Diffusion-weighted MR imaging in chronic non-bacterial osteitis: Proof-of-concept of the apparent diffusion coefficient as an outcome measure

• Published in: Acta radiologica open Vol. 10; no. 9; p. 20584601211044478
• Main Authors: Møller, Jakob M, Andreasen, Caroline M, Buus, Thomas W, Pedersen, Susanne J, Østergaard, Mikkel, Thomsen, Henrik S, Jurik, Anne G
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.09.2021; Sage Publications Ltd
• Subjects: Bacteria; Bone diseases; Bone marrow; Correlation coefficient; Correlation coefficients; Diffusion; Diffusion coefficient; Edema; Feasibility studies; Inflammatory diseases; Lesions; Magnetic resonance imaging; Measurement methods; Osteitis; Reproducibility; Technique (CT/MR); apparent diffusion coefficient; Magnetic resonance imaging; diffusion-weighted imaging; chronic
• ISSN: 2058-4601; 2058-4601
• DOI: 10.1177/20584601211044478

Background The apparent diffusion coefficient (ADC), as determined by whole-body diffusion-weighted MRI, may be useful as an outcome measure for monitoring response to treatment in chronic non-bacterial osteitis. Purpose To test and demonstrate the feasibility of ADC-measurement methods for use as outcome measure in chronic non-bacterial osteitis. Materials and Methods Using data from a randomized pilot study, feasibility of change-score ADC between baseline and second MRI (ΔADC12) and third MRI (ΔADC13) as outcome measure was assessed in three settings: “whole-lesion,” “single-slice per lesion,” and “index-lesion per patient”. Bone marrow edema lesions were depicted on short tau inversion recovery sequence at baseline and copied to ADC maps at the three time-points. Correlations between the three settings were measured as were analysis of variances. Discriminant validity was assessed as inter- and intra-observer reproducibility and smallest detectable change. Results 12 subjects were enrolled, and MRI was performed at baseline and weeks 12 and 36. Pearson correlation was high (r > 0.86; p ≤ 0.01) for ΔADC between single-slice—whole-lesion and whole-lesion—index-lesion and tended to be significant for single-slice—index-lesion settings (p = 0.06). For ΔADC12 and ΔADC13, Bland–Altman plots showed small differences (0.02, 0.03) and narrow 95% limits-of-agreement (−0.13–0.09, −0.07–0.05 μm2/s) between whole-lesion and single-slice ROI settings. Inter-observer reproducibility measured by intra-class correlation coefficient was poor-to-fair (range: 0.09–0.31), whereas intra-observer reproducibility was good-to-excellent (range: 0.67–0.90). Smallest detectable changes were between 0.21–0.28 μm2/s. Conclusion ADC change-score as outcome measure was feasible, and the single-slice per lesion ROI setting performed almost equally to whole-lesion setting resulting in reduced assessment time.