Journal of Biomedical Physics & Engineering
Volume:12 Issue: 1, Jan-Feb 2022

Choroid is one of the structural layers, playing a significant role in physiology of the eye and lying between the sclera and the retina. The segmentation of this layer could guide ophthalmologists in diagnosing most of the eye pathologies such as choroidal tumors and polypoidal choroidal vasculopathy. High signal-to-noise ratio and high speed imaging in Spectral-Domain Optical Coherence Tomography (SD-OCT) make choroidal imaging feasible. Several variables such as pre-operative axial length (AXL), time of day and age affect thickness of the choroidal vascularization and should be considered for segmentation of this layer. These days most of the eye specialists manually segment the choroidal layer which is time-consuming, tiresome and dependent on human errors. To overcome these difficulties, some studies have introduced different automatic choroidal segmentation methods. In this paper, we have conducted a comprehensive review on existing recently published methods for automatic choroidal segmentation algorithms.

Hand tremor is one of the consequences of MS disease degrading quality of patient’s life. Recently DBS is used as a prominent treatment to reduce this effect. Evaluation of this approach has significant importance because of the prevalence rate of disease. The purpose of this study was the nonlinear analysis of tremor signal in order to evaluate the quantitative effect of DBS on reducing MS tremor and differentiating between them using pattern recognition algorithms. In this analytical study, nine features were extracted from the tremor signal. Through statistical analysis, the significance level of each feature was examined. Finally, tremor signals were categorized by SVM, weighted KNN and NN classifiers. The performance of methods was compared with an ROC graph. The results have demonstrated that dominant frequency, maximum amplitude and energy of the first IMF, deviation of the direct path, sample entropy and fuzzy entropy have the potential to create a significant difference between the tremor signals. The classification accuracy rate of tremor signals in three groups for Weighted KNN, NN and SVM with Gaussian and Quadratic kernels resulted in 95.1%, 93.2%, 91.3% and 88.3%, respectively. Generally, nonlinear and nonstationary analyses have a high potential for a quantitative and objective measure of MS tremor. Weighted KNN has shown the best performance of classification with the accuracy of more than 95%. It has been indicated that DBS has a positive influence on reducing the MS tremor. Therefore, DBS can be used in the objective improvement of tremor in MS patients.

Due the long-time admission of patients in the ICU, it is very expensive. Therefore, solutions, which can increase the quality of care and decrease costs, can be helpful. Separation of the patients based on the acute conditions can be useful in providing appropriate therapy. In this study, we present a classifier to predict the OSA based on heart rate variability of patients. In this analytical study, we used the recorded ECG signals from PhysioNet Database. At first, in the preprocessing stage, the noise from the ECG signal was removed, and R spikes were detected to generate the HRV. The next stage was related to linear and non–linear features extraction. We used the paired sample t-test that is a statistical technique to compare two periods (apnea and non-apnea). These features were applied as the inputs of two different classifiers, including MLP and SVM to find the best method and distinguish patients with higher death risk. The results showed that the SVM classifier is more capable to separate the four periods seperated from each other. The sensitivity for detecting the OSA event was 95.46% and the specificity was 97.57% for the non-OSA period. Accurate and timely diagnosis of the disease can ensure the health of the individual, family, and community. Based on the proposed algorithm, the HRV signal and novel feature, presented in this study, had the highest specificity and sensitivity for the detection of the OSA event of the non-OSA, respectively.

The effects of radiation on the cellular compartments of the tumor microenvironment (TME) might be essential in radiotherapy outcomes.

We aimed to assess the effects of the different doses of gamma irradiation on viability, ABCA1 and MMP-9 expression in adipose-derived mesenchymal stem cells (ASCs) as a critical part of TME.

In this experimental study, ASCs were extracted from five healthy donors and irradiated with different doses of 5, 10 and 30 Gy of gamma. Then, RNA was extracted from irradiated ASCs and cDNA was synthesized. The viability of ASCs was determined at 24, 48, 72 and 168 h after irradiation using trypan blue staining. The expression of ABCA1 was checked by quantitative real-time (qRT)-PCR technique and the expression of MMP-9 protein was evaluated by western-blot.

Based on our findings, 10 Gy and 30 Gy but not 5 Gy of gamma irradiation significantly decreased the viability of ASCs after 24, 48, 72 and 168 h compared to the non-irradiated cells (p < 0.05). However, a dose of 5 Gy increased ABCA1 in ASCs significantly compared to 10 Gy and 30 Gy (P=0.01 and P=0.02, respectively). In addition, the analysis of western blot data showed that 5 Gy of gamma irradiation significantly increased the expression of MMP-9 in ASCs (P=0.019).

