Spiral MR fingerprinting at 7 T with simultaneous B1 estimation

Buonincontri, Guido; Schulte, Rolf F.; Cosottini, Mirco; Tosetti, Michela

doi:10.1016/j.mri.2017.04.003

Cited by 44 publications

(59 citation statements)

References 16 publications

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“…A natural avenue to help boost SNR would be to acquire data at higher field strength, such as at 7T, where the B1+ inhomogeneity issue of ultra high-field would also present both a challenge and an opportunity to MRF encoding (Buonincontri et al, 2017; Cloos et al, 2016; Gao et al, 2015). …”

Section: Discussionmentioning

confidence: 99%

3D MR fingerprinting with accelerated stack-of-spirals and hybrid sliding-window and GRAPPA reconstruction

Liao¹,

et al. 2017

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Purpose Whole-brain high-resolution quantitative imaging is extremely encoding intensive, and its rapid and robust acquisition remains a challenge. Here we present a 3D MR fingerprinting (MRF) acquisition with a hybrid sliding-window (SW) and GRAPPA reconstruction strategy to obtain high-resolution T1, T2 and proton density (PD) maps with whole brain coverage in a clinically feasible timeframe. Methods 3D MRF data were acquired using a highly under-sampled stack-of-spirals trajectory with a steady-state precession (FISP) sequence. For data reconstruction, kx-ky under-sampling was mitigated using SW combination along the temporal axis. Non-uniform fast Fourier transform (NUFFT) was then applied to create Cartesian k-space data that are fully-sampled in the in-plane direction, and Cartesian GRAPPA was performed to resolve kz under-sampling to create an alias-free SW dataset. T1, T2 and PD maps were then obtained using dictionary matching. Results Phantom study demonstrated that the proposed 3D-MRF acquisition/reconstruction method is able to produce quantitative maps that are consistent with conventional quantification techniques. Retrospectively under-sampled in vivo acquisition revealed that SW + GRAPPA substantially improves quantification accuracy over the current state-of-the-art accelerated 3D MRF. Prospectively under-sampled in vivo study showed that whole brain T1, T2 and PD maps with 1 mm3 resolution could be obtained in 7.5 min. Conclusions 3D MRF stack-of-spirals acquisition with hybrid SW + GRAPPA reconstruction may provide a feasible approach for rapid, high-resolution quantitative whole-brain imaging.

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Section: Discussionmentioning

confidence: 99%

3D MR fingerprinting with accelerated stack-of-spirals and hybrid sliding-window and GRAPPA reconstruction

Liao¹,

et al. 2017

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“…The spatial variation of the RF transmit field (

B_{1}^{+}

) is another factor influencing MRF that may lead to systematic errors if not properly accounted for . To address the systematic errors from

B_{1}^{+}

variations, prior works have proposed to introduce dedicated

B_{1}^{+}

‐sensitive encoding segments and subsequent matching of the tissue parameters together with

B_{1}^{+}

. An MRF implementation that makes use of parallel transmit uses a segmented acquisition that consists of temporally spaced FISP and fast low‐angle shot (FLASH) segments .…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance field fingerprinting

Körzdörfer

Jiang

Speier

et al. 2018

Magnetic Resonance in Med

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Purpose To develop and evaluate the magnetic resonance field fingerprinting method that simultaneously generates T1, T2, B0, and B1+ maps from a single continuous measurement. Methods An encoding pattern was designed to integrate true fast imaging with steady‐state precession (TrueFISP), fast imaging with steady‐state precession (FISP), and fast low‐angle shot (FLASH) sequence segments with varying flip angles, radio frequency (RF) phases, TEs, and gradient moments in a continuous acquisition. A multistep matching process was introduced that includes steps for integrated spiral deblurring and the correction of intravoxel phase dispersion. The method was evaluated in phantoms as well as in vivo studies in brain and lower abdomen. Results Simultaneous measurement of T1, T2, B0, and B1+ is achieved with T1 and T2 subsequently being less afflicted by B0 and B1+ variations. Phantom results demonstrate the stability of generated parameter maps. Higher undersampling factors and spatial resolution can be achieved with the proposed method as compared with solely FISP–based magnetic resonance fingerprinting. High‐resolution B0 maps can potentially be further used as diagnostic information. Conclusion The proposed magnetic resonance field fingerprinting method can estimate T1, T2, B0, and B1+ maps accurately in phantoms, in the brain, and in the lower abdomen.

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“…The B 0 maps allowed deblurring of the acquired frames, which led to sharper edges according to Figure . Although the technique was not specifically optimized for B 1+ estimation, the results show a reasonable agreement with the double angle method B 1+ map; this consistency of the B 1+ map suggests the potential extension of the method to higher field strengths . We observed a mismatch of fat T 1 (~13%) and B 0 maps, however, this mismatch did not affect the accuracy of the fat fraction and water T 1 maps, which are the parameters of clinical interest.…”

Section: Discussionmentioning

confidence: 99%

Magnetic resonance fingerprinting with dictionary‐based fat and water separation (DBFW MRF): A multi‐component approach

Cencini

Biagi

Kaggie

et al. 2018

Magnetic Resonance in Med

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Purpose To obtain a fast and robust fat‐water separation with simultaneous estimation of water T 1 , fat T 1 , and fat fraction maps. Methods We modified an MR fingerprinting (MRF) framework to use a single dictionary combination of a water and fat dictionary. A variable TE acquisition pattern with maximum TE = 4.8 ms was used to increase the fat–water separability. Radiofrequency (RF) spoiling was used to reduce the size of the dictionary by reducing T 2 sensitivity. The technique was compared both in vitro and in vivo to an MRF method that incorporated 3‐point Dixon (DIXON MRF), as well as Cartesian IDEAL with different acquisition parameters. Results The proposed dictionary‐based fat–water separation technique (DBFW MRF) successfully provided fat fraction, water, and fat T 1 , B 0 , and B 1+ maps both in vitro and in vivo. The fat fraction and water T 1 values obtained with DBFW MRF show excellent agreement with DIXON MRF as well as with the reference values obtained using a Cartesian IDEAL with a long TR (concordance correlation coefficient: 0.97/0.99 for fat fraction–water T 1 ). Whereas fat fraction values with Cartesian IDEAL were degraded in the presence of T 1 saturation, MRF methods successfully estimated and accounted for T 1 in the fat fraction estimates. Conclusion The DBFW MRF technique can successfully provide T 1 and fat fraction quantification in under 20 s per slice, intrinsically correcting T 1 biases typical of fast Dixon techniques. These features could improve the diagnostic quality and use of images in presence of fat.

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Spiral MR fingerprinting at 7 T with simultaneous B1 estimation

Cited by 44 publications

References 16 publications

3D MR fingerprinting with accelerated stack-of-spirals and hybrid sliding-window and GRAPPA reconstruction

3D MR fingerprinting with accelerated stack-of-spirals and hybrid sliding-window and GRAPPA reconstruction

Magnetic resonance field fingerprinting

Magnetic resonance fingerprinting with dictionary‐based fat and water separation (DBFW MRF): A multi‐component approach

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