Assessment of diffusion-weighted Magnetic Resonance imaging to predict the chemotherapy outcome in liver metastases.

Purpose: to find a method that allows an early assessment of response to CHT in liver metastases by Magnetic Resonance Diffusion-weighted Imaging (MR-DwI) Materials and methods: 30 oncologic patients with liver metastases were enrolled from 5 different center and scanned by multi-b MR-DwI before the beginning of CHT (baseline, time 0) and repeated within two weeks (time 1), 20-25 days from the beginning of the first cycle of CHT (time 2), and 20-25 days from the beginning of the second cycle of CHT (time 3). For every metastatic lesion, dimensional variation and ADC values were estimated by fitting procedure. ANOVA and ROC analysis were performed. Sensibility, specificity, positive and negative predictive value and accuracy were obtained for different parameters. Results: 71 metastatic liver lesion were evaluated; 60 classified as responder (R) and 11 as nonresponder (NR). Applying a +25% ADC value increase cut-off, on the basis of the ADC fitted variation, of the 60 lesion classified as R: 25-34 and 35 were true R at time 1, 2 and 3 respectively; of the 11 NR lesion, 4-3 and 3 were true NR at time 1, 2 and 3 respectively. Evaluating the diameter changes, 31 lesions showed dimensional stability either at time 1 and 2. 29 metastatic lesions showed reduction in diameter, 8 of whom at time 1 and 20 at time 2. 11 lesions had dimensional increase, 10 at time 1 and 2 at time 2. Conclusion: an early (20-25 days since the beginning) fine diameter assessment could be a good indicator of the final response to CHT in metastatic liver . A slightly correlation between response to CHT and ADC changes in comparison to the diameter changes of the lesions was found.