Sensitivity analysis of Monte Carlo model of a gantry-mounted passively scattered proton system

Purpose

This study aimed to present guidance on the correlation between treatment nozzle and proton source parameters, and dose distribution of a passive double scattering compact proton therapy unit, known as Mevion S250.

Methods

All 24 beam options were modeled using the MCNPX MC code. The calculated physical dose for pristine peak, profiles, and spread out Bragg peak (SOBP) were benchmarked with the measured data. Track‐averaged LET (LET_t) and dose‐averaged LET (LET_d) distributions were also calculated. For the sensitivity investigations, proton beam line parameters including Average Energy (AE), Energy Spread (ES), Spot Size (SS), Beam Angle (BA), Beam Offset (OA), and Second scatter Offset (SO) from central Axis, and also First Scatter (FS) thickness were simulated in different stages to obtain the uncertainty of the derived results on the physical dose and LET distribution in a water phantom.

Results

For the physical dose distribution, the MCNPX MC model matched measurements data for all the options to within 2 mm and 2% criterion. The Mevion S250 was found to have a LET_t between 0.46 and 8.76 keV.μm^–1 and a corresponding LET_d between 0.84 and 15.91 keV.μm^–1. For all the options, the AE and ES had the greatest effect on the resulting depth of pristine peak and peak‐to‐plateau ratio respectively. BA, OA, and SO significantly decreased the flatness and symmetry of the profiles. The LETs were found to be sensitive to the AE, ES, and SS, especially in the peak region.

Conclusions

This study revealed the importance of considering detailed beam parameters, and identifying those that resulted in large effects on the physical dose distribution and LETs for a compact proton therapy machine.

Clinical impact of serum miR-661 in diagnosis and prognosis of non-small cell lung cancer

OBJECTIVE

The aim of this study was to evaluate whether serum miR-661 could serve as a biomarker for the diagnosis and prognosis of non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

  The expression of serum miR-661 was detected in 150 cases of NSCLC and 114 cases of normal healthy controls by Real-time PCR. Receiver-operating characteristic (ROC) curve analysis was applied to analyze diagnostic value of serum miR-661. The relationship between serum miR-661 expression and clinicopathological characteristics was investigated. Overall survival was analyzed using Kaplan-Meier method. Moreover, Cox proportional-hazards regression analyses were performed to determine the prognostic value of serum miR-661 in NSCLC patients.

RESULTS

We found that the expression of serum miR-661 was significantly upregulated in NSCLC compared with healthy controls (p < 0.01). The expression level of serum miR-661 was positively correlated with histological grade (p = 0.011), lymph node metastasis (p = 0.003), distant metastasis (p = 0.021) and clinical stage (p = 0.005). Then, ROC curve analysis showed that serum miR-661 has considerable diagnostic accuracy, with an area under the ROC curve (AUC) of 0.726 (p = 0.001). Moreover, NSCLC patients with serum miR-661 higher expression have shown significantly poorer overall survival than those with lower serum miR-661 expression (p = 0.004). Furthermore, multivariate analyses showed that serum miR-661 expression levels were an independent prognostic factor for survival in NSCLC patients.

CONCLUSIONS

Overall, these findings indicate that serum miR-661 may be a potential biomarker for the diagnosis and prognosis of NSCLC.

[Suggestions on environmental and health work from Health Environment Promotion Campaigns]

The Health Environment Promotion Campaigns (HEPCs) focus on the major environmental health issues and relevant factors of concern among the general public, and promote the achievement of the national health goal. Based on the summary and analysis of the background, key indicators, specific actions in different domains of the HEPCs, this paper proposes suggestions for scientifically implementing HEPCs from five aspects, namely, formulating implementation plans, establishing pilot areas, building comprehensive service platforms, improving the health literacy of residents and strengthening the development of protection technologies and standards.

