CORRESPONDENCE: LETTER TO THE EDITOR
Comparing Radiation Doses From 2 Diagnostic Tests
C. Richard Conti, MD, MACC*
* University of Florida, Health Science Center, Room M-438, 1600 SW Archer Road, P.O. Box 100277, Gainesville, Florida 32610-0277 (Email: BEAUCTG{at}medicine.ufl.edu).
This letter is a comment on the recent study in JACC by Coles et al. (1) on the "Comparison of Radiation Doses From Multislice Computed Tomography Coronary Angiography and Conventional Diagnostic Angiography."
I would like to congratulate the investigators for pointing out the radiation doses of both of these diagnostic tests. Most cardiologists have no idea of the radiation dose with either technique. In fact, I suspect if polled, most cardiologists would think that coronary angiography delivers more of a radiation dose to the patient than multislice computed tomography (CT).
The administration of contrast agents also puts the patient at risk for kidney damage and allergic reactions, and oftentimes beta-blockers have to be used for rate control. Despite these limitations, I expect that multislice CT is here to stay and will obviously get better as techniques improve and radiation doses decrease. However, it is not clear what the radiation dose will be with 64-slice and beyond.
One of my major concerns is the abuse of multislice CT. Because most nonradiologist physicians do not understand the radiation dose delivered to the patient with this technique, the technique is commonly used in the emergency department when a simple chest X-ray would be adequate. In addition, if patients are admitted to hospital, it is not uncommon for several multislice CT examinations to be done in the same patient.
The excellent accompanying editorial to this piece by Zanzonico et al. (2) argues that multislice CT is "safer" than cine cardiac angiography (excluding contrast reactions). I am not completely willing to buy that position. Cardiac catheterization and angiography is the only method to measure intracardiac and vascular pressures accurately; it readily evaluates left ventricular function, myocardial perfusion, coronary artery pathology, myocardial viability, valve function, peripheral artery disease, and when ultrasound or ocular coherence tomography is used, the coronary arterial wall. Microcirculation can be assessed using coronary flow reserve, myocardial blush, and presence of collaterals (3).
In my opinion, cardiac catheterization and contrast cine angiography still remain the reference standard for everything else we do and is the best buy for the radiation dose delivered.
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References
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1. Coles DR, Smail MA, Negus IS, et al. Comparison of radiation doses from multislice computed tomography coronary angiography and conventional diagnostic angiography J Am Coll Cardiol 2006;47:1840-1845.[Abstract/Free Full Text]2. Zanzonico P, Rothenberg LN, Strauss HW. Radiation exposure of computed tomography and direct intracoronary angiography: risk has its reward J Am Coll Cardiol 2006;47:1846-1849.[Abstract/Free Full Text] 3. Conti CR. One-stop cardiovascular diagnostic imaging (and radiation dose) Clin Cardiol 2005;28:450-453.[Web of Science][Medline]
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