Prescribing and deprescribing guidance for benzodiazepine and benzodiazepine receptor agonist use in adults with depression, anxiety, and insomnia: an international scoping review.

Background: Clinical practice guidelines and guidance documents routinely offer prescribing clinicians' recommendations and instruction on the use of psychotropic drugs for mental illness. We sought to characterise parameters relevant to prescribing and deprescribing of benzodiazepine (BZD) and benzodiazepine receptor agonist (BZRA), in clinical practice guidelines and guidance documents internationally, for adult patients with unipolar depression, anxiety disorders and insomnia to understand similarities and discrepancies between evidence-based expert opinion. Methods: A Scoping Review was conducted to characterize documents that offered evidence-based and/or consensus pharmacologic guidance on the management of unipolar depression, anxiety disorders, obsessive-compulsive disorders, post-traumatic stress disorders and insomnia. A systematic search was conducted of PubMed, SCOPUS, PsycINFO and CINAHL from inception to October 13, 2023 and supplemented by a gray literature search. Documents were screened in Covidence for eligibility. Subsequent data-charting on eligible documents collected information on aspects of both prescribing and deprescribing. Findings: 113 documents offering guidance on BZD/BZRA use were data-charted. Overall, documents gathered were from Asia (n = 11), Europe (n = 34), North America (n = 37), Oceania (n = 7), and South America (n = 4) with the remainder being "International" (n = 20) and not representative to any particular region or country. By condition the documents reviewed covered unipolar depressive disorders (n = 28), anxiety disorders, obsessive-compulsive disorder and post-traumatic stress disorder (n = 42) and Insomnia (n = 25). Few documents (n = 18) were sufficiently specific and complete to consider as de-prescribing focused documents. Interpretation: Documents were in concordance in terms of BZD and BZRA not being used routinely as first-line pharmacologic agents. When used, it is advisable to restrict their duration to "short-term" use with the most commonly recommended duration being less than four weeks. Documents were less consistent in terms of prescriptive recommendations for specific drug, dosing and administration pattern (i.e regular or 'as needed') selection for each condition. Deprescribing documents were unanimously in favor of gradual dose reduction and patient shared decision-making. However, approaches towards dose-tapering differed substantially. Finally, there were inconsistencies and/or insufficiency of detail, among deprescribing documents, in terms of switching to a long-acting BZD, use of adjunctive pharmacotherapies and micro-tapering. Funding: The authors received no funding for this work.

A Review of Current Control and Decoupling Methods for MRI Transmit Arrays.

The shortened radio frequency wavelength in high field MRI makes it challenging to create a uniform excitation pattern over a large field of view, or to achieve satisfactory transmission efficiency at a local area. Transmit arrays are one tool that can be used to create a desired excitation pattern. To be effective, it is important to be able to control the current amplitude and phase at the array elements. The control of the current may get complicated by the coil coupling in many applications. Various methods have been proposed to achieve current control, either in the presence of coupling, or by effectively decouple the array elements. These methods are applied in different subsystems in the RF transmission chain: coil; coil-amplifier interface; amplifier, etc. In this review paper, we provide an overview of the various approaches and aspects of transmit current control and decoupling.

A Four-Channel Broadband MRI Receive Array Coil.

Low-impedance preamplifier decoupling is commonly used in RF coil array construction to minimize coupling between elements through mutual impedance. The trap circuit is an essential component in preamp decoupling techniques, but becomes a limiting factor in constructing multi-tuned, multi-nuclear coil arrays. In principle, it is possible to double-tune or multi-tune the trap circuits, but will add complexity and loss. We present a broadband decoupling approach using high impedance preamplifiers. A dual-tuned prototype four-channel array using this approach which targets 2H and 23 Na at 4.7T, has been previously constructed, evaluated and reported. Without any retuning of the array, the same setup is tested at the 23Na and 31P frequencies for 3T. Initial bench measurements and Chemical Shift Imaging (CSI) results are acquired and presented in this study.Clinical Relevance- This study could reduce the complexity of multi-nuclear array coil design.

