A Modified Quadrature Birdcage Coil Incorporated With a Curved Feature for In Ovo MR Imaging.

Goal: This study presents a novel MRI coil design approach explicitly tailored for chick embryo measurements, with the primary objective of improving sensitivity and coverage. Methods: The limitations posed by conventional birdcage coils were addressed by introducing a curvature feature into a standard coil. The performance of the modified coil was assessed using EM simulations and experimental evaluations, which were subsequently validated using a 7 T MRI scanner. A comparative analysis was conducted against a standard quadrature low-pass birdcage coil to evaluate key factors. Results: The proposed coil demonstrated improved SNR and uniformity, particularly in the proximity of the end-rings. These results were consistent with the findings obtained from the simulations. Conclusions: The use of our innovative birdcage coil design holds promise and offers practical potential for in ovo studies.

Synthesis and Characteristic Valuation of a Thermoplastic Polyurethane Electrode Binder for In-Mold Coating.

A polyurethane series (PHEI-PU) was prepared via a one-shot bulk polymerization method using hexamethylene diisocyanate (HDI), polycarbonate diol (PCD), and isosorbide derivatives (ISBD) as chain extenders. The mechanical properties were evaluated using a universal testing machine (UTM), and the thermal properties were evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The PHEI-PU series exhibited excellent mechanical properties with an average tensile strength of 44.71 MPa and an elongation at break of 190%. To verify the applicability of different proportions of PU as an electrode binder, PU and Ag flakes were mixed (30/70 wt%) and coated on PCT substrates, the electrodes were evaluated by four-point probe before and after 50% elongation, and the dispersion was evaluated by scanning electron microscopy (SEM). The electrical resistance change rate of PHEI-PU series was less than 20%, and a coating layer with well-dispersed silver flakes was confirmed even after stretching. Therefore, it exhibited excellent physical properties, heat resistance, and electrical resistance change rate, confirming its applicability as an electrode binder for in-mold coating.

Design of a Folded, Double-Tuned Loop Coil for ¹H/X-Nuclei MRI Applications.

MR measurement using a combination of X-nuclei and proton MRI is of great interest as the information provided by the two nuclei is highly complementary, with the X-nuclei signal giving metabolic data relating to potential biomarkers and the proton signal affording anatomical details. Due to the relatively weak signal obtained from X-nuclei, combining an X-nuclei coil with a proton coil is also advantageous for [Formula: see text] shimming and scout images. One approach to building a double-resonant coil is to modify the coil geometry. Here, to achieve double-resonance, a 2× 1 ladder network was designed and tuned at both proton and X-nuclei frequencies successfully. Due to coupling between closed wires, the double-tuned coil generates a shifted transmit efficiency pattern compared to that of the single-tuned loop at the 7T MRI proton frequency. To compensate for the shifted pattern, one part of the 2× 1 ladder network was folded, and the tuning and performance of the folded double-tuned coil were evaluated in simulations and MR measurements. The proposed structure was further evaluated with overlapped decoupling in a receive-only array. The results show that our proposed folded double-tuned coil moderated the shifted pattern of a straight double-tuned loop coil and provided minimum losses at both proton and X-nuclei frequencies. The proposed folded double-tuned loop coil has also been further extended to a receive-only array.

Synthesizing Polyurethane Using Isosorbide in Primary Alcohol Form, and Its Biocompatibility Properties.

Isosorbide is a bio-based renewable resource that has been utilized as a stiffness component in the synthesis of novel polymers. Modified isosorbide-based bis(2-hydroxyethyl)isosorbide (BHIS) has favorable structural features, such as fused bicyclic rings and a primary hydroxyl function with improved reactivity to polymerization when compared to isosorbide itself. Polyurethane series (PBH PU series) using polycarbonate diol (PCD) and bis(2-hydroxyethyl)isosorbide (BHIS) were polymerized through a simple, one-shot polymerization without a catalyst using various ratios of BHIS, PCD, and hexamethylene diisocyanate (HDI). The synthesized BHIS and PUs were characterized using proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), and mechanical testing. To determine the feasibility of using these PUs as biomedical materials, we investigated the effects of their BHIS content on PBH PU series physical and mechanical properties. The PBH PU series has excellent elasticity, with a breaking strain ranging from 686.55 to 984.69% at a 33.26 to 63.87 MPa tensile stress. The material showed superb biocompatibility with its high adhesion and proliferation in the bone marrow cells. Given their outstanding mechanical properties and biocompatibility, the polymerized bio-based PUs can contribute toward various applications in the medical field.

