Whole-body diffusion-weighted MR and FDG-PET/CT in Hodgkin Lymphoma: Predictive role before treatment and early assessment after two courses of ABVD

Purpose: To evaluate whether imaging features of pathologic lymph nodes on whole-body diffusion-weighted MR have a predictive role before treatment and may assess the response after two courses of chemotherapy in comparison to FDG-PET/CT in Hodgkin Lymphoma. Materials and methods: We reviewed the whole-body MR and FDG-PET/CT performed on 41 patients with Hodgkin Lymphoma before and after two Doxorubicin-Bleomycin-Vinblastine-Dacarbazine (ABVD). Responder and non-responder lesions were identified on interim-FDG-PET/CT performed after two ABVD. We used Multivariate Generalized Estimating Equations model to assess statistical association between being-responder and baseline-Maximum Standard Uptake Value (SUVmax), baseline and interim-Apparent Diffusion Coefficient (ADC) and size, ADC and size changes during chemotherapy, site of disease, bulky, and stage. Results: 10/41 (24%) patients were positive on interim-FDG-PET/CT. The interim-FDG-PET/CT positivity was associated with worse cumulative survival rate at 24 months in comparison to interim-FDG-PET/CT negativity (P <.05); 3/10 patients with positive interim-FDG-PET/CT and 1/31 with negative interim-FDG-PET/CT experienced disease progression. Baseline-SUVmax was 11.18 ± 5.58 (3.1–28.0) and baseline-ADC was 0.70 ± 0.14 × 10−3 mm2/s (0.39–0.98). There was a significant difference between responder and non-responder lesions based on interim-ADC (1.83 ± 0.34 × 10−3 mm2/s vs. 1.01 ± 0.27 × 10−3 mm2/s;p <.001), interim-size (3.1 cm2 vs. 9.4 cm2;p =.009), and bulky (8.2% vs. 66.7%;p =.002). There was no significant difference between responder and non-responder lesions based on baseline-SUVmax (p =.713), baseline-ADC (p =.253), ADC changes (p =.058), size changes (p =.085), site (p =.209), stage (p =.290), baseline-size (p =.064). Conclusions: Interim-ADC is helpful for identifying non-responder lesions, while size changes are not useful. Baseline-SUVmax and ADC have no predictive role. Bulky is the most useful imaging parameter to predict suboptimal response to chemotherapy.