Evaluating the diagnostic and prognostic value of serum miR-770 in non-small cell lung cancer

OBJECTIVE

Serum miRNAs are promising biomarkers for the diagnosis and prognostication of many diseases. Our present study aimed at assessing the usefulness of serum miR-770 expression as a diagnostic and prognostic tool for non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Quantitative Real-time PCR (qRT-PCR) was used to measure expression level of serum miR-770 in 196 NSCLC patients and 77 healthy controls. The associations of serum miR-770 expression with clinicopathologic variables were analyzed. Receiver operating characteristic analysis (ROC) was used to determine the value of serum miR-770 as a biomarker for diagnosis of NSCLC. Kaplan-Meier and Cox regression analyses were performed to examine the relationship between serum miR-770 expression and prognosis of NSCLC patients.

RESULTS

We found that serum miR-770 levels were significantly decreased in NSCLC patients compared to healthy controls (p < 0.01). Decreasing serum miR-770 expression was significantly correlated with poorer histological grade (p = 0.015), positive lymph node metastasis (p = 0.007), and advanced tumor stage (p = 0.002). Moreover, we found that the diagnostic value of serum miR-770 for NSCLC patients from healthy controls resulted in an AUC of 0.835 (95 % CI, 0.751-0.919) with a sensitivity of 68% and a specificity of 89%, based on a cut-off value of 5.723. Kaplan-Meier analysis showed that decreased serum miR-770 expression was associated with poor overall survival of NSCLC patients (p = 0.000). Multivariate analysis confirmed that serum miR-770 was an independent prognostic factor in patients with NSCLC.

CONCLUSIONS

Our findings suggested that serum miR-770 may represent a novel diagnostic, prognostic biomarker and a potential therapeutic target for NSCLC.

[Computational investigation of Artemisia pollen deposition in realistic nasal cavities of residents in northwest China]

Objective: To investigate the deposition rate of Artemisia pollen in different nasal cavity regions and its influence factors in residents of northwest China. Methods: Thirty healthy adults from northwest China were enrolled. The computational fluid dynamics (CFD) and discrete phase model (DPM) were used for numerical simulation of nasal structures. The pollen deposition fraction in each anatomical part was counted and the effects of pollen density and breathing rate on deposition were analyzed. SPSS 19.0 software was used for statistical analysis. Results: The hottest deposition parts of Artemisia pollen were nasal septum (30.70%±12.27%), vestibule (27.45%±8.21%), middle turbinate area (13.59%±8.98%) and nasopharynx (7.14%±5.90%). When the inspiratory flow rate increased to 30 L/min, the deposition rates of pollen in nasal vestibule and nasal septum were significantly higher than that at the rate of 15 L/min (43.20%±11.14% vs 27.45%±8.21%, 51.48%±9.77% vs 30.70%±12.27%, t value was -8.126,-5.264, respectively, all P<0.05), which indicated that with the increase of the inspiratory flow rate, the deposition hotspot moved forward. Compared with the wet Artemisia pollen, the deposition rate of the dry pollen in nasal vestibule and nasal septum decreased significantly (16.55%±4.33% vs 27.45%±8.21%, 7.09%±3.69% vs 30.70%±12.27%, t value was 8.669, 9.173, respectively, all P<0.05). The escape rate at outlet increased from 17.00%±9.57% to 43.48%±13.43% (t=-9.282, P<0.05). Conclusions: The deposition of Artemisia pollen in nasal cavity is highly concentrated. The inhalation velocity and the dry-wet degree of pollen are the main determinants of the deposition site.

A novel design of proton computed tomography detected by multiple-layer ionization chamber with strip chambers: A feasibility study with Monte Carlo simulation

PURPOSE

Uncertainty in proton range can be reduced by proton computed tomography (CT). A novel design of proton CT using a multiple-layer ionization chamber with two strip ionization chambers on the surface is proposed to simplify the imaging acquisition and reconstruction.

METHODS

Two strip ionization chambers facing the proton source were coupled into a multiple-layer ionization chamber (MLIC). The strip chambers measured locations and lateral profiles of incident proton beamlets after exiting the imaging object, while the integral of depth dose measured in the MLIC was translated into the residual energy of the beamlet. The simulation was performed at five levels of imaging dose to demonstrate the feasibility and performance expectations of our design. The energy of the proton beamlet was set to 150 ± 0.6 MeV. A collimator with a round slit of 1 cm in diameter was placed in the central beam axis upstream from steering magnets. Proton stopping power ratio (SPR) was reconstructed through inverse radon transform on sinograms generated with proton beamlets scanning through an imaging phantom from a half-circle gantry rotation. The imaging phantom was 10 cm in diameter. The base was made of water-equivalent material holding 13-tissue equivalent inserts constructed according to ICRP 1975 (Task Group on Reference Man. "Report of the Task Group on Reference Man: A Report", Pergamon Press 23, 1975). All inserts were 1 cm in diameter with materials ranging from lung to cortical bone. Percentage discrepancies were reported by comparing to the ground truths. The imaging dose and quality were also evaluated.

