ABSTRACT
Objective:To establish O-(2-[ 18F]fluoroethyl)- L-tyrosine( 18F-FET) PET radiomics features-based model and investigate its predictive efficacy for isocitrate dehydrogenase type 1 (IDH1) genotyping in untreated gliomas. Methods:From November 2017 to February 2019, 58 pathologically confirmed glioma patients (36 males, 22 females; age (41.8±15.1) years) with preoperative 18F-FET PET/CT imaging in Huashan Hospital, Fudan University were retrospectively enrolled. PyRadiomics software package was used to extract 105 radiomics features. Least absolute shrinkage and selection operator (LASSO) algorithm with 5-fold cross-validation was used to build the logistic regression model. And radiomic scores (RS) of each lesion were calculated according to their weighted coefficients. The area under the receiver operating characteristic (ROC) curve was used for evaluating the predictive efficacy for IDH1 prediction. The predictive efficacies of radiomics model and traditional semi-quantitative parameters including tumor-to-background ratio (TBR; maximum TBR (TBR max), mean TBR (TBR mean), peak TBR (TBR peak)), metabolic tumor volume (MTV) and total lesion tracer uptake (TLU), were compared by Delong test. Results:Seven radiomics features including maximum 2-dimensional (2D) diameter slice, first order_maximum, first order_range, gray level co-occurrence matrix (GLCM)_joint energy, GLCM_inverse variance, gray level dependence matrix (GLDM)_dependence entropy and GLDM_large dependence low gray level emphasis were selected for the LASSO regression model building and RS calculation. ROC analysis results showed that the predictive accuracy of RS for IDH1 genotyping (mutation, n=20; wild-type, n=38) was 81.0%(47/58), with sensitivity of 65.0%(13/20), specificity of 89.5%(34/38), and area under curve (AUC) of 0.842, respectively. The traditional 18F-FET semi-quantitative parameter TLU ranked the second regarding the diagnostic performance, with accuracy of 60.3%(35/58), sensitivity of 85.0%(17/20), specificity of 47.4%(18/38), and AUC of 0.661( z=3.426, P<0.01). Conclusion:Radiomics analysis based on 18F-FET PET images can improve the predictive efficacy for IDH1 genotyping in untreated adult glioma patients.
ABSTRACT
Objective:To preliminarily explore the effects of tumor treating fields (TTF) arrays on the dose distribution in the treatment of Glioblastoma (GBM) using combined radiotherapy and concurrent TTF.Methods:EDR2 and MatriXX plate ionization chamber were employed to measure the absorbed doses of tissues at different depths (< 1 mm, 3 mm, 5 mm, 1 cm, 1.5 cm, 3 cm, 5 cm, 10 cm, and 15 cm) in the case that TTF arrays and latex-free foam were attached and not attached on the surface. Then the absorbed doses were calculated, compared, and analyzed. For the volumetric arc therapy (VMAT) of 10 GBM patients, deep dose verification was performed using the Sun Nuclear ArcCheck 3D dose verification system and the D99%, Dmean, and D1% of tumors and OARs were assessed. Results:The surface dose increased by 173% in the case that TTF arrays and latex-free foam were attached to the surface compared with the case of the surface with nothing attached. The surface dose increased by 61.7% due to the attachment of low-density latex-free foam. The dose deviation gradually decreased with an increase in the depth and stabilized (about 4%) at a depth of greater than 1.5 cm. As indicated by the VMAT verification result, the D99%, Dmean, and D1% of PTV and CTV decreased by 1.1%-1.2% and the Dmean and D1% of OARs (i.e., brainstem, pituitary gland, optic chiasma, optic nerve, eyeball, and eye crystal) decreased by 0.7%-1.5% in the case that TTF array and latex-free foam were attached on the surface compared with the case the surface with nothing attached. Conclusions:The combined radiotherapy and concurrent TTF in the GBM treatment will lead to a slight reduction of the absorbed doses of targets and OARs but a significant increase in the absorbed doses of the scalp. Therefore, it is recommended that the scalp doses should be reduced as far as possible in the design of the radiation treatment plan to reduce the adverse reactions on the scalp of GBM patients.
ABSTRACT
Objective To investigate the role of autophagy in radiation-induced death response of human nasopharyngeal carcinoma cells.Methods MTT method was used to detect cell viability of CNE-2 cells in different time after irradiation.Clonogenic survival assay was used to evaluate the effect of autophagy inhibitor (chloroquine phosphate) and autophagy inductor (rapamycin) on radiosensitivity of nasopharyngeal carcinoma cells.Cell apoptosis was assessed by flow cytometry.The expressions of LC3 and P62 were measured with Western blot.Cell ultrastructural analysis was performed under an electron microscope.Results Irradiation with 10 Gy induced a massive accumulation of autophagosomes accompanied with up-regulation of LC3-Ⅱ expression in CNE-2 cells.Compared with radiation alone,chloroquine phosphate (CDP) enhanced radiosensitivity significantly by decreasing cell viability (F =25.88,P ＜ 0.05),autophagic ratio (F =105.15,P ＜ 0.05),and LC3-Ⅱ protein level(F =231.68,P ＜0.05),while up-regulating the expression of P62 (F =117.52,P ＜ 0.05).Inhibition of autophagy increased radiation-induced apoptosis (F =143.72,P ＜ 0.05).Rapamycin (RAPA) also significantly decreased cell viability,but increased autophagic ratio and LC3-Ⅱ protein level while down-regulated the expression of P62.Induction of autophagy increased radiation-induced apoptosis(F =167.32,P ＜ 0.05).Conclusions Blockage of autophagy with CDP could enhance radiosensitivity in human nasopharyngeal carcinoma cells,suggesting that inhibition of autophagy could be used as an adjuvant treatment to nasopharyngeal carcinoma.