Magnetic resonance apparent diffusion coefficient values of the completely remitted lesions of primary hepatocellular carcinoma after TACE: a study of their repeatability and consistency

Objective: to assess the repeatability and consistency of magnetic resonance apparent diffusion coefficient (MR ADC) values of the completely remitted lesions of primary hepatocellular carcinoma (HCC) after TACE in order to provide a reference for clinical application. Methods: The MR ADC values of 21 completely remitted lesions were measured at 1, 3 and 6 months after TACE by the same radiologist (radiologist A) using the same sequence, which were measured again by another radiologist (radiologist B) one week later. By calculating the intra-class correlation coefficient (ICC) value and drawing Bland-Altman graph, the respectability and consistency of the ADC value measurement were evaluated. ICC values > 0.75 indicated good reliability and high repeatability. The consistency was considered to be enough high when 75% of the sites were located in the 95% confidence interval within the reference line on the Bland-Altman graph. Results: The ICC values measured by radiologist A 1, 3 and 6 months after TACE were 0.928, 0.878 and 0.934 respectively, which were 0.873, 0.940 and 0.871 respectively measured by radiologist B. The ICC values measured by radiologist A and radiologist B at different time one week before 1, 3 and 6 months after TACE were 0.854, 0.940 and 0.960 respectively, while the values were 0.788, 0.945 and 0.858 respectively one week after 1, 3 and 6 months after TACE. All the above values were greater than 0.75, indicating that the reliability was high. As 90% of the sites were located in the 95% confidence interval within the reference line on the Bland-Altman graph, the repeatability was regarded to be very high. Conclusion: The ADC values of the completely remitted lesions of HCC after TACE are quite stable. The measurements of ADC values for these lesions carry high degree of repeatability and consistency. With the help of ADC values, the stability of HCC lesions after TACE can be dynamically assessed and the therapeutic effectiveness can be promptly evaluated. (authors)