Shohei Fujita^1,2, Naoyuki Takei³, Akifumi Hagiwara¹, Issei Fukunaga¹, Dan Rettmann⁴, Suchandrima Banerjee⁵, Ken-Pin Hwang⁶, Shiori Amemiya², Koji Kamagata¹, Osamu Abe², and Shigeki Aoki^1
1Department of Radiology, Juntendo University, Tokyo, Japan, ²Department of Radiology, The University of Tokyo, Tokyo, Japan, ³MR Applications and Workflow, GE Healthcare, Tokyo, Japan, ⁴MR Applications and Workflow, GE Healthcare, Rochester, MN, United States, ⁵MR Applications and Workflow, GE Healthcare, Menlo Park, CA, United States, ⁶Department of Radiology, MD Anderson Cancer Center, Houston, TX, United States

A rigid real-time prospective motion-corrected multiparametric mapping technique was developed by inserting orthogonal spiral navigators into wait times of a multiparametric imaging technique, 3D-QALAS. The effects of motion correction on the quantitative estimates of a standardized phantom and in volunteers with various head motions were evaluated. Our results demonstrated that the proposed technique did not affect the accuracy of T1 and T2 quantification in vitro, and improved the repeatability and accuracy of T1 and T2 quantification with head motions during scans compared with those without motion correction. The proposed technique may provide robust three-dimensional multiparametric whole-brain mapping for head motions.

Malte Riedel (né Steinhoff)¹, Kawin Setsompop^2,3,4, Alfred Mertins¹, and Peter Börnert^5,6
1Institute for Signal Processing, University of Lübeck, Lübeck, Germany, ²Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, ³Department of Radiology, Harvard Medical School, Boston, MA, United States, ⁴Harvard‐MIT Health Sciences and Technology, MIT, Cambridge, MA, United States, ⁵Philips Research, Hamburg, Germany, ⁶Department of Radiology, C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, Leiden, Netherlands

This work aims at improving the robustness of diffusion-weighted imaging (DWI) against 3D rigid head motion based on simultaneous multi-slice (SMS), interleaved echo-planar imaging (EPI) and image navigators. The proposed method utilizes low-resolution navigators to estimate diffusion phases as well as shot-wise 3D rigid motion through SMS-to-volume registration; providing high temporal resolution motion correction capability. The shot parameters are included into a full-volume reconstruction of the image data per diffusion direction. The method achieves submillimeter registration errors and improved image quality. In conclusion, the presented method enables retrospective 3D rigid motion correction for interleaved SMS DWI.

Steven Kecskemeti¹, Abigail Freeman¹, and Andrew L Alexander^1
1University of Wisconsin-Madison, Madison, WI, United States

A test-retest study of FreeSurfer cortical thickness, surface area, and volume, as well as cortical R1 relaxometry, was performed on pediatric subjects scanned without sedation using SNARE-MPnRAGE.   Reliability was assessed with coefficients of variation (CoVs) and intraclass correlation coefficients (ICCs).  When SNARE motion correction was used all parameters had statistically significant improvements and high reliability.   For the mean (thickness/surface area/volume/R1) across the regions of FreeSurfer’s DK Atlas, the mean CoVs (% x100) were (1.2/1.6/1.9/0.9) and the mean ICCs were (0.88/0.96/0.94/0.83).  When assessed on a per-vertex basis, the CoVs and ICCs for thickness/R1 had mean values of (2.9/1.9) and (0.82/0.68).

Xiaoke Wang¹, Edward Herskovits¹, and Thomas Ernst^1
1Diagnostic Radiology, University of Maryland-Baltimore, Baltimore, MD, United States

MRA at 3T is sensitive to patient motion which sometimes occur due to severe illness. This work investigated the effect of optic prospective motion correction (PMC) on the MRA at 3T.  MRA with optic PMC was tested in phantom and on a healthy volunteer and compared with MRA without PMC. The use of PMC successfully reversed the slab misalignment, artifactual stenosis, and discontinuous major arteries caused by the intentional motion by the volunteer, and enhanced the distal vessels. This study demonstrated the potential of optic PMC in improving the quality of MRA on patients with difficulty holding still.