Hyperelastic, shape-memorable, and ultra-cell-adhesive degradable polycaprolactone-polyurethane copolymer for tissue regeneration.

Novel polycaprolactone-based polyurethane (PCL-PU) copolymers with hyperelasticity, shape-memory, and ultra-cell-adhesion properties are reported as clinically applicable tissue-regenerative biomaterials. New isosorbide derivatives (propoxylated or ethoxylated ones) were developed to improve mechanical properties by enhanced reactivity in copolymer synthesis compared to the original isosorbide. Optimized PCL-PU with propoxylated isosorbide exhibited notable mechanical performance (50 MPa tensile strength and 1150% elongation with hyperelasticity under cyclic load). The shape-memory effect was also revealed in different forms (film, thread, and 3D scaffold) with 40%-80% recovery in tension or compression mode after plastic deformation. The ultra-cell-adhesive property was proven in various cell types which were reasoned to involve the heat shock protein-mediated integrin (α5 and αV) activation, as analyzed by RNA sequencing and inhibition tests. After the tissue regenerative potential (muscle and bone) was confirmed by the myogenic and osteogenic responses in vitro, biodegradability, compatible in vivo tissue response, and healing capacity were investigated with in vivo shape-memorable behavior. The currently exploited PCL-PU, with its multifunctional (hyperelastic, shape-memorable, ultra-cell-adhesive, and degradable) nature and biocompatibility, is considered a potential tissue-regenerative biomaterial, especially for minimally invasive surgery that requires small incisions to approach large defects with excellent regeneration capacity.

A Novel J-Shape Antenna Array for Simultaneous MR-PET or MR-SPECT Imaging.

Simultaneous MR-PET/-SPECT is an emerging technology that capitalises on the invaluable advantages of both modalities, allowing access to numerous sensitive tracers and superior soft-tissue contrast alongside versatile functional imaging capabilities. However, to optimise these capabilities, concurrent acquisitions require the MRI antenna located inside the PET/SPECT field-of-view to be operated without compromising any aspects of system performance or image quality compared to the stand-alone instrumentation. Here, we report a novel gamma-radiation-transparent antenna concept. The end-fed J-shape antenna is particularly adept for hybrid ultra-high field MR-PET/-SPECT applications as it enables all highly attenuating materials to be placed outside the imaging field-of-view. Furthermore, this unique configuration also provides advantages in stand-alone MR applications by reducing the amount of coupling between the cables and the antenna elements, and by lowering the potential specific absorption rate burden. The use of this new design was experimentally verified according to the important features for both ultra-high field MRI and the 511 keV transmission scan. The reconstructed attenuation maps evidently showed much lower attenuation (  âˆ¼ 15 %) for the proposed array when compared to the conventional dipole antenna array since there were no high-density components. In MR, it was observed that the signal-to-noise ratio from the whole volume obtained using the proposed array was comparable to that acquired by the conventional array which was also in agreement with the simulation results. The unique feature, J-shape array, would enable simultaneous MR-PET/-SPECT experiments to be conducted without unduly compromising any aspects of system performance and image quality compared to the stand-alone instrumentation.

The state-of-the-art and emerging design approaches of double-tuned RF coils for X-nuclei, brain MR imaging and spectroscopy: A review.

With the increasing availability of ultra-high field MRI systems, studying non-proton nuclei (X-nuclei), such as 23Na and 31P has received great interest. X-nuclei are able to provide insight into important cellular processes and energy metabolism in tissues and by monitoring these nuclei closely it is possible to establish links to pathological conditions and neurodegenerative diseases. In order to investigate X-nuclei, a well-designed radiofrequency (RF) system with a multi-tuned RF coil is required. However, as the intrinsic sensitivity of non-proton nuclei is lower compared to 1H, it is important to ensure that the signal-to-noise ratio (SNR) of the X-nuclei is as high as possible. This review aims to give a comprehensive overview of previous efforts, with particular focus on the design concept of multi-tuned coils, predominantly for brain applications. In order to guide the readers, the main body of the review is categorised into two parts: state-of-the art according to the single or multiple design structures and emerging technologies. A more detailed description is given in each subsection relating to the specific design approaches of, mostly, double-tuned coils, including using traps, PIN-diodes, nested and metamaterial, together with explanations of their novelties, optimal solutions and trade-offs.

