During the 2005 RSNA meeting there were, as usual, a number of topics that seemed to catch the attention of the crowd. The most popular topics are usually obvious, since there is standing room only at these presentations. This year, the topic of coronary artery CT angiography (CA-CTA) was clearly one of the dominant themes of the meeting. Since our department is now providing the “triple rule-out” study (that, for the non–emergency-oriented among us, is myocardial ischemia, pulmonary embolism, and acute aortic syndrome), I thought that it might be wise to spend some time brushing up on technical aspects and details of interpretation.
Dr. Mirvis
is the Editor-in-Chief of this journal and a Professor of
Radiology, Diagnostic Imaging Department, University of Maryland
Medical Center, Baltimore, MD.
During the 2005 RSNA meeting there were, as usual, a number of
topics that seemed to catch the attention of the crowd. The most
popular topics are usually obvious, since there is standing room
only at these presentations. This year, the topic of coronary
artery CT angiography (CA-CTA) was clearly one of the dominant
themes of the meeting. Since our department is now providing the
"triple rule-out" study (that, for the non-emergency-oriented among
us, is myocardial ischemia, pulmonary embolism, and acute aortic
syndrome), I thought that it might be wise to spend some time
brushing up on technical aspects and details of interpretation. The
interest level was exceptional, and I have never noticed so many
people-including myself-taking notes at the lectures on this
subject.
The availability of multidetector CT-especially the newest 40-
and 64-slice scanners-made the performance of CA-CTA practical,
very rapid, noninvasive, and highly accurate. The ability to
identify areas of critical vascular narrowing as well as to
characterize the physical nature of plaques in terms of
constituents (ie, lipid, fibrous, calcified) is a significant value
that this technique adds. The identification of "vulnerable" plaque
or ruptured plaque provides a new frontier in coronary artery
imaging. The presentation of patients with acute chest pain
accounts for 5 million emergency room visits annually in the United
States, but acute myocardial infarction is responsible for this
symptom in only 10% of these patients.
1
While medical history and physical examination remain critical, and
analysis of cardiac enzymes is often very helpful in determining
which patient has pain of cardiac origin, the question often
remains unresolved, typically requiring costly admission and
observation. In some cases, only invasive and expensive coronary
angiography can resolve the diagnostic dilemma.
With CA-CTA, we can reliably evaluate the results of
interventions in the coronary vasculature, including bypass grafts,
dilatations, and stenting.
2
The potential to noninvasively follow the regression of coronary
artery plaques in patients undergoing "statin" therapy struck me as
another great potential value of CA-CTA.
3
While there is appropriate concern about the radiation exposure
required to achieve high image quality for this procedure, the use
of dose-adjustment during the cardiac cycle (electrocardiographic
modulation) should permit a routine decrease of 30% to 50% from
current levels.
4
Radiology, as a specialty, must promote and continue to perfect
this technique and unequivocally establish its role in assessing
coronary artery pathology and its treatment. Radiologists should
continue to evaluate the impact that this technique can have in
accurately verifying the presence of cardiac ischemia (both acute
and chronic), in lowering the cost of the diagnosis of coronary
artery disease, and in favorably impacting short- and long-term
patient outcome. At the same time, we must reinvigorate our
understanding of cardiac physiology and pathology in order to
contribute as much as possible to optimizing clinical decision
making in treating this all too common disease.