AJR: Patient characteristics may serve as image quality predictors of CT scans

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Image quality of multi-detector CT scans, when utilized for the noninvasive detection of coronary artery stenosis, can be significantly associated with patient characteristics, including ethnicity, body mass index, heart rate and the presence of breathing artifact, but not with coronary artery calcium (CAC) score at a patient level, based on a study in the January issue of the American Journal of Roentgenology.

The multicenter, international study sought to determine the impact that particular patient characteristics may have on image quality and therefore, on the diagnostic accuracy of MDCT scans in detecting coronary artery disease.

Melvin E. Clouse, MD, of Beth Israel Deaconess Medical Center’s department of radiology in Boston, and colleagues recruited 291 patients (214 men and 77 women, with an average age of 59 years) presenting with a CAC score of greater than 600 Agatston units for their study. Of those patients recruited, 196 patients were white, 66 were Asian and 18 were black, with 11 patients remaining unspecified.

According to the authors, the most noteworthy finding of the study was that compared with examinations of white patients, studies of black patients had significantly poorer image quality. Sex, CAC scores and heart rate variability were found as non-contributing factors for poor image quality.

However, the study found that increasing BMI, heart rate and the presence of breathing artifact did contribute to poorer image quality.

In addition, the researchers found that CAC score and age were also significantly associated with reduced diagnostic accuracy at a vessel level.

“Physiologic factors such as high heart rate, arrhythmia, obesity and high coronary calcium burden with motion continue to limit the diagnostic accuracy of MDCT as compared with conventional invasive coronary angiography,” said Clouse.  “Our study is significant because we found a relevant influence of BMI, heart rate, ethnicity, and breathing artifact on the degradation of image quality."

The authors believe that image quality is the basis for determining the diagnostic ability of any imaging method for a particular disease state.  Despite some of the results of the study, non-invasive MDCT scans can be utilized in diagnosing a variety of patients with suspected coronary artery stenosis reliably, concluded the authors.

"With this new knowledge combined with new and advanced CT scanners, we have the potential to improve image quality of coronary CT angiography, further making the test even more accurate and independent of patient characteristics," said Clouse.