MRI Compatible Planar Material Acoustic Lenses

[EN] Zone plate lenses are used in many areas of physics where planar geometry is advantageous in comparison with conventional curved lenses. There are several types of zone plate lenses, such as the well-known Fresnel zone plates (FZPs) or the more recent fractal and Fibonacci zone plates. The selection of the lens material plays a very important role in beam modulation control. This work presents a comparison between FZPs made from different materials in the ultrasonic range in order to use them as magnetic resonance imaging (MRI) compatible materials. Three different MRI compatible polymers are considered: Acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA) and polylactic acid (PLA). Numerical simulations based on finite elements method (FEM) and experimental results are shown. The focusing capabilities of brass lenses and polymer zone plate lenses are compared.This research was funded by spanish Ministerio de Economía y Competitividad (MINECO) TEC2015-70939-R.Tarrazó-Serrano, D.; Castiñeira Ibáñez, S.; Sánchez Aparisi, E.; Uris Martínez, A.; Rubio Michavila, C. (2018). MRI Compatible Planar Material Acoustic Lenses. Applied Sciences (Basel). 8(12):2634-1-2634-9. doi:10.3390/app8122634S2634-12634-981

Medical Devices Having MRI Compatible Metal Alloys

An MRI compatible medical device includes a non-magnetic metal alloy portion including a first and at least a second metal. A surface of the metal alloy portion includes an integral MRI heating resistant surface structure having a thickness greater than or equal to 3 nanometers. The MRI heating resistant surface structure includes one or more of (i) a matrix phase including the first and second metal having a plurality of nanometer or micron scale particles, precipitates and/or inclusions constituting a volume fraction greater than or equal to 3%, wherein the particles, precipitates or inclusions differ in chemical composition and physical characteristics of the matrix phase and are discontinuously distributed therein; (ii) a level of crystalinity at least 5% less as compared to a level of crystalinity in the bulk of the metal alloy portion; (iii) one or more metal atoms different from the first and second metal having a concentration profile evidencing diffusion into the metal alloy portion

GUI for MRI-Compatible Neural Stimulator and Recorder

Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) are useful tools to analyze brain activities given active stimulation. However, the electromagnetic noise from the MRI distorts the brain signal recording and damages the subject with excessive heat generated on the electrodes attached to the skin. MRI-compatible recording and stimulation systems previously developed at LIBI lab were capable of removing the electromagnetic noise during the imaging process. Previously, the hardware systems had required the integrative software that could control both circuits simultaneously and enable users to easily change recording and stimulation parameters. Graphical user interface (GUI) programmed with computer language informed the user to setup safe recording and stimulating parameters and controlled microcontrollers on the MRI-compatible recorder and stimulator. With the stable data transmission, the GUI could send 2 bytes of command and data to a microcontroller on the MRI-compatible stimulation circuit to setup stimulation parameters, inform user of the safety limit, and change desired parameters. Also, the GUI could receive 8-bit resolute recorded data from a microcontroller on the recording circuit and visualize the recorded data from the serial port on the plotting area on the GUI. Therefore, the GUI was successfully integrated into the LIBILAB system to improve safely and provide fast control over the MRI-compatible hardware systems. Furthermore, the GUI will be developed to automatically detect irregular brain response to any change in stimulation parameters and record data with higher resolution

MRI compatible miniature motor system: Proof of Concept

Master's Thesis in PhysicsPHYS399MAMN-PHY

Functional MRI during hippocampal deep brain stimulation in the healthy rat brain

Deep Brain Stimulation (DBS) is a promising treatment for neurological and psychiatric disorders. The mechanism of action and the effects of electrical fields administered to the brain by means of an electrode remain to be elucidated. The effects of DBS have been investigated primarily by electrophysiological and neurochemical studies, which lack the ability to investigate DBS-related responses on a whole-brain scale. Visualization of whole-brain effects of DBS requires functional imaging techniques such as functional Magnetic Resonance Imaging (fMRI), which reflects changes in blood oxygen level dependent (BOLD) responses throughout the entire brain volume. In order to visualize BOLD responses induced by DBS, we have developed an MRI-compatible electrode and an acquisition protocol to perform DBS during BOLD fMRI. In this study, we investigate whether DBS during fMRI is valuable to study local and whole-brain effects of hippocampal DBS and to investigate the changes induced by different stimulation intensities. Seven rats were stereotactically implanted with a custom-made MRI-compatible DBS-electrode in the right hippocampus. High frequency Poisson distributed stimulation was applied using a block-design paradigm. Data were processed by means of Independent Component Analysis. Clusters were considered significant when p-values were <0.05 after correction for multiple comparisons. Our data indicate that real-time hippocampal DBS evokes a bilateral BOLD response in hippocampal and other mesolimbic structures, depending on the applied stimulation intensity. We conclude that simultaneous DBS and fMRI can be used to detect local and whole-brain responses to circuit activation with different stimulation intensities, making this technique potentially powerful for exploration of cerebral changes in response to DBS for both preclinical and clinical DBS

