Purpose: To determine the test-retest reliability and variance of metrics obtained from pancreatic diffusion-weighted magnetic resonance imaging (DW-MRI) and T2-MRI (i.e., apparent diffusion coefficients (ADC) and T2-relaxation times).
Methods: A two scanning session, two observer test-retest study in healthy volunteers (N=10) at 1.5T was performed with DW-MRI and T2-mapping scans acquired. In addition to region-specific (head, neck, body and tail) ADC and T2-relaxation values, coefficients of variation (CVs) and Bland-Altman plots were calculated.
Results: We observed mean ADC values (x 10-3 mm2/sec) of head: 1.50 – 1.56, neck: 1.38 – 1.61, body: 1.32 – 1.37 and tail: 1.19 – 1.20. The mean T2-relaxation times (msecs) were head: 60.23 – 63.14, neck: 57.80 – 58.63, body: 58.78 – 59.69 and tail: 58.82 – 59.99. Based on CVs, lower inter-scan session and inter-observer variability were consistently calculated for T2-relaxation times (CV of ~4%) compared to ADCs (CV of ~18%). Bland-Altman analyses did not reveal any systematic trends in bias.
Conclusions: Given the superior test-retest reliability observed for T2-mapping over DW-MRI, T2-mapping may enable more sensitive pancreatic lesion detection and monitoring. The current set of results can aid the study design of future longitudinal clinical trials, aiming to track the evolution or resolution of pancreatic pathology with DW-MRI or T2-mapping methodologies.
Published on: February 03, 2018
Citation: Upadhyay J, Dolgopolov S, Narang J, Millet C, Patel R, et al. 2018. Prospective Assessment of Variability and Reproducibility of Diffusion-Weighted MRI and T2-Mapping of the Pancreas in Healthy Volunteers. J Med Imaging Case Rep 1(1): 16-23.