Purpose: We assessed the diagnostic value of whole body magnetic resonance (MR) imaging (WB-MRI) using diffusion-weighted images (DWI) for detecting bone metastasis and compared it with that of skeletal scintigraphy (SS).
Materials and Methods: Thirty patients with malignancies (breast cancer, 17 patients; prostate cancer, 9; and one patient each, thyroid cancer, liposarcoma, leiomyosarcoma, and extraskeletal Ewing sarcoma) underwent both WB-MRI and SS to detect bone metastasis. All patients were followed more than 6 months by MR imaging, SS, or computed tomographic (CT) examination. For WB-MRI, patients were placed in feet-first supine position with table-top extender and quadrature body coil.
We acquired DWI (axial plane from lower neck to proximal femur) (single shot short TI inversion-recovery [STIR]: repetition time [TR] 6243/echo time [TE] 59/inversion time [TI] 180 ms; b value: 600 s/mm²; 5-mm slice thickness; 112×112 matrix), T₁-weighted fast spin echo (T₁WI), and STIR (sagittal plane of total spine images and coronal plane of whole body images) images.
Four blinded readers independently and separately interpreted images of combined MR sequences of T₁WI+STIR (session 1) and T₁WI+STIR+DWI (session 2).
Results: In 10 of 30 patients, we detected a total of 52 metastatic bone lesions; in the other 20, follow-up examinations confirmed no metastatic bone lesions.
For these 52 lesions, for session 2, the mean sensitivity was 96% and the positive predictive value (PPV) was 98%. Those values were superior to those of session 1 (sensitivity: 88%; PPV: 95%) and those of SS (sensitivity: 96%; PPV: 94%).
Conclusion: WB-MRI that included DWI was useful for detecting bone metastasis.