CT value analysis and clinical significance before and after percutaneous lumbar discectomy

Objective: To provide theoretical basis for effect and mechanism of percutaneous lumbar discectomy in clinic. Methods: A total of 180 patients with lumbar intervertebral disc herniation were evaluated by CT on the fifth day before and after operation. Meanwhile, CT value was measured in the determined level and region. Results: After operation, CT value of the central and posterior determined point of herniated intervertebral disc was lower significantly than that before operation ( P<0.01 ), but CT value of the anterior determined point was different insignificantly. The excellent and good results of the patients together were 83% postoperatively. Conclusions: The curative effect of percutaneous lumbar discectomy is achieved through reduction of lumbar intradiscal pressure.

Omicron Infections in Otolaryngology Practice: A Retrospective Observational Study on Testing, Symptoms and Vaccination Status

Background: With the appearance of the SARS-CoV-2 Omicron variant the high rate of vaccination breakthroughs showed that current vaccines against COVID-19 can no longer provide adequate protection against infection. However, it is still assumed that vaccination might have a positive effect on the course of the disease. In Germany, general practitioners and specialists are usually the first treatment providers for acute illnesses. In addition, patients with infections of the upper respiratory tract often primarily consult an ear, nose and throat specialist. Most of the Omicron-infected people have a mild course of the disease and, if necessary, receive medical care on an outpatient basis. Little is known about the effectiveness of corona vaccinations on Omicron infections in relation to the clinical symptoms. In our outpatient office, we recorded a sharp increase of corona positive Omicron-infections in the beginning of 2022, despite of vaccinations against COVID-19. In a retrospective analysis, we evaluated the data of our SARS-CoV-2 tested patients with regard to clinical symptoms reported and vaccination status. The focus was particularly on the question to what extent the vaccination status in the case of Omicron infections influences the symptoms of the disease. Methods: We retrospectively evaluated the data of all patients in the first quarter of 2022 who were suspected for COVID-19. At that time, the Omicron variant was dominant in Germany. Clinical symptoms, cycle threshold (Ct) values, and the vaccination status were recorded. Symptomatic patients who tested negative for SARS-CoV-2 served as a control group. Results: Of the total cohort (n = 353), 241 (68%) patients were tested SARS-CoV-2 positive. The symptoms of the corona-positive patients were essentially similar to those of a mild to moderate cold, but compared to SARS-CoV-2-negative patients (n = 69) with a clear shift in favor of fever (35% versus 16%), cough (76% versus 52%) and increased feeling of illness (59% versus 43%), respectively. Ct values revealed no difference between unvaccinated (mean 19.15;SD 3.52) and vaccinated cases (mean 18.15;SD 3.87;p = 0.272). There was no significant correlation between the vaccination status and clinical symptom score in different age groups (age 12 to 17, r (28) = 0.26, p = 0.26;age > 18 to 60, r (191) = 0.06, p = 0.378). Conclusions: According to our results with infections with the Omicron variant, there were no differences between unvaccinated and vaccinated patients concerning clinical symptoms or potential infectivity, especially in children and adolescents. This might have impact on further vaccination programs.

Value of helical CT volume rendering technique in post-operative evaluation of screw in screw fixation of axis fractures

To explore the value of helical CT volume rendering technique (VRT) in post-operative evaluation of screw fixation of axis fractures.Methods There were 21 cases of screw fixation of axis fractures between February 2002 and May 2004 in the study including six cases with fractures on axis body,five on odontoid process and 10 on axis body and odontoid process.All cases received X-ray plain film,helical CT scanning,multi-planar reformatting(MPR) and VRT.Results Screw fixation through axis body and massa lateralis atlantis was performed in 10 cases and that through axis body and odontoid process in 11.VRT could clearly display full aperture of screw orbit,location of screw and angle of fixation and hence was superior to X-ray plain film and MPR.Multi-angle VRT displayed asymmetrical space of odontoid process and massa lateralis atlantis in four cases and medial deviation of 2～5 mm of half screw in screw fixation through axis body and massa lateralis atlantis in six.Conclusion VRT can eliminate false shadow of fixation screw,clearly display full aperture of screw orbit and hence supply improtant imaging evidence for post-operative evaluation of screw fixation of axis fractures.7 refs,1 fig,1 tab.

