Yuxin Wu¹, John Pauly², and Greig Scott^2
1Department of Electronic Engineering, Tsinghua University, Beijing, China, ²Department of Electrical Engineering, Stanford University, Stanford, CA, United States

This work assesses heartbeat detection by continuous-wave (CW) Doppler radar using low and high carrier frequencies of 433MHz and 5GHz as options for non-contact vitals sensing in MRI.  The experimental results show that using the amplitude of received complex signals in low frequency 433MHz-detection can perform as well as 5GHz-detection due to near field interactions within a 20cm range, with similar heartbeat detection efficacy.

Kazuyuki Makihara¹, Kazuki Kunieda¹, Shigehito Yamada², Katsumi Kose³, and Yasuhiko Terada^1
1Graduate School of Science and Technology, University of Tsukuba, Tsukuba, Japan, ²Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan, ³MRI simulations Inc., Minato-ku, Japan

High-resolution MR microscopy is advantageous for the human embryo study, but had not been realized because of many challenges. In this study, we demonstrated high-resolution MR microscopy of a human embryo specimen with 18 µm isotropic resolution. To achieve the higher spatial resolution than the previous system, we improved the hardware and optimized the pulse sequence. The MR images of the embryo showed detailed anatomical structures and were similar in appearance to the stained images obtained from an embryo specimen at the same developmental stage.

Qiaoyan Chen^1,2, Chao Luo^1,2, Xiaoliang Zhang³, Xin Liu^1,2, Hairong Zheng^1,2, and Ye Li^1,2
1Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, ²Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China, ³Department of Biomedical Engineering, State University of New York at Buffalo, New York, NY, United States

 To improve B₀ magnetic field homogeneity and minimize interferences on RF coils, local shimming coils with a few channel number can be applied. In this study, we designed and constructed a 5-channel local B₀ shimming coil for the rat brain. There was a marginal SNR loss within 5% after converting the local shimming coil into a 3-channel RF coil. The reduction of B₀ inhomogeneity for the rat brain with respect to the basic set was about 34%. A large portion of the distortion in EPI images was recovered and some image artifacts were eliminated after using the local shimming coil. 

Yaohui Wang¹, Qiuliang Wang¹, Jigang Zhao¹, Yang Liu¹, Yijie Zheng¹, Zhifeng Chen², and Feng Liu^3
1Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China, ²USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ³School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Australia

A small-size, light-weight, cryogen-free 7T animal MRI system is being developed in IEE CAS. The magnet system has been completed and acceptable magnetic field strength and homogeneity indices have been achieved. The gradient assembly with passive shimming is going into the final assembly stage and the RF coil is ready for tunning. The integration of the whole system will be very soon and a mouse experiment will be conducted then. It is expected the ultimate product will largely boost the scientific research activities that are unapproachable to advanced MRI scanners.

Feng Du^1,2, Jiawen Yuan^1,3, Nan Li^1,2, Chao Zhou^1,2, Qian Wan^1,2, Qikai Qin⁴, Garth J. Thompson⁴, Qiong Ye⁵, Xiaoliang Zhang⁶, Xin Liu^1,2, Hairong Zheng^1,2, and Ye Li^1,2
1Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, ²Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China, ³Southern University of Science and Technology, Shenzhen, China, ⁴iHuman Institute, ShanghaiTech University, Shanghai, China, ⁵High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China, ⁶Department of Biomedical Engineering, State University of New York, Buffalo, NY, United States

Deuterium metabolic imaging (DMI) is an emerging technique, which can measure the metabolism in the brain non-invasively after intake of deuterated glucose. In this work, we construct a versatile and dedicated 1H/2H dual-nuclear transceiver for a 9.4T pre-clinical research system. The performance of the transceiver was evaluated by measuring the in vivo 2H spectra data. The metabolites of water, glucose, Glx and lactate after glucose infusion were quantified in healthy and glioma rats using the constructed double-nuclear transceiver.

Jun Luo^1,2,3, Shengping Liu¹, Jifeng Chen², and Ye Li^2,3
1Chongqing University of Technology, Chongqing, China, ²Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, ³Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China

Parallel transmission technology has attracted much attention because of its advantages of uniform excitation and artifact correction in ultra-high field. A 2kW non-magnetic prototype RF amplifier for 5T multi-channel parallel transmission (pTx) is presented. It is equipped with analogic feedback loops and provides a high linearity up to peak output power. It maintains excellent fidelity performance even without a circulator.

Liyun Zheng^1,2, Chun Yang³, Ruofan Sheng³, Yongming Dai², and Mengsu Zeng^1,3
1Shanghai Institute of Medical Imaging, Shanghai, China, ²United Imaging Healthcare, Shanghai, China, ³Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai, China

Higher magnetic field strength leads to an increase of the SNR. On the other hand, the increase of magnetic field strength implies larger magnetic susceptibility inhomogeneities. Recently, 5.0T whole body magnetic resonance imaging system has been introduced into research and clinical settings. In this study, we evaluated the feasibility of abdominal imaging at 5T and compared the image quality and potential artifacts with 3T. Our results indicated that 5T MRI is able to acquire artifact-free anatomical images of the abdomen. Compared to 3T MRI, abdominal MRI at 5T resulted in comparable image quality and better contrast ratios.

