ctpelvimetry

The first open-source Python package for fully automated CT pelvimetry and body composition analysis.

Automatically measure pelvic dimensions and body composition from CT images — no manual annotation required. Integrates with TotalSegmentator for segmentation and provides a complete DICOM-to-results pipeline.

pip install ctpelvimetry

Why ctpelvimetry?

• Fully automated — from DICOM to structured results in one command, no manual landmark placement
• Reproducible — eliminates inter-observer variability inherent in manual CT pelvimetry
• Batch-ready — process hundreds of patients with progress tracking and failure summaries
• Quality-controlled — automatic detection of pelvic rotation, tilt, and sacrum offset with QC figures
• Modular — use the full pipeline or individual analysis functions via CLI or Python API

Features

Pelvimetry Measurements

Metric	Description
ISD (mm)	Inter-Spinous Distance

| Inlet AP (mm) | Promontory → Upper Symphysis | | Outlet AP (mm) | Coccygeal Apex → Lower Symphysis | | Outlet Transverse (mm) | Intertuberous diameter | | Outlet Area (cm²) | Ellipse approx: π/4 × AP × Transverse | | Sacral Length (mm) | Promontory → Coccygeal Apex | | Sacral Depth (mm) | Max anterior concavity |

Body Composition Measurements

Metric	Description
VAT (cm²)	Visceral Adipose Tissue area
SAT (cm²)	Subcutaneous Adipose Tissue area
V/S ratio	VAT / SAT ratio
SMA (cm²)	Skeletal Muscle Area

Measured at L3 vertebral level and ISD (mid-pelvis) level.

Key Features

• Per-metric error isolation — failure in one metric does not affect the others
• Quality gates — automatic detection of pelvic rotation, tilt, and sacrum offset
• Batch processing — process hundreds of patients with progress tracking and failure summaries
• QC figures — sagittal combined, extended 3-panel, and body composition overlays
• Modular design — use the full pipeline or individual analysis functions

QC Output Example

Sagittal QC figure showing automated landmark detection and pelvimetric measurements: sacral length (magenta), inlet AP (green), outlet AP (orange), and sacral depth (cyan).

Extended QC panel: (a) outlet transverse diameter at tuberosity level, (b) interspinous distance on axial view, and (c) complete pelvimetry measurement summary.

Installation

# Basic install (analyse existing segmentations)
pip install ctpelvimetry

# Full install (includes TotalSegmentator for segmentation)
pip install "ctpelvimetry[seg]"

Note: The full install pulls in TotalSegmentator and its PyTorch dependencies. If you only need to analyse pre-existing segmentations, the basic install is sufficient.

Dependencies

Package	Minimum Version
numpy	≥ 1.24
nibabel	≥ 5.0
pandas	≥ 2.0
scipy	≥ 1.11
matplotlib	≥ 3.7
tqdm	≥ 4.60
TotalSegmentator	≥ 2.0 (optional, pip install ".[seg]")

Usage Examples

CLI — Pelvimetry (from existing segmentation)

ctpelvimetry pelv \
  --seg_folder /path/to/segmentations \
  --nifti_path /path/to/ct.nii.gz \
  --patient Patient_001 \
  --output_root ./output --qc

CLI — Full Pipeline (DICOM → NIfTI → Seg → Measurements)

ctpelvimetry pelv \
  --dicom_dir /path/to/Patient_001 \
  --output_root ./output \
  --patient Patient_001

CLI — Body Composition

ctpelvimetry body-comp \
  --patient Patient_001 \
  --seg_root ./batch_output \
  --nifti_root ./batch_output \
  --pelvimetry_csv ./batch_output/combined_pelvimetry_report.csv \
  --output body_comp.csv --qc

CLI — Batch Processing

# Pelvimetry batch
ctpelvimetry pelv \
  --dicom_root /path/to/DICOMs \
  --output_root ./output \
  --start 1 --end 250

# Body composition batch
ctpelvimetry body-comp \
  --seg_root ./batch_output \
  --nifti_root ./batch_output \
  --pelvimetry_csv ./report.csv \
  --output body_comp.csv \
  --start 1 --end 210 --qc_root ./qc

Python API

from ctpelvimetry import run_combined_pelvimetry, process_single_patient

# Pelvimetry
result = run_combined_pelvimetry(
    "Patient_001", "/path/to/seg", "/path/to/ct.nii.gz"
)

# Body composition
result = process_single_patient(
    "Patient_001", "/path/to/seg_root",
    "/path/to/ct.nii.gz", "/path/to/report.csv"
)

Package Structure

ctpelvimetry/
├── __init__.py          # Public API
├── config.py            # PelvicConfig, constants
├── io.py                # Mask loading, coordinate transforms
├── conversion.py        # DICOM → NIfTI (dcm2niix)
├── segmentation.py      # TotalSegmentator execution
├── landmarks.py         # Midline, symphysis, sacral landmarks
├── metrics.py           # ISD, ITD, sacral depth
├── body_composition.py  # VAT/SAT/SMA analysis
├── qc.py                # QC figure generation
├── pipeline.py          # run_combined_pelvimetry, run_full_pipeline
├── batch.py             # Batch orchestration
└── cli.py               # Unified CLI entry point

Contributing

Contributions are welcome! Please follow these steps:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/your-feature)
3. Commit your changes (git commit -m "Add your feature")
4. Push to the branch (git push origin feature/your-feature)
5. Open a Pull Request

Citation

If you use ctpelvimetry in your research, please cite:

@software{huang2025ctpelvimetry,
  author    = {Huang, Shih-Feng},
  title     = {ctpelvimetry: Automated CT Pelvimetry and Body Composition Analysis},
  year      = {2025},
  url       = {https://github.com/odafeng/ctpelvimetry},
  version   = {1.1.0}
}

A peer-reviewed manuscript describing ctpelvimetry is currently in preparation. Citation details will be updated upon publication.

License

This project is licensed under the Apache License 2.0.