Design, evaluation and comparison of endorectal coils for hybrid MR-PET imaging of the prostate.

Prostate cancer is one of the most common cancers among men and its early detection is critical for its successful treatment. The use of multimodal imaging, such as MR-PET, is most advantageous as it is able to provide detailed information about the prostate. However, as the human prostate is flexible and can move into different positions under external conditions, it is important to localise the focused region-of-interest using both MRI and PET under identical circumstances. In this work, we designed five commonly used linear and quadrature radiofrequency surface coils suitable for hybrid MR-PET use in endorectal applications. Due to the endorectal design and the shielded PET insert, the outer face of the coils investigated was curved and the region to be imaged was outside the volume of the coil. The tilting angles of the coils were varied with respect to the main magnetic field direction. This was done to approximate the various positions from which the prostate could be imaged. The transmit efficiencies and safety excitation efficiencies from simulations, together with the signal-to-noise ratios from the MR images were calculated and analysed. Overall, it was found that the overlapped loops driven in quadrature were superior to the other types of coils we tested. In order to determine the effect of the different coil designs on PET, transmission scans were carried out, and it was observed that the differences between attenuation maps with and without the coils were negligible. The findings of this work can provide useful guidance for the integration of such coil designs into MR-PET hybrid systems in the future.

Roll-to-roll graphene oxide radon barrier membranes.

Graphene oxide as a radon barrier in living environments was introduced by intercalating the polymer resin-coated layer inside a multilayer membrane with an area of 1 × 10 m and a thickness of 2.5 mm, prepared by the roll-to-roll method. A 5 µm-thick graphene oxide polymer resin (GOPR) layer was coated on polyethylene terephthalate (PET) film (100 µm) between the two styrene-butadiene-styrene (SBS)-modified bitumen asphalt layers fitted for construction sites. The inserted graphene oxide materials were characterized by means of infrared, Raman, and X-ray photoelectron spectroscopy (XPS). Dispersion-corrected density functional theory (DFT) calculations suggested weaker binding energies on the oxide surfaces and higher penetration energy barriers of graphene nanopores for radon (222Rn) than in the cases of the atmospheric gas molecules Ar, H2O, CO2, H2, O2, and N2. Theoretical calculations of the graphene nanopores supported the higher barrier energies of 222Rn than most ambient gases. The roll-to-roll prepared graphene materials exhibited good barrier properties for 222Rn as well as for the ambient gases. The purpose of our experimental and theoretical study is to provide a better understanding of using graphene-based materials to reduce the risk of carcinogenic radon gas in construction sites and residential buildings for practical applications.

Design and evaluation of a 1H/31P double-resonant helmet coil for 3T MRI of the brain.

Proton magnetic resonance imaging (MRI) can be combined with signals from non-proton nuclei (X-nuclei) to provide metabolic information. Double-resonant coils are often used for X-nuclei MR studies where the proton element is employed for scout imaging and B 0 shimming. This work describes the development of a new double-resonant coil capable of operating at both proton and X-nuclei frequencies. The proposed design extends the wheel-and-spoke coil, which allows for quadrature drive, by adding an extra ring outside the coil to achieve double-resonance. Furthermore, in order to maximise SNR by increasing the filling factor, the shape of the coil has been modified to a helmet style making it suitable for brain applications. The performance of the double-resonant helmet coil was evaluated by simulation and MR measurements. The helmet coil was successfully tuned to the 1H/31P resonance frequencies of a 3T MR scanner, with high isolation between the two quadrature ports. MR measurements of a phantom were carried out, and the averaged sensitivity of the double-resonant helmet coil over the whole phantom was found to be higher than that of the conventional double-tuned birdcage coil at both frequencies.

MR-compatible, 3.8 inch dual organic light-emitting diode (OLED) in-bore display for functional MRI.

