Bone Marrow Metastases: T2-weighted Dixon Spin-Echo Fat Images Can Replace T1-weighted Spin-Echo Images

Purpose: To test the potential of Dixon T2-weighted fat-only sequences to replace T1-weighted sequences for the detection of bone metastases, with the hypothesis that diagnostic performance with an alternative magnetic resonance (MR) imaging protocol (sagittal spin-echo Dixon T2-weighted fat-only and water-only imaging) would not be inferior to that with the standard protocol (sagittal spin-echo T1-weighted and spin-echo Dixon T2-weighted water-only imaging). Materials and Methods: A total of 121 consecutive whole-spine MR imaging examinations (63 men; mean age 6 standard deviation, 61.4 years 6 +/- 11.8) performed for suspected vertebral bone metastases were included in this retrospective, institutional review board-approved study. Quantitative image analysis was performed for 30 randomly selected spine levels. Qualitative analysis was performed separately by two musculoskeletal radiologists, who registered the number of metastases for each spine level. Areas under the curve with the protocols were compared on the basis of nonparametric receiver operating characteristic curve estimations by using a noninferiority test on paired data, with a best valuable comparator as a reference. Interobserver and interprotocol agreement was assessed by using k statistics. Results: Contrast-to-noise ratio was significantly higher on the alternative protocol images than on the standard protocol images (181.1 [95% confidence interval: 140.4, 221.7] vs 84.7 [95% confidence interval: 66.3, 103.1] respectively; P < .001). Diagnostic performance was not significantly inferior with the alternative protocol than with the standard protocol for both readers in a per-patient analysis (sensitivity, 97.9%-98.9% vs 93.6%-97.9%; specificity, 85.2%-92.6% vs 92.6%-96.3%; area under the curve, 0.92-0.96 vs 0.95, respectively; all P <= .02) and a per-spine level analysis (all P < .01). Interobserver and interprotocol agreement was good to very good (k = 0.70-0.81). Conclusion: Dixon T2-weighted fat-only and water-only imaging provide, in one sequence, diagnostic performance similar to that of the standard combination of morphologic sequences for the detection of probable spinal bone metastases, thereby providing an opportunity to reduce imaging time by eliminating the need to perform T1 sequences. (C) RSNA, 2017