Enhanced vertebra to disk ratio as a new semi-quantitative imaging biomarker for Gaucher disease patients

Abstract

Purpose: Gaucher disease (GD) is an inherited lysosomal storage disorder. The Vertebral Disk Ratio (VDR) is a semi-quantitative imaging biomarker designed to diagnose and monitor GD. Computed from standard T1 MRI images, the VDR is derived from 2D segmentations. This study aimed to evaluate the 3D version of VDR, namely eVDR, and analyze the performances of two eVDR-derived response criteria for GD patients.

Methods: Three datasets were used: 8 longitudinal GD patients, 13 non-GD patients, and 2 longitudinal GD patients with known Bone Marrow Burden (BMB) scores. Two eVDR-derived response criteria were tested: 1) a parametric version (PeVDR) averaging all eVDR measures recorded for the 5 lumbar vertebrae; and 2) a non-parametric version (NPeVDR), considering all eVDR measures as independent and evaluating therapeutic response in a paired fashion. Analyses included assessment of reader variability in eVDR (3D) versus VDR (2D) and comparison with BMB response criteria.

Results: The repeatability of eVDR (3D) versus VDR (2D) demonstrated no difference in mean values but a lower variance (p < 0.004). The PeVDR intra-reader variability had a standard deviation < 0.1 with a coefficient of variation < 5%; the inter-reader variability featured a Limit of Agreement < 5% and a Bias < 3%. Observational comparison of eVDR and BMB scoring and sensitivity indicated a correlation between PeVDR and BMB, with an improved sensitivity with the NPeVDR version.

Conclusions: Based on a standard MRI sequence, the eVDR imaging biomarker and its derived response criteria improved GD assessments and could help assessing other bone marrow diseases.

Keywords: Gaucher disease; Imaging biomarkers; Magnetic resonance imaging; Reliability analysis; Response evaluation criteria.