Key result
Thin-section photon-counting CT reduces Agatston scores vs standard sections, reclassifying AS severity in ~9%.
Why the study?
The study was conducted to evaluate the effect of section thickness on aortic valve calcification quantification using photon-counting detector CT.
Does thin-section photon-counting detector CT alter aortic valve calcium scoring and severity classification compared to standard 3-mm sections in patients undergoing cardiac CT?
Does thin-section photon-counting detector CT alter aortic valve calcium scoring and severity classification compared to standard 3-mm sections in patients undergoing cardiac CT?
Using thinner CT sections (1-mm or 0.4-mm) for aortic valve calcium scoring significantly lowers Agatston scores and volumes, potentially reclassifying nearly 10% of patients from severe to nonsevere aortic stenosis if standard thresholds are used.
Warrants caution using standard Agatston thresholds with thin-section photon-counting CT; leaves open adjusted criteria for AS severity.
Purpose To evaluate the effect of section thickness on aortic valve calcification quantification via photon-counting detector (PCD) CT. Materials and Methods This retrospective study included patients who underwent electrocardiography-gated PCD CT from March 2023 to October 2024. The aortic valve Agatston score (AVAS), aortic valve calcium volume (AVCV), and aortic valve calcium mass (AVCM) were measured at 3-mm, 1-mm, and 0.4-mm sections. Linear mixed model and regression analyses were performed. Sex-specific AVAS thresholds were used for aortic stenosis (AS) severity classification (≥2000 for male patients, ≥1300 for female patients). Results Eighty-four patients (median age: 84 years [IQR: 80-88 years], 58 female) were included. AVAS at 70 keV decreased with thinner sections: 3-mm section, 2141 (95% CI: 1931, 2351); 1-mm section, 1900 (95% CI: 1690, 2110), and 0.4-mm section, 1791 (95% CI: 1581, 2001) (P < .001). AVCV decreased similarly: 1806 mm³ (95% CI: 1640, 1972), 1496 mm³ (95% CI: 1330, 1661), and 1373 mm³ (95% CI: 1207, 1538) (P < .001). AVCM differed minimally: 518 mg (95% CI: 452, 585), 525 mg (95% CI: 459, 592), and 527 mg (95% CI: 461, 594) (P < .001 except for 1 mm vs 0.4 mm, P = .24). Compared with 3-mm sections, seven of 84 (8.3%) and eight of 84 (9.5%) patients were reclassified from CT-severe to CT-nonsevere with 1- and 0.4-mm sections, respectively (P < .001). Regression-based equivalent thresholds were 1770 (male patients) and 1154 (female patients) at 1 mm and 1675 (male patients) and 1087 (female patients) at 0.4 mm. Conclusion Thin-section PCD CT decreased AVAS and AVCV, resulting in AS severity reclassification in 8%-9% of patients. Keywords: Applications-CT, CT-Photon Counting, Cardiac, Aortic Valve, Calcifications/Calculi Supplemental material is available for this article. © RSNA, 2026.
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Murai et al. (2026) studied this question. Thin-section photon-counting detector CT decreased aortic valve Agatston scores compared to 3-mm sections, reclassifying aortic stenosis severity in 8.3% to 9.5% of patients.
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