RSNA: CTA20 years old, but not quite grown up

Coronary CT angiography study rules out coronary artery disease in a 58-year-old asymptomatic man with multiple cardiovascular risk factors. Source: U. Joseph Schoepf, Medical University of South Carolina, Charleston

CHICAGO—A few days shy of the 20th anniversary of performing his first CT angiogram (CTA) on Dec. 10, 1991, Geoffrey D. Rubin, MD, chair of radiology at Duke University in Durham, N.C., pondered the question: Has CT grown up? His answer is no, and he outlined three areas where CT will demonstrate further applicability in disease management, during the opening session panel of the 97th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA).

Before previewing the third decade of CTA, Rubin noted the tremendous advances enabled by CTA over the last two decades. These include replacing multiple invasive diagnostic techniques and improving surgical planning. “Today,” he said, “every arterial and venous bed can be evaluated by CTA.”

Yet, CTA will continue to demonstrate and expand its utility in multiple applications going forward, according to Rubin. These are:

• Endovascular device selection and characterization. Conventional angiograms are hampered by challenges in assessment of the aorta. CTA can provide relevant information, said Rubin, and is becoming the preferred modality for assessment of transcatheter aortic valve implantation (TAVI). TAVI assessment represents a new opportunity for radiologists, said Rubin.
• Computing dynamics from the tree. The FAME trial has demonstrated the role of fractional flow reserve for guiding percutaneous coronary interventions and opened a new possibility for CTA. By applying computational fluid dynamics to the coronary artery tree, radiologists may model fractional flow reserve to provide a characterization of coronary tree not possible with imaging alone. The increased specificity of the technique holds great promise for reducing the false positives with CTA, said Rubin.
• Arterial lesions and organ perfusion. Currently, it is not always clear whether lesions are significant or not. Advances in CTA could further clarify these questions, said Rubin.

Rubin also highlighted multiple other advances in CTA development and said each can be seen at RSNA 2011 in McCormick Place. These include iterative reconstruction, low kVP scanning and wide detector arrays. These and other developments have the potential to reduce radiation exposure by the magnitude of two in the next few years, ushering in the era of sub-millisievert CTA, said Rubin.