Coronary CT angiography serves as a primary diagnostic tool in evaluating coronary artery disease (CAD), yet its effectiveness can be limited in patients with extensive calcifications, or calcium deposits within the coronary artery plaque. A recent advancement in this field is the ultrahigh-spatial-resolution photon-counting detector CT (PCD-CT), which surpasses conventional CT in image quality and spatial resolution, enhancing the ability to distinguish between two closely situated structures. Now, a new study has found that ultrahigh-spatial-resolution PCD-CT significantly improves the assessment of CAD, enabling a reclassification to a less severe disease category in over half of the patients studied. This breakthrough could enhance patient treatment plans and potentially reduce unnecessary medical procedures.

For the study, researchers at the University Medical Center Mainz (Mainz, Germany) assessed coronary stenoses, or narrowing in the coronary arteries in a vessel phantom (in-vitro) containing two different stenosis grades (25%, 50%), and retrospectively in 114 patients (in-vivo) who underwent ultrahigh-spatial-resolution cardiac PCD-CT for the evaluation of CAD. The in-vitro findings were compared against the phantom's manufacturer specifications, while the patient results were examined for their impact on CAD reporting and data system reclassification (CAD-RADS). The in-vitro study showed that ultrahigh-spatial-resolution scans significantly reduced the overestimation of stenosis by minimizing the adverse effects of calcifications on the images.

Patient results from those with suspected or confirmed CAD revealed a more accurate median stenosis degree for calcified plaques using ultrahigh-spatial-resolution PCD-CT compared to standard CT, showing 29% versus 42%. This advanced resolution often led to a lower CAD-RADS category for the patients, with 54% of the 114 participants receiving a downgraded classification. The study also found that the in-vitro quantification of 193 coronary CT angiography-based stenoses was more precise with ultrahigh-spatial resolution than with standard resolution. The researchers suggest that ultrahigh-spatial resolution could potentially overcome the limitations of conventional cardiac CT angiography, specifically by reducing the overestimation of stenosis caused by calcium blooming. This phenomenon can make small, dense structures, such as calcifications, appear larger than their actual size.

"Our study provides a glimpse into the potential impact of performing coronary CT angiography using ultrahigh spatial resolution technology on risk reclassification and recommended downstream testing," said Tilman Emrich, M.D., attending radiologist at the University Medical Center Mainz. We found that ultrahigh-spatial-resolution reconstructions resulted in significant changes in recommendations for over 50% of patients. The impact was particularly notable in cases with calcified plaques, where ultrahigh-spatial-resolution reduced the overestimation of stenosis.”

"This could significantly alter recommendations for downstream testing, potentially leading to a reduction of unnecessary procedures (and their potential complications) and reduced healthcare costs," added Emrich. 

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