Supplemental value of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) technique to whole-body magnetic resonance imaging in detection of bone metastases from thyroid cancer.

INTRODUCTION: We compared the efficacy of whole-body MRI (WBMRI) with and without diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) using a 3.0-T MR scanner to [18F] fluoro-2-D-glucose positron emission tomography with CT (integrated FDG-PET/CT) for the detection of bone metastases in patients with differentiated thyroid carcinoma (DTC).

METHODS: We examined 23 patients (16 women, 7 men; mean age, 56; range 17-74) with DTC who had undergone total thyroidectomy and were hospitalised to receive [I-131I] therapy. All patients underwent both WBMRI with DWIBS and whole-body FDG-PET/CT. The skeletal system was classified into 13 anatomic segments and assessed for the presence of bone metastases. Bone metastases were verified when positive findings were indicated on at least two imaging modalities: post-treated [131I] whole-body scans, WBMRI without DWIBS (T1-weighted images and short-inversion time inversion recovery images), [18F]-FDG-PET and CT.

RESULTS: Bone metastases were confirmed in 78/290 (27%) segments in 20 (87%) of 23 patients. The sensitivities for bone metastases on a segment basis using WBMRI with DWIBS, WBMRI without DWIBS and integrated FDG-PET/CT were 64 of 78 (82%), 50 of 78 (64%) and 62 of 78 (79%), respectively; the difference between values of WBMRI with and without DWIBS was statistically significant (P = 0.0015). The overall accuracies of WBMRI with DWIBS, WBMRI without DWIBS and integrated FDG-PET/CT were 273 of 290 (94%), 261 of 290 (90%) and 272 of 290 (94%), respectively; the difference between values of MRI with and without DWIBS was also statistically significant (P = 0.003). There were only one to three false positive segments and the difference among specificities was not statistically significant in these modalities.

CONCLUSION: Adding DWIBS improved the sensitivity and the overall accuracy of WBMRI using 3.0-T MRI for the detection of bone metastases in patients with DTC. There was no statistically significant difference in diagnostic accuracy between MRI with DWIBS and integrated FDG-PET/CT.