A Left Ventricular Motion Phantom for Cardiac Magnetic Resonance Imaging

The mammalian left ventricle (LV) has two distinct motion patterns: wall thickening and rotation. The purpose of this study was to design and build a low-cost, non-ferromagnetic LV motion phantom, for use with cardiac magnetic resonance imaging (MRI), that is able to produce physiologically realistic LV wall thickening and rotation. Cardiac MRI is continuously expanding its range of techniques with new pulse sequences, including new tissue tagging techniques which allow intra-myocardial deformation to be visualized. An essential step in the development of new cardiac MRI techniques is validating their performance in the presence of motion. MRI-compatible dynamic motion phantoms are of substantial benefit in the development of cardiac specific-magnetic resonance imaging techniques. These phantoms enable the investigation of motion effects images by mimicking the three dimensional motion of the heart. To date, no single study has succeeded in duplicating both LV motion patterns, in an MRI-compatible cardiac motion phantom. In addition, a phantom that is 100 MRI-compatible with low cost to build would be desirable to researchers. We have built two MRI-compatible phantoms, housed within a common enclosure and each filled with MRI-visible dielectric gel (as a surrogate to myocardium),which model the wall thickening and rotation motions of the left ventricle independently. The wall motion phantom is pneumatic, driven by a custom non-ferromagnetic pump which cyclically fills and empties a latex balloon within the phantom. The rotation phantom is manually driven by a plastic actuator which rotates the phantom through a specified angular rotation. Each phantom also generates a TTL pulse for triggering the MRI scanner. Although this circuitry contains ferromagnetic materials, it can be located outside the scanner bore. The wall thickening motion phantom has been tested using segmented cine, real time cine and grid tagged MRI acquisition sequences. Results were significant with 4 average variability and physiologically

A Left Ventricular Motion Phantom for Cardiac Magnetic Resonance Imaging

The mammalian left ventricle (LV) has two distinct motion patterns: wall thickening and rotation. The purpose of this study was to design and build a low-cost, non-ferromagnetic LV motion phantom, for use with cardiac magnetic resonance imaging (MRI), that is able to produce physiologically realistic LV wall thickening and rotation. Cardiac MRI is continuously expanding its range of techniques with new pulse sequences, including new tissue tagging techniques which allow intra-myocardial deformation to be visualized. An essential step in the development of new cardiac MRI techniques is validating their performance in the presence of motion. MRI-compatible dynamic motion phantoms are of substantial benefit in the development of cardiac specific-magnetic resonance imaging techniques. These phantoms enable the investigation of motion effects images by mimicking the three dimensional motion of the heart. To date, no single study has succeeded in duplicating both LV motion patterns, in an MRI-compatible cardiac motion phantom. In addition, a phantom that is 100 MRI-compatible with low cost to build would be desirable to researchers. We have built two MRI-compatible phantoms, housed within a common enclosure and each filled with MRI-visible dielectric gel (as a surrogate to myocardium),which model the wall thickening and rotation motions of the left ventricle independently. The wall motion phantom is pneumatic, driven by a custom non-ferromagnetic pump which cyclically fills and empties a latex balloon within the phantom. The rotation phantom is manually driven by a plastic actuator which rotates the phantom through a specified angular rotation. Each phantom also generates a TTL pulse for triggering the MRI scanner. Although this circuitry contains ferromagnetic materials, it can be located outside the scanner bore. The wall thickening motion phantom has been tested using segmented cine, real time cine and grid tagged MRI acquisition sequences. Results were significant with 4 average variability and physiologically

A Left Ventricular Motion Phantom for Cardiac Magnetic Resonance Imaging

The mammalian left ventricle (LV) has two distinct motion patterns: wall thickening and rotation. The purpose of this study was to design and build a low-cost, non-ferromagnetic LV motion phantom, for use with cardiac magnetic resonance imaging (MRI), that is able to produce physiologically realistic LV wall thickening and rotation. Cardiac MRI is continuously expanding its range of techniques with new pulse sequences, including new tissue tagging techniques which allow intra-myocardial deformation to be visualized. An essential step in the development of new cardiac MRI techniques is validating their performance in the presence of motion. MRI-compatible dynamic motion phantoms are of substantial benefit in the development of cardiac specific-magnetic resonance imaging techniques. These phantoms enable the investigation of motion effects images by mimicking the three dimensional motion of the heart. To date, no single study has succeeded in duplicating both LV motion patterns, in an MRI-compatible cardiac motion phantom. In addition, a phantom that is 100 MRI-compatible with low cost to build would be desirable to researchers. We have built two MRI-compatible phantoms, housed within a common enclosure and each filled with MRI-visible dielectric gel (as a surrogate to myocardium),which model the wall thickening and rotation motions of the left ventricle independently. The wall motion phantom is pneumatic, driven by a custom non-ferromagnetic pump which cyclically fills and empties a latex balloon within the phantom. The rotation phantom is manually driven by a plastic actuator which rotates the phantom through a specified angular rotation. Each phantom also generates a TTL pulse for triggering the MRI scanner. Although this circuitry contains ferromagnetic materials, it can be located outside the scanner bore. The wall thickening motion phantom has been tested using segmented cine, real time cine and grid tagged MRI acquisition sequences. Results were significant with 4 average variability and physiologically