Xiaoming Bi¹, Jianing Pang², Wensha Yang², Matthias Fenchel³, Zixin Deng², Yuhua Chen⁴, Richard Tuli², Debiao Li², Gerhard Laub¹, and Zhaoyang Fan^2
1Siemens Healthcare, Los Angeles, CA, United States, ²Cedars-Sinai Medical Center, Los Angeles, CA, United States, ³Siemens Healthcare GmbH, Erlangen, Germany, ⁴University of Pennsylvania, Philadelphia, PA, United States

4D (respiratory phase-resolved 3D) MRI has been increasingly used for the planning of radiotherapy and minimally invasive surgery. Recently developed self-gating methods showed great potential in 4D MRI by providing high imaging efficiency and isotropic spatial resolution. However, images of individual phases may suffer from decreased SNR and increased streaking artifact since only a subset of data were used for reconstruction. A motion correction and average (MoCoAve) framework was developed in this work to address such limitations. Preliminary results from patients showed that the proposed method can significantly improve SNR and image quality without compromising motion information.

Valentina Taviani¹, Daniel V. Litwiller², Jonathan I. Tamir³, Andreas M. Loening¹, Brian A. Hargreaves¹, and Shreyas S. Vasanawala^1
1Stanford University, Stanford, CA, United States, ²Global MR Applications and Workflow, GE Healthcare, New York, NY, United States, ³University of California Berkeley, Berkeley, CA, United States

Variable density (VD) sampling was implemented into an extended echo train single shot fast spin echo (SSFSE) pulse sequence. Compressed sensing (CS) reconstuction was used. With respect to regular undersampling and ARC (Autocalibrated Reconstruction for Cartesian imaging), VD CS SSFSE allows higher acceleration factors, which translates in increased flexibility in the choice of echo times  for full-Fourier imaging (shorter minimum TEs) and faster acquisitions (shorter breath-holds). 

Jessica AM Bastiaansen¹, Jerome Yerly^1,2, Jean-Baptiste Ledoux², Ruud B van Heeswijk^1,2, Davide Piccini³, and Matthias Stuber^1,2
1Department of Radiology, University hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, ²Center for Biomedical Imaging, Lausanne, Switzerland, ³Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland

Pancreatic MRI is commonly performed during breath-held or navigator-gated acquisitions. The long breath-holds needed for high spatial resolution are not always feasible in patients and residual respiratory motion may still occur. Additionally, in some implementations, the navigator leads to a local signal void that may obscure parts of the anatomy of interest. Here we used a free-breathing self-navigated 3D radial gradient-recalled-echo (GRE) imaging sequence, and compared the 1D motion correction as performed on the scanner versus a motion-resolved 4D sparse iterative reconstruction. We show that non-contrast enhanced pancreatic MRI can be performed at 3T during free-breathing, while motion-resolved sparse reconstruction can efficiently minimize the adverse effects of respiratory motion.

Jakob Weiss¹, Jana Taron¹, Ahmed E. Othman¹, Robert Grimm², Petros Martirosian¹, Christina Schraml¹, Konstantin Nikolaou¹, and Mike Notohamiprodjo^1
1Diagnostic and Interventional Radiology, University of Tuebingen, Tuebingen, Germany, ²Siemens Healthcare, Erlangen, Germany

To evaluate clinical performance of contrast-enhanced 3D-isotropic radial volumetric interpolated breath-hold examination (VIBE) for late-phase MR imaging of the liver. A prototype retrospective self-gating algorithm for more motion-robust data acquisition was implemented and compared to standard Cartesian VIBE. Utilization of self-gating VIBE provides significantly improved image quality, especially in coronal reformations and Gd-EOB-DTPA-enhanced late-phase scans. Moreover, in 11% only radial VIBE provided diagnostic image quality, thus having a direct implication on patient care. Therefore, self-gated radial VIBE seems a valuable approach to improve diagnostic accuracy in late-phase MR imaging of the liver.

Shintaro Ichikawa¹, Utaroh Motosugi¹, Tetsuya Wakayama², Takashi Kakegawa¹, Hiroshi Kumagai¹, and Hiroshi Onishi^1
1University of Yamanashi, Yamanashi, Japan, ²GE Healthcare Japan, Tokyo, Japan

DIfferential Subsampling with Cartesian Ordering (DISCO) is a new high spatiotemporal resolution, dynamic contrast-enhanced magnetic resonance imaging (MRI) technique. We evaluated the usefulness of multiple (n=6) hepatic arterial phases (HAPs) with DISCO in gadoxetic acid-enhanced dynamic MRI for detecting capsular enhancement in hepatocellular carcinoma (HCC). Such capsular enhancement is detected more frequently by combining portal venous phase (PVP) images and multiphasic hepatic arterial images with DISCO. Combining DISCO with PVP improved the liver imaging reporting and data system (LI-RADS) v2014 score from LR4 to LR5.

