Paper Info

• Accepted by MICCAI 2025 (ratings from reviewers: 5,5,3)

Table Of Content

• Introduction
  • VT Screening
  • Scar Projection
• Related Work
  • Scar Segmentation
  • Boundary Aware Segmentation
• Methods
• Experiments
• Extensions

VT Screening

• Ventricular Tachycardia: your heart beats too fast

• Causes: Cardiomyopathy(心肌病), Structural heart disease(结构性), Ischemic heart disease(缺血性), Heart failure(心衰), Myocarditis(心肌炎) and so on

• Treatment: Implantable cardioverter defibrillator(ICD)

VT Screening with CMRI

Our collaborator found that scar projection and classification from LGE CMRI is valuable for VT Screening.

Scar Projection & Classification

In polar-coordinate system, the projection can be easier to understand:

Scar segmentation is necessary in this process and its boundary quality is very important.

Scar Segmentation

Numerous methodologies have been adapted for this task:

• Traditional: thresholding, region growing
• Machine learning:SVMs, CRFs
• Deep learning: UNet-based, Transformer-based

Among them, nn-UNet is a popular SOTA framework:

Boundary Aware Segmentation?

Boundary quality in scar segmentation has received limited attention. Existing methods still struggle to localize scars within the myocardium, largely due to the irregular morphology and blurred boundaries of pathological scars.

Retina OCT Boundary Regression

• He, Yufan, et al. "Structured layer surface segmentation for retina OCT using fully convolutional regression networks." Medical image analysis 68 (2021): 101856.

Methods overview

Methods details: polar transform

• Polar transformation and its inverse transformation: implement with torch.nn.functional.grid_sample
  • polar mesh grid:

• All results are evaluated in Cartesian coordinate system.

Methods details: dual branch

• Dual branch: boundary & region
  • channel-wise softmax --> -->
  • column-wise softmax --> -->
    

Methods details: loss function

1. Loss for :
   

   Where , is the ground-truth radial position of boundary k at angle θ.

2. Loss for
   Where is the final boundary position for boundary, .

Experiments: Scar Classfication

Experiments: Scar Segmentation

Experiments: Case study

Extensions

• Semi-supervised learning(polar + Cartesian)

THANKS