Registration and feature tracking
Registration and feature tracking support deformation-sensitive CardiacNexus phenotypes such as strain, strain rate, torsion, recoil, tagged deformation, and selected motion-derived long-axis metrics.
- Modality
- Cine and tagged CMR
- Pipeline step
- MIRTK-backed tracking, contour propagation, strain analysis, tagged prediction pipeline, smoothing and derivative analysis
- Outputs
- strain_sax.csv, strain_lax.csv, strain_tagged.csv, strain NPZ files, strain and torsion QC plots
- Maturity
- Source-audited high-risk method page
Current dependency boundary
Short-axis strain and long-axis strain use existing feature-tracking/contour workflows and ventricular timing. Tagged MRI uses a separate tagged prediction pipeline after preparing H5 inputs from three tagged slices. The documentation keeps these method families separate because their backends, inputs, smoothing, and QC expectations differ.
Phenotype families that depend on tracking
| Feature family | Dependency | Current output family |
|---|---|---|
| Circumferential strain | SAX contour or feature-tracking workflow | strain_sax.csv |
| Radial strain | SAX contour/thickening and tracking workflow | strain_sax.csv |
| Longitudinal strain | LAX tracking with ventricular ES timing | strain_lax.csv |
| Torsion and recoil | basal/apical rotation with length normalization | strain_sax.csv |
| Tagged mechanics | tagged prediction pipeline and derivative analysis | strain_tagged.csv, strain_tagged.npz |
| AVPD | 4-chamber annular/AV plane geometry | ventricular_atrial_feature.csv |
Backend replacement rule
Registration or tracking backend changes require regression checks for global strain, segmental strain, ED/ES timing consistency, warped contour or segmentation consistency, Jacobian/folding sanity when deformation fields are involved, and outlier behavior. Keep a fallback backend until those checks pass.
Reader caveat
Strain and torsion values depend on motion model, smoothing, contour quality, temporal sampling, peak detection, and sign conventions. Methods should be compared only when analysis conventions are compatible.
Source audit
- SAX strain/torsion boundaries were checked against
eval_strain_sax.py. - LAX strain boundaries were checked against
eval_strain_lax.py. - Tagged MRI boundaries were checked against
eval_strain_tagged.py. - AVPD dependency was checked against
eval_ventricular_atrial_feature.py. - Textbook context boundary: broad clinical textbook context is not surfaced here because this page documents deformation-method boundaries, not disease interpretation.