Liyun Zheng^1,2, Chun Yang³, Ruofan Sheng³, Yongming Dai², and Mengsu Zeng^1,3
1Shanghai Institute of Medical Imaging, Shanghai, China, ²United Imaging Healthcare, Shanghai, China, ³Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai, China

Compared to clinical field strengths, MRI at ultra-high magnetic fields allows higher SNR. However, imaging at 7T remains challenging, especially in renal MRI. This study investigated the feasibility of renal MRI at 5T, with a brand new 5T MR scanner. Compared to 3T examination, 5T renal MRI demonstrated higher SNR and improved corticomedullar discrimination with diagnostic image quality. Functional imaging, including DWI and T2* mapping, was also feasible at 5T. Therefore, in vivo 5T renal MRI may better elucidate the renal diseases with both anatomical and functional imaging, compared to conventional clinical MRI scanners.

Liyun Zheng^1,2, Chun Yang³, Ruofan Sheng³, Yongming Dai², and Mengsu Zeng^1,3
1Shanghai Institute of Medical Imaging, Shanghai, China, ²United Imaging Healthcare, Shanghai, China, ³Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai, China

Moving to higher magnetic field strength (> 3 T) may have clinical advantages because of an intrinsic increase of the signal-to-noise ratio (SNR), while heterogeneity in the transmit radiofrequency (RF) field or B1 can cause signal voids throughout images. This study aimed to evaluate the development of prostate MRI at 5T by providing assessment of image quality on clinical sequences, including T1W, T2W and DWI images. According to current results about image quality, present of artifacts, visibility of anatomical structures of T2W images, and geometric distortion of DWI images, clinical prostate imaging is feasible at 5T MRI.

Liyun Zheng^1,2, Chun Yang³, Ruofan Sheng³, Yongming Dai², and Mengsu Zeng^1,3
1Shanghai Institute of Medical Imaging, Shanghai, China, ²United Imaging Healthcare, Shanghai, China, ³Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai, China

Imaging the hip cartilage using magnetic resonance imaging (MRI) is more challenging compared with other joints. The utilize of higher magnetic field strengths (>3T) is able to improve the assessment of cartilage structures in the hip. In this study we evaluated morphological 5T hip MRI in healthy subjects and compared image quality at 5T with 3T MRI. The results revealed that morphological 5T hip MRI in healthy subjects was superior to 3T MRI in image quality, visibility of the anatomical structures and contrast ratios.

Sadeq S Alsharafi¹, Haile Baye Kassahun¹, Ahmed M Badawi¹, and AbdEl-Monem M El-Sharkawy^1
1Systems and Biomedical Engineering, Cairo University, Giza, Egypt

Eddy-currents are generated in MRI scanners’ metallic structures due to the rapid switching of gradient coils. They may result in image distortions and induce acoustic-noise particularly for fast/spiral sequences. Transient eddy-currents computations can be used to understand the extent of such effects. In this work, a numerical framework was devised to compute transient eddy-currents induced by an amplitude-modulated sinusoidal pulse for a longitudinal gradient coil configuration. Stream functions representation of eddy-currents, Multilayer Integral Method, and an excitation current with amplitude-modulated sinusoidal function are used to solve the circuit equation and efficiently compute transient eddy-currents generated in the cryostat.

Haile Baye Kassahun¹, Sadeq S Alsharafi¹, Ahmed M Badawi¹, and AbdEl-Monem M El-Sharkawy^1
1Systems and Biomedical Engineering, Cairo University, Cairo, Egypt

A two-channel, self-shielded, cylindrical, transverse gradient coil is numerically designed. The four quadrants of both the inner and outer cylinders were each divided into two sections. All symmetric inner sections of the primary and corresponding shielding coil turns are assigned to the first channel where the outer enclosing sections belong to the second channel. Quasi-elliptic curves are used for coil tracks design. Achieving a comparable target gradient field, the DC dissipated power of a two-channel coil is lower compared to a conventional coil designed with similar dimensions and number of turns by at least 20%, thereby reducing ohmic losses.  

Sadeq s Alsharafi¹, Haile Baye Kassahun¹, Ahmed M Badawi¹, and AbdEl-Monem M El-Sharkawy^1
1Systems and Biomedical Engineering, Cairo University, Giza, Egypt

 Eddy-currents induced by MRI gradient coils due to rapid switching result in undesirable thermal effects, field distortions and acoustic-noise. Efficient numerical computations are needed to analyze eddy-currents for complex configurations. The skin-depth adds an extra computational burden for numerical eddy-current computations since meshing in the skin-depth direction may be needed to achieve reliable computations during harmonic analysis. Here, we use a single-layer stream-function method (SSM) applying resistance compensation and compare our results to a multi-layer integral method (MIM) approach. We show that SSM method achieves accurate comparable results relative to both MIM and Ansys albeit at higher computational effeciency.