It is concluded that various doses of gamma radiation elicit differential ASCs responses that may lead to different tumor cell reactions to the radiotherapy through bystander effects.

Glioblastoma is one of the most radioresistant cancers. It is suggested that combination of radiotherapy with other cancer treatment modalities may increase control of tumor. Temozolomide (TMZ) is one of the most known drugs for glioblastoma. It has shown that TMZ via induction of mutation and cell death can kill glioma cells. In the current study, we aimed to show possible radiosensitization effect of TMZ for glioma cells. In addition, results compared to response of normal fibroblast cells to TMZ and irradiation. This is in vitro study for evaluation of the effect of TMZ and irradiation on high grade glioma cells and normal fibroblasts. The human fibroblast and glioma cells were cultured as monolayer. The cells were treated with 2000 μM TMZ, which was equal drug dose for IC50%. In addition, irradiation was done with 5Gy gamma rays. The formation of colony was observed following irradiation, treatment with TMZ, and combination both of them. The formation of colony for both glioma and fibroblast cells showed a reduction following irradiation or treatment with TMZ. Irradiation showed more toxicity compared to TMZ for glioma cells, but not fibroblast cells. Combination of TMZ and irradiation showed a significant reduction in the colony formation compared to irradiation or TMZ treatment alone. This study showed that TMZ increases sensitivity of both glioma and fibroblast cells to ionizing radiation.

From previous studies, we know the correlations of some brain metabolites with a generalized anxiety disorder (GAD) and its symptoms. The response of GAD patients to various treatments is not the same and finding the best treatment option for each patient takes a long period of time. In this study, we try to examine if there is any relationship between a special treatment option and GAD patients’ response and brain metabolite correlation with anxiety level change. This study is a clinical trial type of studies. We have used proton MRS (1H-MRS) with field strength of 3 Tesla to assess whether a different treatment option makes different responses based on metabolite changes. We chose 16 patients based on Hamilton’s anxiety rate and a psychiatrist diagnosis. Patients were divided into two groups randomly. Each group took different treatments. Before treatment started, patients underwent MRS imaging and 8 weeks after treatment as well. Our study lacked a control group, and the results were analyzed by comparing the measured values of metabolites and clinical scores before and after treatment. The NAA and Cho concentration increased after treatments and Cr concentration remained constant in both groups. Both groups showed improvements in their symptoms of anxiety and also in their clinical score rates. Sertraline group showed a more increase in NAA concentration than CBT and also a more decrease in HAMA and HAMD-17 scores. A simultaneously increase in NAA and Cho in both groups and a decrease in clinical anxiety levels demonstrate that NAA and Cho concentration are associated negatively with anxiety levels. In addition, both CBT and sertraline are effective in the improvement of anxiety symptoms.

The Electrocardiogram (ECG) is an important measure for diagnosing the presence or absence of heart arrhythmias. Premature ventricular contractions (PVC) is a relatively large arrhythmia occurring outside the normal tract and being triggered outside the Sino atrial (SA) node of heart. This study has focused on tunable Q-factor wavelet transform (TQWT) algorithm and statistical methods to detect PVC. In this analytical and statistical study, 22 ECGs records were selected from the MIT/BIH arrhythmia database. In the first stage the noise of signal remove and then five sub-bands create by TQWT. In the second stage nine features (minimum, maximum, root mean square, mean, interquartile range, standard deviation (SD), skewness, and variance) extracted of ECG and then the best features selected by using analysis of variance (ANOVA) test. Finally, the system is evaluated by using the learning machines of support vector machine (SVM), the K-Nearest Neighbor (KNN), and artificial neural network (ANN). The best results were verified with KNN learning machine: the sensitivity Se= 98.23% and accuracy Ac= 97.81%. A comparative analysis with the related existing methods shows the method proposed in this study is higher than the other method for classification PVC and can help physicians to classify normal and PVC heart signals in the screening of the patients with coronary artery diseases (CADs).

Porous materials are recommended for orthopedic applications as they eliminate issues of interfacial instability with tissues and reduce mechanical mismatch of the young’s modulus. The current research provides a finite element analysis (FEA) to investigate porous gyroid Ti6Al4V structure compared to a solid stem model for human tibial-knee implantation of total knee replacement (TKR). In this study, the implant proximal portion was designed as porous gyroid Ti6Al4V structure with 500 µm pore size. CATIA V5R18 was used for modeling both gyroid and full solid models. Structural analysis was carried out using ANSYS R18.1 to evaluate the implant performance. After gyroid implantation, the maximum von-Mises stress obtained under the tibial tray was increased to 10.081 MPa. Also, the maximum shear stress at the stem/bone interface was reduced to 0.7347 MPa. The stress concentration at the stem tip and the bone strain energy were also improved. The minimum factor of safety is 4.6 for the gyroid porous implant. A proof of concept model was additively manufactured successfully with pore size 577.7733 ± 34.762 µm. The results indicated enhanced clinical performance of the porous tibial-knee implant compared to the solid titanium implant via increasing the maximum von-Mises bone stresses and decreasing the maximum shear stress at the bone/implant interface.

