Whole-body diffusion-weighted magnetic resonance imaging at 3 Tesla for early assessment of treatment response in non-Hodgkin lymphoma: a pilot study

Objective: To evaluate 3 Tesla (T) whole-body diffusion-weighted magnetic resonance imaging (WB DWI) for early treatment assessment in aggressive non-Hodgkin lymphoma (NHL). Methods: Fourteen patients with NHL treated with standard chemotherapy underwent 3-T WB DWI before and 2 and 4 weeks during treatment, using b-values of 0-1000 s/mm(2) from which the apparent diffusion coefficient (ADC) was calculated. Patient follow-up (average 20.3 months, range 15-23 months) was the reference standard. Volume and ADC changes between baseline and 2 weeks (Vratio(2w), ADCratio(2w)) and 4 weeks (Vratio(4w), ADCratio(4w)) of responding and non-responding lesions (lymph node and organ lesions) were compared using Mann-Whitney U tests. The per patient values of Vratio(N) and ADCratio(N) to predict progression-free survival were determined with a log-rank test. Results: Eight patients showed complete remission and 6 showed tumour progression. The ADCratio(2w) and ADCratio(4w) differed significantly in lesions showing tumour progression versus complete remission (ADCratio(2w) = 4 +/- 21% versus 119 +/- 68%; ADCratio(4w) = 18 +/- 61% versus 155 +/- 78%; both P<0.0001); the Vratio(2w) and Vratio(4w) did not (P>0.05). Per body region, the ADCratio(2w) showed a negative predictive value of 100% and positive predictive value of 86%. Per patient, the ADCratio(2w) and ADCratio(4w) correlated significantly with progression-free survival (P<0.05). Conclusion: 3-T WB DWI with ADC quantification may enable early treatment assessment of aggressive NHL.