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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: magnetic resonance imaging,Quantitative measurement,Basal Nuclei
- چکیده:
- چکیده انگلیسی: Introduction
Quantitative susceptibility mapping (QSM) is a new contrast mechanism in magnetic resonance imaging (MRI). The images produced by the QSM enable researchers and clinicians to easily localize specific structures of the brain, such as deep brain nuclei. These nuclei are targets in many clinical applications and therefore their easy localization is a must. In this study, we aimed to implement two QSM estimation algorithms, threshold-based k-space division (TKD) and morphology enabled dipole inversion (MEDI) in presurgical planning.
Materials and Methods
In this study, susceptibility weighted imaging (SWI) was performed on six patients referred to our center for presurgical planning purposes. The susceptibility values, as well as the contrast-to-noise ratio of few brain regions were estimated. To identify the algorithm, which was best applicable to clinics, a comparison of the two methods was performed.
Results
QSM images were produced; however, the results did not show any significant differences between the susceptibility values of the two methods. The contrast-to-noise ratio for the susceptibility values of the subthalamic nucleus and substantia nigra brain regions were significantly superior using the MEDI approach over TKD, suggesting improved localization of brain regions using the former method.
Conclusion
This study suggests that to identify specific brain regions, such as deep brain nuclei, a QSM contrast would be more beneficial than the conventional MRI contrasts. This study compared MEDI and TKD methods for quantification of brain susceptibility maps, and results showed that the MEDI method resulted in higher-quality images.- انتشار مقاله: 02-07-1395
- نویسندگان: Hadis Alvankar Golpaygan,Mohammad Ali Oghabian,Seyed Amir Hossein Batouli,Arash Zare Sadeghi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: EPI,BOLD Signal,fMRI,Echo Planar Imaging,Geometric Distortion
- چکیده:
- چکیده انگلیسی: Introduction
Echo-planar imaging (EPI) is a group of fast data acquisition methods commonly used in fMRI studies. It acquires multiple image lines in k-space after a single excitation, which leads to a very short scan time. A well-known problem with EPI is that it is more sensitive to distortions due to the used encoding scheme. Source of distortion is inhomogeneity in the static B0 field that causes more geometric distortion in phase encoding direction. This inhomogeneity is induced mainly by the magnetic susceptibility differences between various structures within the object placed inside the scanner, often at air-tissue or bone-tissue interfaces. Methods of reducing EPI distortion are mainly based on decreasing steps of the phase encoding. Reducing steps of phase encoding can be applied by reducing field of view, slice thickness, and/or the use of parallel acquisition technique.
Materials and Methods
We obtained three data acquisitions with different FOVs including: conventional low resolution, conventional high resolution, and zoomed high resolution EPIs. Moreover we used SENSE technique for phase encoding reduction. All experiments were carried out on three Tesla scanners (Siemens, TIM, and Germany) equipped with 12 channel head coil. Ten subjects participated in the experiments.
Results
The data were processed by FSL software and were evaluated by ANOVA. Distortion was assessed by obtaining low displacement voxels map, and calculated from a field map image.
Conclusion
We showed that image distortion can be reduced by decreasing slice thickness and phase encoding steps. Distortion reduction in zoomed technique resulted the lowest level, but at the cost of signal-to-noise loss. Moreover, the SENSE technique was shown to decrease the amount of image distortion, efficiently.- انتشار مقاله: 24-11-1390
- نویسندگان: Golestan Karami,Mohammad Ali Oghabian,Fariborz Faeghi,Mohammad Rasoul Tohidnia
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: X-ray diffraction,Biological Tissues,Coherent Scattering
- چکیده:
- چکیده انگلیسی: Introduction
Individual X-Ray diffraction patterns of biological tissues are obtained via interference of coherent scattering with their electrons. Many scientists have distinguished normal and cancerous breast tissue, bone density, and urinary stone types using the X-Ray diffraction patterns resulting from coherent scattering. The goal of this study was to introduce an optimized method for obtaining X-ray diffraction patterns of different types from biological tissues.
Materials and Methods
A special tool constituting primary and scatter collimators as well as a sample holder was designed and built. All measurements were done using an X-ray tube, the above-mentioned tool, and a semiconductor detector (HPGe). The X-ray diffraction patterns of some tissue-equivalent materials (acrylic, polyethylene, nylon, and calcium carbonate) and biological tissues (adipose, muscle, and bone) were obtained.
Results
The corresponding peak positions for adipose, muscle, bone, acrylic, polyethylene, nylon, and calcium carbonate in corresponding X-ray diffraction patterns are located in 1.1±0.055 nm-1, 1.41±0.072, 1.6±0.08 nm-1, 0.8±0.04 nm-1, 1.03±0.051 nm-1, 1.22±0.061 nm-1, and 1.7 ± 0.085 nm-1, respectively.
Conclusion
The X-ray diffraction patterns obtained in this study were in good agreement relative to previous measurements in terms of peak position. This study introduces a useful setup for extraction of X-ray diffraction patterns from different biological tissues.- انتشار مقاله: 26-10-1390
- نویسندگان: Ali Chaparian,Mohammad Ali Oghabian,Vahid Changizi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Basic Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Nanoparticles,Coating thickness Hydrodynamic size,Relaxivity
- چکیده:
- چکیده انگلیسی: Objective(s):Iron oxide nanoparticles have found prevalent applications in various fields including drug delivery, cell separation and as contrast agents. Super paramagnetic iron oxide (SPIO) nanoparticles allow researchers and clinicians to enhance the tissue contrast of an area of interest by increasing the relaxation rate of water. In this study, we evaluate the dependency of hydrodynamic size of iron oxide nanoparticles coated with Polyethylene glycol (PEG) on their relativities with 3 Tesla clinical MRI.