Imaging in detecting sites of pulmonary fibrosis induced by paraquat

BACKGROUND： The most common cause of death from paraquat （PQ） poisoning is respiratoryfailure from pulmonary fi brosis, which develops through pathological overproduction of extracellularmatrix proteins such as collagens. In this study, a MicroCT system was used to observe dynamicchanges of pulmonary fi brosis in rats with PQ poisoning, and fi nd the characteristics of interstitial lungdiseases via density-based and texture-based analysis of CT images of the lung structure.METHODS： A total of 15 male SD rats were randomly divided into a control group （n=5） and aPQ poisoning group （n=10）. The rats in the poisoning group were intraperitoneally administered with4 mg/ mL PQ at 14 mg/kg, and the rats in the control group were administered with the same volumeof saline. The signs of pulmonary fi brosis observed by the MicroCT included ground-glass opacity,nodular pattern, subpleural interstitial thickening, consolidation honeycomb-like shadow of the lung.RESULTS： Compared with the control group, the rats with acute PQ poisoning had differentsigns of pulmonary fibrosis. Ground-glass opacity and consolidation of the lung appeared at theearly phase of pulmonary fi brosis, and subpleural interstitial thickening and honeycomb-like shadowdeveloped at the middle or later stage. MicroCT images showed that fibrotic lung tissues weredenser than normal lungs, and their density was up-regulated with pulmonary fi brosis. There was nodifference in the progress of pulmonary fi brosis between the right lung and the left lung （P〉0.05）, butthere were differences in fi brosis degree at different sites in the lung （P〈0.05 or P〈0.01）. Pulmonaryfi brosis was mainly seen in the exterior area of the middle-lower part of the lung.CONCLUSION： Imaging can show the development of pulmonary fi brosis in PQ poisoning rats,and this method may help to administer drugs more reasonably in treating pulmonary fi brosis.

THE REAL IN TIME CT MONITORING OF THE MESO-DAMAGE EVOLUTION LAW OF SANDSTONE UNDER TRIAXIAL COMPRESSION

The real in time computerized tomography (CT) testing of the meso damage propagation law of the whole sandstone failure process under triaxial compression has been completed using the newest specified triaxial loading equipment corresponding to the CT machine. Through the CT scanning, the clear CT images which include from the microcracks compressed stage to growth stage, bifurcation stage, development stage, crack fracture stage,the rock sample failure until to unloading stage in the different stress states were obtained. The CT values, CT images and the other data have been analyzed. Based on the results of the CT testing of meso damage evolution law of rock,the stress threshold value of meso damage of rock is given, and the stress strain complete process curve of rock is divided into some sections. The initial rock damage propagation law is given in this paper.

A follow up study of cycle threshold values of SARS-CoV-2 in Hunan Province,China

Since the epidemic of the severe acute respiratory syndrome coronavirus 2(SARS-COV-2),many governments have used reverse transcription polymerase chain reaction(RT-PCR)to detect the virus.However,there are fewer measures of CT values information based on RT-PCR results,and the relationship between CT values and factors from consecutive tests is not clear enough.So in this study,we analyzed the connection between CT values and the factors based on cohort data from Delta variant of SARS-CoV-2 in Hunan Province.Previous studies have showed that the mean age of the cases was 33.34 years(±18.72 years),with a female predominance(55.03%,n=71),and the greatest proportion of clinical symptoms were of the common type(60.47%,n=78).There were statistical differences between the N and ORF1ab genes in the CT values for the cases.Based on the analysis of the association between CT values and the factors,the lowest CT values were obtained for the unvaccinated,older and clinically symptomatic group at 3e10 days,the maximum peak of viral load occurred.Therefore,it is recommended to use patient information to focus on older,clinically symptomatic,unvaccinated patients and to intervene promptly upon admission.

