Application of spectral CT imaging in making early evaluation of the effect of 125I particle interstitial brachytherapy for pancreatic carcinoma: an experimental study / 介入放射学杂志

ABSTRACT

Objective To discuss the application of spectral CT imaging in evaluating the early therapeutic response of 125I seed interstitial brachytherapy for pancreatic carcinoma in experimental nude mice.Methods BxPC-3 human pancreatic cancer cell xenografts were subcutaneously inoculated at the dorsal part of the limbs in 16 BABL/c nude mice. When the tumor developed to the size of 1-1.5 cm, the tumor-bearing mice were randomly divided into the study group (n=8,receiving implantation of 125I seeds of 1.0 mCi) and the control group (n=8,receiving implantation of ghost shell particles of 0 mCi). Two weeks after the procedure, plain spectral CT scan as well as enhanced multiphase (10 s, 25 s and 60 s) spectral CT scan were performed to obtain multi-phasic image series. The contrast-to-noise ratio (CNR) and iodine concentration (IC) inside the lesions were determined, and the normalized iodine concentrations (nIC) of tumor were thus obtained. Immunohistochemical staining of tumor was used to measure microvessel density (MVD) within the tumor;the correlation between nIC and MVD was analyzed. Results The lesion's nICs measured on each of three phases (10 s,25 s and 60 s) in the study group were lower than those in the control group, the differences were statistically significant (P<0.05). MVD count in the study group was lower than that in the control group, the difference was statistically significant (t=5.957,P<0.01). A parallel linear correlation existed between nIC obtained from each phase of three phases and MVD count (r=0.63,P<0.000 1;r=0.51,P=0.002;and r=0.48,P=0.001 7 for 10 s, 25 s and 60 s phases respectively). Conclusion Spectral CT imaging is an effective method for evaluating the therapeutic effect of 125I seed interstitial brachytherapy for pancreatic carcinoma of experimental mice.