Whole-body MRI to assess bone involvement in prostate cancer and multiple myeloma: comparison of the diagnostic accuracies of the T1, short tau inversion recovery (STIR), and high b-values diffusion-weighted imaging (DWI) sequences.

ABSTRACT

PURPOSE: To compare the diagnostic accuracy of whole-body T1, short tau inversion recovery (STIR), high b-value diffusion-weighted imaging (DWI), and sequence combinations to detect bone involvement in prostate cancer (PCa) and multiple myeloma (MM) patients. MATERIALS AND METHODS: We included 50 consecutive patients with PCa at high risk for metastasis and 47 consecutive patients with a histologically confirmed diagnosis of MM who received whole-body MRI at two institutions from January to December 2015. Coronal T1, STIR, and reconstructed coronal high b-values DWI were obtained for all patients. Two musculoskeletal radiologists read individual sequences, pairs of sequences (T1-DWI, T1-STIR, and STIR-DWI), and all combined (T1-STIR-DWI) to detect bone involvement. Receiver operating characteristic curve analysis was used to assess diagnostic performance according to a "best valuable comparator" combining baseline and 6-month imaging and clinical and biological data. Interobserver agreement was calculated. RESULTS: Interobserver agreement for individual and combined MRI sequences was very good in the PCa group and ranged from good to very good in the MM group (0.76-1.00). In PCa patients, T1-DWI, T1-STIR, and T1-STIR-DWI showed the highest performance (sensitivity = 100% [95% CI = 90.5-100%], specificity = 100% [75.3-100%]). In MM patients, the highest performance was achieved by T1-STIR-DWI (sensitivity = 100% [88.4-100%], specificity = 94.1% [71.3-100%]). T1-STIR-DWI significantly outperformed all sequences (p < 0.05) except T1-DWI (p = 0.49). CONCLUSION: In PCa patients, a combination of either T1-DWI or T1-STIR sequences is not inferior to a combination of three sequences to detect bone metastases. In MM, T1-STIR-DWI and T1-DWI had the highest diagnostic performance for detecting bone involvement. KEY POINTS • The sequences used in Whole Body MRI studies to detect bone involvement in prostate cancer and myeloma were evaluated. • In prostate cancer, any pairwise combinations of T1, STIR, and DWI have high diagnostic value. • In myeloma, the combinations T1-STIR-DWI or T1-DWI sequences should be used.