Computed tomography

摘要： The ongoing coronavirus disease 2019(COVID-19)pandemic continues to present diagnostic challenges.The use of thoracic radiography has been studied as a method to improve the diagnostic accuracy of COVID-19.The‘Living’Cochrane Systematic Review on the diagnostic accuracy of imaging tests for COVID-19 is continuously updated as new information becomes available for study.In the most recent version,published in March 2021,a meta-analysis was done to determine the pooled sensitivity and specificity of chest X-ray(CXR)and lung ultrasound(LUS)for the diagnosis of COVID-19.CXR gave a sensitivity of 80.6%(95%CI:69.1-88.6)and a specificity of 71.5%(95%CI:59.8-80.8).LUS gave a sensitivity rate of 86.4%(95%CI:72.7-93.9)and specificity of 54.6%(95%CI:35.3-72.6).These results differed from the findings reported in the recent article in this journal where they cited the previous versions of the study in which a metaanalysis for CXR and LUS could not be performed.Additionally,the article states that COVID-19 could not be distinguished,using chest computed tomography(CT),from other respiratory diseases.However,the latest review version identifies chest CT as having a specificity of 80.0%(95%CI:74.9-84.3),which is much higher than the previous version which indicated a specificity of 61.1%(95%CI:42.3-77.1).Therefore,CXR,chest CT and LUS have the potential to be used in conjunction with other methods in the diagnosis of COVID-19.

摘要： BACKGROUND Teratoma is a common tumor,but rarely occurs in the parotid region.Only nine cases have been reported in the current literature.Although it is generally detected in infancy or childhood,it is commonly asymptomatic.Computed tomography(CT)and magnetic resonance imaging(MRI)have important roles in the diagnosis of teratoma.CASE SUMMARY A 36-year-old man developed a lump located below the left auricular lobule 3 years ago.Physical examination revealed a nearly-circular tumor in the left parotid gland region with a defined border,firm texture,and significant movement.Calcification,fat,keratinized substances,and typical fat-liquid levels was observed on CT and MRI.A diagnosis of cystic teratoma of the parotid gland was established preoperatively and confirmed by postoperative pathology.Following surgery,the patient developed temporary facial paralysis.There was no recurrence of teratoma during the 15-mo follow-up period.CONCLUSION When an asymptomatic mass in the parotid region is identified,parotid gland teratoma should be included in the differential diagnosis.Imaging examinations are helpful in the diagnosis.

摘要： It is not rare for acute coronary syndrome(ACS)patients to present with symptoms that are atypical,rather than chest pain.It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who present with atypical symptoms,normal initial biomarkers of myocardial necrosis,and normal or nondiagnostic electrocardiograms(ECGs).Although cardiac CT allows for assessments of coronary artery stenosis as well as myocardial perfusion defect in patients with suspected ACS,it requires ECG gating and is usually performed with high-performance multislice CT for highly probable ACS patients.However,several recent reports have stated that ACS is detectable by myocardial perfusion defects even on routine non-ECG-gated contrast-enhanced CT.A growing number of contrast-enhanced CT scans are now being performed in emergency departments in search of pathologies responsible for a patient’s presenting symptoms.In order to avoid inappropriate management for this life-threatening event,clinicians should be aware that myocardial perfusion defect is more commonly detectable even on routine non-ECG-gated contrast-enhanced CT performed in search of other pathologies.

摘要： Effective thermal conductivity of soils can be enhanced to achieve higher efficiencies in the operation of shallow geothermal systems.Soil cementation is a ground improvement technique that can increase the interparticle contact area,leading to a high effective thermal conductivity.However,cementation may occur at different locations in the soil matrix,i.e.interparticle contacts,evenly or unevenly around particles,in the pore space or a combination of these.The topology of cementation at the particle scale and its influence on soil response have not been studied in detail to date.Additionally,soils are made of particles with different shapes,but the impact of particle shape on the cementation and the resulting change of effective thermal conductivity require further research.In this work,three kinds of sands with different particle shapes were selected and cementation was formed either evenly around the particles,or along the direction parallel or perpendicular to that of heat transfer.The effective thermal conductivity of each sample was computed using a thermal conductance network model.Results show that dry sand with more irregular particle shape and cemented along the heat transfer direction will lead to a more efficient thermal enhancement of the soil,i.e.a comparatively higher soil effective thermal conductivity.

摘要： BACKGROUND It now seems that all pulmonary hamartomas(PHs)are large cystic-solid lesions that are difficult to diagnose.However,few cases of large cystic-solid PHs have been reported.The present case report presents a large cystic-solid PH and provides a literature review of the imaging features,formation mechanism and histopathological basis of PHs.CASE SUMMARY A 53-year-old woman with no clinical symptoms underwent a chest computed tomography(CT)examination at our hospital.Nonenhanced CT images revealed a large,flat tumor with multiple air-containing cysts in the left thoracic cavity and a cystic part confined to the medial side of the tumor;the solid part of the tumor showed abundant fat and lamellar soft tissue components.Multiple small blood vessels were detected in the solid part of the tumor on contrast-enhanced CT images.Given the large size of the lesion,the patient elected to undergo surgery.Histological examination revealed PH.A detailed review of the patient’s CT imaging showed that the lesion had a small vascular pedicle to the left lower lobe,which was a clue to its lung tissue histological origin.According to immunohistochemical staining,the confined multiple air-containing cysts were caused by the entrapment of respiratory/alveolar epithelium.CONCLUSION This case shows the imaging manifestations of a large PH.Heightened awareness of its formation mechanism and histopathological basis may alert radiologists to consider this diagnosis in their daily workflow.

