Scout and localizer imaging

Scout and localizer imaging provides the vascular geometry route for Aortic structure. The modality is not used as a generic chamber-quantification source in CardiacNexus.

Modality
Scout / localizer CMR
UKB source
Data Field 20207
Pipeline step
Aortic scout segmentation, mesh processing, centerline geometry extraction, and QC visualization
Outputs
aortic_structure.csv, aortic_mesh artifacts, visualization/aorta/aorta_structure*.png
Maturity
Source-audited modality page

Current pipeline role

The current source expects aortic_scout.nii.gz and seg_aortic_scout.nii.gz. It runs the aortic scout inference/mesh workflow, converts the segmentation into a smoothed mesh, extracts centerline and region-level geometry, and writes aortic-structure rows in millimeters, percent tortuosity, and inverse-millimeter curvature/torsion units.

The page scope is intentionally vascular. Scout/localizer images have useful field-of-view coverage for aortic geometry, but they are not optimized for detailed chamber structure, flow, or tissue characterization.

Current outputs

Output familyCurrent rowsSource pathNotes
Centerline geometrydiameter, length, linear distance, tortuosity, curvature, torsionsrc/feature_extraction/Aortic_Scout_20207/eval_aortic_structure.pyglobal aortic centerline family
Regional aortic geometryascending arch, descending arch, descending aorta, arch, lower aortaeval_aortic_structure.py; VMTK-derived helpersunits converted from cm-like source values to mm / 1/mm as implemented
QC and mesh artifactsaortic_mesh, aorta_structure.png, aorta_structure_landmark.pngeval_aortic_structure.pygenerated from segmentation mesh and landmarks

QC and interpretation caveats

The route requires both the scout image and the aortic-scout segmentation. Mesh processing, centerline extraction, landmark placement, and field-of-view coverage can all change whether a subject yields usable geometry. Legacy output labels preserve several source spelling conventions, including Maxium; downstream consumers should not silently rename them without a schema migration.

Scout-derived aortic geometry should be interpreted as vascular morphology context. It should not be mixed with LVOT root diameters or aortic-distensibility cine diameters without naming the acquisition and method.

Source audit

  • Current input names, segmentation dependency, mesh workflow, output unit conversions, and visualization paths were checked against eval_aortic_structure.py.
  • docs/data/output_column_inventory.yml records the aortic_structure artifact contract, and the aortic structure phenotype page documents the exact emitted rows.
  • Textbook context boundary: broad clinical textbook context is not surfaced here because source implementation plus vascular geometry literature context is sufficient for draft rollout.
Aortic geometry context from the CardiacNexus manuscript image cache
Aortic geometry source figure from the manuscript image cache, cited there to Minderhoud et al. 2024, shown to orient the scout/localizer geometry role before page-specific CardiacNexus output boundaries are applied. The figure is not a validation image for UKB localizer acquisition quality.Source: manuscript image cache citing Minderhoud et al. 2024; permission and exact source-panel review pending for draft use.
  • Displayed figure provenance is recorded in docs/data/figure_provenance.yml; permission and exact reuse wording remain pending for public release.