# Vision transformer to differentiate between benign and malignant slices in 18F-FDG PET/CT

## TL;DR

This study uses Vision Transformers to improve the classification of benign and malignant lesions in PET/CT scans, outperforming traditional CNN models.

## Contribution

The novel use of Vision Transformer (ViT) for classifying 18F-FDG PET/CT slices as benign or malignant.

## Key findings

- ViT achieved an AUC of 0.90, outperforming CNN models like EfficientNet and DenseNet.
- ViT maintained strong performance (AUC 0.81) even for low FDG uptake cases, surpassing CNNs.
- The model showed clinical value in identifying hard-to-detect malignant lesions.

## Abstract

Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) is widely used for the detection, diagnosis, and clinical decision-making in oncological diseases. However, in daily medical practice, it is often difficult to make clinical decisions because of physiological FDG uptake or cancers with poor FDG uptake. False negative clinical diagnoses of malignant lesions are critical issues that require attention. In this study, Vision Transformer (ViT) was used to automatically classify 18F-FDG PET/CT slices as benign or malignant. This retrospective study included 18F-FDG PET/CT data of 207 (143 malignant and 64 benign) patients from a medical institute to train and test our models. The ViT model achieved an area under the receiver operating characteristic curve (AUC) of 0.90 [95% CI 0.89, 0.91], which was superior to the baseline Convolutional Neural Network (CNN) models (EfficientNet, 0.87 [95% CI 0.86, 0.88], P < 0.001; DenseNet, 0.87 [95% CI 0.86, 0.88], P < 0.001). Even when FDG uptake was low, ViT produced an AUC of 0.81 [95% CI 0.77, 0.85], which was higher than that of the CNN (DenseNet, 0.65 [95% CI 0.59, 0.70], P < 0.001). We demonstrated the clinical value of ViT by showing its sensitive analysis of easy-to-miss cases of oncological diseases.