RESULTS

The maximum deviation in reconstructed proton SPR from the ground truths was reported to be 1.02% in one of the 13 inserts when the number of protons per beamlet passing through the slit dropped to 10³ . Imaging dose was correlated linearly to incident protons and was determined to be 0.54 cGy if 5 × 10² protons per beamlet were used. Imaging quality was acceptable for planning purpose and held consistently through all levels of imaging dose. Spatial resolution was measured as five line pairs per cm consistently in all simulations varying in imaging dose.

CONCLUSIONS

Proton CT using a multiple-layer ionization chamber with two strip ionization chambers on the surface simplifies data acquisition while achieving excellent accuracy in proton SPR and acceptable spatial resolution. The imaging dose is lower compared to kV CBCT, making it potentially a great tool for localization and plan adaption in proton therapy.

[Research advances on the value of preoperative systemic inflammatory response index in predicting the prognosis of patients with resectable pancreatic cancer]

Pancreatic cancer is a highly malignant gastrointestinal tumor with high invasiveness, easy metastasis, and poor chemoresistance. Surgery is still the preferred treatment for resectable pancreatic cancer. At present, inflammatory scoring systems based on serological indicators in patients with resectable pancreatic cancer can be divided into two types: the inflammatory scoring system based on c-reactive protein albumin and the inflammatory scoring system based on peripheral blood cell count. However, the specific mechanism between these inflammatory markers and the prognostic value of resectable pancreatic cancer remains unclear. This article reviews the correlation between systemic inflammatory response indexes and prognosis of patients with resectable pancreatic cancer, so as to provide help for the comprehensive treatment of pancreatic cancer.

Oral vaccination with the porcine circovirus type 2 (PCV-2) capsid protein expressed by Lactococcus lactis induces a specific immune response against PCV-2 in mice

AIMS

Porcine circovirus type 2 (PCV2) can cause postweaning, multisystemic wasting syndrome in pigs, which leads to enormous losses in the swine industry worldwide. Here, a genetically engineered Lactococcus strain expressing the main protective antigen of PCV2, the Cap protein, was developed to act against PCV2 infection as an oral vaccine.

METHODS AND RESULTS

Expression of the Cap protein was confirmed via western blot, ELISA and fluorescence microscopy. Over 90% of the recombinant pAMJ399-Cap/MG1363 survived a simulated gastrointestinal transit. It also survived the murine intestinal tract for at least 11 days. Then, the safety and immunogenicity of pAMJ399-Cap/MG1363 in orally immunized mice was evaluated. The levels of the sIgA, IgG and cytokines (IL-4 and IFN-γ) obtained from the mice immunized with pAMJ399-Cap/MG1363 were significantly higher than those in the control groups.

CONCLUSIONS

pAMJ399-Cap/MG1363 can survive in the gastrointestinal transit and effectively induce mucosal, cellular and humoral immune response against PCV2 infection via oral administration.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates the potential of the genetically engineered Lactococcus lactis as a candidate for an oral vaccine against PCV2.

Bioinformatics analysis of common differential genes of coronary artery disease and ischemic cardiomyopathy

OBJECTIVE

This paper aims at screening the common differential genes of coronary atherosclerotic heart disease (CAD) and ischemic cardiomyopathy (ICM), and to conduct pathway analysis and protein-protein interaction (PPI) network analysis for the differential genes.

MATERIALS AND METHODS

The CAD and ICM datasets were collected from the Gene Expression Omnibus (GEO) database for human tumors to extract data components of peripheral blood RNA of patients and normal people in GSE71226 and GSE9128 chips; "limma" package of "R" software was used to screen the differential genes, and "pheatmap" package was applied to construct heat maps for the differential genes; Cytoscape, Database for Annotation, Visualization and Integration Discovery (DAVID) and String platforms were utilized for PPI network analysis, Genome Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis on the selected differential genes.

