Posts Tagged: magnetic resonance imaging

Magnetic resonance electrical properties tomography (MR-EPT) is an emerging technology which plays an important role in specific absorption rate monitoring. The current integral-equation (IE) based MR-EPT methods utilize simulated incident radio-frequency (RF) fields, which are inaccurate and lead to reconstruction errors. In this work, the incident field approximation (IFA) is first demonstrated. IFA utilizes a reference subject and RF field mapping techniques to map the incident field, hence the loading effect of the RF coil can be involved in the IE-based MR-EPT. This method may push the IE-based MR-EPT into practical utilization at UHF-MRI systems.

By combining medical imaging data (CT and MRI) with respiratory computer simulations, we create a powerful tool to correlate structure and function abnormalities in asthma subjects. Segmental volume defect percentages (SVDP) measured from hyperpolarized 3He MRI and CT images are used to define resistance-based boundary conditions for the gas flow models. Subjects with central airway remodeling had larger airway resistances, conducting airway pressure gradients, and secondary flow motion compared to the healthy subjects.

We review the basic principle of electrical properties tomography (EPT), reconstruction methods, biomedical applications including tumor imaging, and existing challenges. As an important application of EPT, the estimation of specific absorption rate (SAR) and its current development will also be discussed.

We developed a robust strategy to image and characterize gastric emptying and motility in rats based on contrast-enhanced MRI and computer-assisted image processing. Results demonstrate an optimized MRI-based strategy to assess gastric emptying and motility in rats, paving the way for using this technique to understand GI diseases, or test new therapeutics in rat models.

This work combines the integral equation method with sophisticated numerical techniques, and the newly introduced magnetic resonance Green functions, into an efficient full-wave frequency-domain simulation tool for the analysis of interactions between electromagnetic waves created by arbitrary RF coils and realistic human body models, including the virtual family population.

This paper describes a pipeline for realistic head models of nonhuman primates for simulations of noninvasive brain stimulation, and uses these models together with empirical threshold measurements to demonstrate that the models capture individual anatomical variability…