Coronary CT angiography · CT-FFR · myocardial ischaemia

From a routine coronary CT to vessel-level FFR and an ischaemia map

AI Hexeract analyses a standard CCTA end to end, without stress agents or extra scans. It segments the heart, traces and names every coronary branch, measures the lumen and predicts CT-FFR at every point of the tree. It then maps the result onto the myocardium. Every step is a model of our own, trained on expert-annotated data; each step up to CT-FFR is tested on patients it never saw.

3D rendering of a heart from a coronary CT: blue left-ventricular myocardium, coronary arteries coloured by predicted FFR from yellow (normal) to red (reduced) along the left anterior descending artery.
The software on a study patient: chambers, coronary tree with lumen rings, and CT-FFR along every branch (red = reduced).
FFR 0.51.0
0.95CT-FFR lesion AUC (FFR ≤ 0.80)expert lumen · 0.87 fully automatic
0.97Specificity, ≥ 50 % stenosisLumenNet contours
0.84Coronary lumen DiceLV myocardium 0.93
100 %Left ostia within 5 mmright 95 % within 10 mm
Method

Seven validated steps, then the myocardium

Each step hands an inspectable result to the next: masks, centerlines, named vessels, lumen contours, FFR values and the myocardial map. A clinician can check every intermediate on screen.

  1. Heart & coronary segmentation

    Coronary lumen, aorta, LV myocardium, LV blood pool and the rest of the heart in one pass.

    Dice 0.84 coronary · 0.93 LV
  2. Coronary ostia

    Left and right coronary origins located on the aortic root.

    0 of 42 ostia missed
  3. Centerline tracking

    Network tracker trained on expert centerlines follows every branch from the ostia.

    main-vessel recall 0.93
  4. Artery labelling

    Tree model names LAD, CX, RCA and their side branches.

    territory correct 97–99 %
  5. Lumen contours

    Cross-sectional lumen at every centerline point, from nine reformatted planes.

    radius error 0.14 mm
  6. Stenosis grading

    Diameter stenosis read from the contours along each vessel.

    specificity 0.97 at ≥ 50 %
  7. CT-FFR

    Tree network, monotone along the vessel, predicts FFR at every node.

    vessel accuracy 0.81–0.82
Validation

Held-out results

Every number below comes from a fixed test set of 21 patients that was never used for training, model selection or tuning. The reference is a full expert CT-FFR analysis: centerlines, lumen contours, marked stenoses and FFR on every node, 104,537 nodes across 129 patients in total.

Segmentation

MetricResult
Coronary lumen Dice0.841
Coronary HD95 (mm)4.4
Connectivity (clDice)0.833
Proximal 40 mm coverage L / R0.96 / 0.97
LV myocardium Dice0.930
LV blood pool · aorta · heart Dice0.956 · 0.968 · 0.960

Mean over 21 patients.

CT-FFR

Input lumenExpertAutomatic
Point-wise FFR error (MAE)0.0460.060
Correlation with reference (r)0.910.85
Lesion AUC0.9460.865
Lesion sensitivity / specificity0.93 / 0.650.85 / 0.75
Lesion accuracy0.850.82
Vessel AUC0.9090.884
Vessel sensitivity / specificity0.84 / 0.810.80 / 0.81

39,311 centerline points, 66 lesions (46 with FFR ≤ 0.80), 175 vessel ends. "Automatic" uses our own lumen contours.

Lumen contours and stenosis

MetricResult
Contour Dice0.858
Dice inside stenoses0.861
Radius error (mm)0.141
Diameter-stenosis error0.098
≥ 50 % stenosis: specificity0.97

17,226 expert contours. Results unchanged with centerline offsets up to 0.5 mm and tilts up to 10°.

Ostia, tracking and labelling

MetricResult
Left ostium: median error · within 5 mm2.9 mm · 100 %
Right ostium: median error · within 10 mm3.6 mm · 95 %
Tracking recall, main vessels0.93
RCA / LAD / CX recall0.94 / 0.91 / 0.90
Tracking precision0.80
Territory labelling (LAD / CX / RCA)0.97–0.99
Left / right tree assignment100 % of 93

Tracking: 10 held-out patients, tolerance 1.5 mm, against expert centerlines.

Ischaemia

From coronary physiology to the myocardium

The final stage predicts where the myocardium is under-perfused, from the CCTA alone. It is trained against quantitative stress CT perfusion, mapped patient by patient onto the CCTA, and it already runs inside the software.

Screenshot of the AI Hexeract desktop application: workflow panel with Open case, Chambers and aorta, Arteries, lumen and FFR, and Ischaemia steps; analysis-method selectors; 3D heart with FFR-coloured coronary tree.
AI Hexeract desktop application: four workflow steps from opening the case to the ischaemia result, with the method of each step selectable and every layer switchable.
  • 0.88median myocardial Dice of the CT perfusion to CCTA registration (IQR 0.86–0.90), 92 % median LV coverage
  • AHA 17targets live in an LV-intrinsic coordinate system (apex to base, circumference, wall depth), so CT perfusion, SPECT and PET all train the same model
  • 233patient CCTA + perfusion dataset processed, further 500 secured, with a CCTA-to-SPECT patient mapping, ongoing processing
For cardiologists

Function from the scan you already have

  • Lesion-specific CT-FFR at every point of the tree, so the haemodynamic relevance of each stenosis is visible next to its anatomy.
  • Named vessels and territories: LAD, CX and RCA are labelled automatically and linked to their myocardial territory.
  • Explainable chain: masks, centerlines, contours and FFR values are all on screen and can be checked and corrected.
  • No stress agent, no extra radiation: the analysis uses the routine CCTA only.
  • Minutes on a workstation: segmentation 4–7 min, everything after it about 2 min on a laptop GPU.
Why it is defensible

Own models, own data pipeline, protected method

  • Every model is our own: segmentation, ostia, tracking, labelling, lumen, FFR and ischaemia, trained on expert-annotated data. No third-party segmentation model remains in the product.
  • Strict validation: a fixed held-out test set, patient-level splits and no tuning on test patients.
  • Modality-independent targets: perfusion is learned in AHA 17-segment space, so each new perfusion dataset adds to the same model.
  • Intellectual property: international patent application PCT/IB2023/059985, covering multi-stage anatomical inference, physiological territory mapping and voxel-wise ischaemia estimation.
For investors

The anatomy-to-FFR chain is built. Paired perfusion data is the next step.

Every step from the raw CT to CT-FFR is trained and validated on held-out patients. The ischaemia stage is the one limited by data volume: with about 120 perfusion patients, each coronary territory has only a few dozen ischaemic examples. Scaling to several hundred paired CCTA and perfusion patients is the direct path to a production ischaemia output.

What the next round funds

  • Multi-centre paired CCTA with stress perfusion (CT perfusion, SPECT, PET), building on the secured 233-patient CCTA + SPECT dataset.
  • Prospective clinical validation of CT-FFR and ischaemia against invasive FFR and perfusion imaging.
  • MDR and FDA clearance, and the first reimbursed deployments.

We are preparing a USD 3M pre-Series A round.

Talk to us about the round