Magnetic resonance imaging is an inherently signal-to-noise-starved technique that limits the spatial resolution, diagnostic image quality and results in typically long acquisition times that are prone to motion artefacts. This limitation is exacerbated when receive coils have poor fit due to lack of flexibility or need for padding for patient comfort. Here, we report a new approach that uses printing for fabricating receive coils. Our approach enables highly flexible, extremely lightweight conforming devices. We show that these devices exhibit similar to higher signal-to-noise ratio than conventional ones, in clinical scenarios when coils could be displaced more than 18 mm away from the body. In addition, we provide detailed material properties and components performance analysis. Prototype arrays are incorporated within infant blankets for in vivo studies. This work presents the first fully functional, printed coils for 1.5- and 3-T clinical scanners.

Purpose To develop methods for characterizing materials used in screen-printed MRI coils and improve SNR with new lower-loss materials. Methods An experimental apparatus is created to characterize dielectric properties of plastic substrates used in receive coils. Coils are fabricated by screen printing conductive ink onto several plastic substrates. Unloaded and sample loaded quality factor (QUnloaded/QLoaded) measurements and scans on a 3T scanner are used to characterize coil performance. An experimental method is developed to describe the relationship between a coil's QUnloaded and the SNR it provides in images of a phantom. Additionally, 3T scans of a phantom and the head of a volunteer are obtained with a proof-of-concept printed 8-channel array and the results are compared to a commercial 12-channel array. Results Printed coils with optimized substrates can exhibit up to 97% of the image SNR when compared to a traditional coil on a loading phantom. QUnloaded and the SNR of coils are successfully correlated. The printed array results in images comparable to the quality given by the commercial array. Conclusion With the methods and materials proposed, the SNR of printed coils approaches that of commercial coils while using a new fabrication technique that provides more flexibility and close contact to the patient's body.

ediatric MRI is often performed with heavy, large, and relatively inflexible coil arrays designed and built for adult MRI. For awake children, these arrays can be intimidating and uncomfortable, thereby restricting the child's breathing. For parents, they contribute to the stress of the examination. For pediatric caregivers, the coils complicate the placement of medical support equipment, such as mechanical ventilation tubes, pulse oximeters, anesthetic lines, respiratory bellows, blood pressure cuffs, electrocardiogram probes, and video goggles. For sedated or anesthetized children, respiratory compromise from heavy coils on the torso requires more invasive respiratory support or bolstering of the coils away from the patient, with a resultant decrease in signal-to-noise ratio (SNR) and reduced parallel imaging acceleration capability. As a result, much work has been aimed at the design of custom-fitted pediatric coils to maintain SNR. Such efforts have included a flexible cardiac array (1), a set of small head coils for pediatric patients (2), and even a novel pneumatically adjustable head coil to maintain a close patient fit (3). In comparison, flexible arrays have also been proposed by Neocoil (Pewaukee, Wis) and ScanMed (Omaha, Neb). Recently, screen-printed MRI coil technology has been developed to increase SNR due to a more compact fit with respect to the patient. Screen-printed MRI coils allow printing on a flexible substrate (4,5). These coils also have been shown to be printable on fabric, and a 12-channel receive array has been used at 3 T (4-7). In addition to the beneficial SNR increase of large dense MRI coil arrays in general (1,8-14), screen-printed technology (15,16) offers the advantage

We have developed a process for fabricating patient specific Magnetic Resonance Imaging (MRI) Radio-frequency (RF) receive coil arrays using additive manufacturing. Our process involves spray deposition of silver nanoparticle inks and dielectric materials onto 3D printed substrates to form high-quality resonant circuits. In this paper, we describe the material selection and characterization, process optimization, and design and testing of a prototype 4-channel neck array for carotid imaging. We show that sprayed polystyrene can form a low loss dielectric layer in a parallel plate capacitor. We also demonstrate that by using sprayed silver nanoparticle ink as conductive traces, our devices are still dominated by sample noise, rather than material losses. These results are critical for maintaining high Signal-to-Noise-Ratio (SNR) in clinical settings. Finally, our prototype patient specific coil array exhibits higher SNR (5 × in the periphery, 1.4 × in the center) than a commercially available array designed to fit the majority of subjects when tested on our custom neck phantom. 3D printed substrates ensure an optimum fit to complex body parts, improve diagnostic image quality, and enable reproducible placement on subjects.

