Whole-body MRI, including diffusion-weighted imaging, for the initial staging of malignant lymphoma: comparison to computed tomography.

PURPOSE

To assess the value of whole-body magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI), for the initial staging of malignant lymphoma, compared with computed tomography (CT).

MATERIALS AND METHODS

Thirty-one consecutive patients with newly diagnosed malignant lymphoma prospectively underwent whole-body MRI (T1-weighted and short inversion time inversion recovery [n = 31], and DWI [n = 28]) and CT. Ann Arbor stages were assigned by 1 radiologist according to whole-body MRI findings, and by another radiologist according to CT findings. Differences in staging between whole-body MRI (without and with DWI) and CT were resolved using other (imaging) studies (including 18F-fluoro-2-deoxyglucose positron emission tomography and bone marrow biopsy) and follow-up studies as reference standard.

RESULTS

Staging results of whole-body MRI without DWI were equal to those of CT in 74% (23/31), higher in 26% (8/31), and lower in 0% (0/31) of patients, with correct/incorrect/unresolved overstaging relative to CT in 3, 2, and 2 patients, respectively, and incorrect staging of both modalities in 1 patient. Staging results of whole-body MRI with DWI were equal to those of CT in 75% (21/28), higher in 25% (7/28), and lower in 0% (0/28) of patients, with correct/incorrect overstaging relative to CT in 6 and 1 patient(s), respectively.

CONCLUSION

Our results suggest that initial staging of malignant lymphoma using whole-body MRI (without DWI and with DWI) equals staging using CT in the majority of patients, whereas whole-body MRI never understaged relative to CT. Furthermore, whole-body MRI mostly correctly overstaged relative to CT, with a possible advantage of using DWI.