Use of ultrahigh spatial-resolution photon-counting detector CT improves assessment of calcified stenoses: Study

"Ultrahigh-spatial-resolution reconstructions led to the reclassification of 54.4% patients to lower CAD-RADS (Coronary Artery Disease Reporting and Data System) category than that assigned using standard resolution," the researchers reported.

Coronary CT angiography is a first-line test in coronary artery disease (CAD) but is limited by severe calcifications. Photon-counting–detector CT improves spatial resolution. Therefore, Moritz C. Halfmann, University Medical Center of the Johannes Gutenberg-University, Langenbeckstr 1, Mainz, Germany, and colleagues aimed to investigate the effect of improved spatial resolution on coronary stenosis assessment and reclassification.

For this purpose, the researchers performed a prospective evaluation of coronary stenoses in a vessel phantom (in vitro) containing two stenoses (25%, 50%), and coronary stenoses were evaluated retrospectively in patients (in vivo) who underwent ultrahigh-spatial-resolution cardiac PCD CT (from July 2022 to April 2023).

Image reconstruction was done at standard resolution (section thickness, 0.6 mm; increment, 0.4 mm; Bv44 kernel), high spatial resolution (section thickness, 0.4 mm; increment, 0.2 mm; Bv44 kernel), and ultrahigh spatial resolution (section thickness, 0.2; increment, 0.1 mm; Bv64 kernel). Percentages of DS were compared between reconstructions.

In vitro values were compared with the manufacturer specifications of the phantom, and patient results were assessed regarding the impact on CAD-RADS reclassification.

The in vivo sample included 114 patients (mean age, 68 years; 71 male patients).

The study led to the following findings:

• In vitro, percentage DS measurements were more accurate with increasing spatial resolution for 25% and 50% stenoses (mean bias for standard resolution, high spatial resolution, and ultrahigh spatial resolution, respectively: 10.1%, 8.0%, and 2.3%).
• In vivo, results confirmed decreasing median percentage DS with increasing spatial resolution for calcified stenoses (n = 161) (standard resolution, high spatial resolution, and ultrahigh spatial resolution, respectively: 41.5%, 34.8%, and 26.7%), whereas noncalcified (n = 13) and mixed plaques (n = 19) did not show evidence of a difference.
• Ultrahigh-spatial-resolution reconstructions led to a reclassification of 54.4% of patients to a lower CAD-RADS category than that assigned using standard resolution.

"Ultrahigh spatial resolution at photon-counting detector coronary CT angiography (CCTA) results in relevant rates of stenosis reclassification, which may impact the rate of downstream testing in patients with stable chest pain and may improve the role of CCTA as a gatekeeper for follow-up studies," the researchers concluded.

Reference:

Halfmann MC, Bockius S, Emrich T, Hell M, Schoepf UJ, Laux GS, Kavermann L, Graafen D, Gori T, Yang Y, Klöckner R, Maurovich-Horvat P, Ricke J, Müller L, Varga-Szemes A, Fink N. Ultrahigh-Spatial-Resolution Photon-counting Detector CT Angiography of Coronary Artery Disease for Stenosis Assessment. Radiology. 2024 Feb;310(2):e231956. doi: 10.1148/radiol.231956. PMID: 38376407.