PURPOSE: Functional MRI (fMRI) is a well-established method used to investigate localised brain activation by virtue of the blood oxygen level dependent (BOLD) effect. It often relies on visual presentations using beam projectors, liquid crystal display (LCD) screens, and goggle systems. In this study, we designed an MR compatible, low-cost display unit based on organic light-emitting diodes (OLED) and demonstrated its performance. METHODS: A 3.8" dual OLED module and an MIPI-to-HDMI converter board were used. The OLED module was enclosed using a shielded box to prevent noise emission from the display module and the potentially destructive absorption of high power RF from the MRI transmit pulses. The front of the OLED module was covered by a conductive, transparent mesh. Power was supplied from a non-magnetic battery. The shielding of the display was evaluated by directly measuring the electromagnetic emission with the aid of a pickup loop and a low noise amplifier, as well as by examining the signal-to-noise ratio (SNR) of phantom MRI data. The visual angle of the display was calculated and compared to standard solutions. As a proof of concept of the OLED display for fMRI, a healthy volunteer was presented with a visual block paradigm. RESULTS: The OLED unit was successfully installed inside a 3 T MRI scanner bore. Operation of the OLED unit did not degrade the SNR of the phantom images. The fMRI data suggest that visual stimulation can be effectively delivered to subjects with the proposed OLED unit without any significant interference between the MRI acquisitions and the display module itself. DISCUSSION: We have constructed and evaluated the MR compatible, dual OLED display for fMRI studies. The proposed OLED display provides the benefits of high resolution, wide visual angle, and high contrast video images during fMRI exams.

Design of a Quadrature 1H/31P Coil Using Bent Dipole Antenna and Four-Channel Loop at 3T MRI.

MRI using nuclei other than protons is of clinical interest due to the important role of these nuclei in cellular processes. Phosphorous-31 (31P), for example, plays an important role in energy metabolism. However, measurement of 31P can be challenging, as the receive signal is weak compared with that of proton (1H). Consequently, it is often necessary to integrate 1H elements for localizations and B0 shimming in RF coils intended for 31P measurements. Good decoupling between the 1H and the 31P elements is therefore essential. In this paper, bent dipole antennas tuned to 1H were integrated with a four channel 31P loop coil array, in a manner providing strong geometric decoupling between dipoles and loops. As the physical length of a resonant dipole antenna is too long at 3T, the dipole antennas were bent around the load. The loss of 31P elements due to the presence of the dipole antennas was evaluated by measuring scattering parameters and comparing the SNR of 31P spectra with and without the presence of the dipole antennas. The performance of the bent dipole antenna was evaluated by simulation and sensitivity measurement. The Q-factors and the SNR of the four-loop array were reduced by less than 5% when the bent dipole antennas were introduced. The measured sensitivity of the bent dipole was higher (15%) than that of dual-tuned birdcage. The combined bent dipole and loop array is therefore a promising design for 1H/31P applications at 3T.

Design and construction of a novel 1H/19F double-tuned coil system using PIN-diode switches at 9.4T.

A double-tuned 1H/19F coil using PIN-diode switches was developed and its performance evaluated. The is a key difference from the previous developments being that this design used a PIN-diode switch in series with an additionally inserted inductor in parallel to one of the capacitors on the loop. The probe was adjusted to 19F when the reverse bias voltage was applied (PIN-diode OFF), whilst it was switched to 1H when forward current was flowing (PIN-diode ON). S-parameters and Q-factors of single- and double-tuned coils were examined and compared with/without a phantom on the bench. Imaging experiments were carried out on a 9.4T preclinical scanner. All coils were tuned at resonance frequencies and matched well. It is shown that the Q-ratio and SNR of double-tuned coil at 19F frequency are nearly as good as those of a single-tuned coil. Since the operating frequency was tuned to 19F when the PIN-diodes were turned off, losses due to PIN-diodes were substantially lower resulting in the provision of excellent image quality of X-nuclei.

Facile preparation of antibacterial, highly elastic silvered polyurethane nanofiber fabrics using silver carbamate and their dermal wound healing properties.