A Novel Voltage Controlled Decoupling Method for Transmit Coils in MRI.

Array coils are ubiquitous in MRI and are becoming more widely used in MR spectroscopy. Conventional PIN diode decoupling circuits require significant currents to forward bias the diodes. The approach proposed here does not require significant current and thus reduces concerns for contaminating the B0 homogeneity with the detune current. Additionally, the proposed approach will facilitate the construction of array coils for MRI due to its simplicity.Clinical Relevance- Decoupling is critical for constructing RF coil arrays and enables rapid MR imaging.

Low-cost MRI System for Teaching.

Magnetic resonance imaging instrumentation is taught at Texas A&M University through the ECEN 463 course and its graduate level equivalent. This class guides students through several labs where they design their own desktop MRI system using various hardware components and LabVIEW. Because the system uses professional grade equipment, the cost of each lab station is high. As a result, there are only four lab stations available, which limits the class to 32 students. The equipment also contains parts that have become obsolete, inhibiting the ability to maintain the system long term. This project focuses on using easily accessible and more affordable equipment for the MRI system. It can also potentially provide opportunities for remote learning, where students could work on assignments off-campus. Other projects have aimed to design low-cost MRI systems with an emphasis on clinical applications or which require advanced FPGA programming skills or pre-programmed modules. This project will develop the MRI instrumentation with updated off-the-shelf components. The current equipment will be replaced with two Analog Discovery 2 devices, which are low-cost teaching tools. It will also feature inexpensive transmit and receive chains, off-the-shelf gradient amplifiers suitable for teaching, gradient coils for signal localization, and a lighter-weight Halbach magnet. In this stage of the project, projections and images have been captured using a 0.06T permanent magnet. In addition to validating successful system operation, each lab of the course will be integrated with current materials to comply with the new equipment. Hardware and software resources will also be prepared and scaled to meet classroom needs and ensure a smooth transition. The goal of the project is to use the new system starting in the fall 2023 semester.Clinical Relevance- This project shows that low-cost equipment can be implemented into a working MRI system. The intent for this project may be educationally focused, but it shows that extremely light and low-cost systems can be created. It may be reconstructed to have a deployable system that could be used in the field.

Solvent-pumped evaporation concentration on paper in linear and radial geometries.

Solvent-pumped evaporation-driven concentration of an initial distribution of solutes on a porous substrate is considered in one and two dimensions. Approximate analytic solutions to the isotropic advection-dispersion equations are first found for a Gaussian kernel and an infinite domain, following the smoothed particle approximation. Analytic solutions for more general initial distributions are then found as sums of Gaussians, and comparison is made with numerical solutions. In each case, initial distributions are advected toward the stagnation point and concentrated. Two-dimensional analysis is then extended to describe anisotropy in permeability and diffusion, and hydrodynamic dispersion. Radial-flow experiments are performed using filter papers and water-soluble dyes. Diffusion coefficients, temperature and humidity profiles, and the evolution of spot distributions are measured. The results confirm minor anisotropy in permeability and diffusion, limited hydrodynamic dispersion, and largely uniform evaporation. Péclet numbers over 2500 are demonstrated. Evaporation-driven concentration provides a mechanism for solute transport over long timescales. Potential applications lie in the design of paper spray microanalytical devices operating by solvent pumping rather than capillary flow.

Wideband receive-coil array design using high-impedance amplifiers for broadband decoupling.

