Ten emerging uses for cardiac CT from SCCT 2013

Dr Matthew Budoff (Los Angeles Biomedical Research Institute, CA), a longtime researcher in the use of cardiac CT, described what he believes to be the most important uses for CT today [1].

First, CT angiography is emerging as “a single tool that gives us [information about] function and anatomy,” he told the audience.

Second, it is now known that patients are more likely to have a cardiovascular event if they have low-attenuation plaque (soft plaque), positive remodeling, and spotty calcification, he explained. If a clinician were limited to looking only at plaque or stenosis, he would advise him or her to “just read the CTA for plaque and plaque characteristics and [don’t] read it for stenosis severity, and you’ll probably serve your patients better in predicting risk” of a cardiovascular event. “I think in future we’re going to be using plaque characterization in every case,” he added. “I certainly don’t advocate stenting these patients [who have vulnerable plaque] yet, but . . . I do treat these patients more aggressively.”

Third, coronary CT angiography is a noninvasive way to identify complex aortic-valve geometry and guide TAVR.

“With perfusion imaging, TAVR, and plaque assessment leading the way, the increased utilization of CTA is certain,” Budoff concluded. “However, more validation work is needed to ensure that industry and payers accept these applications.”

Speaking to heartwire, Budoff singled out TAVR as “an easy launching point for doctors to get familiar with” CT angiography. He also believes that using CT for “heart-failure assessment or even plaque assessment . . . will really add value to their practice.” CT also allows clinicians to “start getting a handle on what’s causing stenosis [in a patient], what it looks like, and . . . how severe the stenosis is.”

In a separate presentation [2], Dr James K Min (Cedars-Sinai, Los Angeles, CA) identified the same three clinical applications as Budoff in his “top 10 things to watch” in coronary CT in the coming year. He identified his “up-and-coming areas to watch” in the following order:

Dual-energy CT scanners. This hardware, when combined with new software, is producing enhanced image quality that allows, for example, a “plaque biopsy,” which provides detailed information about plaque characteristics.

Myocardial CT perfusion. “We’ve looked at this for seven years, and I think it’s starting to become ready for prime time,” said Min. In the next year, he expects investigators to figure out exactly how to use CT to look at coronary flow reserve.

Computational fluid dynamics. Exciting work is being done, for example, using a virtual stent to see how a real stent would potentially resolve a patient’s ischemia.

Plaque. Coronary CT can do more than identify how many vessels are blocked, he said, echoing Budoff’s words. It is enabling investigators to study the pathogenesis of atherosclerosis. “We’re going to be able to identify plaque characteristics beyond stenosis for the prediction of acute MI,” Min said.

Structural heart disease. CT is already being used to help guide TAVR to reduce postsurgery complications.

Radiation-dose reduction. Min weighed in and said, “I think it’s becoming a nonissue.” He noted that during the past year, investigators reported how coronary CT angiography can be used with radiation doses as low as 0.01 mSv, whereas a screening mammogram exposes a woman to 0.05 mSv of radiation.

Contrast-agent reduction.”I think we will see improvements—we will get to the 10-cc scan,” Min predicted.

Appropriate-use criteria. Physicians are continuing to identify which patients benefit from cardiac CT, as the technology is advancing.

Two trials. Among the many ongoing trials in the field, Min identified two to watch. The PROMISE study is comparing functional vs anatomic testing to identify heart disease. The Coronary Computed Tomographic Angiography for Selective Cardiac Catheterization (CONSERVE) trial is looking at using CT as a “gatekeeper” to the cath lab, to identify which patients should be sent for invasive coronary angiography and which ones have only have mild stenosis and could be sent home and treated with medical therapy .

Worldwide growth in CT. Collaboration with investigators around the world is growing, and the SCCT meetings next year in Hawaii and China will offer more opportunities for this.