Advances in Cardiac CT & MRI

 
 
 

Journal Editors Highlight Significant Progress in Cardiovascular Imaging

 
  (Left) Patrick M. Colletti, MD, assistant editor of the American Journal of Roentgenology and professor of radiology, medicine, biokinesiology, pharmacology and pharmaceutical sciences at the University of Southern California in Los Angeles. (Right) Uwe Joseph Schoepf, MD, associate editor of Radiology and professor of radiology and cardiology at the Medical University of South Carolina in Charleston

Heart disease has been the leading cause of death in the United States for the past 80 years and is a major cause of disability, according to the Centers for Disease Control and Prevention. An estimated 61 million Americans have coronary artery disease; therefore, accurate cardiovascular imaging is a critical component for diagnosis and treatment. Two of diagnostic imaging’s most powerful modalities—CT and MR—have seen rapid growth in utilization for cardiovascular indications.

The past year has seen great strides in cardiac CT and MR technology available for cardiovascular clinicians to assist their efforts in diagnosing heart disease. A pair of imaging’s most widely read clinical journals, Radiology and the American Journal of Roentgenology (AJR), have published a number of compelling scientific studies this year exploring the cardiac capabilities of these modalities.

“Significant events have happened over the past year on a variety of different levels,” notes Uwe Joseph Schoepf, MD, associate editor of Radiology and professor of radiology and cardiology at the Medical University of South Carolina in Charleston.

Technology advances, particularly in cardiac CT, have led the way as detectors have grown from 64-slice to 128-slice to 256- and 320-slice deployments, Schoepf says; in addition, the clinical introduction of dual-source capabilities has expanded the scientific possibilities for cardiovascular CT.

“On the near horizon for cardiac CT is volume imaging with multiple arrays of detectors; that’s coming and that’s coming fast,” says Patrick M. Colletti, MD, assistant editor of AJR as well as professor of radiology, medicine, biokinesiology, pharmacology and pharmaceutical sciences at the University of Southern California in Los Angeles.

“Dual-energy CT will help us do tissue characterization for myocardium, particularly for plaque,” Colletti says. “It may be able to help us eliminate some of the artifact from calcified plaque to help us evaluate the non-calcified plaque adjacent to calcified plaque.”

Advances in cardiac MR imaging this year have been devoted to further refinement and focus of the modality in areas in which it has demonstrated strong clinical capabilities; namely, imaging of the myocardium, Schoepf says.

 “We’re seeing a further refinement of the dividing line between cardiac CT and cardiac MRI,” he notes. “These have been two very different and very complementary modalities; CT has been used predominantly for looking at the coronary arteries and cardiac MRI has been used predominantly for looking at the myocardium.”

A study from Radiology (April 2008) demonstrates that usage of the modalities can successfully overlap for some cardiac indications; particularly for patients who present with contraindications for CT or MR imaging.

A team of researchers from Massachusetts General Hospital in Boston prospectively compared the use of 64-slice CT and cardiac MRI for the early assessment of myocardial enhancement and infarct size after acute reperfused myocardial infarction.

They found that early hypoenhancement was recognized on all CT and MR images; however, delayed hyperenhancement was better observed with cardiac MR than with cardiac CT.

“Our results show delayed-enhancement imaging of myocardial CT is possible and can be considered for imaging of infarct size in patient with contraindications to MR imaging,” the authors wrote.

A pair of articles in AJR (December 2007) explored the targeted use of MR angiography (MRA) after 64-slice CT angiography (CTA) in assessing the severity of focal calcific coronary lesions.

An international team from the United States and China found that coronary MRA has higher image quality for coronary segments with nodal calcification than for coronary segments with diffuse calcification. In addition, their results showed that coronary MRA has better diagnostic performance than coronary CTA for the detection of significant stenosis in patients with high calcium scores.

“The results open the door