PURPOSE: Multinuclear MRI/S is of increasing interest. Currently, most multinuclear receive array coils are constructed by nesting multiple single-tuned array coils or using switching elements to control the operating frequency, in which case more than one set of conventional isolation preamplifiers and associated decoupling circuits is required. These conventional configurations rapidly become complicated when greater numbers of channels or nuclei are needed. In this work, a novel coil decoupling mechanism is proposed to enable broadband decoupling for array coils with one set of preamplifiers. METHODS: Instead of using conventional isolation preamplifiers, a high-input impedance preamplifier is proposed to create broadband decoupling of the array elements. A matching network consisting of a single inductor-capacitor-capacitor multi-tuned network and a wire-wound transformer was used to interface the surface coil to the high-impedance preamplifier. To validate the concept, the proposed configuration was compared to the conventional preamplifier decoupling configuration on both bench and scanner. RESULTS: 2 The approach can provide more than 15dB decoupling over a range of 25MHz, covering the Larmor frequencies of 23 Na and 2 H at 4.7T. This multi-tuned prototype obtained 61% and 76% of the imaging SNR at 2 H and 23 Na respectively, 76 and 89% in a higher loading test phantom, when compared to the conventional single-tuned preamplifier decoupling configuration. CONCLUSION: With the multinuclear array operation and decoupling achieved using only one layer of array coil and preamplifiers, this work provides a simple approach of building high element-count arrays to enable accelerated imaging or SNR improvement from multiple nuclei.

Multiple slot modules for high field magnetic resonance imaging array coils.

PURPOSE: Mitigating coupling effects between coil elements represents a continuing challenge. Here, we present a 16-bowtie slot volume coil arranged in eight independent dual-slot modules without the use of any decoupling circuits. METHODS: Two electrically short "bowtie" slot antennas were used to form a "module." A bowtie configuration was chosen because electromagnetic modeling results show that bowtie slots exhibit improved B 1 + P in $$ \frac{B_1^{+}}{\sqrt{P_{in}}} $$ efficiency when compared to thin rectangular slots. An eight-module volume coil was evaluated through electromagnetic modeling, bench tests, and MRI experiments at 4.7 T. RESULTS: Bench tests indicate that worst-case coupling between modules did not exceed -14.5 dB. MR images demonstrate well-localized patterns about single excited modules confirming the low coupling between modules. Homogeneous MR images were acquired from a synthesized quadrature birdcage transmit mode. MRI experiments show that the RF power requirements for the proposed coil are 9.2 times more than a birdcage coil. Whereas from simulations performed to assess the proposed coil losses, the total power dissipated in the phantom was 1.1 times more for the birdcage. Simulation results at 7 T reveal an equivalent B1 + homogeneity when compared with an eight-dipole coil. CONCLUSION: Although exhibiting higher RF power requirements, as a transmit coil when the power availability is not a restriction, the inherently low coupling between electrically short slots should enable the use of many slot elements around the imaging volume. The slot module described in this paper should be useful in the design of multi-channel transmit coils.

Paper-based evaporation concentrators: Comparison of linear and radial geometries.

Paper-based evaporation concentrators with linear and radial geometries are compared. A new method of finding approximate analytic solutions of the advection-dispersion equation is proposed, based on the behavior of concentrators with infinite sources. Analytic approximations are compared with numerical solutions, and the advantage of radial concentration is highlighted: linear concentration rates scale with the square root of the Péclet number Pe while radial rates scale with Pe itself, leading to faster radial concentration beyond a critical value. Experiments are performed with Brilliant Blue FCF dye, using optical transmission and the Beer-Lambert law for quantitation. Dye concentrations are chosen for operation in the linear absorbance regime. Radial concentration is demonstrated under ambient conditions on filter paper disks with 60 mm diameter evaporation areas fed from a perimeter source, in a reverse of the well-known "coffee stain" experiment. Airflow enhanced concentration in strips and wedges is compared directly, using laser-patterned chromatography paper. The advantage of radial concentration is confirmed (and enhanced by diversion of concentrate to the corners of strips) and concentration factors greater than ∼ 500 (the dynamic range of measurement) are obtained in ∼2 h using 30 mm long columns.