Application of Dual-Energy Computed Tomography for Breast Cancer Diagnosis

The present study aimed to investigate the possibility of using dual-energy computed tomography (CT) before therapy to discriminate between normal breast tissue and tumor tissue in patients with breast cancer, without the need to use a contrast medium. The following patient data were extracted by interview and from the hospital’s radiology information system: height, weight, age, menstrual cycle, CT images of normal tissue and tumors with or without contrast medium, and the histopathological diagnosis of the aspiration biopsy. The median age of the 43 participants was 56 years (range, 30 - 80 years). The CT values were evaluated using a clinical analytical program based on the three-material decomposition technique. Breast cancer was classified into ductal carcinoma in situ, invasive ductal carcinoma, invasive lobular carcinoma, fibromatosis-like metaplastic carcinoma, and apocrine carcinoma. In all conditions, regardless of contrast medium, the CT values of tumor tissues were higher than those of normal breast tissue, indicating the effectiveness of dual-energy CT (DE-CT) in the diagnosis of breast cancer. By contrast, DE-CT showed limited potential for distinguishing ductal carcinoma in situ from invasive ductal carcinoma. There have only been a few reports regarding CT examination of breast cancer, and it is expected this study encourage the development of DE-CT imaging to improve tumor detection in patients with breast cancer.

Mutations in Spike Gene of SARS-CoV-2 that Are Associated with a Higher Viral Load: A Clinical Case Study

Background: Quantitative PCR (qPCR) can be used to detect and quantify a load of a pathogen. It is a good indicator of the degree of transmissibility. While performing routine qPCR, we observed an unusually short cycle threshold (Ct) value of SARS-CoV-2 for a clinical specimen obtained in Bamako, Mali. This prompted us to sequence the short-cycle SARS-CoV-2 sample to identify potential mutations in the Spike gene (S gene) gene. Methods: Post-infection, Quantitative Reverse Transcription (qRT-PCR) was performed over a defined time course to estimate the Ct of the SARS-CoV-2 specimen collected from the patient. Sanger sequencing was done on the entire fragment of the S gene to identify mutations. Findings: Sanger sequencing revealed mutations in the lineage of interest, designated B.1.525 by Pango, and also known as “Eta” using the nomenclature defined by WHO. This variant was originally found in Nigeria and Italy. The four novel mutations identified in Eta (D228N, Y451N, I1172M, and C1250F) were otherwise observed with a low frequency worldwide. Although the initial Ct was 10 in the case study patient, he did not exhibit severe symptoms of SARS-CoV-2, for example, pneumonia. However, we observed a longer viral clearance period than usual, of 3 weeks. We note that as compared to SARS-CoV-2 samples obtained during the first peaks of SARS-CoV-2 infection in Mali, when the infection was at its peak in March 2020 (Ct = 30.4), circulating strains evaluated at the time the Eta sample was obtained demonstrated a lower mean Ct (Ct = 24). Conclusions: The short cycle threshold associated with this variant, and the temporal association with a decrease in the mean Ct in the region of Bamako, may indicate higher levels of transmissibility due to a circulating variant. This variant is a lineage of interest designated B.1.525 by Pango or Eta by WHO.

Meso-damage cracking characteristics analysis for rock and soil aggregate with CT test

The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interest(ROI)is used to analyze the cracking characteristics.Also,the mathematical morphology method based on the image threshold segmentation is used to obtain characteristic parameters of cracks to describe the cracking evolution of RSA.Results show that the elastic mismatch between rock blocks and soil matrix is the primary reason for RSA cracking.The mean CT value for the RSA specimen,rock block inclusions,and their adjacent soil regions decreases with the increasing stress level.However,it is more sensitive for block inclusions than soil regions.Using the image segmentation method,length,area and mean width of cracks obey to power function distribution.Crack statistical characteristics are closely related to the rock block’s distribution and morphology.These results may be useful to reveal the mesoscopic cracking mechanism,establish meso-damage evolution equation,and constitutive relation for RSA.