RESULTS

A total of 575 differential genes were screened from GSE71226, including 350 genes with up-regulated expression and 225 with down-regulated expression, which was statistically significant (p<0.05, fold change >1). 75 differential genes were screened from GSE9128, including 47 genes with up-regulated expression and 28 with down-regulated expression. By virtue of String, DAVID and Cytoscape software, the PPI network diagram was constructed, and GO and KEGG analyses were performed successfully.

CONCLUSIONS

A total of 8 common differential genes are screened, and functional annotation and pathway analysis are conducted, which is conducive to further studying the interactions between the differentially expressed genes.

Rosuvastatin inhibits inflammatory response and resists fibrosis after myocardial infarction

OBJECTIVE

To study the effect of rosuvastatin on myocardial infarction in rats and its mechanism of action.

MATERIALS AND METHODS

24 Sprague-Dawley (SD) rats were randomly divided into 3 groups: intensive statin group (n=8), myocardial infarction control group (n=8) and sham-operation group (n=8). The left anterior descending coronary artery was ligated to establish myocardial infarction models. Rats in intensive statin group were treated with gavage via rosuvastatin (1 mg × kg) and 1.5 mL distilled water suspension at 3 d before operation, while rats in the other two groups received gavage via the same amount of distilled water till 4 weeks after operation. Venous blood was collected using capillary glass tubes at 3 d before operation (before medication) and the last day in the 4th week after operation. Interleukin-6 (IL-6) was detected via chemiluminescence assay, and tumor necrosis factor-α (TNF-α) was detected via immunofluorescence assay. Hematoxylin and eosin (HE) staining and Masson staining were performed for myocardium to detect the inflammation and fibrosis. Finally, the expressions of inflammatory protein p65, peroxisome proliferator-activated receptor (PPAR) and fibrin were detected via Western blotting, and the Snail expression was detected by immunohistochemical assay.

RESULTS

The survival rate and cardiac function of rats in intensive statin group were superior to those in control group. HE staining and detection of blood IL-6 and TNF-α, and p65 and PPAR protein expressions revealed that the inflammatory levels in the body and myocardium of rats in intensive statin group were decreased compared with those in control group. Masson staining and detection of fibrin level showed that the myocardial fibrosis level of rats in intensive statin group was reduced compared with that in control group.

CONCLUSIONS

Rosuvastatin can reduce the level of myocardial fibrosis through alleviating the inflammatory response in rats with myocardial infarction.

P5568Disease stages of structural and functional cardiac changes associate with outcomes in patients with mitral regurgitation receiving mitral valve intervention

Background/Introduction

Severe mitral regurgitation (MR) produces volume overload resulting in progressive cardiac dysfunction that can extend beyond the left-sided chambers. It is unknown whether a specific MR staging system, that would quantify the extent of structural and functional cardiac changes, would be associated with outcomes in severe MR patients receiving mitral valve (MV) intervention.

Purpose

To examine the clinical utility of a novel MR staging system, based on the extent of cardiac damage, for prediction of clinical outcomes for patients with severe MR who underwent surgical or transcatheter therapy.

Methods

Patients were categorized into five stages using pre-procedural echocardiography; Stage 0: no other cardiac damage detected; Stage 1: Left atrium (LA) abnormality, as defined by the presence of atrial fibrillation or LA chamber enlargement; Stage 2: LV dysfunction, as defined by LV ejection fraction <60%; Stage 3: Pulmonary artery vasculature or tricuspid valve abnormality, as defined by the presence of systolic pulmonary arterial pressure ≥60 mmHg) or ≥grade 2 tricuspid regurgitation; and Stage 4: Right ventricular (RV) disease as defined by the presence of >mild RV dysfunction. The primary outcomes were all-cause mortality, and the combined endpoint of death or heart failure rehospitalization at one-year follow-up.

