Computed Research Articles

Subcapsular Hepatic Hematoma Post-Endoscopic Retrograde Cholangiopancreatography Requiring Surgical Necrosectomy

Cholelithiasis is a common gastrointestinal pathology with a prevalence of over 6% in the USA. Symptomatic patients can develop cholangitis, biliary colic, pancreatitis and cholecystitis. Surgical management involves laparoscopic or open cholecystectomy. Stones within the common bile duct can be treated with endoscopic retrograde cholangiopancreatography (ERCP). Well-known ERCP complications include pancreatitis, perforation, bleeding and cholangitis. Hepatic hematomas as a complication of ERCP are extremely rare, with fewer than 50 reported cases in the literature. Approximately 22% have required operative management. We present an extremely rare case of ERCP-associated subcapsular hepatic hematoma in a 43-year-old lady that was initially non-operatively managed. She did not improve with antibiotics alone and underwent attempted interventional radiology drainage. Despite this, due to on-going sepsis, the patient underwent laparoscopic necrosectomy and drain placement with continued post-operative irrigation. After a long course of antibiotics and drain irrigation, the patient was discharged with repeated computed tomography imaging showing almost total resolution of the infected collection. This case highlights the extreme rarity of surgical management for post-ERCP subcapsular hepatic hematoma and its successful outcome. J Med Cases. 2021;12(5):186-189 doi: https://doi.org/10.14740/jmc3672

WEIERSTRASS SEMIGROUPS AT PAIRS OF NON-WEIERSTRASS POINTS ON A SMOOTH PLANE CURVE OF DEGREE 5

We classify all semigroups each of which arises as a Weierstrass semigroup at a pair of non-Weierstrass points on a smooth plane curve of degree 5. First we find the candidates of semigroups by computing the dimensions of linear series on the curve. Then, by constructing examples of smooth plane curves of degree 5, we prove that each of the candidates is actually a Weierstrass semigroup at some pair of points on the curve. We need to study the systems of quadratic curves, which cut out the canonical series on the plane curve of degree 5.

Experimental and numerical investigation of a surface-fixed horizontal porous wave barrier

Experimental and numerical investigations were conducted to study the performance of a surface-fixed horizontal porous wave barrier in regular waves. The characteristics of the reflection and transmission coefficients, energy dissipation, and vertical wave force were examined versus different porosities of the barrier. Numerical simulations based on 3D Reynolds Averaged Navier-Stokes equations with standard low-Re k-e turbulent closure and volume of fluid approach were accomplished and compared with the experimental results conducted in a 2D wave tank. Experimental measurements and numerical simulations were shown to be in satisfactory agreement. The qualitative wave behavior propagating over a horizontal porous barrier such as wave run-up, wave breaking, air entrapment, jet flow, and vortex generation was reproduced by CFD computation. Through the discrete harmonic decomposition of the vertical wave force on a wave barrier, the nonlinear characteristics were revealed quantitatively. It was concluded that the surface-fixed horizontal barrier is more effective in dissipating wave energy in the short wave period region and more energy conversion was observed from the first harmonic to higher harmonics with the increase of porosity. The present numerical approach will provide a predictive tool for an accurate and efficient design of the surface-fixed horizontal porous wave barrier.

Subarachnoid Hemorrhage

Intracranial aneurysms or arterial dissections are major causes of subarachnoid hemorrhage(SAH). Early surgical or endovascular repair of the bleeding source is crucial because rebleeding mostly occurs within a few days after the initial attack. Radiological examination is an initial step for the appropriate diagnosis of ruptured intracranial aneurysms and arterial dissections. However, misdiagnosis may occur, especially in patients with minor bleeding or multiple aneurysms. In addition to computed tomography, magnetic resonance imaging, including FLAIR and SWI, and T2*WI are useful for detecting minor SAH. Vessel-wall imaging has recently been applied to diagnosing the site of rupture in patients with multiple cerebral aneurysms or microaneurysms, but not to assessing the instability of unruptured cerebral aneurysms or intracranial arterial dissections. In this article, we discuss the current radiological modalities and their usefulness for diagnosing SAH.

