Variations in The Apparent Diffusion Coefficient Based on The Number of Applied B-Values in Brain Parenchymal Tissue on Diffusion Weighted Magnetic Resonance Imaging

Abstract

The purpose of this study was to investigate the changes in apparent diffusion coefficient of brain parenchymal tissue according to the number of application of b-values in diffusion weighted images. The diffusion weighted image was obtained from 13 subjects using 3.0 Tesla MRI scanner. At this time, each ADC map image was created after obtaining the image by dividing it into the method for applying b-values 0, 1,000 and b-values 0, 500, 1,000 and 1,500 respectively. To quantitatively compare the ADC values, two observers measured the mean ADC values by setting four ROIs in each white matter, gray matter, thalamus, globus pallidus in the ADC map images. The ADC values measured from the two methods were validated with statistical analysis tools. In the two imaging methods, the inter-observer reliability of the measured ADC values is analyzed by using the ICC, there was a good correlation and a significant difference in white matter, thalamus and the globus pallidus excluding gray matter (p 0.05). Also, Mann Whitney U test are used to verify statistical Results of significance verification of ADC values changes in the intra-observer, Observers 1 were significant in all ROIs between the two methods (p 0.05). Observers 2 were significant in the white matter, thalamus and globus pallidus (p 0.05). However, Gray matter was unable to identify significant results (p 0.05). As a results, the variation of the ADC values according to the number of applying of b-values in a brain parenchyma usually is statistically significant. So, since the ADC value of the brain parenchyma tissue is a relative value for various conditions, it is necessary to apply it considering the time required for imaging and the characteristics of the brain disease rather than necessarily applying a large number of b-value sampling.