Intravascular OCT

What it does

Intravascular OCT reads one coronary optical coherence tomography pullback. At an axial resolution of 10–20 micrometres, OCT shows fibrous-cap thickness, calcium thickness and single stent struts, but analysing them frame by frame is labour-intensive and mostly left to core labs.

The run traces the lumen on every frame, classifies the plaque along the pullback with lipid arc and fibrous-cap thickness, measures calcium arc, thickness and length with the OCT calcium score, proposes stent-sizing references before PCI, and after stenting detects struts to report expansion, apposition, edge findings, tissue protrusion and strut coverage.

Intended use

Decision support for interventional cardiologists using OCT to plan and optimise PCI: plaque-modification decisions before stenting, sizing, and a strut-level check of the result. It also supports follow-up studies of stent healing and the review of archived pullbacks.

Who it is for

Interventional cardiologists, fellows learning intravascular imaging, imaging core labs and research teams studying plaque and stent healing.

Accepted input

• IVOCT or OFDI pullback: one Intravascular Optical Coherence Tomography Image object, For Presentation or For Processing.
• One run reads one pullback; baseline, post-PCI and follow-up pullbacks are separate runs.

Requirements

Requirement	Why
ALineRate, ALinesPerFrame and CatheterRotationalRate	Frame geometry and timing of the rotating catheter
ALinePixelSpacing	Radial distances, cap and calcium thickness in micrometres and millimetres
IntravascularLongitudinalDistance	Frame spacing along the vessel for lengths and landing zones
OCTZOffsetCorrection	Correct catheter calibration for areas and diameters
Adequate blood clearance (flush)	Residual blood hides the lumen border and is flagged per frame

The guidewire shadow is handled in the lumen contour. Because light penetration is limited, the EEM is often not visible behind lipid; reference diameters then fall back to the lumen and the result says so.

Optional context

The clinical stage (pre-PCI, post-PCI, follow-up), the target lesion and the implanted stent can be passed in clinical_context.

The result

One structured result per pullback, with frame-wise contours, measurements, findings and the frames that show them.

Section	Content
Lumen segmentation	Lumen contour on every frame, lumen area and diameters, minimal lumen area
Plaque characterisation	Plaque type per frame, lipid arc, fibrous-cap thickness, TCFA, macrophages, thrombus, rupture or erosion
Calcium	Calcium arc, thickness and length, with the OCT calcium score
Stent sizing	Reference lumen and EEL diameters, landing zones, suggested stent diameter and length
Stent and strut analysis	Strut detection, expansion, malapposition, edge dissection, tissue protrusion and strut coverage
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: no DICOM report template exists for IVOCT, so measurements are encoded as SR Measurement Report TID 1500; SEG for contours; Secondary Capture of key frames.
• Definitions: IWG-IVOCT consensus on acquisition, terminology and measurement (Tearney, JACC 2012).
• Optimisation: EAPCI expert consensus on intracoronary imaging for PCI optimisation (Räber, EHJ 2018).
• Calcium: OCT calcium score (Fujino, EuroIntervention 2018), combining maximal arc, thickness and length.

Terminology notes

Plaque types, TCFA, macrophages, thrombus, rupture, erosion and stent findings use the IWG-IVOCT consensus terms and definitions. Each finding returns the frames that show it.