摘要： The present letter to the editor corresponds to the article entitled“Comprehensive literature review on the radiographic findings,imaging modalities,and the role of radiology in the coronavirus disease 2019(COVID-19)pandemic”by Pal et al,published in World J Radiol.2021;13(9):258-282.With zero to unknown prevalence,COVID-19 has created a heterogeneous and unforeseen situation across the world.Healthcare providers encountered new challenges in image interpretation,characterization,and prognostication of the disease.Pal et al delineated the radiological findings,which would guide the radiologists to identify the early signs of severe infection.

摘要： The coronavirus disease 2019(COVID-19)global pandemic can be a severe illness that leads to morbidity and mortality.With the increasing number of COVID-19 pneumonia survivors,several long-term changes may persist,including abnormal imaging of lung parenchyma.In addition to the clinical course,it is vital to follow up on pulmonary imaging during the post-infectious period,which is not routinely required in other common pulmonary diagnoses.Computed tomography(CT)scan of the chest is an effective and diagnostic tool for pneumonia which gives an insight into structural abnormalities within the lungs,complications,and possible progression of the disease.Several studies have monitored COVID-19 pneumonia and its complications using serial CT chest imaging from the initial phase of infection,hospitalization,and post-discharge.Nonetheless,long-term follow-up imaging data in post-COVID-19 is still limited.We have summarized the findings utilizing a systematic review of the literature regarding COVID-19 pneumonia imaging,including long-term follow-up.

摘要： BACKGROUND:Spontaneous isolated superior mesenteric artery(SMA)dissection(SISMAD)is a rare cause of abdominal pain.The aim of the study is to investigate the role of a new parameter,the ratio of the SMA diameter to the superior mesenteric vein(SMV)diameter(SMA/SMV)based on non-enhanced computed tomography(CT),in the early diagnosis of SISMAD.METHODS:In a registry study from December 2013 to June 2021,97 abdominal pain SISMAD patients(SISMAD group)admitted to our hospital were enrolled.Meanwhile,the matched sex and age abdominal pain non-SISMAD patients at 1:2 were collected in reverse chronological order as the control group.Student’s t-test,Wilcoxon rank-sum test,and Chi-square test were used to compare differences between the SISMAD and control groups.Med Calc was used to generate receiver operating characteristic(ROC)curve.RESULTS:A total of 291 abdominal pain patients,including 97 SISMAD patients and 194 nonSISMAD patients,were included in the current study.The maximum SMA diameter,perivascular exudation,and SMA/SMV based on non-enhanced CT were significant between the two groups(all P<0.05).ROC curves showed that for the maximum SMA diameter,the area under the curve(AUC),cut-off,sensitivity,and specificity were 0.926,9.80,93.8%,and 79.4%,respectively.For SMA/SMV,its AUC,cut-off,sensitivity,and specificity were 0.956,0.83,88.7%,and 92.3%,respectively.The diagnostic efficiency of SMA/SMV was better than that of the maximum SMA diameter(P<0.05).The combined parameters of SMA/SMV and maximum SMA diameter had the best diagnostic efficiency(AUC=0.970).CONCLUSION:SMA/SMV may be a potential marker for SISMAD.

摘要： Background: The medical imaging world is currently changing with the introduction of advanced modalities to help with diagnosis. There is then the need for the application of Artificial Intelligence (AI) in areas such as radiation protection to improve the safety as far as radiations are concerned. This review article discusses the principles, some of the challenges of radiation protection and the possible role of Artificial Intelligence (AI) regarding radiation protection in computed tomography and fluoroscopy exams. Methods: A literature search was done using Google Scholar, Science Direct and Pubmed to search for relevant articles concerning the review topic. Results: Some of the challenges identified were outdated and old X-ray machines, lack of QA programs on the machines amongst others. It was discovered that AI could be applied in areas like scan planning and positioning, patient positioning amongst others in CT imaging to reduce radiation doses. With fluoroscopy, an AI enabled system helped in reducing radiation doses by selecting the region of interest of pathology and exposing that region. Conclusion: The application of AI will improve safety and standards of practice in medical imaging.

摘要： The introduction of coronavirus disease-2019(COVID-19)as a global pandemic has contributed to overall morbidity and mortality.With a focus on understanding the immunology and pathophysiology of the disease,these features can be linked with the respective findings of imaging studies.Thus,the constellation between clinical presentation,histological,laboratory,immunological,and imaging results is crucial for the proper management of patients.The purpose of this article is to examine the role of imaging during the particular stages of severe acute respiratory syndrome coronavirus 2 infection–asymptomatic stage,typical and atypical COVID-19 pneumonia,acute respiratory distress syndrome,multiorgan failure,and thrombosis.The use of imaging methods to assess the severity and duration of changes is crucial in patients with COVID-19.Radiography and computed tomography are among the methods that allow accurate characterization of changes.