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In an update of the original CAD-RADS™ consensus document on coronary artery disease (CAD) imaging and reporting published in 2016, expert panelists incorporated emerging evidence for CAD-RADS 2.0 to recommend new categorization for coronary plaque burden and suggested modifiers to reflect the level of ischemia and high-risk plaque in patients undergoing cardiac computed tomography.
In order to reflect the most recent research on the use of computed tomography (CT) in cardiovascular imaging, the Society of Cardiovascular Computed Tomography (SCCT), the American College of Radiology (ACR), the North America Society of Cardiovascular Imaging (NASCI) and the American College of Cardiology (ACC) have unveiled an updated Coronary Artery Disease Reporting and Data System (CAD-RADS), also referred to as CAD-RADS™ 2.0.
New additions for the updated expert consensus recommendations, recently published in Radiology: Cardiothoracic Imaging, include an emphasis on the reporting of coronary plaque burden and ischemia findings on coronary CT angiography (CCTA). Here are five takeaways from the consensus recommendations.
1. Acknowledging emerging techniques for assessing CCTA and physiologic aspects of decision making with respect to coronary revascularization, the consensus panel recommended an “I” modifier to indicate testing for ischemia via computed tomography fractional flow reserve (CT-FFR) or stress computed tomography perfusion (Stress-CTP).
2. The consensus panel noted multiple benefits of utilizing stress myocardial CTP. In addition to enabling radiologists to discern fixed perfusion effects due to prior myocardial infarction (MI), stress myocardial CTP can prevent downstream testing by allowing radiologists to potentially exclude myocardial ischemia in cases of moderate coronary stenosis or severe coronary stenosis in the presence of mixed or densely calcified plaque.
In regard to stress CTP interpretation, the consensus authors recommended an “I+” modifier to denote myocardial ischemia or peri-infarct ischemia. An “I-” modifier could be employed when there is no detected ischemia, a previously fixed myocardial infarct or an ischemic segment that does not have a concordant anatomic lesion, according to the consensus panel. When there are indeterminate or questionable findings, or a high likelihood of false-positive results with stress CTP, the consensus authors recommended a “I=/-” modifier.
3. Noting recent research that has suggested a link between characteristics of high-risk plaque (previously referred to as vulnerable plaque) viewed on CCTA and acute coronary syndrome (ACS), the consensus authors said there is a need for a “HRP” modifier to denote high-risk plaque.
If CCTA reveals two or more high-risk plaque features, ranging from low attenuation plaque (less than 30 Hounsfield units) and positive remodeling to the “napkin ring sign” and spotty calcifications, the consensus panel suggested using the “HRP” modifier in these cases.
4. In order to reflect recent studies that have detailed a robust association between the coronary plaque amount found on CCTA and incident coronary heart disease, the consensus authors added the categories P1 to P4 to designate mild, moderate, severe and extensive coronary plaque. While reporting methods for coronary plaque burden assessment include qualitative visual estimates of plaque in coronary vessels, quantitative assessment of total coronary plaque, a segment involvement score (SIS) and coronary calcium (CAC) testing, the consensus authors maintained that CAC and SIS may provide more reproducible approaches for categorizing the amount of coronary plaque.
5. While non-atherosclerotic etiologies of coronary abnormalities, such as anomalous coronary arteries or coronary artery aneurysms, can be key considerations in a differential diagnosis, the consensus panel noted that CAD-RAD scores are commonly not utilized in these cases.
Accordingly, the consensus authors recommend using an “E” modifier to document exceptions in the form of non-atherosclerotic causes of coronary obstruction with CAD-RADS reporting. Not only could the E modifier aid in tracking these etiologies, it could also signal to referring clinicians that the case in question involves a coronary abnormality that may fall outside of the traditional CAD-RADS classification adherence to atherosclerotic coronary artery disease, according to the consensus panel.