Rapid MR Scanner Independent B1 Field Measurement System for Phased Arrays.

This paper demonstrates a rapid B1 field benchtop measurement system that is independent of an MR scanner and network analyzer. This system can be used to obtain radiofrequency (B1 field) strength distribution plots of multiple 2D slices (with an extension to 3D) of a liquid cylindrical phantom for multi-element phased arrays used in MRI. The system can be used in three modes- element, phased array, and multiple fixed point pattern measurement. These modes are demonstrated for a 7T 1H eight-channel dipole array and a corn-syrup based phantom. The system can measure complex phase and amplitude measurements from up to 8 elements in the first mode one or 8 different phase settings in the second mode at a rate of approximately 37 positions per minute, allowing a full 2D B1 mapping for 1303 points in 33.05 minutes. The scan patterns obtained using this setup are compared to the ones obtained using an HP network analyzer and simulations. This work can be extended to measure the E field, SAR and upon increasing the speed of measurement, could be used for applications such as Transmit SENSE. Clinical Relevance- This work benefits a faster and more widely accessible measurement system for phased array antennas for MRI. As phased arrays are becoming very important in MRI, the ability to assess individual element performance more rapidly and B1 shimming performance is important to aid in their further development.

Benzodiazepine and Z-hypnotic stewardship.

These agents are not first-line treatments for many of the conditions for which they are used. When they are used, there should be a plan in place for deprescribing.

Mesothelial cell-derived antigen-presenting cancer-associated fibroblasts induce expansion of regulatory T cells in pancreatic cancer.

Recent studies have identified a unique cancer-associated fibroblast (CAF) population termed antigen-presenting CAFs (apCAFs), characterized by the expression of major histocompatibility complex class II molecules, suggesting a function in regulating tumor immunity. Here, by integrating multiple single-cell RNA-sequencing studies and performing robust lineage-tracing assays, we find that apCAFs are derived from mesothelial cells. During pancreatic cancer progression, mesothelial cells form apCAFs by downregulating mesothelial features and gaining fibroblastic features, a process induced by interleukin-1 and transforming growth factor ß. apCAFs directly ligate and induce naive CD4+ T cells into regulatory T cells (Tregs) in an antigen-specific manner. Moreover, treatment with an antibody targeting the mesothelial cell marker mesothelin can effectively inhibit mesothelial cell to apCAF transition and Treg formation induced by apCAFs. Taken together, our study elucidates how mesothelial cells may contribute to immune evasion in pancreatic cancer and provides insight on strategies to enhance cancer immune therapy.

Surviving Benzodiazepines: A Patient's and Clinician's Perspectives.

Although benzodiazepines have been used for 6 decades, many questions remain unanswered by research. The lived experiences of those adversely affected long term can provide insights into how these agents might be more thoughtfully prescribed. Here, perspectives of one such experience encompassing benzodiazepine initiation, ongoing use with adverse consequences and difficult discontinuation are presented through the eyes of an affected individual and a clinician. This experience highlights the importance of limited initiation and duration of use (2-4 weeks) as well as a supported, slow tapering process led by patients. Because researched evidence about deprescribing benzodiazepines is insufficient and because individual experiences vary so widely, it is the patient's expertise-that of her or his lived experience-that should assume a primary role in determining the course and pace of discontinuing these medications.

Assessing the Feasibility of Dynamic 31P Spectroscopy for Metabolic Studies With a 1.0T Extremity Scanner.