Alan Chu¹, Yulin Chang², André J. W. van der Kouwe³, and M. Dylan Tisdall^1
1Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, ²Siemens Medical Solutions USA, Inc., Malvern, PA, United States, ³Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States

We demonstrate the feasibility and validity of field mapping using a dual-echo vNav based on a fly-back EPI readout. A human subject was scanned using the proposed method and a standard FLASH acquisition for comparison. The proposed method does not require additional reconstruction or acquisition complexity and is easily computed on typical MR scanners to support real-time motion and shim correction.

Elisa Marchetto^1,2, Kevin Murphy^1,3, and Daniel Gallichan^1,2
1Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom, ²School of Engineering, Cardiff University, Cardiff, United Kingdom, ³School of Physics, Cardiff University, Cardiff, United Kingdom

FatNav motion-parameter estimation relies on GRAPPA reconstruction of the highly accelerated navigator fat-volumes, which might be compromised by strong changes in the head position. Data from three MPRAGE brain images have been used to find the motion corresponding to four image quality boundaries and assess motion tolerance when FatNavs are used. Results suggests that FatNavs can compensate for a large range of motion artifacts compared to when no motion correction is applied. Better correction is expected if GRAPPA weights are updated throughout the entire duration of the scan.

Liyuan LIANG¹, Chim-Lee Cheung², Ge Fang², Justin Di-Lang Ho², Chun-Jung Juan^3,4,5, Hsiao-Wen Chung⁶, Ka-Wai Kwok², and Hing-Chiu Chang^1
1Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, Hong Kong, ²Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, Hong Kong, ³Department of Medical Imaging, China Medical University Hsinchu Hospital, Hsinchu, Taiwan, ⁴Department of Radiology, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan, ⁵Department of Medical Imaging, China Medical University Hospital, Taichung, Taiwan, ⁶Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan

Head motion is a significant problem for the challenging populations, and the wireless tracking coils has previously been proposed to enable prospective motion correction in MRI. In this study, we evaluated the tracking performance of a novel tiny wireless tracking marker by using a linear motion phantom, and tested the feasibility in omnidirectional 3D head motion tracking using three tiny wireless tracking markers. Both phantom and in-vivo results suggest that the novel tiny wireless tracking markers can provide good fidelity in 3D position tracking, with improved subject comfort and better flexibility in fixation of markers.

Maxim Zaitsev¹, Michael Woletz¹, and Martin Tik^1
1High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria

Although it is theoretically possible to prospectively correct for deteriorative effects of known rigid body motions in any arbitrary MRI pulse sequence, no practical open implementation was reported to date. In this work we extend Puseq, an open-source pulse sequence development environment with a prospective motion correction capability based on external tracking. Real-time motion information in six degrees of freedom is received from an optical motion tracking system by libXPACE (a generic library for eXternal Prospective Acquisition CorrEction). The framework is capable of both motion correction and motion artifact simulation of arbitrary pulse sequences saved in Pulseq format.

Laura Bortolotti¹ and Richard Bowtell^1
1Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom

A novel approach to motion tracking has been successfully tested during a EPI scan in a 7T scanner. A set of NMR field probes, placed in between the standard head transmit and receiver coils,  was used to measure the extra-cranial field changes due to head movement every 150 ms during quiet periods of the EPI sequence. These measurements were used in conjunction with a regression method to predict head motion parameters. This represents a step forward in integrating a marker-less motion correction technique with standard imaging.

Chunyao Wang¹, Zhensen Chen¹, Yishi Wang², and Huijun Chen^1
1Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing, China, ²Philips Healthcare, Beijing, China

This study proposed a parallel line Structure Light based Optical Motion Tracking system (SLOMO) and verified its feasibility in respiratory detection and motion correction in MR liver imaging.