Multimodality treatment is required for the management of head and neck cancer. Functional impairment and toxicities associated with surgery and radiation accentuate the need to develop innovative therapeutic strategies in the management of these patients to improve survival and reduce toxicity. In this study, we have compared treatment effects in patients of advanced head and neck squamous cell cancer treated by open field and 3DCRT treatment planning techniques. This study aims to evaluate open field and 3DCRT treatment planning techniques in advanced head and neck squamous cell cancer patients managed by chemoradiation in the scenario of limited resources. In this analytical study, 40 histologically proven unresectable advanced squamous cell carcinoma patients of oropharynx and larynx were allocated in two groups to receive 70 Gy in 35 fractions in 7 weeks with concurrent cisplatinum35 mg/m2 weekly either with open-field technique or three dimensional conformal radiotherapy (3DCRT) by ElektaSynergy linear accelerator. Target volume coverage and dose received by organ at risk (OARs) were compared. Clinical outcome in terms of response and toxicities is also evaluated in this study. Plans with best possible coverage of the target volume were obtained. No significant difference was found in the dose received by the spinal cord; however, it was possible to prevent higher dose to brain stem with 3DCRTin node negative patients of oropharynx cancer and larynx cancer. Skin toxicities were significantly lower in 3DCRT arm. In low resource settings with increased burden of locally advanced disease, both open-field and 3DCRT treatment techniques are comparable in terms of target coverage, OARs preservation, toxicity and treatment response.

Cerebral palsy (CP) is a non-progressive encephalopathy before, during, or after childbirth with almost the most common type, i.e. spastic diplegic, leading to a frequent walking problem, In-toeing. Orthoses can reduce the consequences of CP. This study aimed to evaluate the effect of combining twister wrap orthoses (TWO) with high-top shoes on the balance parameters of children with spastic diplegic CP. In this quasi-experimental study, twenty children (aged 6.8 ± 0.5 years) with spastic diplegic CP with in-toeing gait participated. The tests were conducted in three conditions: 1) in bare-foot, 2) with high-top shoes, and 3) with high-top shoes plus TWO and the orthoses effects on balance parameters were compared. High-top shoes positively decreased center of pressure (COP) sway in the anterior-posterior (AP) direction. Both high-top shoes and high-top shoes with TWO conditions compared to bare-foot conditions significantly improved standing balance by decreasing the ellipse area. Pairwise, wearing TWO and high-top shoes significantly reduced the COP sway in the medial-lateral (ML) and AP directions with a significant difference between using the combined orthoses and the shoe without TWO in ML of COP displacement. High-top shoes alone and the combination of high-top shoes with TWO conditions may enhance the stability of children with spastic diplegia more than barefoot. Although the use of combined orthoses induced significant improvement in the ML direction of COP displacement.

Superficial tumours can be treated with megavoltage electron beams. The underlying tissue can be spared through the steep dose fall-off gradients over a range of a few centimetres.An accurate Monte Carlo model for an Elekta Precise was determined and dose distribution was simulated. Dosimetric parameters were calculated to set guidelines for tumour irradiation. Elekta Precise multi-leaf collimators (MLC), which shaped electron fields were investigated using a benchmarked Monte Carlo model. BEAMnrc modelled the Elekta Precise and results were benchmarked against measurements. Percentage depth dose and beam profile data were simulated within 2% / 2 mm accuracy of the measured data. The DOSXYZnrc code simulated the 3-D dose data in water between 4 and 15 MeV. The relative (p 80-20) penumbra, percentage depth dose (PDD), range to 90% of dose maximum (R90), dose fall-off range R80-20 (DFR), and the percentage bremsstrahlung dose (BSD), were extracted from the simulated data.The relative penumbra ranged from 90% to 10% at 6 MeV and 15 MeV, respectively. R90 values ranged between 0.8 cm at 4 MeV and 4.5 cm at 15 MeV. The DFR ranged between 0.8 cm at 4 MeV and 3.5 cm at 15 MeV. The BSD was the highest for low beam energies and small fields. Developed guidelines indicated that intermediate-sized MLC fields are most suited for therapy since they have lower BSD, longer R90, shorter DFR but larger P80-20. The DFR increases and R90 decreases for small fields at higher beam energies and more distal tissue will receive doses > 20%.