Objective: To evaluate the efficacy, feasibility and safety of contrast-enhanced CT-guided core biopsy of retroperitoneal masses. Materials and Methods: Contrast-enhanced CT-guided biopsy of retroperitoneal masses was...Objective: To evaluate the efficacy, feasibility and safety of contrast-enhanced CT-guided core biopsy of retroperitoneal masses. Materials and Methods: Contrast-enhanced CT-guided biopsy of retroperitoneal masses was performed in 26 patients. Histopathological diagnosis was obtained and accuracy was calculated. Two blinded radiologists determined feasibility of biopsy procedures on routine CT-guidance, and compared accessibility of target lesions using contrast-enhanced and non-contrast-enhanced CT. Results: Satisfactory samples were obtained in all 26 patients and pathological diagnosis was made in 24. Accuracy was 95.5%. Routine CT-guided biopsy punctures were not satisfaction in 4/26 patients, and contrast-enhanced CT scans rendered the target lesions more accessible in 16 patients. Conclusion: Contrast-enhanced CT-guided biopsy increases the feasibility of biopsy of retroperitoneal masses.展开更多
On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular ...On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of CGWs.An appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the circumference.Using a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode selected.The theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic generated.Potential applications of the enhancement effect of cumulative SHG of CGWs are considered and discussed.The theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube.展开更多
The scattering and absorption of light propagating underwater cause the underwater images to present lowcontrast,color deviation,and loss of details,which in turn make human posture recognition challenging.To address ...The scattering and absorption of light propagating underwater cause the underwater images to present lowcontrast,color deviation,and loss of details,which in turn make human posture recognition challenging.To address these issues,this study introduced the dual-guided filtering technique and developed an underwater diver image improvement method.First,the color distortion of the underwater diver image was solved using white balance technology to obtain a color-corrected image.Second,dual-guided filtering was applied to the white balanced image to correct the distorted color and enhance its details.Four feature weight maps of the two images were then calculated,and two normalizedweightmapswere constructed formulti-scale fusion using normalization.To better preserve the obtained image details,the fusion image was histogram-stretched to obtain the final enhanced result.The experimental results validated that this method has improved the accuracy of underwater human posture recognition.展开更多
The traditional small target detection algorithm often results in a high false alarm rate on the sea surface background. To address this issue, a small target detection method based on guided filtering and local avera...The traditional small target detection algorithm often results in a high false alarm rate on the sea surface background. To address this issue, a small target detection method based on guided filtering and local average gray level difference was proposed in this paper for the sea surface. Firstly, the method enhanced the details of the small targets by employing guided filtering to suppress the background clutter and noise in the sea surface image. Subsequently, the local average gray level difference of each point in the image was calculated to further distinguish the targets from other interference points. Finally, the threshold segmentation method was utilized to obtain the actual small targets on the sea surface. After conducting experiments on various sea surface scenes, the LSCRG, BSF, and ROC curve were computed for the proposed method and five other algorithms. Comparative analysis with BS, Top-hat, TDLMS, Max-median, and LCM demonstrates the superiority of the proposed method for infrared small target detection on the sea surface.展开更多
文摘Objective: To evaluate the efficacy, feasibility and safety of contrast-enhanced CT-guided core biopsy of retroperitoneal masses. Materials and Methods: Contrast-enhanced CT-guided biopsy of retroperitoneal masses was performed in 26 patients. Histopathological diagnosis was obtained and accuracy was calculated. Two blinded radiologists determined feasibility of biopsy procedures on routine CT-guidance, and compared accessibility of target lesions using contrast-enhanced and non-contrast-enhanced CT. Results: Satisfactory samples were obtained in all 26 patients and pathological diagnosis was made in 24. Accuracy was 95.5%. Routine CT-guided biopsy punctures were not satisfaction in 4/26 patients, and contrast-enhanced CT scans rendered the target lesions more accessible in 16 patients. Conclusion: Contrast-enhanced CT-guided biopsy increases the feasibility of biopsy of retroperitoneal masses.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11834008,11704410,11632004,11474361,and U1930202).
文摘On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of CGWs.An appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the circumference.Using a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode selected.The theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic generated.Potential applications of the enhancement effect of cumulative SHG of CGWs are considered and discussed.The theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube.
基金National Natural Science Foundation of China(No.61702074)the Liaoning Provincial Natural Science Foundation of China(No.20170520196)the Fundamental Research Funds for the Central Universities(Nos.3132019205 and 3132019354).
文摘The scattering and absorption of light propagating underwater cause the underwater images to present lowcontrast,color deviation,and loss of details,which in turn make human posture recognition challenging.To address these issues,this study introduced the dual-guided filtering technique and developed an underwater diver image improvement method.First,the color distortion of the underwater diver image was solved using white balance technology to obtain a color-corrected image.Second,dual-guided filtering was applied to the white balanced image to correct the distorted color and enhance its details.Four feature weight maps of the two images were then calculated,and two normalizedweightmapswere constructed formulti-scale fusion using normalization.To better preserve the obtained image details,the fusion image was histogram-stretched to obtain the final enhanced result.The experimental results validated that this method has improved the accuracy of underwater human posture recognition.
文摘The traditional small target detection algorithm often results in a high false alarm rate on the sea surface background. To address this issue, a small target detection method based on guided filtering and local average gray level difference was proposed in this paper for the sea surface. Firstly, the method enhanced the details of the small targets by employing guided filtering to suppress the background clutter and noise in the sea surface image. Subsequently, the local average gray level difference of each point in the image was calculated to further distinguish the targets from other interference points. Finally, the threshold segmentation method was utilized to obtain the actual small targets on the sea surface. After conducting experiments on various sea surface scenes, the LSCRG, BSF, and ROC curve were computed for the proposed method and five other algorithms. Comparative analysis with BS, Top-hat, TDLMS, Max-median, and LCM demonstrates the superiority of the proposed method for infrared small target detection on the sea surface.
