Are patients undergoing unnecessary gated calcium CT imaging?

A new study suggests many patients are undergoing unnecessary coronary artery gated calcium score CT imaging.

Coronary artery calcification (CAC) measured on gated calcium score CT is a strong predictor of adverse coronary artery disease (CAD) events, including death, but such measurements are often underreported, according to authors of the study published by Current Problems in Diagnostic Radiology.

“Knowledge of CAC on a prior chest CT may eliminate the need for a subsequent dedicated gated calcium score CT, leading to earlier diagnosis and management of cardiovascular disease as well as decreasing radiation exposure and health care costs,” wrote Joan M. Chi, MD, with the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell in New York, and colleagues.

The researchers hypothesized that prior chest CTs accurately predict CAC and sought to evaluate the percentage of patients undergoing gated calcium score CTs who had prior non-gated chest CT.

To do this, they analyzed 441 patients who received a gated calcium score CT scan at one institution between October 2014 and 2016. Of that total, 42 patients (10%) had a prior non-gated chest CT with a mean time difference of 810 days.

Looking at those 42 prior chest CTs, 69% had CAC scoring while 31% didn’t. Those scans had 100% predictive accuracy for the presence or absence of CAC on subsequent gated calcium score CTs, the authors noted.

“This study shows that many of the subjects with a dedicated gated calcium score study had a prior chest CT which can be readily used to identify the presence or absence of coronary calcium," Chi and colleagues wrote.

"Physicians should also inquire about prior chest CTs before ordering a gated calcium score CT, and if calcium is not reported they should review the exam with a radiologist or cardiologist to help make clinical decisions without further unnecessary testing.”

The researchers also found that a “majority” of final chest CT reports made no mention to the presence of CAC, and zero described an absence. Although the institution that provided data for this study uses a standardized chest CT reporting template, it does not categorize CAC as its own section, the authors noted.

“Requiring a standardized template with a mandatory CAC reporting section within the template would improve the reporting rates for CAC and possibly reduce the number of dedicated gated calcium score CTs,” Chi and colleagues concluded.