# MSA-Net: a multi-scale and adversarial learning network for segmenting bone metastases in low-resolution SPECT imaging

## TL;DR

This paper introduces a new deep learning model for better detection of bone metastases in lung cancer using SPECT imaging.

## Contribution

A novel adversarial learning network with multi-scale feature extraction for improved segmentation of bone metastases in low-resolution SPECT images.

## Key findings

- The model achieved a DSC of 0.6671, outperforming existing methods in segmenting bone metastases.
- It showed improved performance for small and clustered lesions in SPECT imaging.

## Abstract

Single-photon emission computed tomography (SPECT) plays a crucial role in detecting bone metastases from lung cancer. However, its low spatial resolution and lesion similarity to benign structures present significant challenges for accurate segmentation, especially for lesions of varying sizes.

We propose a deep learning-based segmentation framework that integrates conditional adversarial learning with a multi-scale feature extraction generator. The generator employs cascade dilated convolutions, multi-scale modules, and deep supervision, while the discriminator utilizes multi-scale L1 loss computed on image-mask pairs to guide segmentation learning.

The proposed model was evaluated on a dataset of 286 clinically annotated SPECT scintigrams. It achieved a Dice Similarity Coefficient (DSC) of 0.6671, precision of 0.7228, and recall of 0.6196 — outperforming both classical and recent adversarial segmentation models in multi-scale lesion detection, especially for small and clustered lesions.

Our results demonstrate that the integration of multi-scale feature learning with adversarial supervision significantly improves the segmentation of bone metastasis in SPECT imaging. This approach shows potential for clinical decision support in the management of lung cancer.