Quantitative Analysis of the Characteristics of Sacral Giant Cell Tumors Using Contrast-Enhanced Computed Tomography

  Although CT morphological characteristics of giant cell tumors (GCTs) of the sacrum have been reported in the literature, the enhanced CT quantitative characteristics of GCTs have not been extensively evaluated. The aim of our study was to analyze the enhancement characteristics of giant cell tumors of the sacrum. Patients and Sixty-one cases were reviewed, including 20 GCTs, 22 sacral chordomas (SCs) and 19 sacral schwannomas (SSs). The CT images of all the three types of tumors were retrospectively analyzed. The enhancement index (EI) of each mass was calculated by the formula: EI(a/v) = [D(a/v) - D(pre)]/D(pre), where D(a/v) was the density of the mass on the enhanced CT (a = arterial phase; v = portal venous phase), and D(pre) was the density of the mass on the pre-enhanced images. The maximum enhancement (Emax) was determined by the following equation: Emax = D(v) - D(pre). The parameters of the different enhancement phases among the 3 groups were compared with One-way ANOVA. On the noncontrast images, the densities of the SCs were lower than those of the GCTs and SSs, but there was no difference between the GCTs and SSs (P > 0.05). In the arterial phase, the EIa of the GCTs was the highest among the three groups (P < 0.05), and that of the SCs was the lowest. In the venous phase, the EIv of the GCTs was higher than that in the arterial phase and was also the highest among the three groups (P < 0.05). A difference was found among the groups, namely, the GCTs, SCs, and SSs (P < 0.05). The EIa and EIv of the SCs were the lowest among the three groups. The Emax of the GCTs was the highest among the three groups (P < 0.05). Quantitative analysis of the characteristics of contrast-enhanced CT is a useful method for diagnosing sacral GCTs and differentiating these tumors from SCs and SSs.