Panoramic Magnetic Resonance Imaging of the Breast With a Wearable Coil Vest

Adaptable, wearable, and stretchable coils: A review

Over the last four decades, there have been various evolutions in the design and development of coils, from volume coils to the recent introduction of wireless receive arrays. A recent aim has been to develop coils that can closely conform to the anatomy of interest to increase the acquired signal. This goal has given rise to designs ranging from adaptable transmit coils to on-body stretchable receive arrays made using fabric or elastomer substrates. This review covers the design, fabrication details, experimental setup, and MRI results of adaptable, wearable, and stretchable MRI coils. The active and passive automatic tuning and matching strategies are examined with respect to mitigating signal-to-noise ratio reduction when the coil form is altered. A brief discussion of wireless MRI coils, which provide a solution to overcome the cabling issues associated with MRI coil development, is also included. The adaptable, wearable, and stretchable coils and various coil tuning techniques represent innovative radiofrequency coil solutions that pave the way for next-generation MRI hardware development.

Meta-analysis of the synergistic effect of magnetic resonance imaging and mammography in breast cancer detection in women with dense breasts

OBJECTIVES

This meta-analysis aimed to evaluate the combined effectiveness of Magnetic Resonance Imaging (MRI) and mammography in detecting breast cancer in women with dense breasts.

METHODS

A comprehensive search was conducted across PubMed, Web of Science, and EMBASE databases up to December 31, 2023, to identify relevant studies. Studies focusing on breast cancer detection in women with dense breast tissue and providing data on the sensitivity, specificity, or positive predictive value of combined MRI and mammography screening, or the use of MRI following a negative mammogram, were included. The meta-analysis was conducted using Stata 15.0, and study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool.

RESULTS

Ten studies, involving 51,602 participants, were included in the meta-analysis. The combined use of MRI and mammography for breast cancer detection in women with dense breasts yielded a pooled sensitivity of 0.87 (95% CI: 0.79-0.92), specificity of 0.95 (95% CI: 0.89-0.97), positive likelihood ratio of 2.55 (95% CI: 1.45-4.46), negative likelihood ratio of 0.11 (95% CI: 0.07-0.17), diagnostic score of 3.18 (95% CI: 2.35-4.02), and diagnostic ratio of 24.14 (95% CI: 10.44-55.81), and an area under the Summary Receiver Operating Characteristic curve of 0.97 (95% CI: 0.95-0.98).

CONCLUSION

This meta-analysis demonstrated that the combination of MRI and mammography enhanced breast cancer detection in women with dense breasts. This synergistic approach significantly improves detection sensitivity in this high-risk group.

Supine breast MRI using a wearable coil facilitates the translation of MR imaging findings to clinical practice

PURPOSE

The aim of this study is the evaluation of a wearable radiofrequency coil vest (BraCoil) for supine breast MRI, comparing lesion displacement and size with standard prone MRI and supine ultrasound, and assessing its potential impact on clinical workflows for targeted ultrasound and ultrasound-guided biopsy.

MATERIAL AND METHODS

MRI and ultrasound data were collected from 11 female patients with 18 breast lesions. Patients underwent two MRI exams: standard prone MRI using a commercial coil and supine MRI using the BraCoil. Lesion positions were compared between prone MRI, supine MRI, and supine ultrasound using anatomical landmarks (skin, pectoral muscle, nipple). Statistical analysis was performed on the mean absolute differences in lesion positions.

RESULTS

With ultrasound lesion positions as a reference, supine MRI acquired with the BraCoil showed significantly less lesion displacement compared to prone MRI, with on average 7.3 mm less lesion-skin (p = 0.004) and 26.7 mm less lesion-pectoral muscle (p = 0.0001) displacement. Lesion-nipple distances in supine MRI showed strong deviations compared to prone MRI (p < 0.004). Lesion size in supine MRI was more comparable to ultrasound than prone MRI (p = 0.03) but changed insignificantly across modalities. 4 out of 18 lesions were only detectable in targeted ultrasound after supine BraCoil MRI.

CONCLUSIONS

Supine MRI with the BraCoil offers a significant advantage over prone MRI by providing more accurate lesion positioning relative to ultrasound. This approach could improve lesion localization in radiotherapy planning, surgery, targeted ultrasound, and ultrasound-guided biopsy, potentially reducing the need for MR-guided biopsies.

Reproducible and highly miniaturized bazooka RF Balun using a printed capacitor

PURPOSE

There is currently a strong trend in developing RF coils that are high-density, lightweight, and highly flexible. In addition to the resonator structure of the RF coil itself, the balun or cable trap circuit serves as another essential element in the functionality and sensitivity of RF coils. This study explores the development and application of reproducible highly miniaturized baluns in RF coil design.