Results

A total of 696 patients with MR (age 70±14 years; 60% men) who underwent MV surgery (69%) or transcatheter MV repair with MitraClip device (31%) were examined. Prevalences of stage 0, 1, 2, 3, and 4 were 6.6%, 34.6%, 20.0%, 26.6%, and 12.2%, respectively. The median follow-up time was 15 months (IQR, 6.4, 24.4 months). At one-year, there was graded increase in all-cause death and in the combined endpoint of death or heart failure rehospitalization with each MR stage (Figure). In multivariate models, these associations remained independently associated with both one-year endpoints for patients receiving either surgical or transcatheter interventions.

Figure 1

Conclusion

This novel MR staging system is practical and may improve clinical risk stratification of patients with severe MR being considered for MV interventions.

[Effect of non-diabetic postoperative hyperglycemia on complications after pancreaticoduodenectomy]

Objective: To examine the association of hyperglycemia and postoperative complications in non-diabetic patients underwent pancreaticoduodenectomy(PD). Methods: The clinical data of 209 non-diabetic patients who underwent PD from January 2012 to June 2018 at Department of Pancreatic and Biliary Surgery, the First Affiliated Hospital of Harbin Medical University and met the inclusion criteria were retrospectively analyzed. According to the diagnostic criteria of postoperative hyperglycemia, the patients were divided into postoperative hyperglycemia group (167 cases, 79.9%) and control group(42 cases, 20.1%). The propensity score matching(PSM) method was used to eliminate the difference between groups(caliper value=0.02; 38 cases in control group including 30 males and 8 females with age of 59.0 years;38 cases in postoperative hyperglycemia group including 32 males and 6 females with age of 61.0 years;37 cases of pancreatic head carcinoma,30 cases of periampullary carcinoma and 9 cases of benign diseases). A comparative analysis was applied for preoperative data, surgical related indicators and postoperative complication rates.The receiver operating characteristic(ROC) curve was used to calculate the area under the curve(AUC) of blood glucose values on postoperative day 1,3 and 5(POD1, POD3, POD5), to determine the high-risk blood glucose cutoff value of complications and to evaluate its sensitivity and specificity for the prediction of postoperative complications. Results: Univariate analysis showed that the differences in gender, body mass index, preoperative blood glucose, and serum urea nitrogen levels were statistically significant before PSM.There was no significant difference in the preoperative data between the two groups after PSM. Compared with the control group, the incidence of postoperative pancreatic fistula (31.6% vs. 5.3%), abdominal infection(29.0% vs. 7.9%) and Clavien-Dindo Ⅲ-Ⅴ complications(31.6% vs.7.9%) were statistically different(χ(2)=7.092,P=0.008; χ(2)=4.290,P=0.038; χ(2)=5.316,P=0.021), respectively. According to the AUC on POD3,the blood glucose value ≥8.860 mmol/L was an independent risk factor for pancreatic fistula with sensitivity of 58.3% and specificity of 76.9%,the blood glucose value ≥9.130 mmol/L was an independent risk factor for abdominal infection with sensitivity of 54.5% and specificity of 81.5% and the blood glucose value ≥7.685 mmol/L was independent risk factor of Clavien-Dindo Ⅲ-Ⅴ complications with sensitivity of 75.0% and specificity of 57.7%. Conclusions: Postoperative hyperglycemia in non-diabetic patients is associated with postoperative pancreatic fistula, abdominal infection, and Clavien-Dindo Ⅲ-Ⅴ complications.According to the early postoperative blood glucose value,the occurrence of postoperative pancreatic fistula, abdominal infection and Clavien-Dindo Ⅲ- Ⅴ complications can be effectively predicted.

[Surgical intervention strategy for severe acute pancreatitis in minimally invasive era]

With the development of minimally invasive concept, the treatment mode of severe acute pancreatitis has changed greatly. The tendency of surgical intervention has changed from excessive intervention to inadequate intervention. The timing of intervention has changed from earlier to later, and the mode of intervention has changed from openness as the main way to minimally invasive as the guidance. The transformation of surgical intervention tendency conforms to both minimally invasive trend and the step-up approach, but there are still some shortcomings: inadequate surgical intervention, inappropriate timing and indications, and over dependence on minimally invasive surgery. Correctly grasping the indications of surgical intervention, accurately grasping the timing of surgical intervention, and reasonably choosing the mode of surgical intervention are the keys to solve the insufficiency of surgical intervention. Laying emphasis on multidisciplinary team and correctly recognizing the role and status of surgical intervention can effectively reduce the mortality of severe acute pancreatitis patients.

