To the ever-growing number of radiologists performing multidetector CT (MDCT) coronary CT angiography (CCTA), it is readily apparent that CCTA is diagnostically superior to SPECT stress tests. Although plagued by small patient numbers, several studies consistently reveal that when comparing CCTA to coronary artery catheterization in its ability to detect a 50% stenosis, CCTA has sensitivity, specificity, and positive and negative predictive values in the range of 99%, 90%, 85%, and 100%. This far exceeds the performance of stress tests, which have a threshold of 70% stenosis needed to test positive. Also, CCTA is revealing a new diagnostic category of patients, who are stress-test negative but CCTA positive for nonstenotic plaque and may benefit from early medical management of their coronary artery disease (CAD).

Though physician acceptance of CCTA is almost universal from a diagnostic imaging standpoint, criticism has been levied, and appropriately so, that the acceptance and proliferation of CCTA have outpaced the scientific evidence supporting it. This is the price of living in the age of great technological advancement. A comparison with what happened with the workup of pulmonary embolism (PE) is fruitful in evaluating the current path of CCTA.

  1. There was no outcry when ventilation/perfusion lung scans for PE were replaced with CTA of the chest. The improvements and benefits were obvious. CTA, compared with V/Q scans, gave us images with better spatial resolution of not only the pulmonary arteries but also of the pulmonary parenchyma, pleural space, and the mediastinum. Not only could we diagnose PE with previously unforeseen speed, but we also could diagnose non-PE causes of the patient’s symptoms.
  2. Concerns were not raised over unnecessary radiation exposure from “PE studies” demanded by emergency departments across the country. For CCTA, this has been a significant bone of contention. Most people are shocked to learn that the dose of retrospectively gated CCTA using ECG dose modulation is in the same range of a SPECT sestamibi stress test and is far less than a SPECT thallium stress test. Prospectively gated CCTA reduces the radiation exposure by 50% to 70% when compared to retrospectively gated CCTA. This does not even take into account how many elective, negative diagnostic coronary catheterizations could be prevented by CCTA with its 100% negative predictive value. CCTA offers a net loss in radiation exposure if its utilization is confined to patients considered to be candidates for a SPECT stress test, providing it is used as a replacement for the same stress test.
  3. The insurance companies didn’t balk at reimbursing CTA for PE. The reason is numbers. The potential volume of CCTA represents a tidal wave of imaging in an already financially distressed health care insurance environment. For CCTA to be pivotal in patient care without breaking the bank, it must replace stress tests as the primary test performed in patients who may have CAD. Currently, it is reimbursed at a level less than SPECT stress studies, which, when considering the cost of 64-slice MDCT scanners, is far below market value. Cole et al show that when using CCTA only in patients with an equivocal stress test and before diagnostic catheterization, the cost savings per patient was $1,454.1 The negative predictive value of CCTA promises to squeeze money out of the workup of CAD. Insurance companies no longer believe in replacement technology, and until the CCTA community demonstrates in good faith that CCTA can decrease health care costs, obtaining appropriate reimbursement will be an uphill battle.
  4. Pulmonologists did not wage a turf war over CTA for PE because there was no income at stake. It is becoming clear that CCTA will replace many stress tests as well as many elective, diagnostic catheterizations. Combine this with radiologists moving in on cardiac imaging, and you have the makings of the mother of all turf battles. As a radiologist, I think CCTA clearly and best belongs in the hands of radiologists, who have had years of training in CT, understand the physics of CT, have been trained in radiation safety, can evaluate the entire study, and are used to examine CT images. With this responsibility comes the obligation of radiologists to become educated in cardiac pathophysiology, and, in some instances, refresh their knowledge of coronary artery anatomy.

CCTA is the best example of replacement technology in medical imaging since MRI. If it is used to streamline the workup of CAD, patients should get better and quicker care, and less-invasive testing at a reasonable price. So, why shouldn’t CCTA be as quickly accepted as CTA was for PE?

David A. Dowe, MD, is the CEO and COO of Atlantic Medical Imaging, Galloway, NJ.


  1. Cole JH, Chunn V, Phillips GM, et al. 64-slice CT angiography is a cost-saving strategy for patients with mildly abnormal nuclear stress tests. J Amer Coll Card. 2006;47(suppl 1):113a.