Sebastian Dietrich¹, Johannes Mayer¹, Christoph Stephan Aigner¹, Christoph Kolbitsch¹, Jeanette Schulz-Menger^2,3,4, Tobias Schaeffter^1,5, and Sebastian Schmitter^1,6
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berin, Germany, ²Charité Medical Faculty University Medicine, Berlin, Germany, ³DZHK partner site Berlin, Working Group on Cardiovascular Magnetic Resonance, Experimental and Clinical Research Center (ECRC), Berlin, Germany, ⁴Department of Cardiology and Nephrology, HELIOS Klinikum Berlin Buch, Berlin, Germany, ⁵Department of Medical Engineering, Technische Universität Berlin, Berlin, Germany, ⁶University of Minnesota, Center for Magnetic Resonance Research, Minneapolis, MN, United States

This work demonstrates 3D respiratory motion-corrected and cardiac resolved fat-water separation in the human body at 7T. Accurate fat fraction quantification using bipolar readout gradients was validated in a phantom. The impact of motion compensation on the underlying motion resolved $$$\Delta\text{B0}$$$ maps is investigated and estimated. In total the 3D fat-water separation and fat fraction quantification is successfully demonstrated in 10 healthy volunteers at 7T with a large BMI range from $$$19$$$ to $$$34 \text{kg/m}²$$$.

Takumi Ogawa¹, Michinobu Nagao², Masami Yoneyama³, Yasutomo Katsumata³, Yasuhiro Goto¹, Isao Shiina¹, Yutaka Hamatani¹, Kazuo Kodaira¹, Mamoru Takeyama¹, Isao Tanaka¹, and Shuji Sakai^2
1Department of Radiological Services, Women's Medical University Hospital, tokyo, Japan, ²Department of Diagnostic imaging & Nuclear Medicine, Women's Medical University Hospital, tokyo, Japan, ³Philips Japan, tokyo, Japan

Myocardial mapping such as T1 and T2 is widely used clinically for evaluating the properties of myocardium. We evaluated the feasibility of the combined use of Motion-Sensitive (MoSe) CINE imaging for determining accurate TD setting and fast elastic image registration (FEIR), which is a registration-based nonrigid motion correction for minimizing the influence of cardiac motion-related artifacts.

Fotios Tagkalakis¹, Kanishka Sharma², Irvin Teh¹, Bashair al-Hummiany¹, David Shelley¹, Margaret Saysell³, Julie Bailey³, Kelly Wroe³, Cherry Coupland³, Michael Mansfield³, and Steven Sourbron^2
1University of Leeds, Leeds, United Kingdom, ²University of Sheffield, Sheffield, United Kingdom, ³Leeds Teaching Hospitals NHS Trust, St James's Hospital, United Kingdom

Current approaches for motion correction of quantitative MRI include model-driven registration (MDR) and model-free registration (MFR). This study compared MDR against a state-of-the-art groupwise MFR (GMFR) on T1-mapping, DTI and DCE from 10 patients with diabetic kidney disease. The results demonstrate the benefits of MDR in the context of quantitative imaging: MDR scores better on most quality and error metrics (up to 20% improvement) and offers a substantial gain in computation times (up to 17hrs per slice). Furthermore, there is potential for translation to other applications.

Katja Bogner¹, Elisabeth Weiland², Thomas Benkert², and Karl Engelhard^1
1Institute of Radiology, Martha-Maria Hospital, Nuremberg, Germany, ²MR Application Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany

The major reason for artifacts in T2-weighted prostate imaging is motion-induced blurring caused by slight displacements between averages. Here, a non-rigid elastic registration is proposed to properly align the images before averaging. The method is evaluated in 12 patients and is shown to improve image quality in 71% of all investigated cases. Identification of pathology was improved in 42%. While only 58% of the conventional images achieved good or excellent image quality, this was the case for 88% when applying motion correction. As demonstrated, non-rigid registration results in clearly reduced motion artifacts and improves image quality and diagnostic confidence. 