Valentina Taviani¹, Shreyas S. Vasanawala¹, and Brian A. Hargreaves^1
1Stanford University, Stanford, CA, United States

A diffusion-weighted (DW) imaging method was developed to mitigate off-resonance-induced distortion and signal loss, which are problematic for body applications. A 2D RF pulse is used in place of the conventional spectral-spatial excitation used for DW spin echo echo-planar imaging. In the presence of off-resonance, a narrow band of frequencies is excited due to the different bandwidths between excitation and refocusing pulses. By progressively shifting the center frequency, the whole range of off-resonance can be excited and a composite image, corrected for off-resonance-induced distortion, can be reconstructed by estimating the field map from the spectral information. 

Li Jiang¹, Chenguang Zhao¹, Andy Jiang¹, Ming Yang¹, Wengu Su¹, Allan Jin¹, Ping Yang¹, Stephon Xu¹, and Feng Huang^1
1Philips Healthcare (Suzhou), Suzhou, Jiangsu, China, People's Republic of

Liver black blood imaging helps to detect and characterize focal liver lesions and thus is highly desirable clinically. The commonly used low b-value DWI sequence is limited due to inherent limitations of EPI, such as low spatial resolution and motion artifacts including blurring and ghosting. We proposed a 3D whole liver black blood imaging solution within 3 min. By combining with existing black blood preparation, a respiratory triggered VISTA sequence and a free breathing imaging technique utilizing GROWL reconstruction were proposed. Six healthy volunteers with stable and irregular respiration were scanned to further validate the feasibility of our proposed solution.

Yilin Liu¹, Fang-Fang Yin², Brian Gary Czito², Mustafa R. Bashir ³, Manisha Palta ², Xiaodong Zhong ⁴, Brian M. Dale ⁵, and Jing Cai^2
1Medical Physics Graduate Program, Duke University Medical Center, Durham, NC, United States, ²Radiation Oncology, Duke University Medical Center, Durham, NC, United States, ³Department of Radiology, Center for Advanced Magnetic Resonance Development, Duke University Medical Center, Durham, NC, United States, ⁴MR R&D Collaborations, Siemens Healthcare, Atlanta, GA, United States, ⁵MR R&D Collaborations, Siemens Healthcare, Cary, NC, United States

Diffusion-weighted imaging (DWI) has been shown to have superior tumor-to-tissue contrast for cancer detection in abdominal region. However, the respiratory motion may induce severe imaging errors or artifacts for DWI images. This study aims at developing and evaluating a respiratory correlated 4D-DWI technique using a retrospective sorting method for imaging respiratory motion on human subjects. Comparing to free breathing DWI, 4D-DWI can lead to more accurate measurement of ADC. This has a great potential to improve the visualization and delineation of cancer tumors for radiotherapy.

Christina Schraml¹, Jana Taron¹, Nina F Schwenzer¹, Holger Schmidt¹, Thomas Kuestner², Michael Erb³, Mike Notohamiprodjo¹, Konstantin Nikolaou¹, Fritz Schick⁴, and Petros Martirosian^4
1Diagnostic and Interventional Radiology, Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany, ²Institute of Signal Processing and System Theory, University of Stuttgart, Stuttgart, Germany, ³Department of Biomedical Magnetic Resonance, University Hospital Tuebingen, Tuebingen, Germany, ⁴Section on Experimental Radiology, Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany

SMS-acceleration allows for considerable scan time reduction in hepatic DWI without substantial drawbacks in image quality both using respiratory-triggering and free-breathing acquisitions. In the present study set-up, ADC measured in SMS-DWI were lower than in standard DWI which should be considered when using absolute ADC for clinical reading. The demonstrated high image quality of SMS-DWI obtained in FB indicates great potential for scan time reduction in DWI for abdominal and whole-body applications.

Stefanie Hectors¹, Mathilde Wagner¹, Cecilia Besa¹, Hadrien Dyvorne¹, Octavia Bane¹, M. Isabel Fiel², Hongfa Zhu², and Bachir Taouli^1,3
1Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ²Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ³Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States

We assessed the correlation between intravoxel incoherent diffusion-weighted imaging (IVIM-DWI) and dynamic contrast-enhanced MRI (DCE-MRI) in hepatocellular carcinoma (HCC) and liver parenchyma. DCE-MRI-derived arterial fraction and arterial flow were significantly negatively correlated with IVIM-DWI-derived perfusion fraction and pseudodiffusion in the liver, while IVIM-DWI parameters did not correlate with DCE-MRI parameters in HCC. These results indicate that IVIM-DWI and DCE-MRI provide non-redundant information in HCC.