R. Oyen

Whole-body diffusion-weighted magnetic resonance imaging for staging and early treatment response assessment in malignant lymphoma

SUMMARY

Diffusion-weighted magnetic resonance imaging (DW/MRI) is a radiation-free functional imaging technique reflecting tissue cellularity by probing the diffusion of water molecules on a microstructural level. This can be assessed visually, but also quantified by calculating the apparent diffusion coefficient (ADC). Although established in many solid tumours and multiple myeloma, its role in disease assessment in malignant lymphoma has yet to be determined. Therefore, the main purpose of this work was twofold: exploring the performance of whole-body DW/MRI (WB-DW/MRI) in staging malignant lymphoma and assessing treatment response early during treatment with 18F-FDG-PET/CT in combination with bone marrow biopsy results serving as the gold standard. Regarding staging, we found that WB-DW/MRI is a feasible imaging technique. Visual image analysis sufficed to accurately detect extranodal disease, while adequate nodal characterisation required ADC calculations. Lymph node characterisation was further improved by using a more elaborate quantitative analysis based on ADC parameters derived from whole-lesion ADC histogram analysis next to the commonly used mean ADC. In the context of treatment response assessment, mean ADC changes between the baseline and interval scan performed after one cycle of (immuno)chemotherapy significantly correlated with progression-free-survival in patients with aggressive non-Hodgkin lymphoma (NHL). For Hodgkin lymphoma, taking into account the typical intralesional heterogeneity, an advanced 3-D texture analysis was performed, which demonstrated that ADC parameters associated with tumour heterogeneity (energy, local homogeneity, and entropy) were predictive of outcome in contrast to conventional ADC parameters.

(BELG J HEMATOL 2018;9(6):242–4)

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