OBJECTIVE: The feasibility of conducting in vivo non-localized 31P Magnetic Resonance Spectroscopy (MRS) with a 1.0T extremity scanner and the potential to increase accessibility of this important diagnostic tool for low cost applications is revisited. METHODS: This work presents a custom transmit-only quadrature birdcage, four-element receive coil array, and spectrometer interfaced to a commercial ONI 1.0T magnet for enabling multi-channel, non-1H frequency capabilities. A custom, magnetic resonance compatible plantar flexion-extension exercise device was also developed to enable exercise protocols. The coils were assessed with bench measurements and 31P phantom studies before an in vivo demonstration. RESULTS: In pulse and acquire spectroscopy of a phantom, the array was found to improve the signal-to-noise ratio (SNR) by a factor of 1.31 and reduce the linewidth by 13.9% when compared to a large loop coil of the same overall size. In vivo testing results show that two averages and a four second repetition time for a temporal resolution of eight seconds was sufficient to obtain phosphocreatine recovery values and baseline pH levels aligned with expected literature values. CONCLUSION: Initial in vivo human skeletal muscle 31P MRS allowed successful monitoring of metabolic changes during an 18-minute exercise protocol. SIGNIFICANCE: Adding an array coil and multinuclear capability to a commercial low-cost 1.0T extremity scanner enabled the observation of characteristic 31P metabolic information, such as the phosphocreatinerecovery rate and underlying baseline pH.

Dynamic 13 C MR spectroscopy as an alternative to imaging for assessing cerebral metabolism using hyperpolarized pyruvate in humans.

PURPOSE: This study is to investigate time-resolved 13 C MR spectroscopy (MRS) as an alternative to imaging for assessing pyruvate metabolism using hyperpolarized (HP) [1-13 C]pyruvate in the human brain. METHODS: Time-resolved 13 C spectra were acquired from four axial brain slices of healthy human participants (n = 4) after a bolus injection of HP [1-13 C]pyruvate. 13 C MRS with low flip-angle excitations and a multichannel 13 C/1 H dual-frequency radiofrequency (RF) coil were exploited for reliable and unperturbed assessment of HP pyruvate metabolism. Slice-wise areas under the curve (AUCs) of 13 C-metabolites were measured and kinetic analysis was performed to estimate the production rates of lactate and HCO3- . Linear regression analysis between brain volumes and HP signals was performed. Region-focused pyruvate metabolism was estimated using coil-wise 13 C reconstruction. Reproducibility of HP pyruvate exams was presented by performing two consecutive injections with a 45-minutes interval. RESULTS: [1-13 C]Lactate relative to the total 13 C signal (tC) was 0.21-0.24 in all slices. [13 C] HCO3- /tC was 0.065-0.091. Apparent conversion rate constants from pyruvate to lactate and HCO3- were calculated as 0.014-0.018 s-1 and 0.0043-0.0056 s-1 , respectively. Pyruvate/tC and lactate/tC were in moderate linear relationships with fractional gray matter volume within each slice. White matter presented poor linear regression fit with HP signals, and moderate correlations of the fractional cerebrospinal fluid volume with pyruvate/tC and lactate/tC were measured. Measured HP signals were comparable between two consecutive exams with HP [1-13 C]pyruvate. CONCLUSIONS: Dynamic MRS in combination with multichannel RF coils is an affordable and reliable alternative to imaging methods in investigating cerebral metabolism using HP [1-13 C]pyruvate.

Regional and organ-level responses to local lung irradiation in sheep.