Michael Bush¹, Thomas Vahle², Uday Krishnamurthy¹, Thomas Benkert², Xiaodong Zhong¹, Bradley Bolster¹, Paul Kennedy³, Octavia Bane³, Bachir Taouli³, and Vibhas Deshpande^1
1Siemens Medical Solutions USA, Inc., Malvern, PA, United States, ²Siemens Healthcare GmbH, Erlangen, Germany, ³The Department of Radiology and Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mt. Sinai, New York, NY, United States

Respiratory motion is a significant problem in MRI and is further amplified in abdominal imaging. Traditional methods to correct for motion in abdominal DWI significantly increase overall scan time. In this work, motion vectors derived from non-rigid registration of low b-value diffusion volumes are used to correct for motion in higher b-values, where low signal to noise and contrast make intra and inter b-value registration challenging. Initial results suggest the proposed method can produce images similar in quality to respiratory gating, while maintaining reduced acquisition times.

Mehdi Khalighi¹, Timothy Deller², Floris Jansen², Mackenzie Carlson³, Tyler Toueg⁴, Steven Tai Lai¹, Dawn Holley¹, Kim Halbert¹, Elizabeth Mormino⁴, Jong Yoon¹, Greg Zaharchuk¹, and Michael Zeineh^1
1Radiology, Stanford University, Stanford, CA, United States, ²Engineering Dept., GE Healthcare, Waukesha, WI, United States, ³Bioengineering, Stanford University, Stanford, CA, United States, ⁴Neurology, Stanford University, Stanford, CA, United States

Using the anatomical priors in PET image reconstruction by exploiting the correlation between similar voxels in addition to the correlation between neighboring voxels to control noise, will improve the image quality and resolution. However, motion can degrade the outcome if they anatomical priors are not perfectly registered with PET images. Here we have combined PET image reconstruction with anatomical priors and rigid motion correction for PET/MR brain images to address this. The results show improved image resolution in addition to higher signal-to-noise ratio.

Tom Neumann¹, Juliane Ludwig¹, Kirsten M. Kerkering¹, Frank Seifert¹, and Christoph Kolbitsch^1
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany

In this work we introduce a motion correction approach based on a calibrated ultra-wide-band radar signal acquired simultaneously to the MR scan. Our method is contactless and entirely independent from scanner setups or applied imaging sequences which makes it a viable alternative to established motion correction approaches, like navigator sequences or breathholds. We could demonstrate in phantom and in-vivo scans that the proposed motion-correction approach strongly improves T1 quantification.

Eddy Solomon^1,2, Syed Saad Siddiq^1,2, Daniel K Sodickson^1,2, Hersh Chandarana^1,2, and Leeor Alon^1,2
1Radiology, New York University School of Medicine, New York, NY, United States, ²New York University Grossman School of Medicine, New York, NY, United States

MRI scans are often under continues involuntary motion which weakens their reliability and diagnostic utility for examining the chest and abdomen. Acquisitions using traditional external sensors (e.g. respiratory belt) and self-gated techniques tend to be highly sensitive to patient position and setup, and on MR sequence parameters. Here, we demonstrate the use of accelerometer sensors for detecting respiratory signals. We show how the use of this simple sensor, with its relatively small dimensions, high sampling rate capability, and low cost, can produce motion corrected-images under free-breathing conditions.

Thomas Ulrich¹ and Klaas Paul Pruessmann^1
1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland

We propose a novel algorithm for motion estimation with k-space navigators. The algorithm operates on the complex k-space navigator signal. It uses a linear signal model, which describes how the navigator signal changes under rotation and translation of the imaged object. Rotation and translation are estimated simultaneously by means of linear least-squares parameter fitting using the linear model. We show that the algorithm achieves high accuracy and precision through a phantom experiment with a motionless phantom. Furthermore, we show the algorithms's applicability in-vivo during a volunteer experiment with and without intentional head motion.

Mads Andersen¹ and Vincent Oltman Boer^2
1Philips Healthcare, Copenhagen, Denmark, ²Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark

High resolution structural brain imaging at 7T can benefit from motion correction with volumetric navigators. Echo-planar-imaging (EPI) can reduce navigator durations and therefore allow for higher resolution navigators which are tempting to use to increase accuracy of the movement parameters. However, the severe B0 inhomogeneities at 7T lead to geometric distortions that change with head position and therefore lower navigator accuracy. We investigated the navigator accuracy for water and fat navigators of different resolutions and EPI readout durations. We found that the realignment parameter error grows with the amount of motion, voxel size, and EPI readout duration.