نتایج جستجو برای: diffusion adc
تعداد نتایج: 167870 فیلتر نتایج به سال:
Background: Despite the existence of various imaging methods, the accurate diagnosis of many neurodegenerative diseases is still controversial. The use of advanced imaging techniques, such as the diffusion weighted imaging can be help the early detection of MS and evaluation of the treatment efficacy in these patients. Materials and method: 24 MS patients with acute attack and thirty healthy s...
The apparent diffusion coefficient (ADC) of water in tissues is dependent on the size and spacing of structures in the cellular environment and has been used to characterize pathological changes in stroke and cancer. However, the factors that affect ADC values remain incompletely understood. Measurements of ADC are usually made using relatively long diffusion times; so they reflect the integrat...
PURPOSE We aimed to investigate the effect of key imaging parameters on the accuracy of apparent diffusion coefficient (ADC) maps using a phantom model combined with ADC calculation simulation and propose strategies to improve the accuracy of ADC quantification. METHODS Diffusion-weighted imaging (DWI) sequences were acquired on a phantom model using single-shot echo-planar imaging DWI at 1.5...
PURPOSE To evaluate the diagnostic contribution of diffusion-weighted magnetic resonance imaging (MRI) using apparent diffusion coefficient (ADC) values to the characterization of hepatic masses and differentiation of benign and malignant lesions. MATERIALS AND METHODS The study included 30 patients that underwent upper abdominal MRI examinations because of hepatic masses that were found to b...
Diffusion MRI provides a non-invasive means to characterize tissue microstructure at varying length scales. Temporal diffusion spectra reveal how the apparent diffusion coefficient (ADC) varies with frequency. When measured using oscillating gradient spin echo sequences, the manner in which ADC disperses with gradient frequency (which is related to the reciprocal of diffusion time) provides inf...
Breast imaging represents a relatively recent and promising field of application of quantitative diffusion-MRI techniques. In view of the importance of guaranteeing and assessing its reliability in clinical as well as research settings, the aim of this study was to specifically characterize how the main MR scanner system-related factors affect quantitative measurements in diffusion-MRI of the b...
The diffusion parameters in rat cortex were studied 3-35 days following a cortical stab wound, using diffusion-weighted MR to determine the apparent diffusion coefficient of water (ADC(W)) in the tissue, and the real-time iontophoretic tetramethylammonium (TMA) method to measure the extracellular space (ECS) diffusion parameters: ECS volume fraction alpha and the ADC of TMA(+) (ADC(TMA)). Sever...
Objective Differentiating unicystic ameloblastomas from keratocystic odontogenic tumors (KCOT) is necessary for the planning of different treatment strategies; however, it is difficult based on conventional CT and MR sequences alone. The purpose of this study was to investigate the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADCs) in the differentiation of t...
PURPOSE To determine whether a relationship exists between water diffusion coefficients or diffusion anisotropy and MR-defined regions of normal or abnormal brain parenchyma in patients with cerebral gliomas. METHODS In 40 patients with cerebral gliomas, diffusion was characterized in a single column of interest using a motion-insensitive spin-echo sequence that was applied sequentially at tw...
OBJECTIVE To validate the usefulness of a diffusional anisotropic capillary array phantom and to investigate the effects of diffusion tensor imaging (DTI) parameter changes on diffusion fractional anisotropy (FA) and apparent diffusion coefficient (ADC) using the phantom. MATERIALS AND METHODS Diffusion tensor imaging of a capillary array phantom was performed with imaging parameter changes, ...
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