Differentiation of myeloma and metastatic cancer in the spine using dynamic contrast-enhanced MRI

Spinal myeloma and metastatic cancer cause similar symptoms and show similar imaging presentations, thus making them difficult to differentiate. In this study, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was performed to differentiate between 9 myelomas and 22 metastatic cancers that present as focal lesions in the spine. The characteristic DCE parameters, including the peak signal enhancement percentage (SE%), the steepest wash-in SE% during the ascending phase and the wash-out SE%, were calculated by normalizing to the precontrast signal intensity. The two-compartmental pharmacokinetic model was used to obtain K-trans and K-ep. All nine myelomas showed the wash-out DCE pattern. Of the 22 metastatic cancers, 12 showed wash-out, 7 showed plateau, and 3 showed persistent enhancing patterns. The fraction of cases that showed the wash-out pattern was significantly higher in the myeloma group than the metastatic cancer group (9/9 = 100% vs. 12/22 = 55%, P=.03). Compared to the metastatic cancer group, the myeloma group had a higher peak SE% (226%+/- 72% vs. 165%+/- 60%, P=.044), a higher steepest wash-in SE% (169%+/- 51% vs. 111%+/- 41%, P =.01), a higher K-trans (0.114 +/- 0.036 vs. 0.077 +/- 0.028 1/min, P=.016) and a higher k(ep) (0.88 +/- 0.26 vs. 0.49 +/- 0.23 1/min, P=.002). The receiver operating characteristic analysis to differentiate between these two groups showed that the area under the curve was 0.798 for K-trans, 0.864 for k(ep) and 0.919 for combined k(trans) k(ep). These results show that DCE-MRI may provide additional information for making differential diagnosis to aid in choosing the optimal subsequent procedures or treatments for spinal lesions. (C) 2013 Elsevier Inc. All rights reserved.