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Updated: Jul 16, 2025
Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans
Published on: August 28, 2018
Investigating the impact of non-gated thoracic CT prior to CTCA to reduce layered testing
D Murphy1, J Stephenson2, Y Bouhbib3
1Department of Cardiology, Royal United Hospitals Bath, Bath, UK; Department for Health, University of Bath, Bath, UK.
Insights
Coronary artery calcification (CAC) on prior CT scans significantly impacts coronary artery disease (CAD) diagnosis. Identifying severe CAC on non-cardiac CT can streamline testing and reduce costs for patients.
Area of Science:
- Cardiovascular Imaging
- Radiology
- Health Economics
Background:
- Coronary artery calcification (CAC) is a marker of atherosclerosis.
- Non-cardiac CT scans can incidentally detect CAC.
- The impact of incidental CAC on subsequent cardiac imaging is not fully understood.
Purpose of the Study:
- To assess the prevalence of CAC on non-cardiac CT in patients referred for coronary CT angiography (CTCA).
- To evaluate how detected CAC influences CTCA diagnostic yield and the need for further testing.
- To analyze the cost-effectiveness of managing patients with incidental CAC.
Main Methods:
- Retrospective review of 2140 CTCA examinations (2018-2020).
- Cross-referencing with prior non-gated thoracic CT scans.
- Semi-quantitative assessment of CAC and analysis of diagnostic yield, further testing, and costs.
Main Results:
- 13% of CTCA referrals had prior non-gated CT showing CAC.
- Incomplete CTCA diagnostic yield increased with CAC severity (mild 32%, moderate 64%, severe 75%).
- Direct-to-functional testing for severe CAC cases was cost-effective, saving £171/patient (DSE) and £61/patient (MPS).
Conclusions:
- Incidental CAC on non-cardiac CT is common in CTCA referrals.
- Severe CAC necessitates a change in diagnostic strategy.
- A direct-to-functional testing pathway for severe CAC is cost-effective and alters management.
Aim:
To determine the proportion of computed tomography (CT) coronary angiography (CTCA) referrals with coronary artery calcification (CAC) evident on previous non-cardiac CT imaging and how this impacted the diagnostic yield for CTCA, the requirement for additional diagnostic testing, and the associated costs to confirm or refute obstructive coronary artery disease (CAD).
Materials And Methods:
A retrospective review of CTCA examinations was undertaken between 01/05/2018 and 31/05/2020 in which the examinations were cross referenced for previous non-gated thoracic CT at Royal United Hospitals Bath. Major epicardial vessel CAC on baseline CT was re-evaluated by published semi-quantitative methods, giving a per-patient CAC score (mild = 1-3, moderate = 4-6, severe >6). Subsequent incomplete CTCA diagnostic yield, further testing, and cost implications were examined.
Results:
Of the 2140 CTCA examinations identified, 13% (280/2140) had a preceding non-gated thoracic CT (53% female, age 63 ± 11 years). The incomplete diagnostic rate increased with CAC grade, mild 32%, (RR 12; 95% CI 4-40), moderate 64% (RR 25; 95% CI 8-80), severe 75%, (RR 29; 95% CI 9-94). Additional diagnostic testing occurred in 4% for the mild CAC category, and 14% and 42% for moderate and severe, respectively. When severe CAC was identified on a non-gated thoracic CT a cost saving of £171/patient (dobutamine stress echo [DSE]) and £61/patient (myocardial perfusion scintigraphy [MPS]) was established with a direct to functional testing pathway.
Conclusions:
In patients referred for CTCA where severe CAC was identified on a preceding non-gated thoracic CT a direct to functional testing altered management in 42% of cases and was cost-effective.
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