Assisting Scalable Diagnosis Automatically via CT Images in the Combat against COVID-19

Introductory paragraphThe pandemic of coronavirus Disease 2019 (COVID-19) caused enormous loss of life globally. 1-3 Case identification is critical. The reference method is using real-time reverse transcription PCR (rRT-PCR) assays, with limitations that may curb its prompt large-scale application. COVID-19 manifests with chest computed tomography (CT) abnormalities, some even before the onset of symptoms. We tested the hypothesis that application of deep learning (DL) to the 3D CT images could help identify COVID-19 infections. Using the data from 920 COVID-19 and 1,073 non-COVID-19 pneumonia patients, we developed a modified DenseNet-264 model, COVIDNet, to classify CT images to either class. When tested on an independent set of 233 COVID-19 and 289 non-COVID-19 patients. COVIDNet achieved an accuracy rate of 94.3% and an area under the curve (AUC) of 0.98. Application of DL to CT images may improve both the efficiency and capacity of case detection and long-term surveillance.

Feasibility of 80 kVp tube voltage coronary CTA combined with volume-based adaptive statistical iterative reconstruction in overweight or class obesity patients / 中国介入影像与治疗学

Objective: To explore the feasibility of using 80 kVp tube voltage coronary CTA (CCTA) combined with volume-based adaptive statistical iterative reconstruction (ASiR-V) in overweight or class obesity patients. Methods: Totally 120 overweight or class obesity patients who underwent CCTA were randomly divided into 80 kVp group or 100 kVp group (each n=60), and 60% ASiR-V was used for image reconstructions. The image quality, CT value, SNR, contrast noise ratio (CNR), CT dose index volume (CTDIvol), dose length product (DLP), contrast agent dose and effective radiation dose were compared between the two groups. Results: There was no significant difference of image quality score between 2 groups (P>0.05). There were statistical differences of CTDIvol, DLP, contrast agent dose and effective radiation dose between 2 groups (all P0.05). No significant difference of SNR nor CNR of right coronary artery, left anterior descending branch and left circumflex branch was found between 2 groups (all P>0.05). Conclusion: Adopting 80 kVp tube voltage combined with 60% ASiR-V image reconstruction for CCTA in overweight or class obesity patients can obtain equivalent image quality to 100 kVp tube voltage, while the contrast agent dose and effective radiation dose are reduced.

Application value of different sequences magnetic resonance imaging in rectal cancer re-staging after neoadjuvant chemoradiation therapy / 中国医师进修杂志

Objective@#To evaluate the value of different sequences magnetic resonance imaging (MRI) in rectal cancer re-staging after neoadjuvant chemoradiation therapy (NCRT).@*Methods@#The clinical data of 117 patients with rectal cancer who underwent NCRT before surgery operation in Peking University cancer hospital from January 2016 to December 2018 were retrospectively analyzed. Among 117 patients, 101 patients underwent MRI scanning before and after NCRT, and 16 patient underwent MRI scanning after NCRT; T2 weighted imaging (T2WI) and diffusion weighted imaging (DWI) scanning were performed in all patients, and dynamic contrast enhancement (DCE) scanning was performed in 96 patients. T2WI, T2WI combined with DWI, T2WI combined with DCE were used for T re-staging of rectal cancer after NCRT respectively, and the results of which were compared with those of pathology after operation.@*Results@#The sensitivity of diagnosis of ypT0-2 rectal cancer after NCRT using T2WI combined with DWI, T2WI combined with DCE respectively was significantly higher than that using T2WI: 52.7% (29/55) and 30.4% (14/46) vs. 10.9% (6/55), and there was statistical difference (P<0.05). The accuracy rate and specificity of diagnosis of ypT3 and ypT4 rectal cancer after NCRT using T2WI combined with DWI were significantly higher than that using T2WI, with an accuracy rate of 60.7% (71/117) vs. 47.0%(55/117) and 92.3% (108/117) vs. 80.3% (94/117), and a specificity of 55.9% (33/59) vs. 23.7% (14/59) and 92.9% (105/113) vs. 80.5% (91/113), and there were statistical differences (P<0.05). The accuracy rate of down-staging after NCRT using T2WI combined with DWI was significantly higher than that using T2WI: 72.3% (73/101) vs. 58.4% (59/101), and there was statistical difference (P<0.05); there was no significant difference in accuracy rate between using T2WI and using T2WI combined with DWI and between using T2WI combined with DWI and using T2WI combined with DCE (P > 0.05).@*Conclusions@#T2WI combined with DWI is superior to T2WI in re-staging of rectal cancer after NCRT.

Multi-slice CT imaging analysis of basal cell adenoma in the parotid gland / 中国基层医药

Objective To investigate the CT imaging features of basal cell adenoma in the parotid gland and thus to improve the preoperative diagnostic accuracy.Methods The clinical materials and image findings of 8 cases with parotid basal cell tumor,which were proved by pathology,were retrospectively studied.Results All 8 patients had solitary BCA lesion,which involved both the superficial and deep lobe(n =1) and located at the superficial lobe of parotid gland(n =7).All the 6 tumors were clear boundary and round shape without lobular appearance.The diameters of the max lesions ranged from 10.3-27.6 mm.CT scan showed that all lesions were solid nodules with uniform or uneven density.Cystic degeneration was displayed in 5 lesions,among them,cystic area was ≥90％ in 1 lesion.At enhanced scanning phase,most tumors showed a strong enhancement at the arterial phase and a pattern of persistent strong enhancement or slow decline at the venous phase.Conclusion The multi-slice CT imaging features of BCA in parotid gland are characteristic,which is helpful to make qualitative diagnosis in combination with clinical materials.

The applicated value of intraperitoneal free gas in diagnosis of the site of gastrointestinal perforation using multi-slice CT / 中国基层医药

Objective To study the distribution characteristics of intraperitoneal free gas and the location value of the site of gastrointestinal perforation using multi-slice CT (MSCT).Methods 60 cases of gastrointestinal perforation were retrospectively collected.The distribution of the intraperitoneal free gas in CT image was analyzed and observed.The digestive tract were divided to the upper digestive tract and the lower digestive tract by Treitz ligament.The distribution of the intraperitoneal free gas was analyzed using χ2 test.The distribution of the intraperitoneal free gas between each different perforational site was analyzed.Results 38 cases of the site of gastrointestinal perforation located in upper gastrointestinal tract and 22 cases located in lower gastrointestinal tract,there was statistically significant difference between the upper digestive tract and the lower digestive tract about the distribution of the intraperitoneal free gas(χ2=22.33,P0.05).In the cases of lower gastrointestinal tract perforation,11 cases of the site located in bowel and 11 cases located in colon,there was statistically significant difference between bowel and colon(χ2=8.98,P<0.05).Conclusion The MSCT distribution of the intraperitoneal free gas has important value in localization diagnosis of gastrointestinal perforation.