With the advent of multislice computed tomography (MSCT), noninvasive coronary
angiography by using CT has become practical for clinical purposes. The
accuracy of MSCT in evaluation of coronary artery stenosis challenges that of conventional
X－ray coronary arteriography. The essential component of the CT technique
in evaluation of coronary arteries on a beating heart consists of a multidetector
row system, which enables thin－sliced volume scan during one breath－hold, and
the fast rotation speed of gantry, which is most important to increase the time resolution.
However, the technical development so far achieved just allows CT to acquire
diagnostic－quality images only with lowering the heart rate less than 65 beats per
minute using a β－blocker. Motion artifacts caused by physiologic or diseased complex
movement of the heart and blooming artifacts from dense calcification are the
major limitations compromising accurate interpretation of coronary CT angiograms.
Although many problems related to coronary CT angiography has not been solved at
present, we should remember that the present CT technique is just at its infancy,
and CT has many benefits as a noninvasive diagnostic modality. In addition, measurement
of a cross－sectional area at stenosis of coronary artery will improve diagnostic
accuracy, which is also a major advantage over the projection image of X－ray
angiography. Characterization of a vulnerable plaque by density measurement of an
atherosclerotic plaque of the coronary vessel wall and evaluation of in－stent
restenosis should be other possibilities of CT.
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