Definition of EBCT (electron beam computerized tomography)
< b>EBCT (electron beam computerized tomography): A new (and controversial)
noninvasive test for the detection of coronary artery disease (CAD).
EBCT, or Ultrafast CT (as the technique will be termed here) is designed to measure
calcium deposits in the coronary arteries.
In patients with CAD, the plaques which make up the blockages contain significant
amounts of calcium, which can be detected with Ultrafast CT. This test will identify
calcium in blockages as mild as 10-20%, which would not be detected by standard
physiologic stress testing.
The importance of detecting such mild blockages is controversial, however, because
the only "treatment" that is used for such blockages typically involves risk factor
modification (especially cholesterol reduction and smoking cessation as well as
aspirin and certain vitamins).
A potential limitation of Ultrafast CT is that only a total calcium score
is reported. This means that two or three separate blockages of about 30% each will
result in the same score as a single 70-80% blockage. The Ultrafast CT does not
give an image of specific separate areas of calcification.
The major value of Ultrafast CT appears to be in screening young patients with
one or more risk factors for the development of CAD. Ultrafast CT scanning is of
limited value for older patients in whom some degree of calcification is commonly
found. Additionally, for the reasons described above, the detection of some calcification
may not be reflective of significant CAD.
Ultrafast CT was reported to be a better test than treadmill-ECG or technetium-stress
test for detecting CAD (J Am Coll Cardiol 2000;36:32-38,326-340). The authors favored
it as "a reasonable alternative to traditional stress testing" (pointing also to
its cost, brief test time and the fact that a physician does not usually need to
be present during the scan). In the same journal, the American College of Cardiology
and the American Heart Association issued a consensus statement opposing the widespread
use of Ultrafast CT. The controversy continues.
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