Low-dose coronary artery calcium scoring compared to the standard protocol

Area of Science:

• Cardiology
• Radiology
• Medical Imaging

Background:

• Coronary artery disease (CAD) risk stratification is crucial.
• Coronary artery calcium scoring (CACS) using computed tomography (CT) is a key diagnostic tool.
• Optimizing CT protocols for CACS is essential for accurate patient management.

Purpose of the Study:

• To compare CACS derived from 80 kVp (low-dose) versus 120 kVp (standard-dose) CT.
• To evaluate the impact of low-dose CT on CACS-based cardiovascular risk classification.
• To determine if the prognostic significance of a zero calcium score is maintained with low-dose CT.

Main Methods:

• A large cohort of 1511 patients with suspected CAD undergoing myocardial perfusion scans (MPS) were retrospectively analyzed.
• Coronary artery calcium scoring (CACS) was performed using both 80 kVp and 120 kVp CT protocols.
• Risk stratification categories were compared between the two CT protocols.

Main Results:

• A strong correlation (R=0.94) was observed between 80 kVp and 120 kVp CACS.
• A significant difference was found in the proportion of patients classified in the <25% percentile risk group (P=.03).
• The number of patients with a CACS of 0 differed substantially between protocols (264 vs. 437, P<.001).

Conclusions:

• Despite good correlation, low-dose CT (80 kVp) systematically underestimates CACS compared to standard CT (120 kVp).
• This underestimation may affect the prognostic value of CACS, particularly for cardiovascular risk stratification.
• The established "power of zero" for CACS may not be reliable when using low-dose CT protocols.