Fig. 2

Further examples of combined two-colour index maps. Combined index maps I_Df are given in comparison to index maps I_ADC together with I_D and I_f, overlaid to b-800 images, for (a) FNH, (b) HCC, (c) metastasis of breast cancer, and (d) HCC. The FNH with central scar (a) and the HCC with central necrosis (b) show similar behaviour on all index maps with nearly all voxels being red on I_D and about half of the voxels being red with scattered distribution on I_f and also on I_ADC and I_Df. On I_ADC, visual assessment of FNH is “probable malignant” and of HCC “probably benign,” which is wrong in both cases. Quantitative values are both (50% and 45%, respectively) just below the threshold to malignancy (at 53%) leading to correct assignment for FNH and wrong for HCC. On I_Df, visual assessment of FNH is “probable benign” and of HCC “probably malignant,” which is correct in both cases. Quantitative values (38% and 55%, respectively) were below and above threshold (50%), respectively, leading also to correct assignments. The metastasis with central necrosis (c) shows only a small margin of vital tumour, which can be easier captured by visible judgment than by ROI analysis with unclear tissue boundary. The HCC (d) shows the typical behaviour of a haemangioma (see Fig. 1a) and the assignment is false negative. However, the hypointense area of the left liver lobe adjacent to the lesion on b-800 indicates motion influences, which raise the diffusion coefficient of the liver tissue and lesion artificially as can be seen on I_D, I_ADC, and I_Df index maps. CCC Cholangiocellular carcinoma, FNH Focal nodular hyperplasia, HCC Hepatocellular carcinoma