Multicentre repeatability of ADC estimates from diffusion weighted (DW) MRI in lung cancer: influence of segmentation methodology and statistical descriptor

Using a multi-platform diffusion weighted MRI protocol in lung tumors, apparent diffusion coefficient (ADC) repeatability was well below the change expected for treatment response. ADC coefficients of variation (CoV) varied depending on lesion size and segmentation methodology (range 2.6-10.8%; three times greater for lesions >3cm than lesions<3cm). Performing tumor segmentation on high-b-value images produced lower, more repeatable ADC estimates than if segmenting on low-b-value images. Using median versus mean statistical descriptors for signal averaging prior to ADC calculation did not affect ADC quantitation or repeatability.