ABSTRACT
Objective:To assess the predictive efficacy of 18F-FDG PET/CT-based radiomics models for the mutation status of Kirsten rats sarcoma viral oncogene homolog (KRAS) in patients with non-small cell lung cancer (NSCLC). Methods:From January 2016 to January 2021, the 18F-FDG PET/CT images and KRAS testing of 258 NSCLC patients (180 males, 78 females; age: 33-91 years) in the First Affiliated Hospital of the Air Force Military Medical University were retrospectively analyzed. Patients were randomly divided into training set ( n=180) and validation set ( n=78) in the ratio of 7∶3. Tumor lesions on PET and CT images were drawn respectively, and the radiomics features of PET and CT lesions were extracted. The radiomics features were screened by least absolute shrinkage and selection operator (LASSO). CT radiomics score (RS) model, PET/CT RS model and composite models of PET/CT RS combined with screened clinical information were eventually developed. ROC curves were used to assess the predictive efficacy of these models. Results:The CT RS model included 4 radiomics features and the PET/CT RS model included 4 CT radiomics features and 8 PET radiomics features. The CT RS model and the PET/CT RS model both had significant differences in RS between KRAS mutant and wild-type patients in the training set and validation set ( z values: from -8.30 to -4.10, all P<0.001). In predicting KRAS mutations, the composite model of PET/CT RS combined with age showed AUCs of 0.879 and 0.852 in the training and validation sets respectively, which were higher than those of the CT RS model (0.813 and 0.770) and the PET/CT RS model (0.858 and 0.834). The accuracy of the composite model of PET/CT RS combined with age were 81.67%(147/180) and 79.49%(62/78) in the training set and validation set respectively, which were also higher than those of the CT RS model (75.00%(135/180) and 74.36%(58/78)) and the PET/CT RS model (78.89%(142/180) and 78.21%(61/78)). Conclusion:Models based on radiomics features can predict KRAS gene mutation status, and the composite model combining PET/CT RS and age can improve the prediction performance.
ABSTRACT
BACKGROUND:Except for mechanical properties and physical and chemical properties, corrosion resistance testing is necessary for a variety of biomedical materials applied in the oral environment to ensure the biocompatibility of materials. OBJECTIVE:To explore the corrosion resistance of titanium abutment and different titanium aloysin vitro. METHODS:Corrosion environment byin vitroartificial saliva was constructed with pH=6.0 at (37±0.5)℃. Potentiodynamic polarization technique, scanning electron microscope and X-ray diffraction methods were employed to assess the corrosion resistance of titanium aloy, gold aloy, nickel-chromium aloy, and titanium abutment immersed in the artificial saliva for 24 hours. RESULTS AND CONCLUSION:Different aloys had different steady-state potentials, and the range of passivation region was the largest for gold aloy, folowed by titanium abutments and titanium aloys, and the smalest for nickel-chromium aloy. After 24 hours of immersion in the artificial saliva, passivation films appeared on the surface of different materials. under the scanning electron microscope, the nickel-chromium aloy surface showed obvious traces of corrosion and there were a large number of large-diameter deep pits, but no corrosion occurred on the surface of the remaining three kinds of aloys; on the surface of nickel-chromium aloy, the contents of chromium, molybdenum and aluminum were decreased, and the contents of nickel and oxygen were increased, but there were stil no changes on the surface of the remaining aloys. Cr2O3 was found on the surfaceof nickel-chromium aloy, TiO2 was generated on the surface of titanium abutment and titanium aloy, but Au and Pt stil existed in a single phase on the surface of gold aloy. These findings indicate that titanium aloy and titanium abutment have similar corrosion resistance that is inferior to the gold aloy, but better than the nickel-chromium aloy.
ABSTRACT
The report introduces a microcomputer controlled instrument which can be used to identify and diagnose acute cerebral apoplexy.The methods of statistics and probability theory are adopted by the instrument to select “body omen” and compute “value”.Z80A is used as the central processing unit and the external device is processed as an internal storage by using linear encodige.The instrurrent uses ZSOA assembly language to make software.