease is invasive coronary angiography ((CA) an X-ray fluoroscopy guided procedure), which is associated with a low rate of life-threatening complications. More than 40% of the invasive CA studies are also carried out for the purpose of ruling out CAD. Non-invasive cardiac assessment has therefore been a goal of investigators for decades; echocardiography (ECG), nuclear medicine techniques, and MRI have been used non-invasively for a variety of cardiac indications, although no single technique provides a comprehensive assessment.
 

Citation
US Cardiology 2006;2005:2(1):115-118

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Coronary artery disease (CAD) represents the major cause of morbidity and mortality in Western populations. The prime diagnostic tool that allowed the development of rational treatment techniques for this disease is invasive coronary angiography ((CA) an X-ray fluoroscopy guided procedure), which is associated with a low rate of life-threatening complications. More than 40% of the invasive CA studies are also carried out for the purpose of ruling out CAD. Non-invasive cardiac assessment has therefore been a goal of investigators for decades; echocardiography (ECG), nuclear medicine techniques, and MRI have been used non-invasively for a variety of cardiac indications, although no single technique provides a comprehensive assessment.

The prospect of imaging the heart and coronary arteries using computed tomography (CT) has been anticipated since the development of CT more than three decades ago. The lack of speed and poor temporal resolution of previous generations of CT scanners prevented meaningful evaluation of the coronary arteries and cardiac function. Most early assessments of the coronary arteries with CT were performed with electron beam computed tomography (EBCT), developed in the early 1980s. EBCT has been mostly used for the non-invasive evaluation of coronary artery calcium (CAC), but other applications, including assessment of coronary artery stenosis (CAS), have been reported in limited cases; however, EBCT is expensive and is not widely available.

Recent advances in CT technologies, especially multiple-row detector computed tomography (MDCT), have dramatically changed the approach to the non-invasive imaging of cardiac disease. With sub-millimeter spatial resolution (less than 0.75mm), improved temporal resolution (50-200ms), and ECG gating, the current generation of CT scanners (16-64-row detectors) makes imaging possible, and has the potential to accurately characterize the coronary tree.

Technical Differences Between CA Performed Under X-ray Fluoroscopy and MDCT

Even though both techniques utilize X-ray radiation, there are potential risk differences (stochastic and non-stochastic risks) due to the nature of exposure. There are also fundamental technical differences between CA performed invasively with X-ray fluoroscopy (conventional method) and non-invasively with MDCT.

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