Fracture evolution analysis of soil-rock mixture in contrast with soil by CT scanning under uniaxial compressive conditions

Soil-rock mixture(SRM),as a type of extremely heterogeneous geomaterial,is very common in nature and engineering.The fracture and damage of SRM often induce severe geological disasters.Hence,it is important to analyze the fracture evolution process of this material.In the present research,real-time computed tomography(CT)scanning was conducted on SRM and pure soil samples under uniaxial compressive experiments to investigate the influence of rocks on fracture evolution in SRM.The initiation of cracks,the original values of,and variations in,average density and heterogeneity in the soil matrix,the crack width evolution during loading,and the final failure modes were all studied.Cracks with a width greater than 0.1 mm will not arise until over 90%of ultimate stress is reached.In general,in SRM,areas where the initial average density of the soil matrix is smaller and the initial heterogeneity is greater,are much easier to crack,but the results for pure soil show the opposite effect.According to fracturing conditions shown in CT slices,fracturing and non-fracturing areas in the soil matrix were investigated.The average density of the soil matrix decreases in all areas under loading,except non-fracturing areas in SRM.For the whole sample,the increase in heterogeneity in the soil matrix of SRM is greater than that of pure soil;but for the fracturing areas,this increase in pure soil is greater.Besides,the average and standard deviations of crack width both follow logarithmic distributions with high correlation coefficients.

Mathematical modeling for Delta and Omicron variant of SARS-CoV-2 transmission dynamics in Greece

A compartmental,epidemiological,mathematical model was developed in order to analyze the transmission dynamics of Delta and Omicron variant,of SARS-CoV-2,in Greece.The model was parameterized twice during the 4th and 5th wave of the pandemic.The 4th wave refers to the period during which the Delta variant was dominant(approximately July to December of 2021)and the 5th wave to the period during which the Omicron variant was dominant(approximately January to May of 2022),in accordance with the official data from the National Public Health Organization(NPHO).Fitting methods were applied to evaluate important parameters in connection with the transmission of the variants,as well as the social behavior of population during these periods of interest.Mathematical models revealed higher numbers of contagiousness and cases of asymptomatic disease during the Omicron variant period,but a decreased rate of hospitalization compared to the Delta period.Also,parameters related to the behavior of the population in Greece were also assessed.More specifically,the use of protective masks and the abidance of social distancing measures.Simulations revealed that over 5,000 deaths could have been avoided,if mask usage and social distancing were 20%more efficient,during the short period of the Delta and Omicron outbreak.Furthermore,the spread of the variants was assessed using viral load data.The data were recorded from PCR tests at 417 Army Equity Fund Hospital(NIMTS),in Athens and the Ct values from 746 patients with COVID-19 were processed,to explain transmission phenomena and disease severity in patients.The period when the Delta variant prevailed in the country,the average Ct value was calculated as 25.19(range:12.32e39.29),whereas during the period when the Omicron variant prevailed,the average Ct value was calculated as 28(range:14.41e39.36).In conclusion,our experimental study showed that the higher viral load,which is related to the Delta variant,may interpret the severity of the disease.However,no correlation was confirmed regarding contagiousness phenomena.The results of the model,Ct analysis and official data from NPHO are consistent.

Comparative Evaluation of RT-PCR Kits Available in Sri Lanka for Diagnosis of COVID-19

Identification of gene targets by real-time reverse transcriptase PCR(rRT-PCR)is considered as the gold standard for diagnosis of se-vere acute respiratory syndrome coronavirus 2(SARS-CoV-2)infections.Although many commercial rRT-PCR kits are currently used in Sri Lanka,analytical performance of these kits have not been investigated adequately.Therefore,the objective of the present study was to evaluate the analytical performance of rRT-PCR kits used in the laboratory of the Faculty of Medicine,University of Jaffna(five kits).Performance of the five rRT-PCR kits selected for this study was compared with the CDC 2019-Novel Coronavirus(2019-nCoV)RT-PCR Diagnostic Panel as reference standard.The sensitivity,specificity,positive predictive value,negative predictive value and Cohen’sκcoefficient of the five different commercial kits were analyzed.SARS-CoV-2 positive(62)and negative(32)respiratory sam-ples collected respectively from symptomatic individuals and asymptomatic healthy individuals were used in this study.Comparison of the cycle threshold(Ct)values of the five commercial kits revealed heterogeneity.Among them,the TaqPathTM kit showed the highest sensitivity(98.4%)and interrater reliability(0.976).The HBRT-COVID-19 kit showed the lowest sensitivity(91.9%),specificity(93.7%)and interrater reliability(0.838).Although the five RT-PCR kits exhibited varying sensitivity,specificity and Ct values,all of them are suitable for the routine diagnosis of SARS-CoV-2 infections as all values were higher than 90%.