sCT Generation from Nuclear Medicine Scans

A Patch-Based Ensemble Approach to Generate High-Fidelity Synthetic CT (sCT) Images from PET Scans

The Challenge: Adding Anatomy to Function

Nuclear Medicine Scan (PET)

Reveals metabolic function but lacks detailed anatomical information.

High-Fidelity Synthetic CT

Provides rich anatomical context, enhancing diagnostic value and treatment planning.

Visualizing the Results

PET vs. Original CT vs. Synthetic CT

This comparison highlights the anatomical accuracy of our synthetic CT (right), which closely mirrors the ground truth of the original CT (middle) while retaining the functional context from the PET scan (left).

Comparison of PET, original CT, and synthetic CT scans

Key Innovations & Expertise

1. The Ensemble of Experts

Five independent nnU-Net models, pretrained as "experts" on specific anatomical regions, work together to generate a highly detailed sCT.

Expert 1: Organs
Expert 2: Vertebrae
Expert 3: Cardiac
Expert 4: Muscles
Expert 5: Ribs

2. The “Anatomical Supervisor”

A frozen, parallel ensemble of models acts as a "supervisor," constantly evaluating the generated sCT for anatomical correctness and sending a strong loss signal to correct errors.

Generator → sCT → Supervisor
Strong Loss Signal if Incorrect

3. Efficient Patch-Based Training

The model trains on smaller 128x128x128 patches of the full-resolution image, overcoming memory limitations and making advanced model development feasible.

CT SCAN
128³

Clinical Impact & Significance

Enhance Diagnostic Confidence

Provides crucial anatomical context for functional scans.

Improve Attenuation Correction

Leads to more accurate quantification in PET imaging.

Enable More Precise Treatment Planning

Allows clinicians to better localize tumors and pathologies.