To investigate the use of multi-parameter spectral computed tomography (CT) for the evaluation of rat C6 glioma, 15 male Wistar rats were seeded with C6 glioma cells into the right basal ganglia and scanned 12 days later using spectral CT. Brain sections corresponding to scanned regions were immunostained for proliferation marker protein Ki67 (Ki67). Pearson's correlation coefficients between spectral CT parameters and Ki67 expression were determined. Thirteen rats survived 12 days and developed tumors. Optimal contrast-to-noise ratio achieved was 65 keV. Brain regions containing liquefactive necrosis, solid tumor, peripheral tumor and normal tissue differed significantly with regard to the spectral curve slope (0.24±0.46, 1.81±1.09, 0.8±0.43 and 0.11±0.27, respectively; P<0.01), CT value (27.2±4.51, 103.18±35.48, 65.19±13.72 and 38.07±7.36, respectively; P<0.01) and iodine concentration (2.41±3.86, 16.05±9.75, 6.76±3.66 and 1.06±2.35, respectively; P<0.0001). The percentage of Ki67-positive cells correlated with the CT value (r=0.903; P<0.001), spectral curve slope (r=0.821; P<0.001) and iodine concentration (r=0.813; P<0.001). Spectral CT can detect microstructural changes within malignant gliomas and potentially provide important information regarding tumor proliferation and the extent of the invasion.
Keywords: Ki67; glioblastoma; histopathology; rat C6 glioma; spectral CT.