Open AccessRepeatability and reproducibility of MRI apparent diffusion coefficient applied on four different regions of interest for patients with axial spondyloarthritis and healthy volunteers scanned twice within a week
Author(s) -
Jakob M. Møller,
Mikkel Østergaard,
Henrik S. Thomsen,
Stine Hangaard,
Inge Juul Sørensen,
Ole Rintek Madsen,
Susanne Juhl Pedersen
Publication year - 2020
Publication title -
bjr|open
Language(s) - English
Resource type - Journals
ISSN - 2513-9878
DOI - 10.1259/bjro.20200004
Subject(s) - reproducibility , repeatability , intraclass correlation , region of interest , medicine , nuclear medicine , effective diffusion coefficient , axial spondyloarthritis , correlation coefficient , coefficient of variation , magnetic resonance imaging , radiology , mathematics , sacroiliitis , statistics
Objectives: The apparent diffusion coefficient (ADC) may be used as a biomarker for diagnosis and/or monitoring treatment response in patients with axial spondyloarthritis (axSpA), but this requires reliable ADC measurements. This study assessed test–retest repeatability and reproducibility of ADC measurements using four different region of interest (ROI) settings. Methods: In this prospective study, the sacroiliac joints (SIJs) of 25 patients with axSpA and 24 age- and sex-matched healthy volunteers were imaged twice at a mean interval of 6.8 days in a 1.5 T scanner using, multishot echoplanar diffusion-weighted sequences. ADCs at four ROI settings were assessed: 5 mm and 10 mm anatomic band-shaped, 15 mm linear, and 40 mm 2 circular. Results: Intraclass correlation coefficient (ICC) assessments showed that the interstudy repeatability was good for median ADC (ADC med ) and 95th-percentile ADC (ADC 95 ) measurements in patients with axSpA (0.77–0.83 and 0.75–0.83, respectively), but poor-to-moderate in healthy subjects (0.27–0.55 and 0.13–0.37, respectively). For all ROI settings, intrareader reproducibility was excellent for ADC med -measurements (ICC:0.85–0.99) and moderate-to-excellent for ADC 95 measurements (ICC:0.68–0.96). The 5 mm ROI had the least estimated bias and highest level of agreement on Bland–Altman plots. The interreader reproducibility was moderate (ICC:0.71). The 15 mm linear ROI produced significantly greater ADC med and ADC 95 measurements than all other ROI settings ( p < 0.01–0.02), except for the circular ROI ADC 95 measurements. Conclusion: ROI settings influence ADC measurements. Interstudy repeatability of SIJ ADC measurements is independent of ROI settings. However, the 5 mm ROI showed the least bias and random error and seems preferable. Advances in knowledge: ADC measurements are affected by ROI settings, and this should be taken into account when assessing ADC maps.