Cardiac CT

What it does

Cardiac CT reads ECG-gated heart studies: the non-contrast calcium-score scan, coronary CT angiography for chest pain, and the structural protocols for transcatheter aortic valve implantation (TAVI) and left atrial appendage occlusion (LAAO). The run tells these protocols and cardiac phases apart and computes what each one supports.

From a calcium scan it returns the Agatston score per coronary artery with its CAC-DRS category and the epicardial fat volume. From a CCTA it returns the labelled coronary tree, stenosis per segment with a CAD-RADS 2.0 category and modifiers, plaque volumes by composition, chamber volumes and CT-FFR per lesion. A TAVI or LAAO study adds the device-sizing measurements the heart team needs.

Intended use

Decision support for the reader of a cardiac CT and for the team that acts on it: a CAD-RADS category with the segment measurements behind it, and TAVI or LAAO sizing values taken at defined landmarks. When a patient goes on to invasive angiography, the Coronary Angiography model reads the cath-lab study.

Who it is for

Cardiac radiologists, imaging and interventional cardiologists, structural-heart teams and cardiac surgeons. Developers add calcium scoring, CAD-RADS or TAVI sizing to a reporting system or a structural-heart planning workflow.

Accepted input

• Gated CT series as CT Image Storage or Enhanced CT.
• Calcium scan: ECG-gated non-contrast series of the heart.
• CCTA: gated contrast series; when several phases are reconstructed, the run picks the one with least motion and multiphase data add function.
• TAVI protocol: gated aortic-root CTA plus the aorto-iliofemoral run-off acquisition.
• LAAO protocol: cardiac CTA covering the left atrium and appendage.

Requirements

Requirement	Why
ECG gating and cardiac phase fields	Phase detection and selection of the motion-free reconstruction
Rescale Slope and Intercept	Calcium scoring and plaque composition are both defined in Hounsfield units
Full coverage of the coronary tree	Segments outside the volume are reported as not evaluable
Several phases of the cardiac cycle	Ejection fraction is computed only from multiphase data
For TAVI, run-off from the aortic root to the femoral arteries	Iliofemoral minimal lumen diameters for the access route

Motion and step artefacts, calcium blooming and coronary stents are flagged per segment.

Optional context

The indication (chest pain, pre-TAVI, pre-LAAO, risk assessment), known stents or bypass grafts and the intended device go in clinical_context. The targets option extends the calcium score to the aortic valve and mitral annulus.

The result

A sectioned JSON result built on the coronary segment model; every stenosis and plaque value points to its segment.

Section	Content
Calcium score	Agatston, volume and mass per vessel (LM, LAD, LCX, RCA) and in total, with the CAC-DRS category
Coronary tree segmentation	Coronary mask, centrelines and segment labels
CAD-RADS stenosis	Stenosis grade per segment, plaque burden and modifiers (N, HRP, S, G, E), category and management
Coronary plaque	Calcified, non-calcified and low-attenuation plaque volumes, total plaque volume, high-risk features
CT-FFR	Lesion-specific fractional flow reserve computed from the CCTA
Cardiac chambers	LA, LV, RA, RV, LV myocardium, aorta and pulmonary artery; volumes, LV mass and EF when multiphase
TAVI planning	Annulus area, perimeter and diameters, LVOT, sinus and STJ diameters, coronary ostial heights, cusp calcium, iliofemoral minimal lumen diameters
LAA occlusion planning	Appendage morphology, ostium and landing-zone diameters, depth, filling-defect flag (thrombus or slow flow)
Epicardial fat	Epicardial adipose tissue volume and mean attenuation inside the pericardium
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Standards

• DICOM: SR TID 3900 CT/MR Cardiovascular Analysis Report, with TID 3905 Calcium Scoring Results, TID 3902 Vascular Analysis for stenosis and TID 3920 Ventricular Analysis for chambers; SEG for the coronary tree and chambers; calcium distribution coded with CID 3489.
• Coronary disease: CAD-RADS 2.0 (2022), with its plaque-burden and high-risk-plaque modifiers.
• Calcium: Agatston score (1990) and CAC-DRS (2018).
• Structural planning: SCCT 2019 expert consensus on CT for TAVI/TAVR.