Triple-phase dynamic MRI: a new clue to predict malignant transformation of giant cell tumor of bone.

ABSTRACT

OBJECTIVE: Our purpose was, through the comparison of the characteristics of time-intensity curve on triple-phase dynamic contrast-enhanced MRI among groups of giant cell tumor of bone (GCTB), recurrent benign giant cell tumor of bone (RBGCTB), and secondary malignant giant cell tumor of bone (SMGCTB), to find clues to predict the malignant transformation of GCTB. SUBJECTS AND METHODS: 21 patients diagnosed as GCTB were included in this study. All cases took recurrence after intralesional curettage. 9 cases were confirmed as SMGCTB and 12 cases were confirmed as RBGCTB. Cases were divided into four groups group A, GCTB (n=9); group B, SMGCTB (n=9); group C, GCTB (n=12); group D, RBGCTB (n=12). Enhancement index(EI) of lesions on DCEMRI was calculated using formula EI(t)=[S(t)-S(0)]/S(0), where S(0) was signal intensity of lesion on non-contrast-enhanced T1-weighted images and S(t) was signal intensity of lesion on DCEMRI (t=30, 60, 180s). Enhancement index of each group in each phase was compared using One-Way ANOVA analysis. Slope values of time-intensity curve were compared by the same way. RESULTS: Time-intensity curve of SMGCTB was characterized by a steep upward slope followed by an early and rapid washout phase. Time-intensity curve of GCTB and RBGCTB was characterized by a steep slope followed by a relatively slow washout phase. No significant difference in enhancement index was found in the first phase (p>0.05). There was significant difference in the second and the third phase (p<0.05). Enhancement index of group B (SMGCTB) was smaller. There was no difference in rising slope value (p>0.05). CONCLUSIONS: Dynamic contrast-enhanced MRI appears a helpful method to find new clues to predict malignant transformation of GCTB.