METHODS

We introduce a novel approach to producing Bazooka baluns with printed coaxial capacitors, enabling the achievement of significant capacitance per unit length. Rigorous electromagnetic simulations and thorough hardware fabrication validate the efficacy of the proposed design across various magnetic field strengths, including 1.5 T, 3 T, and 7 T MRI systems.

RESULTS

Bench testing reveals that the proposed balun can achieve an acceptable common-mode rejection ratio even when it is highly miniaturized. The use of printed capacitors allows for a notable reduction in balun length and ensures high reproducibility. Findings demonstrate that the proposed balun exhibits no RF field distortion even when placed close to the sample, making it suitable for flexible coils, wearable coils, and high-density coils, particularly in high-field MRI.

CONCLUSION

The reproducibility inherent in the manufacturing process of printed coaxial capacitors allows for simple fabrication and ensures consistency in production. These advancements pave the way for the development of flexible coils, wearable coils, and high-density coils.

Wireless, customizable coaxially shielded coils for magnetic resonance imaging

Anatomy-specific radio frequency receive coil arrays routinely adopted in magnetic resonance imaging (MRI) for signal acquisition are commonly burdened by their bulky, fixed, and rigid configurations, which may impose patient discomfort, bothersome positioning, and suboptimal sensitivity in certain situations. Herein, leveraging coaxial cables' inherent flexibility and electric field confining property, we present wireless, ultralightweight, coaxially shielded, passive detuning MRI coils achieving a signal-to-noise ratio comparable to or surpassing that of commercially available cutting-edge receive coil arrays with the potential for improved patient comfort, ease of implementation, and substantially reduced costs. The proposed coils demonstrate versatility by functioning both independently in form-fitting configurations, closely adapting to relatively small anatomical sites, and collectively by inductively coupling together as metamaterials, allowing for extension of the field of view of their coverage to encompass larger anatomical regions without compromising coil sensitivity. The wireless, coaxially shielded MRI coils reported herein pave the way toward next-generation MRI coils.

Citizen science approach to assessing patient perception of MRI with flexible radiofrequency coils

Magnetic Resonance Imaging (MRI) is a major medical imaging modality, which is non-invasive and provides unique soft tissue contrast without ionizing radiation. The successful completion of MRI exams critically depends on patient compliance, and, thus patient comfort. The design, appearance and usability of local MRI radiofrequency (RF) coils potentially influences the patients' perception of the exam. However, systematic investigations and empirical evidence for these aspects are missing. A questionnaire specifically evaluating the impact of RF coils on patient comfort in MRI would be a valuable addition to clinical studies comparing the performance of novel flexible RF coils with standard rigid coils. This paper describes the development of such a questionnaire in the scope of a citizen science (CS) initiative conducted with a group of students at the upper secondary school level. In this work, the CS initiative is presented in the format of a case report and its impact on scientific projects and the students' education is outlined. The resulting questionnaire is made available in German and English so as to be directly applicable by researchers working on the clinical evaluation of novel RF coils or the comfort evaluation of specific hardware setups in general.

Feasibility of online non-rigid motion correction for high-resolution supine breast MRI

PURPOSE

Conventional breast MRI is performed in the prone position with a dedicated coil. This allows high-resolution images without breast motion, but the patient position is inconsistent with that of other breast imaging modalities or interventions. Supine breast MRI may be an interesting alternative, but respiratory motion becomes an issue. Motion correction methods have typically been performed offline, for instance, the corrected images were not directly accessible from the scanner console. In this work, we seek to show the feasibility of a fast, online, motion-corrected reconstruction integrated into the clinical workflow.

METHODS

Fully sampled T2 -weighted (T2 w) and accelerated T1 -weighted (T1 w) breast supine MR images were acquired during free-breathing and were reconstructed using a non-rigid motion correction technique (generalized reconstruction by inversion of coupled systems). Online reconstruction was implemented using a dedicated system combining the MR raw data and respiratory signals from an external motion sensor. Reconstruction parameters were optimized on a parallel computing platform, and image quality was assessed by objective metrics and by radiologist scoring.

RESULTS

Online reconstruction time was 2 to 2.5 min. The metrics and the scores related to the motion artifacts significantly improved for both T2 w and T1 w sequences. The overall quality of T2 w images was approaching that of the prone images, whereas the quality of T1 w images remained significantly lower.

CONCLUSION

The proposed online algorithm allows a noticeable reduction of motion artifacts and an improvement of the diagnostic quality for supine breast imaging with a clinically acceptable reconstruction time. These findings serve as a starting point for further development aimed at improving the quality of T1 w images.