Combined Pulmonary Fibrosis and Emphysema: A Case Report and Literature Review

The syndrome of combined emphysema of the upper lobes and fibrosis of the lower lobes on chest computed tomography results in a characteristic functional profile, with preserved lung volumes, hypoxemia at exercise. Despite subnormal spirometry, combined pulmonary fibrosis and emphysema is a severe entity. The presence of pulmonary arterial hypertension at diagnosis is a critical determinant of prognosis.

Computational Study of Mass Reduction of a Conceptual Microsatellite Structural Subassembly Utilizing Metal Perforations

A subassembly from the structural subsystem for a conceptual microsatellite designed for earth resources missions underwent normal modes analyses, after implementing an alternative approach to mass reduction, other than implementing advanced space qualified materials. This approach involved developing and implementing a set of geometric patterns that imposed upon certain components of the structural subassembly as perforation patterns, hence achieving mass reduction through straightforward material removal. This approach was proposed to introduce a relatively low-cost and easily implemented mass reduction methodology, which can be utilized by entities with little or no infrastructure and experience in advanced materials, though aspiring to develop their own satellite developing capabilities. The subassembly was the primary load path through which the launch loads pass, the so-called central box, consisting of four Aluminum 6061 identical planar plates, fastened together by titanium fasteners. The subassembly's fundamental natural frequency and attendant mode shape, for all cases, were computed utilizing the finite element method. The current work's approach to mass reduction resulted in an approximate 20% percent reduction in mass from the unperforated case, depending upon the exact thickness value employed for the subassembly plates, hence indicating that the perforation approach is valid.

MAGIC-f gel dosimeter reading: a comparison between an in-house optical CT and MRI imaging

Introduction: According to new developments in radiation therapy techniques, accurate ‎dose verification in three-dimensions has become more critical. Polymer gel dosimeters ‎‎(PGDs) are valuable tools to be used for this purpose. Nowadays, various imaging ‎modalities are employed to read out the gels. This study was aimed to investigate the ‎measured dose distribution recorded in MAGIC-f PGD with optical computed tomography ‎‎(OCT) by comparison with MRI. ‎Material and methods: We developed an in-house CCD based cone-beam OCT scanner. A ‎phantom of MAGIC-f PGD was used to measure a four-field box dose distribution. MRI and ‎OCT scanners were performed for gel readouts. Both measurement results were compared ‎by gamma index analysis with various acceptance criteria. The temporal stability of the gel ‎was also evaluated with the OCT readout system.‎Results: The percentage of isodose lines from two measured datasets agreed well together. ‎The pass rates were 99.02%, 96.8%, and 89.8% with 5%/5mm, 4%/4mm, and 3%/3mm ‎criteria, respectively, at the phantom's central axial slice. ‎Conclusion: The results indicate that the performance of this OCT system is almost the ‎same with acceptable discrepancies to the MRI as accepted standard readout modality, and ‎it can be used for three-dimensional dose verifications.‎

Comprehensive Phenotypic Assessment of Hypertrophic Cardiomyopathy with Spectral Computed Tomography

Comprehensive Phenotypic Assessment of Hypertrophic Cardiomyopathy with Spectral Computed Tomography

Transient memory response of a thermoelectric half-space with temperature-dependent thermal conductivity and exponentially graded modulii

In this work, we consider a problem in the context of thermoelectric materials with memory-dependent derivative for a half space which is assumed to have variable thermal conductivity depending on the temperature. The Lame's modulii of the half space material is taken as a function of the vertical distance from the surface of the medium. The surface is traction free and subjected to a time dependent thermal shock. The problem was solved by using the Laplace transform method together with the perturbation technique. The obtained results are discussed and compared with the solution when Lame's modulii are constants. Numerical results are computed and represented graphically for the temperature, displacement and stress distributions. Affectability investigation is performed to explore the thermal impacts of a kernel function and a time-delay parameter that are characteristic of memory dependent derivative heat transfer in the behavior of tissue temperature. The correlations are made with the results obtained in the case of the absence of memory-dependent derivative parameters.

