Application of the apparent diffusion coefficient in magnetic resonance imaging in an assessment of the early response to treatment in Hodgkin's and non-Hodgkin's lymphoma - pilot study.

Purpose: Lymphoproliferative neoplasms are the largest and most frequently diagnosed entities in the group of haema-tological malignancies. The aim of the study was to assess whether apparent diffusion coefficient (ADC) measured on the first day of the second cycle of chemotherapy could be a predictor of prognosis and of the final treatment's outcome. Material and methods: The study included 27 patients with diagnosed Hodgkin's and non-Hodgkin's lymphoma, who had magnetic resonance (MR) performed with diffusion weighted imaging/apparent diffusion coefficient (DWI/ADC) before and on the first day of the second cycle of chemotherapy. Imaging was performed using a 1.5 T MR scanner. ADC was measured in lymphoma infiltration in the area of the lowest signal in the ADC map and the highest signal on b 800 images in post-treatment study. After that, the corresponding area was determined in a pre-treatment study and an ADC value was measured. Results: The difference between ADC values in pre-treatment (ADC = 720 mm2/s) and post-treatment (ADC = 1059 mm(2)/s) studies was statistically significant (p < 0.001). Cutoff values for estimating response to treatment were established at the level of ADC 1080 mm(2)/s, and ADC to muscle ratio at 0.82 in post-treatment study. Patients with ADC > 752 mm(2)/s before treatment manifested lower probability of progression than patients with ADC < 752 mm(2)/s. Conclusions: ADC measurement's before treatment and on the first day of the second cycle of chemotherapy can be used as a prognostic marker in lymphoma therapy. ADC values lower than 1080 mm(2)/s and an increase of the ratio after the treatment can be considered as a marker of disease progression.