Clinical significance of diffusion-weighted whole body magnetic resonance imaging with background body signal suppression (DWIBS) as a staging procedure for lymphoma patients in comparison with FDG-PET

Abstract

8084 Background: FDG-PET is thought to be an important staging tool in lymphomas. However, high cost and exposure to radioactive agents are of disadvantage. Diffusion weighted whole body magnetic resonance imaging with background body signal suppression (DWIBS) is recently reported to be a new way of magnetic resonance imaging which can make FDG-PET-like imaging possible to detect tumors (Takahara et al; Radiation Medicine 22: 275–282, 2004). This study is aimed to compare accuracy and clinical significance of DWIBS to FDG - PET. Methods: We examined 19 lymphoma (Ly) patients (pts) by using both DWIBS and FDG -PET at the time of diagnosis before therapy. There were follicular Ly in 3 pts, nodal marginal zone Ly in 1, diffuse large B-cell Ly in 9 including primary stomach Ly in 2, peripheral T -cell Ly in 4, and MALT Ly of stomach (GI-MALT) in 2. DWIBS was performed with a 1.5 -Tesla system as previously reported (Ochiai et al; Nichidoku -Iho 50: 86–98, 2005). Clinical staging was made according to the Ann Arbor classification. Results: Both DWIBS and FDG -PET had positive findings in 18 of 19 pts except for a case of GI -MALT. In nodal lesions, DWIBS was positive in 16 pts at 66 sites compared to 16 pts at 68 sites with FDG -PET. DWIBS was negative in 3 pts at 5 sites in spleen, hilar and mediastinal lymphnodes where positive in FDG -PET. DWIBS was positive in 2 pts at 4 sites in iliac and inguinal lymphnodes that are negative in FDG -PET. In extranodal lesions, DWIBS was positive in 12 pts at 17 sites as compared to 12 pts at 18 sites with FDG -PET. Involvement of bone and stomach were equally identified at 8 sites. DWIBS was negative in 2 pts at 2 sites in liver and pleura with FDG -PET positive. Small skin lesions were clearly identified on DWIBS. Discordance of clinical staging was not observed between DWIBS and FDG -PET. Conclusions: Although some discrepancy was seen between DWIBS and FDG -PET, there was no disadvantage of DWIBS compared to FDG -PET. Furthermore, DWIBS has no risk of radiation exposure and is even advantageous to detect lesions with FDG -PET negative. We conclude DWIBS is a new useful tool to assess tumor spread in lymphomas. No significant financial relationships to disclose.