Radiology: New CT combo technique improves detection of CAD
A technique involving the combination of adenosine perfusion CT imaging and cardiac CT angiography adds incremental value in the detection of obstructive coronary artery disease (CAD) for high-risk individuals, according to the results of a study published in the February issue of Radiology.

Jose Rocha-Filho, MD, of the department of radiology at Massachusetts General Hospital in Boston, and colleagues separated their study into two parts. The first portion sought to determine if a dual-source protocol involving CT evaluated stress-induced perfusion and cardiac CT angiography--together in one exam--was a feasible option, while the second segment assessed the incremental value of perfusion imaging over cardiac CT angiography in the detection of CAD.

The HIPAA-compliant study recruited 35 patients, all of whom were considered to be high risk for CAD. All patients enrolled in the study first underwent a retrospective electrocardiographically gated (helical) adenosine stress CT perfusion imaging, followed by prospectively electrocardiographically gated (axial) rest myocardial CT perfusion imaging.

The researchers analyzed the patients in three steps:
  • Coronary arterial stenoses were scored for severity and reader confidence by cardiac CT angiography;
  • Myocardial perfusion defects were also identified and scored for severity and reversibility by CT perfusion imaging; and
  • Coronary stenosis severity was reclassified according to perfusion findings from combined cardiac CT angiography and CT perfusion imaging.
In addition, Rocha-Filho and colleagues also calculated the sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) of cardiac CT angiography before and after CT perfusion analysis.

According to the authors, each parameter of diagnostic accuracy was increased after the addition of CT perfusion analysis, noting a sensitivity increase from 83 percent to 91 percent, as well as an increase in specificity from 71 percent to 91 percent.

Both PPV and NPV were also found to have increased following the addition of myocardial stress perfusion CT, from 66 percent to 86 percent for PPV and from 87 percent to 93 percent for NPV.

The authors wrote that they found the combination protocol to be feasible for the assessment of myocardial perfusion and coronary anatomy with acceptable contrast material and radiation doses and that the addition of myocardial stress perfusion CT improved diagnostic accuracy.

Specifically, the researchers concluded that the technique may be particularly useful in assessing the need for invasive angiography and revascularization.