Malignant Bone Tumor Intramedullary Invasion: Evaluation With Dual-Energy Computed Tomography in a Rabbit Model

Purpose: The aim of this study was to investigate the usefulness of dual-energy computed tomography (CT) spectral imaging for differentiating intramedullary microscopic invasion from simple marrow edema in a rabbit VX2 carcinoma model. Methods: VX2 tumors were implanted into the right tibiae of 30 New Zealand white rabbits. After 4 weeks, single-source dual-energy spectral CT was performed, and tumor specimens were cut into sagittal sections and partitioned into pathological slices. Multiplanar reconstruction images corresponding to the sagittal sections were selected for dot-to-dot comparisons to determine the macroscopic tumor, transition, and normal marrow areas. The regions of interest were classified into the above 3 areas according to the pathological maps to construct the CT spectral curves, and the slopes of the curves were calculated. Results: The slope of the spectral curve in the transition area (7.78 +/- 3.40) was significantly greater than that in the macroscopic tumor area (3.71 +/- 2.15) and smaller than that in the normal marrow area (12.88 +/- 4.12) (P < 0.001). Regarding the transition area, the slope of the spectral curve of the microscopic tumor invasion zone (10.87 +/- 2.69) was greater than that of the simple bone marrow edema zone (5.84 +/- 2.11) (P < 0.001). Conclusions: The properties of transition areas (microscopic invasion or simple bonemarrow) can be determined by comparing spectral curves generated using dual-energy CT.