| Other Abstract | Purposes: To investigate whether the quantitative parameters of spectral CT (iodine concentration, single energy CT value, spectral curve slope) can evaluate the efficacy of radiotherapy combined with temozolomide (TMZ) in the rat model of C6 glioma.
Methods: Fifty healthy male Wister rats were inoculated with C6 glioma cells in their brains to establish the rat model of C6 glioma. Spectral enhanced CT examination was performed on the rats on the 14th day after inoculation to observe the tumor formation. Forty-eight tumor-forming rats were randomly divided into control group, TMZ group, radiotherapy group and radiotherapy combined with TMZ group. Spectral CT enhanced scan was performed on the 1st and 7th day after the intervention for each group, and the changes of quantitative parameters of spectral CT (iodine concentration, 70 keV CT value and spectral curve slope) after treatment were observed in each group. After the completion of spectral enhanced CT scan at each time point, 3 rats were randomly sacrificed for heart perfusion and brain was collected. The brain tissue of rats was stained with HE and the number of Ki67 and CD105-MVD immunohistochemical positive cells was counted. One-way analysis of variance was used to compare the quantitative parameters of spectral CT among each group, and independent sample t test was used to compare the quantitative parameters of spectral CT before and after intervention. The Pearson correlation analysis was used to analyze the CT quantitative parameters and immunohistochemical counts of different groups.
Results: 1.There were no significant differences in tumor iodine concentration, 70 keV CT value and spectral curve slope between the four groups (p>0.05). After intervention, iodine concentrations in TMZ group, radiotherapy group and combined group were (8.75±1.05), (8.41±0.76), (6.84±0.76) 100ug/cm3 on day 1,and compared with the control group (11.12±2.48) 100ug/cm3 , all p<0.001;(7.61±0.70), (7.11±0.56), (5.70±0.76) 100ug/cm3 on day 7 and compared with the control group(13.65±2.51) 100ug/cm3 , all p<0.001.The 70 keV CT values of TMZ group, radiotherapy group and combined group were (61.54±4.46), (59.57±6.07), (56.25±4.92)HU on day 1 ,and compared with the control group (77.64±9.27) HU,all p<0.001;(57.87±5.00), (54.47±3.71), (48.19±6.44)HU on day 7,and compared with the control group (90.28±16.07)HU, all p<0.001. The spectral curve slope were (1.61±2.42), (1.55±0.13), (1.43±0.35) on day 1, and compared with the control group (2.01±0.53), all p<0.001;(1.34±0.24), (1.30±0.14), (1.06±0.70) on day 7, and compared with the control group (2.55±0.07), all p<0.001. The difference of 70 keV CT value between the 1st day after intervention and before intervention in TMZ group was statistically significant (p<0.01), the difference of iodine concentration, 70 keV CT value and slope between the 7th day and before intervention in TMZ group was statistically significant (p<0.01). The difference of spectral CT parameters between the1st day and the 7th day after intervention in radiotherapy group and combination group was statistically significant (p<0.05).
2.The correlation coefficients r between iodine concentration and Ki67 in the control group, TMZ group, radiotherapy group and combined group were 0.7619, 0.6997, 0.8235 and 0.8783, respectively, p<0.05;The coefficients r between 70 keV CT value and Ki67 in the four groups were 0.6892, 0.7382, 0.8511, 0.7629, p<0.05. The correlation coefficient r between the spectral curve slope of four groups of curves and Ki67 were 0.6888, 0.6399, 0.8524 and 0.8833, respectively, p<0.05. The correlation coefficients r between iodine concentration and CD105-MVD in the four groups were 0.8393, 0.8011, 0.7974 and 0.8743, respectively, p<0.05;The correlation coefficients r between 70 keV CT value and CD105-MVD in the four groups were 0.6558, 0.8072, 0.6816 and 0.8776, respectively. Except for the control group (p =0.0551), the others (p<0.05). The correlation coefficients r between spectral curve slope and CD105-MDV in the four groups were 0.7487, 0.7283, 0.8374 and 0.8651, respectively, p <0.05.
Conclusion: 1.The quantitative parameters of spectral CT (iodine concentration, 70 keV CT value, spectral curve slope) were well correlated with tumor proliferation index and microvessel density. The quantitative parameters of spectral CT could be used to reflect the aggressiveness of brain glioma and the formation of tumor microvessels in rats.
2. Spectral parameters (iodine concentration, 70 keV CT value, slope of spectral curve slope) can realize the early efficacy evaluation of radiotherapy combined with TMZ in rats, which provides a new method and a new idea for clinical efficacy evaluation of glioma. |
