2023 CiteScore: 0.8
pISSN: 2345-5829
eISSN: 2345-5837
Editor-in-Chief:
Mohammad Reza Ay
Chairman:
Saeid Sarkar
Executive Director:
Hossein Ghadiri
Vol 5 No 1-2 (2018)
Original Article(s)
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Purpose: In soft tissues, tumors have generally different sound speeds than normal tissues, so that sound speed images could be used to characterize breast cancer and to study the tumor invasion process. Ultrasound Computed Tomography (UCT) has a great potential to provide quantitative estimations of physical properties of normal and abnormal tissues that provides accurate characterization capability for breast cancer. The goal of this study is a comparison of two different detector arrangement and image reconstruction filters on image quality parameters in fan-beam back projection method to introduce the modified arrangement and filter to achieve high-quality USCT images.
Materials and Methods: Two USCT systems with two different detector arrangement of the ultrasound array, ring-shape and parallel shape, have been
simulated and Point Spread Function (PSF), Modulate Transform Function (MTF) and spatial resolution are three image quality parameters, have been investigated in both systems. In this study, a modified filter introduced that apply on the sinogram in two dimensions in spite of the Ram-Lak that apply on sinogram in one dimension.
Results: These study results show that the spatial resolution affected by not only detector arrangement but also reconstruction filters. In addition, applying the modified filter improves the resolution of the ring-shaped system and destroy the resolution of the line one and we have higher resolution in the modified filter than Ram-Lak.
Conclusion: The result suggests that to have high-resolution USCT images, the difference filters specially modified filter can be used and ring-shaped system has higher resolution images than line one. -
Purpose: The mechanical map of liver tissue like stiffness is as important as its anatomical image for clinical purposes like staging the liver fibrosis. Acoustic radiation force-based shear waves interference patterns elastography is an interesting independent imaging rate technique which can generate shear waves in the liver tissue in any desired depth by means of the high intensity focused, long duration push beams. Because of wave attenuation and absorption process the sound wave energy is dissipated in the tissue and due to energy conservation law is turned into heat thus like any other ultrasound imaging modality, shear waves interference patterns elastography carries the risk of tissue heating and thermal ablation specially at the focal spot. Therefore, particular attention must be paid to the thermal safety assessment to shear waves interference patterns elastography. The aim of the present simulation study is the thermal safety evaluation in the liver tissue.
Materials and Methods: The liver tissue has been simulated in the presence of its adjacent tissues like skin, muscle, ribs and intercostal muscles in 3 dimensions during shear waves interference patterns elastography. With 4 seconds exposure time and 2 MPa focal pressure.
Results:Temperature at the focal point increases from normal body temperature (37˚C) to 47˚C.
Conclusion: Thermal effects appraisal, indicates that the general tissue heating stays within the safe region. -
Purpose: Electroencephalography based biomarkers including the measurement of the brain’s theta/beta waves in the vertex(Cz) region can be useful to achieve diagnostic and therapeutic objectives in Attention/Deficit-Hyperactivity Disorder (ADHD). EEG biomarkers have been under extensive use in ADHD researchs, even though they have not been clinically confirmed so far. This study attempted to examine the relationship between theta/beta ratio and the disease intensity in ADHD children as well as the sensitivity and theta/beta ratio characteristic to detect ADHD and healthy children. The accuracy of this ratio would help differentiate diseased children from the healthy ones in terms of ADHD.
Materials and Methods: This study is a case-control test, in which the statistical population consisted of 59 healthy children and 61 children with ADHD who had been chosen through simple random sampling. All patients were examined in terms of disease intensity using parental Conner’s questionnaire. The theta/beta ratio in Cz and Fz points was tested and recorded individually each once during waking hours with open eyes with no mental task, and another time during a specific mental task by neurofeedback.
Results: Theta/beta without test was larger in the Fz region in the cases than in the controls (p<0.001). There was a medium relationship between theta/beta (p<0.001) in Fz region and Conner’s score. Theta/beta without test in Fz(sensitivity=62%; specificity=71%) and in Cz (sensitivity=51%; specificity=73%) would differentiate two groups only at a medium level.
Conclusion: It seems that further research should be conducted using more precise tools like QEEG with a larger sample volume and more limited age group. -
Purpose: Variations in the mechanical properties of soft tissues may be a sign of a disease. Since some disease like fibrosis or cancer change the stiffness of related tissues, we can assess the disease of a soft tissue with its elasticity. The elastic stiffness properties of soft tissues can be estimated using locally induced displacements and shear waves.
Materials and Methods: A two-dimensional plane finite element model has been created as soft tissue. The soft tissue has been exposed to two Amplitude Modulated High Intensity Focused Ultrasound transducer (AMHIFU), hence shear wave interference patterns which can be captured by lower frame rate imaging are generated. The acoustic radiation force created by a self-focusing ultrasound transducer has been determined from an ultrasound pressure field simulation. A Gaussian function was fitted to the resulting Acoustic Radiation Force (ARF) field and implemented in the form of a body force in the finite element model.
Results: The effect of different excitation parameters for their optimization in the elasticity estimation has been investigated.
Conclusion: In the result section, the effect of ARF excitation parameters on shear wave elasticity measurements has been represented. Shear wave interference pattern elastography which does not need high frame rate imaging with optimized parameters can be used as a non-invasive method for measuring the elastic stiffness of soft tissues. -
Purpose: Glioblastoma is the most common subset of glioma with a high grade of mortality. Early diagnosis may cause better therapeutic interventionsand brain MRI shows a good performance on tumor localization. Since manual tumor localization is time-consuming, an automatic tumor segmentation is usually recommended. Convolutional Neural Network (CNN) has a wide range application for machine vision and visual recognition.
Materials and Methods: In this study, an automatic brain tumor segmentation based on a fully CNN is presented. This method has been used to localize and differentiate active tumors including high grade and low-grade from edema in multi-modal MRI containing T1 weighted, T1 enhanced, T2 weighted and FLAIR. For assessing the segmentation performance, a dataset was used and divided into train and test subset. Each image was investigated by sliding the window with different sizes contained 5, 10, 15, 20 and 25 pixels.
Results: The results showed that increasing the window size improves the segmentation performance in training phase. It had no significant effect on the segmentation performance in testing phase, therefore increasing the window size improved the learnig of the neural network. The training accuracy for the window with 5 pixels size was 81.6% and for the window with 25 pixels was 96.5%. The test accuracy for the window with 5 pixels size was 80.5% and for the window with 25 pixels was 82.8%. Overall, the best segmentation performance of traning dataset was 97.6% and the best test segmentation performance was 89.7%.
Conclusion: The result with training dataset shows that increasing the sliding windows size may cause the increment of accuracy, but this increment may not necessarily increase the accuracy of test dataset.