Materials and Methods: We used three groups of nanoparticles with nominal sizes 20, 50 and 100 nm with a core size of 8.86 nm, 8.69 nm and 10.4 nm that they were covered with PEG 300 and 600 Da. A clinical magnetic resonance scanner determines the T1 and T2 relaxation times for various concentrations of PEG-coated nanoparticles.
Results: The size measurement by photon correlation spectroscopy showed the hydrodynamic sizes of MNPs with nominal 20, 50 and 100 nm with 70, 82 and 116 nm for particles with PEG 600 coating and 74, 93 and 100 nm for particles with PEG 300 coating, respectively. We foud that the relaxivity decreased with increasing overall particle size (via coating thickness). Magnetic resonance imaging showed that by increasing the size of the nanoparticles, r2/r1 increases linearly.
Conclusion: According to the data obtained from this study it can be concluded that increments in coating thickness have more influence on relaxivities compared to the changes in core size of magnetic nanoparticles.- انتشار مقاله: 09-12-1394
- نویسندگان: Farzaneh Hajesmaeelzadeh,Saeed Shanehsazzadeh,Cordula Grüttner,Fariba Johari Daha,Mohammad Ali Oghabian
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Cytotoxicity,Nanocomposite magnetic particles,Silica shell
- چکیده:
- چکیده انگلیسی: Background: Multifunctional core-shell magnetic nanocomposite particles with tunable characteristics have been paid much attention for biomedical applications in recent years. A rational design and suitable preparation method must be employed to be able to exploit attractive properties of magnetic nanocomposite particles. Objectives: Herein, we report on a simple approach for the synthesis of magnetic mesoporous silica nanocomposite particles (MMSPs), consisted of a Fe3O4 cluster core, a nonporous silica shell and a second shell of the mesoporous silica of suitable sizes for biomedical applications and evaluate their cytotoxicity effects on human cancer prostate cell lines. Materials and Methods: Clusters of magnetite (Fe3O4) nanoparticles were coated by a layer of nonporous silica using Stöber method. The coating step was completed by an outer layer of mesoporous silica via template-removing method. Structural properties of MMSPs were investigated by FTIR, HR-S(T)EM, BET, XRD techniques and magnetic properties of MMSPs by VSM instrument. MTT and LDH assays were employed to study the cytotoxicity of MMSPs. Results: Obtained results revealed that decreasing the precursor concentration and the reaction time at the nonporous silica shell formation step decreases the thickness of the nonporous silica shell and consequently leads to the formation of smaller MMSPs. The as-prepared MMSPs have a desirable average size of 180±10 nm, an average pore size of 3.01 nm, a high surface area of 390.4 m2.g-1 and a large pore volume of 0.294 cm3.g-1. In addition, the MMSPs exhibited a superparamagnetic behavior and a high magnetization saturation value of 21±0.5 emu/g. Furthermore, the viability tests of DU-145 cell lines exposed to various concentrations of these particles demonstrated negligible cytotoxicity effects of the as-prepared particles. Conclusions: These results demonstrate interesting properties of MMSPs prepared in this study for biomedical applications.
- انتشار مقاله: 16-09-1393
- نویسندگان: Forough Toubi,Abdolkhalegh Deezagi,Gurvinder Singh,Mohammad Ali Oghabian,Seyed Safa Ali Fatemi,Ayyoob Arpanaei
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Pacific Journal of Cancer Prevention
- نوع مقاله: Journal Article
- کلمات کلیدی: qualitative,Adnexal mass,DCE-MRI,semi-quantitative,quantitative
- چکیده:
- چکیده انگلیسی: Objective: The present study aimed to compare the qualitative (time intensity curve analysis), the semi-quantitative
and the quantitative multiphase 3T dynamic contrast-enhanced (DCE) MRI parameters as predictors of malignancy
in adnexal masses. Materials and Methods: In this prospective study, women with an adnexal mass who were
scheduled for surgical resection or were followed for more than one year period to confirm the benignity of their
lesions, underwent multiphase 3T DCE-MRI. The qualitative (time intensity curve), semi-quantitative (SImax, SIrel,
WIR) and quantitative (Ktrans, Kep, Vb) analyses were performed on DCE-MRI sequences and their predictive values
were compared. Results: A total of 17 benign and 14 malignant lesions were included. According to the qualitative
analysis, none of the lesions with Type I time intensity curves (TIC) were malignant and none of the masses with Type
III TICs were benign. The accuracy of the quantitative parameters in detection of malignancy was found to be higher
than that of semi-quantitative variables, particularly when calculated for a small ROI within the high signal area of the
mass (sROI) rather than the largest ROI including the whole mass (lROI), and when inter-MRI variations were omitted
using ratios. The Kep(tumor)/Kep(myometrium) ratio measured from sROI was the best parameter for differentiating
a malignant lesion with a sensitivity of 100% and a specificity of 92.3%. Conclusion: We concluded that a Type I TIC
confirms a benign lesion, and a type III TIC confirms the malignancy and further evaluation is not recommended for
these lesions. So complementary quantitative analysis is only recommended for adnexal masses with type II TICs.- انتشار مقاله: 17-02-1396
- نویسندگان: Mehrooz Malek,Zeynab Oghabian,Elnaz Tabibian,Maryam Rahmani,Seyedeh Nooshin Miratashi Yazdi,Mohammad Ali Oghabian,Sara Parviz
- مشاهده