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In this article, we survey a complete MRI systematic pipeline from theoretical modelling and numerical simulations to analysis and optimization of three different types of MRI coils. After a preliminary parametric exploration using generic models based on standard equations, a Method of Moments (MoM) study of geometrically representative coil structures was conducted to explore the nearer field effects. Then, Finite Difference Time Domain (FDTD) analysis was performed to realize the optimized-designed devices to be fabricated using MEMS process and confirmed its performance by using Vector Network Analyzer (VNA) and an anechoic chamber measurement. Performance comparisons based on parameters like resonance frequency, gain and radiated power were performed. Then for the Roger’s 6010TM RT/Duroid substrate material (ε=10.5) thickness 1.6 mm, the rectangular resonance frequency and return loss for the MRI coil are 8.06 GHz and 52.73 dB respectively. The gain on this coil is 36.45 dBm and the radiated powers were 59.25 dBi and 53.56 dBi. In comparison, using similar substrate material, it obtained a return loss of 52.73 dB and a gain of 45.89 dBm, while the circular MRI coil works at the same resonance frequency and could be found in the literature. Using Teflon-PTFE substrate with dielectric constant of 2.1, the resultant triangular MRI coil is fabricated which shows resonance frequency of 8 GHz return loss of 45.81 dB and gains of 49.35 dBm. This study’s performance metrics are closure with regularization results, and the closure is the validation of the enhanced performance of the proposed resonators for medical imaging applications. The designs were also extrapolated to bio-phantom models for further exploration. These RF coils could improve MRI diagnostic technologies as confirmed by the electromagnetic simulation results.

The research work proposed for the X-band microstrip line-based magnetic resonance imaging (MRI) coils has been accomplished with coplanar waveguide feeding and ha highlighted the design parameters to be employed in the internet of medical things (IoMT) features. The proposed research has focused on the wireless body area networks (WBAN) phenomenon in simulated human organs. It has been employed to study the electro-magnetic (EM) parameters of the simulated human organ and the functioning of wearable MRI coils on the human body. Therefore, these coils have been configured in triangle-shaped hierarchical structures, and each layer has been printed on both sides of the conductive strips. These proposed coils utilize a Bakelite substrate with a 1.6-mm thickness and an equivalent dielectric strength of 1.2. It has 69.9 × 85.2 × 1.6 mm3 dimensions and was fabricated using microwave integrated circuits (MIC). These coils have been generated at 8 GHz and this spectrum has been justified with the microwave X band (8–12 GHz) using the standard measured results. Hence, these coils have demonstrated 45.81-dB signal attenuation with a 1-dB standing wave ratio (SWR). Therefore, this research has extended to the different kinds of virtual simulation scenarios in diagnosis applications. Additionally, the research delves into the electromagnetic characteristics, encompassing electric and magnetic fields, the specific absorption ratio (SAR), and temperature. These characteristics are thoroughly analyzed using MRI phantom models within virtual environments. As a result of this comprehensive analysis, the suitability and efficacy of these MRI coils have met rigorous standards. These coils are highly demanded by complicated systems functioning in these bands for IoMT and MRI diagnosis applications.

Clinical MRI/MRS applications require radio frequency (RF) surface coils positioned at an arbitrary angle alpha with respect to B(0). In these experimental conditions the standard circular loop (CL) coil, producing an axial RF field, shows a large signal loss in the central region of interest (ROI). We demonstrate that transverse-field figure-of-eight (FO8) RF surface coils design are not subject to the same amount of signal loss in the central ROI as loop coils when their orientations are changed. The 1.5-T CL and FO8 prototypes (diameter = 10 cm) were built on Plexiglas using copper strips (width = 4 mm, thickness = 100 mum). The two linear elements of the FO8 coil were 1 cm apart. Axial spoiled gradient echo (SPGR) images of a phantom containing doped water were acquired with the coil plane at alpha=0 degrees , 45 degrees , and 90 degrees . As alpha increases, the CL images show, in the central ROI, a signal that decreases from a maximum value to zero. Whereas the FO8 images show, in the same ROI, a signal that varies little from the maximum value (20%). Optimized FO8 coils can be oriented with the coil plane positioned along any direction with respect to B(0) without significant signal loss. Transverse RF coil design should be useful for clinical MRS studies and also for parallel imaging techniques where versatile RF coils disposed along arbitrary directions are required.

