Chenhui li¹, Liling Long¹, Huiting Zhang², and Fei Han^3
1The First Affiliated Hospital of Guangxi Medical University, Nanning, China, ²MR Scientific Marketing, Siemens Healthineers, Wuhan, China, ³Siemens Medical Solutions, Los Angeles, CA, United States

Multi-echo MRS (HISTO) and a novel radial TSE (RadTSE) sequence were compared in patients with hepatic cellular cancer (HCC). Results showed that T2 from RadTSE with fat saturation had a good consistency with that from HISTO. The difference in T2 between RadTSE without and with FS showed excellent correlation with fat fraction from HISTO. Radial TSE and multi-echo MRS sequences may have similar value in terms of quantitative imaging of the liver.

Haotian Li¹, Yi-Cheng Hsu², Tao Zu¹, Yi Sun², Yi Zhang¹, and Dan Wu^1
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China, ²MR Collaboration, Siemens Healthineers Ltd., Shanghai, China

3D pulse sequences enable high-resolution acquisition with high SNR and ideal slice profiles, which however, is particularly difficult for diffusion MRI (dMRI) due to the additional phase errors from diffusion encoding. Here we proposed a twin-navigator based 3D diffusion-weighted gradient spin-echo (DW-GRASE) sequence to correct the phase errors between shots for human whole-brain acquisition. Moreover, we tested whether acquisitions may impact the fiber-tracking results by comparing the 3D-GRASE with 2D-EPI using the fixel-based analysis, which indicated a significant difference between the 3D and 2D sequences in several microstructural parameters of the long cerebrospinal tract and splenium of corpus callous.

Ye-Feng Yao¹, Jia-Xiang Xin¹, Guang Yang¹, Huojun Zhang², Jiaqi Li¹, Caixia Fu³, Jiachen Wang¹, Rui Tong¹, and Daxiu Wei^1
1Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China, ²Shanghai Changhai Hospital, Shanghai, China, ³Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China

This study developed a molecularly targeted magnetic resonance imaging/magnetic resonance spectroscopy (MRI/MRS) method to selectively probe a specific metabolite molecule of tissues/organs in vivo. Several biomolecules have been used for molecularly targeted MRI and MRS. We used N-acetyl aspartate (NAA)- and glutamate (GLU)-targeted ¹H MRS spectra of the human brain and reported a novel approach to measure the local pH values of tissue in vivo.

Yigang Pei¹, Yu Bai¹, Wenzheng Li¹, Wenguang Liu¹, Weiyin Vivian Liu², Zhangxuan Hu², and Lingling Peng^2
1Radiology, Xiangya Hospital Central South University, Changsha, China, ²GE heathcare, Beijing, China

Based on field-of-view optimized and constrained undistorted single shot (FOCUS) combined with multiplexed sensitivity-encoding (MUSE) techinique, a new diffusion-weighted imaging (DWI) sequence was developed in our study (named FOCUS MUSE-DWI). Our aim is to assess FOCUS MUSE-DWI’ reliability with comparison to single-shot DWI (ss-DWI), FOCUS-DWI and MUSE-DWI with the evaluation of apparent diffusion coefficient (ADC) repeatability, surrogate signal-to-noise ratio (sSNR) and image quality. FOCUS MUSE-DWI can provide sufficient sSNR and excellent image quality, best ADC repeatability in above four DWIs. It suggests that FOCUS MUSE-DWI is a reliability technique and should be recommended for the clinical application of pancrentic DWI.

Mengze Gao¹, Huihui Ye², Tae Hyung Kim^3,4, Zijing Zhang², Seohee So⁵, and Berkin Bilgic^3,4
1Department of Precision Instrument, Tsinghua University, Beijing, China, ²State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China, ³Harvard Medical School, Boston, MA, United States, ⁴Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, ⁵School of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea, Republic of

We propose an unsupervised convolutional neural network (CNN) for relaxation parameter estimation. This network incorporates signal relaxation and Bloch simulations while taking  advantage of residual learning and spatial relations across neighboring voxels. Quantification accuracy and robustness to noise is shown to be significantly improved compared to standard parameter estimation methods in numerical simulations and in vivo data for multi-echo T2 and T2* mapping. The combination of the proposed network with subspace modeling and MR fingerprinting (MRF) from highly undersampled data permits high quality T1 and T2 mapping.

Shahrzad Moinian^1,2, Viktor Vegh^1,2, and David Reutens^1,2
1ARC training Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, Australia, ²Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia

We previously showed that magnetic resonance fingerprinting (MRF) residual signals can be used for in vivo voxel-wise parcellation of the human cerebral cortex, using supervised machine learning classification algorithms. However, previous work relied on brain atlases to provide probabilistic masks of cortical region to label samples to train a classification model. Here, we investigate the feasibility of developing automated atlas-free cortical border delineation in individuals. We demonstrate that 90% of the cortical border voxels identified by the proposed framework are co-localised with the borders between two cortical areas on the Juelich maximum probability map of cerebral cortex in six participants.