In this study, polycarbonate diol/isosorbide-based antibacterial polyurethane nanofiber fabrics containing Ag nanoparticles were prepared by electrospinning process. Bio-based highly elastic polyurethane was prepared from hexamethylene diisocyanate and isosorbide/polycarbonate diol (8/2) by a simple one-shot bulk polymerization. Ag nanoparticles were formed using simple thermal reduction of silver 2-ethylhexylcarbamate at 120℃. The structural and morphological properties of polyurethane/Ag nanofibers were characterized by X-ray diffraction and scanning electron microscopy. The polyurethane nanofiber fabrics were flexible, with breaking strains from 355% to 950% under 7.28 to 23.1 MPa tensile stress. The antibacterial effects of the treated polyurethane/Ag fabrics against Staphylococcus aureus and methicillin resistant Staphylococcus aureus were examined and found to be excellent. Cell proliferation using the immortalized human keratinocyte HaCaT cell line was performed in order to determine cell viability in the presence of polyurethane and polyurethane/Ag fabrics, showing cytocompatiblility and a lack of toxicity.

Extended Monopole antenna Array with individual Shield (EMAS) coil: An improved monopole antenna design for brain imaging at 7 tesla MRI.

PURPOSE: To propose a new Extended Monopole antenna Array with individual Shields (EMAS) coil that improves the B1 field coverage and uniformity along the z-direction. METHODS: To increase the spatial coverage of Monopole antenna Array (MA) coil, each monopole antenna was shielded and extended in length. Performance of this new coil, which is referred to as EMAS coil, was compared with the original MA coil and an Extended Monopole antenna Array coil with no shield (EMA). For comparison, flip angle, signal-to-noise ratio (SNR), and receive sensitivity maps were measured at multiple regions of interest (ROIs) in the brain. RESULTS: The EMAS coil demonstrated substantially larger flip angle and receive sensitivity than the MA and EMA coils in the inferior aspect of the brain. In the brainstem ROI, for example, the flip angle in the EMAS coil was increased by 45.5% (or 60.0%) and the receive sensitivity was increased by 26.9% (or 14.9%), resulting in an SNR gain of 84.8% (or 76.3%) when compared with the MA coil (or EMA). CONCLUSION: The EMAS coil provided 25.7% (or 24.4%) more uniform B1+ field distribution compared with the MA (or EMA) coil in sagittal. The EMAS coil successfully extended the imaging volume in lower part of the brain. Magn Reson Med 75:2566-2572, 2016. © 2015 Wiley Periodicals, Inc.

A form-fitted three channel (31) P, two channel (1) H transceiver coil array for calf muscle studies at 7 T.

PURPOSE: To enhance sensitivity and coverage for calf muscle studies, a novel, form-fitted, three-channel phosphorus-31 ((31) P), two-channel proton ((1) H) transceiver coil array for 7 T MR imaging and spectroscopy is presented. METHODS: Electromagnetic simulations employing individually generated voxel models were performed to design a coil array for studying nonpathological muscle metabolism. Static phase combinations of the coil elements' transmit fields were optimized based on homogeneity and efficiency for several voxel models. The best-performing design was built and tested both on phantoms and in vivo. RESULTS: Simulations revealed that a shared conductor array for (31) P provides more robust interelement decoupling and better homogeneity than an overlap array in this configuration. A static B1 (+) shim setting that suited various calf anatomies was identified and implemented. Simulations showed that the (31) P array provides signal-to-noise ratio (SNR) benefits over a single loop and a birdcage coil of equal radius by factors of 3.2 and 2.6 in the gastrocnemius and by 2.5 and 2.0 in the soleus muscle. CONCLUSION: The performance of the coil in terms of B1 (+) and achievable SNR allows for spatially localized dynamic (31) P spectroscopy studies in the human calf. The associated higher specificity with respect to nonlocalized measurements permits distinguishing the functional responses of different muscles.

Intracranial microvascular imaging at 7 T MRI with transceiver RF coils.