miR-191 is involved in renal dysfunction in arsenic-exposed populations by regulating inflammatory response caused by arsenic from burning arsenic-contaminated coal

Chronic exposure to arsenic may result in the manifestation of damage in multiple organs or systems of the body. Arsenic-induced renal dysfunction has been determined, but their pathogenesis has not been fully examined. In this study, we measured the expression levels of miR-191 in plasma, the contents of pro-inflammatory (interleukin (IL)-6 and tumor necrosis factor alpha) and anti-inflammatory (IL-2 and transforming growth factor beta) cytokines, and renal dysfunction indicators (blood urea nitrogen, blood creatinine, uric acid, and cystatin C) in serum from control and arsenic poisoning populations and analyzed the relationship between the miR-191, cytokines, and renal dysfunction indicators. The results clearly show the alteration of miR-191 expression was significantly associated with arsenic-induced renal dysfunction. Overall, the association of miR-191, inflammatory response and renal dysfunction, is clearly supported by the current findings. In other words, miR-191 is involved in renal dysfunction in exposed populations by regulating inflammatory response caused by coal-burning arsenic. The study provides a scientific basis for further studies of the causes of the arsenic-induced renal dysfunction, the biological role of miR-191, and targeted prevention strategies.

Association between rs12742784 polymorphism and hip fracture, bone mineral density, and EPHB2 mRNA expression levels in elderly Chinese women

Objective: This study aimed to determine the association between rs12742784 polymorphism in the non-coding area and hip fracture, bone mineral density (BMD), and EPHB2 mRNA expression levels in elderly Chinese women.Methods: We investigated 250 Chinese women (mean age: 63.5 ± 8.3 years) including 123 hip fracture patients and 127 non-fracture controls. All participants underwent clinical examination to meet the inclusion criteria. Lumbar and hip BMD were detected by dual-energy X-ray absorptiometry. rs12742784 polymorphism was determined by restriction fragment length polymorphism and EPHB2 mRNA expression levels were measured by real-time polymerase chain reaction.Results: Distribution of rs12742784 genotypes agreed with Hardy-Weinberg equilibrium. The frequency of the CT + TT genotype was significantly associated with decreased risk of hip fracture (adjusted odds ratio = 0.57, p < 0.01) after adjusting for age and body mass index, and with increased BMD and EPHB2 mRNA expression levels. The T allele of the rs12742784 single nucleotide polymorphism (SNP) was a protective factor for hip fracture (adjusted odds ratio = 0.56, p < 0.01).Conclusion: rs12742784 polymorphism was associated with EPHB2 mRNA expression levels, BMD, and hip fracture in Chinese women. The T allele of the rs12742784 SNP was a protective factor for osteoporosis and hip fracture.

[Comparison of flow conditions of adhesives and retention force of restorations among four cement-retained methods of implant-supported fixed prostheses]

Objective: To compare the effect on the flow conditions of adhesives and the retention force of restorations among different cement-retained methods of implant-supported fixed prostheses. Methods: Four common cement-retained methods were selected, including the occlusal hole for screw access (OH), the lingual hole for adhesives overflow (LH), the resin replica for titanium abutment (RR), and the traditional cement-retained method (the control group). The adhesive used in this study was resin-modified glass ionomer cement. The two-dimensional analysis models of computational fluid dynamics (CFD) were established. The flow conditions of adhesives in the adhesion process was analyzed by the CFD analysis. The internal filling ratio and the amount of neck overflow of adhesives below the edge of the prosthesis were calculated. Ten zirconia prostheses in each group were processed and cemented. The retention force was examined by mechanical tensile experiments in vitro. Results: The CFD analysis showed the internal filling ratio of adhesives from high to low was the LH group, the OH group, the RR group and the control group. The amount of neck overflow of adhesives below the edge of the prosthesis from less to more was the RR group, the OH group, the LH group and the control group. The retention force was (240.7±33.9) N in the control group, (278.2±59.1) N in the OH group, (292.9±47.9) N in the LH group, and (262.8±59.4) N in the RR group. There was a statistically significant difference in the retention force between the LH group and the control group (P=0.029). There was no significant difference among the other groups (P>0.05). Conclusions: The modified cement-retained methods can effectively reduce the amount of neck overflow of adhesives, and improve the filling condition of adhesive in the adhesive clearance to ensure the retention force of the prostheses. Clinically, the appropriate modified cement-retained method should be selected according to the three-dimensional position of the implant and the position of prosthetic margin.