Wei Liu¹, Michael Koehler², Flavio Carinci², Adam Kettinger², Thorsten Feiweier², Kun Zhou¹, and Mario Zeller^2
1Siemens Shenzhen Magnetic Resonance Ltd, Shenzhzen, China, ²Siemens Healthcare GmbH, Erlangen, Germany

In this work, we propose to compensate the residual eddy current field caused by diffusion gradients at the time when chemically selective fat suppression gets applied with an additional gradient applied after the EPI readout. Using an analytic solution, the amplitude of the eddy currents can be cancelled under certain assumptions. The experimental results based on a volunteer scan demonstrate improved fat suppression in diffusion MRI with the proposed method.

Qing Li¹, Xinyu Song², Jienan Wang², Caixia Fu³, Yi Sun¹, and Yuehua Li^2
1MR Collaborations, Siemens Healthineers Ltd., Shanghai, China, ²Institute of Diagnostic and Interventional Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China, ³MR Application Development, Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China

In this work, a new acquisition scheme is proposed for directly measuring the continuous quantitative T1 changes during the contrast enhancement. By alternatively changing the flip angles from phase to phase, the temporal resolution of T1 mapping could be the same as conventional DCE (conv-DCE) imaging, i.e., 4.36 s in our experiments. The dynamic quantitative T1 mapping (dyQT1) DCE method were validated on animal study (rabbit with VX2 tumor), and compared with conv-DCE. The preliminary results showed dyQT1-DCE was more time efficient without native T1 scans and higher sensitivity in the detection of tumor than conv-DCE.

Qiaoling Wu¹ and Geli Hu^2
1Department of Radiology, Peking Union Medical College Hospital,Chinese Academy of Medical Sciences, Beijing, China, ²Philips Healthcare, Beijing, China

Banding artifacts are frequently observed in brachial plexus imaging, particularly within the spinal canal, with the balanced FFE sequence (b-FFE) at 3.0T due to increased influence of higher magnetic field inhomogeneity compared with clinical 1.5T. In this work we propose using a RF phase cycling technique with b-FFE (namely b-FFE-XD) to reduce the banding artifacts in clinical. This design RF phase limits the intravoxel dephasing of scan object voxels, therefore the artifacts caused by field inhomogeneity decrease. Meanwhile, the compressed SENSE technique was adopted to reduce the scan time. Results demonstrated successful removal of banding artifacts with the proposed technique.

Xinpei Wang¹, Jichang Zhang¹, and Chengbo Wang^1
1Faculty of Science and Engineering, University of Nottingham Ningbo China, Ningbo, China

Plenty of studies have reported correlations between the tissue pathological changes and abnormal T₁ value. However, T₁ mapping pulse sequences often suffer from the B₁ inhomogeneity and long scan time. To improve the time efficiency without leading to the worse robustness to B₁ inhomogeneity, we develop an accelerated MPRAGE-based 3D T₁ mapping method by using SPGR steady state. Our proposed method is demonstrated in phantom experiments and the preliminary in-vivo brain scan. 

Zhiyong Chen¹, Yunjing Xue¹, Bin Sun¹, and Yang Song^2
1Radiology, Fujian Medical University Union Hospital, Fuzhou, China, ²MR Scientific Marketing, Siemens Healthineers Ltd, Shanghai, China, Shanghai, China

The modified 3D-BH-PI-MRCP technique allowing direct exciting the area of interest, could not only decrease the slice number but also could eliminate folding artifacts.

Shang Wan¹, Yi Wei¹, Hehan Tang¹, Lisha Nie², Xiaocheng Wei², and Bin Song^3
1Radiology, West China Hospital, Sichuan University, Cheng Du, China, ²GE Healthcare Beijing China, Beijing, China, ³West China Hospital, Sichuan University, Cheng Du, China

Gd-EOB-DTPA has been widely used in liver MR imaging for the evaluation of hepatic lesion, whereas, the long intervals between the dynamic enhanced imaging and hepatobiliary phase imaging usually influence patient throughput. Notably, the adjustment of diffusion weighted imaging (DWI) sequence’s scanning order from pre-contrast to post-contrast is crucial to overcome this limitation. However, few studies have investigated the apparent diffusion coefficient (ADC) values that at low and high b values should be affected, respectively, thus, we aimed to prospectively determine whether DWI at both low and high b-values should be affected before and after gadoxetic acid-enhanced MR imaging.

You Seon Song¹, In Sook Lee¹, Moon jung Hwang², Kyungeun Jang², Maggie Fung³, and Xinzeng Wang^4
1Pusan National University Hospital, Busan, Korea, Republic of, ²GE Healthcare Korea, Seoul, Korea, Republic of, ³GE Healthcare, New York, NY, United States, ⁴GE Healthcare, Houston, TX, United States

We evaluated the utility of PROPELLER T2 FSE with deep-learning (DL) reconstruction in the cervical spine MRI, with the goal of overcoming respiratory and swallowing motion, improving image sharpness, and achieving high-resolution imaging within a comparable scan time to the conventional T2 FSE sequences. With utilization of DL reconstruction, the axial PROPELLER T2 was able to obtain images with high resolution and reduced noise.