ISMRM 24th Annual Meeting & Exhibition • 07-13 May 2016 • Singapore

Scientific Session: Simultaneous Multi-Slice

Wednesday, May 11, 2016
Summit 1
10:00 - 12:00
Moderators: Justin Haldar, Benedikt A Poser

Generalized SLIce Dithered Enhanced Resolution Simultaneous MultiSlice (gSlider-SMS) to increase volume encoding, SNR and partition profile fidelity in high-resolution diffusion imaging.
Kawin Setsompop1, Jason Stockmann1, Qiuyun Fan1, Thomas Witzel1, and Lawrence L. Wald1
1A.A. Martinos Center for Biomedical Imaging, charlestown, MA, United States
In this work, we propose generalized Slider (gSlider) method which utilizes RF encoding to markedly improve the ability of slice super-resolution in acquiring a large number of imaging slices simultaneously in diffusion imaging, to increase volume encoding and SNR. In particular, we show that gSlider can be use to acquire 5 slices simultaneously to provide close to the theoretical √5 SNR gain, while retaining sharp slice/partition resolution, comparable to that of conventional 2-D slice-selective imaging. Through a combined gSlider-SMS acquisition (5x-gSlider and MB-2), we demonstrate a highly efficient 10 simultaneous slice acquisition for high quality whole-brain 660μm isotropic diffusion imaging.  

Online Radial Multiband Magnetic Resonance Fingerprinting
Martijn A Cloos1,2, Tiejun Zhao3, Florian Knoll1,2, and Daniel K Sodickson1,2
1Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, United States, 2Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, United States, 3Siemens Medical Solutions USA Inc., Malvern, PA, United States
Magnetic resonance fingerprinting (MRF) is a promising new approach for rapid quantitative imaging. So far, multi-slice acceleration (MSA) for MRF has been based on a gradient t-Blipped multi-slice scheme. However, for traditional MR sequences using thick slices, it has been shown that radiofrequency based phase encoding works better than the gradient blipped implementation. In this work we demonstrate an RF based MSA approach for radial sampled MRF experiments such as PnP-PTX including a fully integrated online image reconstruction pipeline that creates both quantitative maps (T1, T2, PD and B1+) and synthesized contras weighted images (MP-RAGE, T1-TSE and T2-TSE).

Analytical G-factor for Cartesian Simultaneous Multi-Slice Imaging
Kangrong Zhu1, Hua Wu2, Robert F. Dougherty2, Matthew J. Middione3, John M. Pauly1, and Adam B. Kerr1
1Electrical Engineering, Stanford University, Stanford, CA, United States, 2Center for Cognitive and Neurobiological Imaging, Stanford University, Stanford, CA, United States, 3Applied Sciences Laboratory West, GE Healthcare, Menlo Park, CA, United States
In simultaneous multi-slice (SMS) imaging, a commonly used method to compute the g-factor is the pseudo multiple replica method, whose accuracy depends on the number of simulated replicas. In this work, we derive analytical g-factor maps for SMS acquisitions with arbitrary Cartesian undersampling patterns basing on a hybrid-space SENSE reconstruction. Brain images demonstrate that the analytical g-factor maps agree with those calculated by the pseudo multiple replica method, but require less computation time for high quality maps. The analytical maps enable a fair comparison between coherent and incoherent Cartesian SMS undersampling patterns.

Correction of Chemical-Shift Ghost Artifact in Blipped Controlled Aliasing Parallel Imaging
JaeJin Cho1, Dongchan Kim1, Hyunseok Seo1, Kinam Kwon1, Seohee So1, and HyunWook Park1
1Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, Republic of
Blipped-CAIPI imaging is widely used for fast imaging, which is one of the simultaneous multi-slice imaging methods. Conventional water-fat separation methods can be combined with the blipped-CAIPI technique. However, it results in the chemical-shift ghost artifact because fat signal on slightly shifted position is exited in the slice-selection process. This geometric error in slice-selection generates additional phase cycling, which causes the ghost artifacts on each slice’s fat image. In this abstract, a SENSE-based water-fat separation method is proposed, which considers the additional phase cycling on fat signal and obtains more accurate water-fat separated images.