PURPOSE: To investigate intracranial microvascular images with transceiver radio-frequency (RF) coils at ultra-high field 7 T magnetic resonance imaging (MRI). MATERIALS AND METHODS: We designed several types of RF coils for the study of 7 T magnetic resonance angiography and analyzed quantitatively each coil's performance in terms of the signal-to-noise ratio (SNR) profiles to evaluate the usefulness of RF coils for microvascular imaging applications. We also obtained the microvascular images with different resolutions and parallel imaging technique. RESULTS: The overlapped 6-channel (ch) transceiver coil exhibited the highest performance for angiographic imaging. Although other multi-channel coils, such as 4- or 8-ch, were also suitable for fast imaging, these coils performed poorly in homogeneity or SNR for angiographic imaging. Furthermore, the 8-ch coil was poor in SNR at the center of the brain, while it had the highest SNR at the periphery. CONCLUSION: The present study has demonstrated that the overlapped 6-ch coil with large-size loop coils provided the best performance for microvascular imaging or angiography with the ultra-high-field 7 T MRI, mainly because of its long penetration depth together with high SNR.

New design concept of monopole antenna array for UHF 7T MRI.

PURPOSE: We have developed and evaluated a monopole antenna array that can increase sensitivity at the center of the brain for 7T MRI applications. METHODS: We have developed a monopole antenna array that has half the length of a conventional dipole antenna with eight channels for brain imaging with a 7T MRI. The eight-channel monopole antenna array and conventional eight-channel transceiver surface coil array were evaluated and compared in terms of transmit properties, specific absorption ratio (SAR), and sensitivity. The sensitivity maps were generated by dividing the SNR map by the flip angle distribution. RESULTS: A single surface coil provides asymmetric sensitivity resulting in reduced sensitivity at the center of the brain. In contrast, a single monopole antenna provides higher sensitivity at the center of the brain. Moreover, the monopole antenna array provides uniform sensitivity over the entire brain, and the sensitivity gain was 1.5 times higher at the center of the brain compared with the surface coil array. CONCLUSION: The monopole antenna array is a promising candidate for MRI applications, especially for brain imaging in a 7T MRI because it provides increased sensitivity at the center of the brain.

Contrast echo-a simple diagnostic tool for a coronary artery fistula.

Coronary artery fistulas have been diagnosed with aortography, coronary angiography, and coronary computed tomography (CT). A large fistula can be occasionally found as a mass lesion on echocardiography but cannot be easily confirmed. Here, we report a new diagnostic approach to coronary artery fistulas using a contrast agent and transthoracic echocardiography. Transthoracic echocardiography of a 46-year-old female suffering from dyspnea revealed suspicious small turbulent flow in the main pulmonary artery. Following infusion of a contrast agent, we found whitish flow in the main pulmonary artery during the diastolic phase, and aortic CT revealed two huge right coronary artery fistulas in the main pulmonary artery. A simple diagnostic approach to a coronary artery fistula using contrast agent helped us confirm the diagnosis because of the typical diastolic whitish flow in the pulmonary artery.

A warm footbath improves coronary flow reserve in patients with mild-to-moderate coronary artery disease.

BACKGROUNDS: Recent studies have shown that thermal therapy by means of warm waterbaths and sauna has beneficial effects in chronic heart failure. However, a comprehensive investigation of the hemodynamic effects of thermal vasodilation on coronary arteries has not been previously undertaken. In this study, we studied the effect of a warm footbath (WFB) on coronary arteries in patients with coronary artery disease (CAD), as well as any adverse effect. METHODS: We studied 21 patients (33.3% men, mean age 60.8 ± 13.5 years) with CAD. Coronary flow Doppler examination of the left anterior descending coronary artery and coronary flow reserve (CFR) were performed and measured using adenosine before and after a WFB. RESULTS: Systolic and diastolic blood pressure and heart rate did not change with the WFB. Mean velocity of diastolic coronary flow significantly increased (diastolic mean flow velocity: 18.3 ± 7.1 cm/sec initial, 21.5 ± 8.0 cm/sec follow-up, P = 0.002) and CFR significantly improved (1.6 ± 0.4 vs. 2.2 ± 0.5, P < 0.001) after WFB. The WFB was well accepted and no relevant adverse effects were observed. The change of CFR after WFB correlated well with diastolic function (E', r = 0.51, P = 0.031; E/E', r =-0.675, P = 0.002). CONCLUSIONS: A WFB significantly improved CFR without any adverse effects in patients with mild-to-moderate CAD and can be applied with little risk of a coronary artery event if appropriately performed.