Comparison of intra- and inter-patient intensity standardization methods for multi-parametric whole-body MRI

Jakub Ceranka; Frédéric Lecouvet; Nicolas Michoux; Johan de Mey; Hubert Raeymaekers; Thierry Metens; Jef Vandemeulebroucke

doi:10.1088/2057-1976/acc80e

Comparison of intra- and inter-patient intensity standardization methods for multi-parametric whole-body MRI

Biomed Phys Eng Express. 2023 Apr 10;9(3). doi: 10.1088/2057-1976/acc80e.

Authors

Jakub Ceranka^{1

2}, Frédéric Lecouvet³, Nicolas Michoux³, Johan de Mey⁴, Hubert Raeymaekers⁴, Thierry Metens⁵, Jef Vandemeulebroucke^{1

2

4}

Affiliations

¹ Vrije Universiteit Brussel, Department of Electronics and Informatics, Pleinlaan 2, Brussels, Belgium.
² Imec, Kapeldreef 75, B-3001, Leuven, Belgium.
³ Cliniques universitaires Saint Luc, Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCLouvain), Brussels, Belgium.
⁴ Universitair Ziekenhuis Brussel, Department of Radiology, Brussels, Belgium.
⁵ Department of Radiology, ULB-Hôpital Erasme, Université Libre de Bruxelles (ULB), Brussels, Belgium.

PMID: 36975189
DOI: 10.1088/2057-1976/acc80e

Abstract

Objective.To test and compare different intensity standardization approaches for whole-body multi-parametric MR images, aiming to compensate voxel intensity differences between scans. These differences, common for magnetic resonance imaging, pose problems in image quantification, assessment of changes between a baseline and follow-up scan, and hinder performance of image processing and machine learning algorithms.Approach.In this work, we present a comparison on the accuracy of intensity standardization approaches with increasing complexity, for intra- and inter-patient multi-parametric whole-body MRI. Several approaches were used: z-scoring of the intensities, piecewise linear mapping and deformable mapping of intensity distributions into established reference intensity space. For each method, the impact on standardization algorithm on the use of single image or average population distribution reference; as well as, whole image and region of interest were additionally investigated. All methods were validated on a data set of 18 whole-body anatomical and diffusion-weighted MR scans consisting of baseline and follow-up examinations acquired from advanced prostate cancer patients and healthy volunteers.Main results.The piecewise linear intensity standardisation approach provided the best compromise between standardization accuracy and method stability, with average deviations in intensity profile of 0.011-0.027 and mean absolute difference of 0.29-0.37 standard score (intra-patient) and 0.014-0.056 (inter-patient), depending on the type of used MR modality.Significance.Linear piecewise approaches showed the overall best performance across multiple validation metrics, mostly because of its robustness. The inter-patient standardization proved to perform better when using population average reference image; in contrary to intra-patient approach, where the best results were achieved by standardizing towards a reference image taken as the baseline scan.

Keywords: average image population; intensity standardization; multi-parametric MRI; whole-body MRI.

MeSH terms

Algorithms
Humans
Image Processing, Computer-Assisted* / methods
Machine Learning
Magnetic Resonance Imaging* / methods
Male
Reference Standards