English

English

X-ray computed tomography

X-ray computed tomography

Simulation of Lueders bands using regularized large strain elasto-plasticity

This paper deals with the numerical simulation of an instability phenomenon called Lueders bands with two regularized material models: viscoplasticity and gradient-enhanced plasticity. The models are based on large strain kinematics and temperature-dependence is incorporated. The Huber–Mises–Hencky yield condition and multi-branch hardening are employed. After a brief presentation of the constitutive description, test computations are performed using AceGen and AceFEM symbolic packages for Wolfram Mathematica. The first benchmark is a rectangular tensile plate in plane strain isothermal conditions. For the viscoplastic model, simulation results for different values of viscosity, loading duration and enforced displacement are compared. For the gradient model different internal lengths are used. Mesh sensitivity of the results and the influence of boundary conditions are also examined. Next to the Lueders-type response to a softening-hardening yield strength function, an additional softening stage leading to failure is also considered. The second example concerns a bone-shape sample under tension, for which, next to mesh sensitivity and the effect of regularization, the influence of heat conduction on simulation results is evaluated.

A model implementation of a scalable data store for scientific computing with DataLad

A model implementation of a scalable data store for scientific computing with DataLad

Project Planning for Improvement in a Healthcare Environment: Developing a Prioritization approach to manage patients' access to the Urodynamics exam

The first in-first out rule does not seem the most appropriated to manage the access of patients to health exams or services such as surgery. Indeed, each patient has his/her level of urgency and, furthermore the utility that each patient retires from the service differs according to several clinical but also risk and social related aspects. The decision of which patient to prioritize is tough because, in the current context where capacity is much lower than demand, choosing one patient means to delay others. Thus, this paper proposes a project methodology to prioritize patients into a Urodynamic service. The methodology, developed by a multidisciplinary team, is applied in a public hospital in Brazil, taking into consideration clinical and social criteria. We interviewed Urodynamics specialists, and a Fuzzy-AHP method is used to compute the weight of each criterion. Our preliminary results show the potential of the proposed methodology and methods, and that not only for the described case, but to other health services facing similar problems.

Computing the Winner of 2-Player TANHINMIN

Computing the Winner of 2-Player TANHINMIN

Pulmonary Adenosquamous Cell Carcinoma With Systemic Lymphadenopathy due to Immunoglobulin G4-Related Disease: A Case Report

A 75-year-old man with diabetes mellitus showed elevated C-reactive protein (CRP) level at his regular visit. Computed tomography scan showed a lung tumor in his left lower lobe and systemic lymphadenopathy including abdominal lymph nodes. The patient was diagnosed as primary pulmonary squamous cell carcinoma with systemic lymph node metastasis. Thereafter, unexpected steroid pulse therapy for accidental acute exacerbation of interstitial pneumonia rapidly shrank lymphadenopathy. At this time, we also found elevated serum immunoglobulin G4 (IgG4) level (385 mg/dL). Considering these findings, we doubted the lymph nodes metastases at the initial staging, and then corrected cancer-staging (C-staging) from inferior vena cava (IVC) to inferior abdomen (IA). In addition, during the steroid tapering, sudden onset and uncontrollable left pneumothorax required surgical approach. Curative-intent left lower lobectomy with lymphadenectomy was performed for the lung cancer. Pathological findings revealed coexistence of adenosquamous carcinoma and infiltration of IgG4-positive plasma cells in the resected mediastinal lymph node. We detected 384 IgG4-positive cells per high power field. IgG4/IgG-positive cell ratio was 54%. Based on these findings, the diagnosis of IgG4-related disease with primary adenosquamous carcinoma (p-stage IIIA) was confirmed. The patient died 24 days after surgery because of another acute exacerbation of interstitial pneumonia. Our case alerts oncologists to IgG4-related disease as a possible underlying comorbidity which may confuse pretreatment clinical stage. J Med Cases. 2021;12(4):164-171 doi: https://doi.org/10.14740/jmc3649

