A Priori Subcell Limiting Approach for the FR/CPR Method on Unstructured Meshes

A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on modal energy coefficients is proposed to detect troubled cells, where discontinuities exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR method. Numerical investigations show that the proposed subcell limiting strategy on unstructured quadrilateral meshes is robust in shock-capturing.     

Diabetic macular ischaemia- a new therapeutic target?

Diabetic macular ischaemia (DMI) is traditionally defined and graded based on the angiographic evidence of an enlarged and irregular foveal avascular zone. However, these anatomical changes are not surrogate markers for visual impairment. We postulate that there are vascular phenotypes of DMI based on the relative perfusion deficits of various retinal capillary plexuses and choriocapillaris. This review highlights several mechanistic pathways, including the role of hypoxia and the complex relation between neurons, glia, and microvasculature. The current animal models are reviewed, with shortcomings noted. Therefore, utilising the advancing technology of optical coherence tomography angiography (OCTA) to identify the reversible DMI phenotypes may be the key to successful therapeutic interventions for DMI. However, there is a need to standardise the nomenclature of OCTA perfusion status. Visual acuity is not an ideal endpoint for DMI clinical trials. New trial endpoints that represent disease progression need to be developed before irreversible vision loss in patients with DMI. Natural history studies are required to determine the course of each vascular and neuronal parameter to define the DMI phenotypes. These DMI phenotypes may also partly explain the development and recurrence of diabetic macular oedema. It is also currently unclear where and how DMI fits into the diabetic retinopathy severity scales, further highlighting the need to better define the progression of diabetic retinopathy and DMI based on both multimodal imaging and visual function. Finally, we discuss a complete set of proposed therapeutic pathways for DMI, including cell-based therapies that may provide restorative potential.     

The scope of computerized simulation in competency-based maxillofacial training: a systematic review

Oral and maxillofacial surgery (OMS) teaching is set to undergo a paradigm shift towards competency-based training. With increasing focus on resident skill development and patient safety, computerized simulators are likely to play a more mainstream role in OMS training. A systematic review of the available literature was conducted, in accordance with the PRISMA guidelines, to highlight the scope of computerized simulation in OMS teaching. A PubMed search was performed by two independent reviewers, and 35 articles published in English between 2010 and 2021 that reported the use of computerized simulation for teaching maxillofacial procedures were included in the analysis. Eight articles on minor oral surgery, seven on orthognathic surgery, five on maxillofacial trauma, five on cleft lip and palate surgery, three articles each on nerve block techniques, endoscopic procedures, and reconstructive surgery, and one article on fibre-optic intubation reported the use of computerized simulation that can be applied to OMS training. Ten randomized controlled trials were identified in the search. However there was marked heterogeneity among the studies. Simulator training for skill acquisition mentored by an expert OMS educator could offer holistic resident training; however more studies that test common themes of resident training such as knowledge acquisition and skill development are necessary.     

Intervention rates and outcomes in medically managed uncomplicated descending thoracic aortic dissections

ObjectiveTo evaluate the long-term incidence and outcome of aortic interventions for medically managed uncomplicated thoracic aortic dissections.MethodsBetween January 2012 and December 2018, 91 patients were discharged home with an uncomplicated, medically treated aortic dissection (involving the descending aorta with or without aortic arch involvement, no ascending involvement). After a median period of 4 (first quartile: 2, third quartile: 11) months, 30 patients (33%) required an aortic intervention. Patient characteristics, radiographic, treatment, and follow-up data were compared for patients with and without aortic interventions. A competing risk regression model was analyzed to identify independent predictors of aortic intervention and to predict the risk for intervention.ResultsPatients who underwent aortic interventions had significantly larger thoracic (P = .041) and abdominal (P = .015) aortic diameters, the dissection was significantly longer (P = .035), there were more communications between both lumina (P = .040), and the first communication was significantly closer to the left subclavian artery (P = .049). A descending thoracic aortic diameter exceeding 45 mm was predictive for an aortic intervention (P = .001; subdistribution hazard ratio: 3.51). The risk for aortic intervention was 27% ± 10% and 36% ± 11% after 1 and 3 years, respectively. Fourteen patients (47%) underwent thoracic endovascular aortic repair, 11 patients (37%) thoracic endovascular aortic repair and left carotid to subclavian bypass, 3 patients (10%) total arch replacement with the frozen elephant trunk technique, and 2 patients (7%) thoracoabdominal aortic replacement. We observed no in-hospital mortality.ConclusionsThe need for secondary aortic interventions in patients with initially medically managed, uncomplicated descending aortic dissections is substantial. The full spectrum of aortic treatment options (endovascular, hybrid, conventional open surgical) is required in these patients.     

Brilliance型16排螺旋CT的故障分析与维修

针对日常使用中遇到的Brilliance 16排螺旋CT高压系统、机架以及控制器局域网络(CAN)通讯等故障现象进行分析与维修,最终通过更换滤波电容、机架数据采集控制器(DMC)电源以及信号刷等配件得以排除故障。通过对故障准确判断以及合理运用厂家Service模式下的维修工具软件快速解决故障,保障了影像科检查工作的顺利进行,从而提高设备的稳定性。     

Diagnostic performance of positron emission tomography in the staging of pseudomyxoma peritonei

BackgroundPseudomyxoma peritonei (PMP) is a rare clinical entity, commonly derived from a mucin-producing tumour of the appendix. International consensus is unclear on the role of positron emission tomography (PET) in preoperative staging. This study aimed to assess the ability of preoperative PET in predicting the histological grade of PMP.MethodsAll patients scheduled for cytoreductive surgery (CRS) +/? hyperthermic intraperitoneal chemotherapy (HIPEC) for PMP who underwent preoperative PET at a single centre between June 2007 and June 2020 were included. A nuclear medicine physician, blinded to patient outcomes, retrospectively reviewed imaging studies to assess for maximum tumour standardised uptake value (SUV) to mean liver SUV ratio (SUV_TLR) and maximum porta hepatis SUV to mean liver SUV ratio (SUV_PLR).ResultsBetween April 2007 and December 2020, a total of 204 patients underwent surgical intervention for PMP. Of these, 124 (60.8%) met the inclusion criteria. Median peritoneal carcinomatosis index for the entire cohort was 9 and complete cytoreduction (CC0/1) was achieved in 109 (88%) patients. Patients with high-grade PMP were more likely to have diffuse peritoneal disease (p < 0.001) and higher SUV_TLR (p<0.001). The area under the ROC curve (AUC) of SUV_TLR in predicting high-grade pathology was 71% (p = 0.003). Patients with a SUV_TLR ≤ 0.78 had improved disease-free survival (p = 0.042).ConclusionPreoperative PET showed positive correlation with high-grade PMP and acceptable sensitivity and specificity as a diagnostic tool. PET should be considered a useful adjunct to standard imaging for predicting histological grade in the staging of patients with PMP.