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. Author manuscript; available in PMC: 2016 Jan 1.
Published in final edited form as: Acad Radiol. 2015 Jan;22(1):25–32. doi: 10.1016/j.acra.2014.09.001

Fig. 2.

Fig. 2

Repeatability of apparent diffusion coefficient (ADC) measurements from diffusion-weighted MRI (DW-MRI) in a breast cancer patient (color overlay = tumor). Panel A shows the distributions of the ADC values from the tumor obtained on two separate scans within one week of each other. Panels B (visit 1) and C (visit 2) show the spatial variations at the voxel level. The mean with 95% confidence intervals for the two visits were 1.06 +/− 0.01 mm2/ms and 1.03 +/− 0.01 mm2/ms, respectively. The lack of overlap in the confidence intervals, despite the apparent similarity in the histograms, illustrates the importance of analytical validation studies to establish ranges of measurement error before deploying quantitative techniques to interrogate changes in underlying biology. (Image courtesy of Lori Arlinghaus, Ph.D, Vanderbilt University.)