A Rare Cause of Abdominal Pain: Intestinal Angioedema

Angioedema with evidence of mucosal swelling is a rare condition that can be caused by angiotensin-converting enzyme inhibitors. The authors describe a case of a 28-year-old woman medicated with lisinopril 2 months before, with abdominal pain associated with nausea, vomiting and a onetime watery stool. A small volume of ascites was found in the abdominal ultrasound and the parietal thickening of the middle ileum in the abdominal computed tomography (CT). The complementary study was negative. The symptoms stopped after drug withdrawal. The authors intend to warn to this diagnosis, which has non-specific symptoms and if not suspected, can lead to a great morbidity for patients. The authors also intend to identify various signs that can be clues for its correct diagnosis. J Med Cases. 2021;12(4):138-140 doi: https://doi.org/10.14740/jmc3651

Giant Cell Tumor of the Temporal Bone With Skull Base and Middle Ear Extension

We report on a patient who presented to the ear, nose, and throat (ENT) clinic with an 8-month-old left non-pulsatile tinnitus. Imaging studies, Neck computed tomography (CT) and magnetic resonance imaging (MRI) revealed soft tissue mass in the left middle ear with invasion to the middle cranial fossa and external auditory canal. J Med Cases. 2021;12(4):149-151 doi: https://doi.org/10.14740/jmc3627

A porous circulation model of the human brain for in silico clinical trials in ischaemic stroke: A human brain model for ischaemic stroke

The advancement of ischaemic stroke treatment relies on resource-intensive experiments and clinical trials. In order to improve ischaemic stroke treatments, such as thrombolysis and thrombectomy, we target the development of computational tools for in silico trials which can partially replace these animal and human experiments with fast simulations. This study proposes a model that will serve as part of a predictive unit within an in silico clinical trial estimating patient outcome as a function of treatment. In particular, the present work aims at the development and evaluation of an organ-scale microcirculation model of the human brain for perfusion prediction. The model relies on a three-compartment porous continuum approach. Firstly, a fast and robust method is established to compute the anisotropic permeability tensors representing arterioles and venules. Secondly, vessel encoded arterial spin labelling magnetic resonance imaging and clustering are employed to create an anatomically accurate mapping between the microcirculation and large arteries by identifying superficial perfusion territories. Thirdly, the parameter space of the problem is reduced by analysing the governing equations and experimental data. Fourthly, a parameter optimization is conducted. Finally, simulations are performed with the tuned model to obtain perfusion maps corresponding to an open and an occluded (ischaemic stroke) scenario. The perfusion map in the occluded vessel scenario shows promising qualitative agreement with computed tomography images of a patient with ischaemic stroke caused by large vessel occlusion. The results highlight that in the case of vessel occlusion (i) identifying perfusion territories is essential to capture the location and extent of underperfused regions and (ii) anisotropic permeability tensors are required to give quantitatively realistic estimation of perfusion change. In the future, the model will be thoroughly validated against experiments.

Optimization of Photovoltaic Array Orientation and Performance Evaluation of Solar Tracking Systems

In recent years, solar energy has received tremendous attention in accordance with the global efforts in moving towards clean energy generation. A solar tracking system shifts the position of solar panel following the Sun's movement, allowing more energy to be harvested. This paper aims to evaluate the performance of solar tracking system in Malaysia, including the east-west single-axis tracking system, north-south single-axis tracking system, vertical axis tracking system, and dual-axis tracking system. The periodical tilt angle adjustment of fixed-tilt photovoltaic system is also investigated to optimize its performance. A mathematical model is formulated to compute the amount of solar radiation collected in a photovoltaic system and the optimization model is solved using genetic algorithm to determine the optimal tilt and azimuth angles for maximum solar radiation yield. Based on the results, PV system with dual-axis solar tracker has 22.14 % more solar radiation collected compared to the fixed-tilt system, while monthly tilt angle adjustment improves the yield by 2.15 %.