Simultaneous Multislice AcquisitioN G-noise reduction & Reshifted CAIPI In Angiography (SANGRIA) - Permission Withheld
Zahra Fazal1, Jennifer Schulz1, Jose P Marques1, and David G Norris 1,2
1Donders Center for Cognitive Neuroimaging, Radboud university, Nijmegen, Netherlands, 2Erwin L.Hahn institute for Magnetic Resonance Imaging, Essen, Germany
To reconstruct blood vessel in 2D and 3D MB TOF MRA without using coil sensitivity profile to reduce g-factor noise. The idea is to use CAIPRINHA on sparse angiographic data that first shift each slice/slab differently and then apply CAIPI reshift to shift each slab to its original position to form a continuous vessel tree. Results showed that the vessel reconstruction in 2D and 3D MB is comparable to standard single band MS TOF. Vessel reconstruction in MB angiography without using coil sensitivity profile can lead to high MB factors reducing the aquistion time and high sensitivity in detecting small vessels

Optimized CS-Wave imaging with tailored sampling and efficient reconstruction
Berkin Bilgic1, Huihui Ye1, Lawrence L Wald1, and Kawin Setsompop1
1Martinos Center for Biomedical Imaging, Charlestown, MA, United States
Wave-CAIPI utilizes additional gradients during the readout to improve controlled aliasing and fully harness coil sensitivity encoding. Recently proposed CS-Wave extended Wave-encoding with Poisson sampling and wavelet regularization. This work proposes optimized CS-Wave with i) tailored data-sampling and ii) highly efficient reconstruction. At 15-fold acceleration, proposed CS-Wave provides 20% RMSE improvement over Wave-CAIPI, which nearly doubles the improvement achieved with previously proposed CS-Wave. This permits single head-orientation Quantitative Susceptibility Mapping at 1×1×2mm3resolution in 25s. Combining CS-Wave with SMS Echo-Shift strategy further increases the acceleration to 30-fold, thus enabling multi-orientation QSM at long-TE from three head-rotations at 1.5mm isotropic in 72s.

Multiband and Multishot EPI Using Hadamard Encoding for Functional MRI at 7T
Alexander D. Cohen1, Andrew S. Nencka1,2, and Yang Wang1,2
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, 2Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States
In this study a novel technique was tested combining multiband and multishot imaging for functional MRI at 7T. Hadamard and segmented multi-shot encoding were applied to yield short TR, reduced distortion fMRI images without the need for parallel imaging reconstruction techniques. Furthermore, acquiring segmented data allows for datasets to be reconstructed with effective in-plane accelerations up to the number of segments. Thus, one can reconstruct a dataset with higher SNR and the reduced geometric distortion of a highly accelerated  acquisition. 

SMS-HSL: Simultaneous Multi-Slice Aliasing Separation Exploiting Hankel Subspace Learning
Suhyung Park1 and Jaeseok Park2
1Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon, Korea, Republic of, 2Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of
Simultaneous multi-slice (SMS) acquisition has recently gained attention in clinical and research applications. However, since the spatial variation of coil sensitivity along the slice direction is typically insufficient and thus SMS reconstruction including SENSE/GRAPPA and slice-GRAPPA is potentially ill-conditioned, it is challenging to separate the aliased slices in the presence of noise with increasing multi-band factors (MB). In this work, we propose a novel, SMS reconstruction method that exploits Hankel subspace learning (SMS-HSL) for aliasing separation in the slice direction, in which SMS signals are projected onto an individual subspace specific to each slice by incorporating the proposed SMS model into a constrained optimization with low rank and magnitude priors. Simulation and experiments were performed at high MB factors to demonstrate the effectiveness of the proposed SMS-HSL over conventional SMS methods.

High resolution simultaneous multi-slice GRE at 9.4T using 16-channel SMS-pTX spokes excitations for slice-by-slice flip-angle homogenisation
Desmond H Y Tse1, Christopher J Wiggins2, and Benedikt A Poser1
1Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, 2Scannexus, Maastricht, Netherlands
RF inhomogeneity at ultra-high field MRI leads to unwanted variations in image contrast and SNR. RF homogenisation at 9.4T was achieved with parallel transmission (pTx) of slice-specific spokes pulses designed offline using acquired B0 and B1+ maps. These spokes pulses were combined on-the-fly on the scanner to form simultaneous multi-slice (SMS) excitations, with optimised inter-slice phases to minimise the SMS pulse amplitude. The pTx spokes SMS pulse allowed a time efficient high resolution 2D GRE T2*-weighted imaging at 9.4T with whole brain coverage and minimal artefacts caused by RF inhomogeneity. 

Phase-cycled simultaneous multi-slice balanced SSFP imaging with CAIPIRINHA for efficient banding reduction
Yi Wang1, Xingfeng Shao1, Thomas Martin1, Steen Moeller2, Essa Yacoub2, and Danny JJ Wang1
1Neurology, UCLA, Los Angeles, CA, United States, 2Center of Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States
The application of balanced SSFP (bSSFP) is limited by the banding artifact resulting from its sensitivity to field inhomogeneity.  A common approach for band reduction involves multiple measurements with different RF phase cycling, at the cost of lengthened total imaging time. In this work, we present a novel time-efficient bSSFP banding reduction technique by utilizing simultaneous multi-slice (SMS) imaging with CAIPIRINHA to acquire multiple phase-cycled images within the same imaging time of a single-band bSSFP scan. Effective band reduction is demonstrated in phantom, abdominal and brain imaging with SMS factor up to four.

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.