To evaluate the clinical application of phased-array surface coil intensity correction in magnetic resonance imaging (MRI) in spinal metastases. 3 phantoms and 50 patients with a corresponding total number of 80 spinal metastases were included in this study. Fast spin echo T1- and T2- weighted MRI with and without surface coil intensity correction was routinely performed for all phantoms and patients. Phantoms were evaluated by means of variance to mean ratio of signal intensity on both T1- and T2- weighted MRI obtained with and without surface coil intensity correction. Spinal metastases were evaluated by image quality scores; reading time per case on both T1- and T2- weighted MRI obtained with and without surface coil intensity correction. Spinal metastases were diagnosed more successfully on MRI with surface coil intensity correction than on MRI with conventional surface coil technique. The variance to mean ratio of signal intensity was 53.36% for original T1-weighted MRI and 53.58% for original T2-weighted MRI. The variance to mean ratio of signal intensity was reduced to 18.99% for T1-weighted MRI with surface coil intensity correction and 22.77% for T2-weighted MRI with surface coil intensity correction. The overall image quality scores (interface conspicuity of lesion and details of lesion) were significantly higher than those of the original MRI. The reading time per case was shorter for MRI with surface coil intensity correction than for MRI without surface coil intensity correction. Phased-array surface coil intensity correction in MRIs of spinal metastases provides improvements in image quality that leads to more successfully detection and assessment of spinal metastases than original MRI.

Since the risks for thrombosis are more dependent on plaque composition than on the degree of luminal narrowing, the radiological assessment of atherosclerosis should extend beyond mere depiction of the arterial lumen. High-resolution MRI of the vessel wall can provide important information about the individual makeup of atherosclerotic plaques, potentially enabling early detection and characterization of lesions before narrowing of the vessel lumen occurs. The MR-based assessment of the vessel wall with sufficient spatial resolution and image contrast, however, remains challenging. Requirements include high signal-to-noise ratio, high contrast-to-noise ratio, good signal penetration depth and homogeneous signal throughout the vessel under investigation, as well as imaging protocols encompassing various contrast weightings. Numerous dedicated radiofrequency (RF) coils have been developed to achieve these goals employing either external surface phased-array coils, or alternatively, utilizing intravascular coils to image the vessel wall from inside the vessel and thus being invasive. For the non-invasive approach of imaging with surface coils, the carotid and the right coronary arteries have been favoured since they are of critical importance and since they are relatively superficial structures, accessible from the outside. To detect the early development of plaque and visualize it globally rather than locally, intravascular contrast agents on the basis of ultrasmall particles of iron oxide can be used as a marker of macrophage activity within the plaque. In the long run, it appears likely that the combination of luminal MR angiography with the administration of susceptibility-based contrast agents and subsequent high-resolution MR of detected atherosclerotic lesions with dedicated RF coils could evolve as the diagnostic concept of choice for the assessment of atherosclerotic disease.

Magnetic resonance imaging (MRI) strongly relies on signal-to-noise ratio (SNR) parameter that must be as high as possible. The electrical performance of the RF coil is critical to achieve this purpose. Using higher magnetic fields is the most common way to increase the amount of detectable nuclear magnetization, but this generates more complex interactions between the RF field and the subject. This, forces to find the best coil design to obtain an optimal RF signal, for example using a device that fits the very variable anatomies in dimension and shape, leading to the develop of coils that are geometrically adjustable to the subject to analyse. Moreover, the need to have a bigger field of view (FOV) without losing significant SNR, is usually reached increasing the number of coils for the signal detection. The main challenges of designing a flexible array coil is to develop geometry-achieved decoupling for the coil elements. In fact, mutual inductance among coil elements varies with the coil size, thus the flexibility of the coil creates even more complicated decoupling issues. Furthermore, to fit high-density receiver arrays for MRI closely around individual target anatomies, there is a need to provide a high degree of geometric adjustability with ease of handling and patient comfort. In this work is first performed an electrical characterization of the coil to evaluate the RF sensitivity of these flexible devices. Then, this work focuses on the advantages of an array of two smaller coils over a single larger coil, on the decoupling issues performing an MRI simulation over a saline and body-like phantom, measuring the magnetic field penetration with a high frequency (7T) experiment.