MR-diffusion weighted imaging of healthy liver parenchyma: repeatability and reproducibility of apparent diffusion coefficient measurement
Colagrande, S.; Pasquinelli, F.; Mazzoni, L.N.; Belli, G.; Virgili, G.
Journal of Magnetic Resonance Imaging Jmri 31(4): 912-920
To compare repeatability and reproducibility of four different methods of apparent diffusion coefficient (ADC) evaluation of liver parenchyma. In fact, repeatability and reproducibility assessment is mandatory in quantitative evaluations, however, these have not been accurately investigated in liver MR-diffusion-weighted studies. Diffusion-weighted sequences, b-value = 0-1000 s/mm(2), were acquired on 30 healthy volunteers by a 1.5T scanner whose reliability has been validated by a phantom study. Four sampling methods, evaluating various parenchyma percentages by different-sized region-of-interests (ROIs), were compared by two observers: 70% and 30% of the volume, 4%-one-ROI-per-segment, and 4%-one-ROI-per-slice in the right-lobe. Ninety-five percent limits of agreement and intraclass correlation coefficient (ICC) were calculated. Complete measurements on the left lobe could be obtained in less than half of patients. The 4%-one-ROI-per-slice and 4%-one-ROI-per-segment yielded lower mean values compared with 30-70% volume methods (1343-1373 versus 1463-1560.10(-6) mm(2)/s, respectively). Repeatability was acceptable (ICCs approximately 0.80) whereas reproducibility was low (ICCs