Morphological Change Forecasting for Prostate Glands using Feature-based Registration and Kernel Density Extrapolation

TL;DR

This paper introduces a novel framework combining feature-based image registration and kernel density estimation to forecast prostate gland morphological changes over time, aiding early detection and treatment planning.

Contribution

It develops an efficient registration method and a new KDE-based approach for predicting future prostate morphology changes without future data.

Findings

Achieved an average Dice score of 0.865 on unseen data

Validated the approach on a longitudinal dataset of 331 images from 73 patients

Demonstrated effective prediction of prostate morphological changes

Abstract

Organ morphology is a key indicator for prostate disease diagnosis and prognosis. For instance, In longitudinal study of prostate cancer patients under active surveillance, the volume, boundary smoothness and their changes are closely monitored on time-series MR image data. In this paper, we describe a new framework for forecasting prostate morphological changes, as the ability to detect such changes earlier than what is currently possible may enable timely treatment or avoiding unnecessary confirmatory biopsies. In this work, an efficient feature-based MR image registration is first developed to align delineated prostate gland capsules to quantify the morphological changes using the inferred dense displacement fields (DDFs). We then propose to use kernel density estimation (KDE) of the probability density of the DDF-represented \textit{future morphology changes}, between current and future time points, before the future data become available. The KDE utilises a novel distance function that takes into account morphology, stage-of-progression and duration-of-change, which are considered factors in such subject-specific forecasting. We validate the proposed approach on image masks unseen to registration network training, without using any data acquired at the future target time points. The experiment results are presented on a longitudinal data set with 331 images from 73 patients, yielding an average Dice score of 0.865 on a holdout set, between the ground-truth and the image masks warped by the KDE-predicted-DDFs.