Lung is a dose-limiting organ in radiotherapy. This may limit tumour control when effort is made in planning to limit the likelihood of radiation-induced lung injury (RILI). Understanding the factors that dictate susceptibility to radiation-induced pulmonary fibrosis will aid in the prevention and management of RILI, and may lead to more effective personalized radiotherapy treatment. As the interaction of regional and organ-level responses may shape the chronic consequences of RILI, we sought to characterise both aspects of the response in an ovine model. A defined volume of left pulmonary parenchyma was prescribed 5 fractions of 6 Gy within 14 days while the contralateral lung dose was constrained. Radiographic changes via computed tomography (CT) were documented to define differences in radio-exposed lung relative to non-exposed lung at d21, d63 and d171 (n = 2), and at d21, d147 and d227 (n = 2). Gross and histologic lung changes were evaluated in samples derived at necropsy examination to define the chronic pulmonary response to radiation. Irradiated lung demonstrated reduced radio-density and increased homogeneity as evidenced from texture based radiomic feature analysis, relative to the control lung. At necropsy, the radiation field was readily defined by pallor on the pleural surface, which was also evident on the cut surface of fixed lung specimens. The degree and homogeneity of pallor reflected the sparse presence of erythrocytes in alveolar septal capillaries of radiation-exposed lung. These changes contrasted with dilated and congested microvasculature in the contralateral control lung. Referencing data to measurements made in control lung volumes of sheep experiencing acute RILI indicated that interstitial collagen continues to deposit in the radio-exposed lung field. Overall lung vascularity increased during the chronic response, as evidenced by increased expression of endothelial cell marker (CD31); however, vascularity was consistently decreased in irradiated lung and was negatively correlated with lung collagen. Other organ-level responses included increased expression of alpha smooth muscle actin (ASMA), increased numbers of proliferating cells (Ki67 positive), and cells expressing the dendritic cell-lysosomal associated membrane protein (DC-LAMP) antigen. The chronic response to RILI in this model is effected at both the whole organ and local lung level. Whilst the long-term consequences of exposure to radiation involved the continued deposition of collagen in the radiation field, organ-level responses also included increased vascularization and increased expression of ASMA, Ki67 and DC-LAMP. Interrupting the interplay between these aspects may influence susceptibility to pulmonary fibrosis after radiotherapy. We advocate for the importance of large animal model systems in pursuing these opportunities to target local, organ-level and systemic mechanisms in parallel within the same subject over time.

A 16-Channel 13C Array Coil for Magnetic Resonance Spectroscopy of the Breast at 7T.

OBJECTIVE: Considering the reported elevation of ω-6/ω-3 fatty acid ratios in breast neoplasms, one particularly important application of 13C MRS could be in more fully understanding the breast lipidome's relationship to breast cancer incidence. However, the low natural abundance and gyromagnetic ratio of the 13C isotope lead to detection sensitivity challenges. Previous 13C MRS studies have relied on the use of small surface coils with limited field-of-view and shallow penetration depths to achieve adequate signal-to-noise ratio (SNR), and the use of receive array coils is still mostly unexplored. METHODS: This work presents a unilateral breast 16-channel 13C array coil and interfacing hardware designed to retain the surface sensitivity of a single small loop coil while improving penetration depth and extending the field-of-view over the entire breast at 7T. The coil was characterized through bench measurements and phantom 13C spectroscopy experiments. RESULTS: Bench measurements showed receive coil matching better than -17 dB and average preamplifier decoupling of 16.2 dB with no evident peak splitting. Phantom MRS studies show better than a three-fold increase in average SNR over the entirety of the breast region compared to volume coil reception alone as well as an ability for individual array elements to be used for coarse metabolite localization without the use of single-voxel or spectroscopic imaging methods. CONCLUSION: Our current study has shown the benefits of the array. Future in vivo lipidomics studies can be pursued. SIGNIFICANCE: Development of the 16-channel breast array coil opens possibilities of in vivo lipidomics studies to elucidate the link between breast cancer incidence and lipid metabolics.

A retrofit to enable dynamic B1+ steering for transmit arrays without multiple amplifiers.