In magnetic resonance guided focused ultrasound (MRgFUS) therapy sound waves are focused through the body to selectively ablate difficult to access lesions and tissues. A magnetic resonance imaging (MRI) scanner non-invasively tracks the temperature increase throughout the tissue to guide the therapy. In clinical MRI, tightly fitted hardware comprised of multichannel coil arrays are required to capture high quality images at high spatiotemporal resolution. Ablating tissue requires a clear path for acoustic energy to travel but current array materials scatter and attenuate acoustic energy. As a result coil arrays are placed outside of the transducer, clear of the beam path, compromising imaging speed, resolution, and temperature accuracy of the scan. Here we show that when coil arrays are fabricated by additive manufacturing (i.e., printing), they exhibit acoustic transparency as high as 89.5%. This allows the coils to be placed in the beam path increasing the image signal to noise ratio (SNR) five-fold in phantoms and volunteers. We also characterize printed coil materials properties over time when submerged in the water required for acoustic coupling. These arrays offer high SNR and acceleration capabilities, which can address current challenges in treating head and abdominal tumors allowing MRgFUS to give patients better outcomes.

Objectives Essential Tremor (ET) is one of the most common neurologic conditions, and conservative measures are frequently suboptimal. Recent data from a multi-institution, randomized controlled clinical trial demonstrated that Magnetic Resonance-guided Focused Ultrasound (MRgFUS) thalamotomy improves upper limb tremor in medically refractory ET. This study assesses the cost-effectiveness of this novel therapy in comparison to existing procedural options. Methods PubMed and Cochrane Library searches were performed for studies of MRgFUS, Deep Brain Stimulation (DBS), and Stereotactic Radiosurgery (SRS) for ET. Pre-and post-operative tremor-related disability scores were collected from 32 studies involving 83 MRgFUS, 615 DBS, and 260 SRS cases. Utility (defined as percent change in functional disability) was calculated, and Medicare reimbursements were collected as a proxy for societal cost -costs of MRgFUS for ET were derived from a combination of available costs of approved indications and SRS costs where appropriate. A decision and cost-effectiveness analysis was then constructed, implementing meta-analytic techniques. Results MRgFUS thalamotomy resulted in significantly higher utility scores compared with DBS and SRS based on estimates of Medicare reimbursement (p < 0.001). MRgFUS was also the most inexpensive procedure out of the three (p < 0.001). Conclusions Preliminary experience with MRgFUS for ET suggests that this novel therapeutic may be more effective than available alternatives and potentially less costly for society. It thus will likely "dominate" DBS and SRS as a more cost-effective option for medically refractory ET. Our findings support further investigation of MRgFUS for ET and broad adoption. Objectives The ventral intermediate nucleus (VIM) is not visible on conventional Magnetic Resonance Imaging (MRI).A novel method for tractography-based VIM identification has recently been described. We report the short-term clinical results of prospective VIM targeting with tractography in a cohort of patients undergoing Focused Ultrasound thalamotomy. Methods All patients underwent structural and diffusion weighted imaging (60 diffusion directions, 2 mm isovoxel) with 3 Tesla MRI scanner (Philips Ingenia CX). The images were processed using streamline tractography (Stealth Viz, Medtronic Inc.). The lateral and posterior borders of VIM were defined by tracking the pyramidal tract and medial lemniscus respectively. A VIM region of interest (ROI) was placed 3 mm away from these borders (Figs. 1, 2 and 3). The structural connectivity of this VIM ROI was confirmed to the motor cortex (M1) and cerebellum. The coordinates of tractography-based VIM in relation to posterior commissure were noted for surgical targeting. The parameters analyzed include a clinical tremor scale (pre-, intraoperative, and post operative), operative time, and number of sonications. Results Tractography-based VIM targeting was successful in 7 out of 8 patients. The coordinates of tractography-based VIM were significantly different from...