Association of Fractional Flow on 3D-TOF-MRA with Cerebral Perfusion in Patients with MCA Stenosis

BACKGROUND AND PURPOSE

Fractional flow measured on 3D-TOF-MRA was proposed to quantify cerebral hemodynamic changes in patients with artery stenosis. We investigated the association between fractional flow and cerebral perfusion changes in patients with symptomatic MCA stenosis.

MATERIALS AND METHODS

This prospective study was approved by the institutional review board, and all participants provided written informed consent. From June 2015 to May 2018, four hundred twenty-nine patients with symptomatic intracranial arterial stenosis were consecutively recruited and underwent conventional brain MR imaging, 3D-TOF-MRA, and brain CTP. A total of 91 patients with unilateral M1 segment stenosis of the MCA and a stenosis degree of 50%∼99% were included in the analysis. Fractional flow was measured by comparing distal and proximal signal intensity changes across the stenosis on 3D-TOF-MRA. The cutoff value for fractional flow for discriminating between normal perfusion and hypoperfusion was obtained from the receiver operating characteristic curve. Associations between fractional flow and hypoperfusion were assessed using univariate and multivariate analyses.

RESULTS

The receiver operating characteristic curve showed a significant fractional flow threshold value at 0.90 (sensitivity, 70.1%; 95% CI, 55.9%-81.2%; specificity, 69.6%; 95% CI, 47.6%-84.1%). Participants with a fractional flow of ≤0.90 were independently associated with cerebral hypoperfusion downstream from the stenosis site (adjusted OR, 3.68; 95% CI, 1.63-11.62; P = .027).

CONCLUSIONS

Fractional flow measured on 3D-TOF-MRA may serve as a noninvasive and practical tool for determining the cerebral hypoperfusion in patents with symptomatic MCA stenosis.

[Endogenous Klebsiella pneumoniae endophthalmitis associated with Klebsiella pneumoniae pneumonia: 3 cases report and literature review]

Objective: To study the clinical features and the diagnosis and treatment of endogenous Klebsiella pneumoniae endophthalmitis associated with Klebsiella pneumoniae pneumonia. Methods: Three cases of endogenous Klebsiella pneumoniae endophthalmitis associated with Klebsiella pneumoniae with microbiological evidence were studied. The related literatures published from January 2008 to June 2018 were reviewed with "pneumonia" , "endogenous endophthalmitis" and "Klebsiella pneumoniae" as the keywords in CNKI, Wanfang, PubMed and Web of Science databases. Results: The 3 patients, all males, aged 54 years, 82 years and 48 years respectively. They all had a history of type 2 diabetes mellitus. Endophthalmitis occurred in one eye in all of them, and the patients had eye symptoms including eye pain, progressive loss of vision, periorbital area inflammation, conjunctivitis, weakening or disappearance of pupil light reflex, corneal edema and anterior chamber effusion. All of 3 cases had multiple patchy pulmonary lesions, and Klebsiella pneumoniae was proven to be the pathogen by blood culture. Two cases had pulmonary abscess and liver abscess, and one of them had brain abscess. A total of 28 literatures with 81 cases of endogenous Klebsiella pneumoniae endophthalmitis associated with Klebsiella pneumoniae pneumonia were retrieved from CNKI, WanFang, PubMed and Web of Science database. Conclusions: Klebsiella pneumoniae was one of the most common pathogens of pneumonia and endogenous endophthalmitis, which would seriously damage the lung and the eye. The early clinical features were not specific. Misdiagnosis or missed diagnosis might cause serious consequences. Eye pain and visual disturbance symptoms, ophthalmic examination, chest imaging, blood and aqueous humor etiology were of great value in the diagnosis of this disease.