PURPOSE: B1+ shimming is an important method for mitigating B1 inhomogeneity in high-field MRI. Using independent power amplifiers for each transmit (Tx) element is the preferred method for B1 shimming but comes with a high cost. Conversely, the simplest approach to control a Tx array is by using coaxial cables of varying length in the Tx chain, but this approach is cumbersome and impractical for dynamic shimming. In this article, a system is described that enables dynamic, phase-only, eight-channel B1+ steering on a 7T MR scanner with only two power amplifiers. METHODS: Power dividers were utilized to first split the existing two-channel Tx signal into eight channels. Digitally controlled phase shifters on each channel were designed to provide independent phase shifts with a resolution of 22.5° (from 0°, 22.5° … 337.5°). To validate the system, an eight-channel body dipole array was simulated and constructed for bench and 7T imaging and evaluation. RESULTS: The phase conjugate B1+ steering method was employed at three different spatial positions in simulation, bench measurements, and scanner measurements-all with matching results. At the desired points, regions with homogenous B1+ were generated, indicating good Tx steering to the selected region. CONCLUSION: The described system can be used as a simple retrofit to existing hardware to provide phase control while avoiding the need to manually switch cables and without requiring independent power amplifiers for each channel, thus demonstrating the ability to perform dynamic B1+ shimming with increased degrees of freedom but without significantly increased hardware cost.

Local Policy and Programmatic Activity to Address the US Opioid Crisis: A Cross-Sectional Survey of County Governments.

CONTEXT: Despite attention to federal and state governments' response to the US opioid crisis, few studies have systematically examined local governments' role in tackling this problem. OBJECTIVES: To determine what opioid policy and programmatic activities local governments are implementing, which activities are more challenging and require a greater latent ability to implement, and what community, environmental, and institutional factors shape such ability. DESIGN: A cross-sectional survey and multistage sampling procedure. SETTING/PARTICIPANTS: Of all 358 county governments in 5 purposively selected states (Colorado, North Carolina, Ohio, Pennsylvania, and Washington) surveyed, 171 counties (response rate = 47.8%) with complete data on self-reported policy and programmatic activities and predictor variables were eligible for analysis. MAIN OUTCOME MEASURES: Nineteen opioid policy and programmatic activities were analyzed individually and combined into a latent implementation ability index using empirical Bayes means estimates. RESULTS: Item response theory and bivariate analysis were applied. Item response theory estimates suggested that having police officers carry naloxone and establishing a task force of community leaders were easier to implement than more challenging activities such as establishing needle exchanges and allowing arrest alternatives for opioid offenses. Covering individuals' treatment costs was predicted to involve the highest ability. County population size (r = 0.34; 95% confidence interval [CI], 0.20-0.47), population density (r = 0.35; 95% CI, 0.21-0.47), and being a Pennsylvania county (r = 0.45; 95% CI, 0.32-0.56) showed the strongest associations with latent implementation ability. CONCLUSIONS: Counties appear engaged in opioid policy and programmatic activity, although some activities are likely more difficult and may require greater ability to implement than others. More sparsely populated counties appear more disadvantaged in implementing activities for tackling the opioid crisis and may need additional assistance to leverage their ability to build a comprehensive policy and programmatic infrastructure.

A 32-channel receive array coil for bilateral breast imaging and spectroscopy at 7T.

PURPOSE: This work describes the construction and evaluation of a bilateral 32-channel receive array for breast imaging at 7T. METHODS: The receive array consisted of 32 receive coils, placed on two 3D-printed hemispherical formers. Each side of the receive array consisted of 16 receive loops, each loop having a corresponding detachable board with match/tune capacitors, active detuning circuitry, and a balun. Coil performance was evaluated on homogeneous canola oil phantoms using a Philips Achieva 7T system. Array coil performance was compared with a bilateral forced current excitation volume coil in transmit/receive mode and with a previously reported 16-channel unilateral coil with a similar design. RESULTS: The 32-channel array had an increase in average SNR throughout both phantoms by a factor of five as compared with the volume coil, with SNR increases up to 10 times along the periphery and three times in the center. Noise measurements showed low interelement noise correlation (average: 5.4%; maximum: 16.8%). Geometry factor maps were acquired for various acceleration factors and showed mean geometry factors <1.2, for combined acceleration factors of up to six. CONCLUSIONS: The improvements achieved demonstrate the clear potential for use in dynamic contrast-enhanced or diffusion-weighted MR studies, while maintaining diagnostically relevant spatial and temporal resolutions.