Unsupervised Anomaly Detection of Diseases in the Female Pelvis for Real-Time MR Imaging

TL;DR

This paper introduces a real-time, unsupervised anomaly detection framework for pelvic MRI using a residual variational autoencoder trained on healthy scans, enabling detection of various diseases without labeled abnormal data.

Contribution

It presents a disease- and parameter-agnostic, real-time compatible anomaly detection method for pelvic MRI, trained solely on healthy data, with a benchmark framework and evaluation on multiple datasets.

Findings

Achieved an average AUC of 0.736 in detecting anomalies.

Reconstruction time of approximately 92.6 frames per second.

Demonstrated robustness with augmented synthetic data.

Abstract

Pelvic diseases in women of reproductive age represent a major global health burden, with diagnosis frequently delayed due to high anatomical variability, complicating MRI interpretation. Existing AI approaches are largely disease-specific and lack real-time compatibility, limiting generalizability and clinical integration. To address these challenges, we establish a benchmark framework for disease- and parameter-agnostic, real-time-compatible unsupervised anomaly detection in pelvic MRI. The method uses a residual variational autoencoder trained exclusively on healthy sagittal T2-weighted scans acquired across diverse imaging protocols to model normal pelvic anatomy. During inference, reconstruction error heatmaps indicate deviations from learned healthy structure, enabling detection of pathological regions without labeled abnormal data. The model is trained on 294 healthy scans and augmented with diffusion-generated synthetic data to improve robustness. Quantitative evaluation on the publicly available Uterine Myoma MRI Dataset yields an average area-under-the-curve (AUC) value of 0.736, with 0.828 sensitivity and 0.692 specificity. Additional inter-observer clinical evaluation extends analysis to endometrial cancer, endometriosis, and adenomyosis, revealing the influence of anatomical heterogeneity and inter-observer variability on performance interpretation. With a reconstruction time of approximately 92.6 frames per second, the proposed framework establishes a baseline for unsupervised anomaly detection in the female pelvis and supports future integration into real-time MRI. Code is available upon request (https://github.com/AniKnu/UADPelvis), prospective data sets are available for academic collaboration.