RESUMO
The aim of this study was to evaluate the oxygen partial pressure of the rabbit model of the VX2 tumor using a 64-slice perfusion CT and to compare the results with that obtained using the oxygen microelectrode method. Perfusion CT was performed for 45 successfully constructed rabbit models of a VX2 brain tumor. The perfusion values of the brain tumor region of interest, the blood volume (BV), the time to peak (TTP) and the peak enhancement intensity (PEI) were measured. The results were compared with the partial pressure of oxygen (PO2) of that region of interest obtained using the oxygen microelectrode method. The perfusion values of the brain tumor region of interest in 45 successfully constructed rabbit models of a VX2 brain tumor ranged from 1.3-127.0 (average, 21.1 ± 26.7 ml/min/ml); BV ranged from 1.2-53.5 ml/100g (average, 22.2 ± 13.7 ml/100g); PEI ranged from 8.7-124.6 HU (average, 43.5 ± 28.7 HU); and TTP ranged from 8.2-62.3 s (average, 38.8 ± 14.8 s). The PO2 in the corresponding region ranged from 0.14-47 mmHg (average, 16 ± 14.8 mmHg). The perfusion CT positively correlated with the tumor PO2, which can be used for evaluating the tumor hypoxia in clinical practice.
Assuntos
Neovascularização Patológica/diagnóstico por imagem , Neovascularização Patológica/metabolismo , Oximetria/métodos , Oxigênio/metabolismo , Imagem de Perfusão/métodos , Neoplasias de Tecidos Moles/diagnóstico por imagem , Neoplasias de Tecidos Moles/metabolismo , Animais , Velocidade do Fluxo Sanguíneo , Feminino , Masculino , Coelhos , Radiografia , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
CT perfusion imaging is a promising technique for delineating the target volume for three-dimensional conformal radiotherapy, but it is difficult in humans to obtain gross pathological samples at the same level of the brain tumor to evaluate this technique. The aim of this study was to use the BV map of CT perfusion imaging to assess the target volume in the rabbit VX2 brain tumor model, which has similar characteristics to human brain tumor, and compare the results to those of CECT. New Zealand white rabbits were used for the animal model. After tumor cell implantation 21 rabbits underwent 64-slice CT scanning. The target slice was selected and the maximum major axis length and minimum minor axis length of the tumor in the target slice on BV maps and contrast-enhanced CT images were measured. Pathological specimens were obtained from the rabbit brains which were removed intact. The GTV and CTV of the imaging methods were compared. Scanning was successful in 20 rabbits. The CECT images showed the target area for the VX2 tumor in 16 rabbits. The BV maps showed the target area for the tumor in 20 rabbits. The probability was 95% that the GTV determined by pathology can be covered completely when BV maps are used. CT perfusion imaging appears to be a promising technique for delineating the GTV of brain tumors in clinical practice.