Bringing spiral sampling efficiency to fMRI: VASO fMRI with SMS spiral read-out

Poster No:

1534 

Submission Type:

Abstract Submission 

Authors:

Denizhan Kurban1, Laurentius Huber1, Gilad Liberman2, Sriranga Kashyap3, Dimo Ivanov4, Benedikt Poser5

Institutions:

1Maastricht University, Maastricht, Limburg, 2Martinos Center for Biomedical Imaging, Charlestown, MA, 3Maastricht University, Maastricht , Limburg , 4Maastricht University, Maastricht, Please select an option below, 5University of Maastricht, Maastricht, N/A

First Author:

Denizhan Kurban  
Maastricht University
Maastricht, Limburg

Co-Author(s):

Laurentius Huber, Ph.D.  
Maastricht University
Maastricht, Limburg
Gilad Liberman  
Martinos Center for Biomedical Imaging
Charlestown, MA
Sriranga Kashyap  
Maastricht University
Maastricht , Limburg
Dimo Ivanov  
Maastricht University
Maastricht, Please select an option below
Benedikt Poser  
University of Maastricht
Maastricht, N/A

Introduction:

Blood-volume-sensitive (VASO) fMRI[1] can be advantageous compared to conventional GE-EPI based BOLD methods, especially at ultra-high field or when high spatial resolution is required. VASO provides improved spatial specificity down to the level of cortical layers and columns, and allows quantification of meaningful physiological parameters. Its neuroscientific application, however, is limited by BOLD contrast contaminations, partial brain coverage, and temporal sampling efficiency.
The purpose of this study is to overcome these limitations of VASO fMRI, specifically to develop a VASO method that allows CBV fMRI free of BOLD contamination at sub-second TR. To achieve this, we combine efficient spiral k-space sampling and SMS[2] acceleration with blood-volume-sensitive VASO contrast. The flexibility and efficiency of spirals have been previously shown at 7T, including BOLD fMRI acquisitions[3,4,5]. Spiral sampling enables faster VASO acquisitions than previously possible. Furthermore, for high spatial resolution we show that the proposed method is less sensitive to large draining veins; which allows better separation of fMRI signals from 'kissing' gyri, e.g. in sensory and motor cortex.

Methods:

Two spiral read-out schemes were developed: 1) dual-echo spiral out-in for simultaneous acquisition of VASO and BOLD contrasts at 2mm3 iso, nominal TE1/TE2=2/25ms, TRavg=875ms, 24 slices, SMS-factor=2. High resolution spiral-out readout at 1.25x1.25x1.2mm3 resolution, TE=2ms, TRavg=2.1s, 30 slices, SMS-factor=2. 7T scanner, SIEMENS Healthineers. Cartesian acquisitions with matched parameters were performed (TE2mm/TEhighres=11/20ms). Slice-selective slab inversion (SS-SI) VASO[6] with SMS-EPI readout was implemented in the vendor-provided IDEA environment (VB17A-UHF). The VASO specific inversion was implemented by means of a 10ms TR-FOCI pulse 650ms before the first excitation pulse of the readout module. A visuo-motor task (block-design) was used to confirm the stability of the novel sequence setup in N=6 independent fMRI experiments (including test-retest). The image reconstruction of the spiral data was performed with MLN reconstruction that is trained on session specific B0 maps[6]. No smoothing was applied during any stage of the analysis in SPM(MOCO),AFNI,FSL(GLM) and LAYNII(profile plot).

Results:

Nii data can be downloaded from here: http://doi.org/10.18112/openneuro.ds002367.v1.0.0 Figure 1 shows the mean image and tSNR maps of the VASO time series, corrected for BOLD contamination. Compared to Cartesian acquisitions, spiral acquisitions at very short TE show superior temporal stability for VASO contrast. The visuomotor task leads to strong signal changes in CBV. High resolution spiral VASO (fig 2) shows higher spatial specificity compared to BOLD , which is visible in the profiles as two separate activations for M1 and S1.
Supporting Image: fig1_Sequence_FINAL.jpg
Supporting Image: fig2_highres_FINAL.jpg
 

Conclusions:

Here we present an alternative and highly promising approach for acquiring VASO fMRI. For the first time, we combined spiral non-Cartesian readouts with blood volume sensitive VASO contrast preparations. The proposed approach provides superior signal stability, unprecedented sampling efficiency (sub-second TRs) and avoids unwanted sensitivity to large veins. The technique might become valuable for neuroscientific applications that require high spatio-temporal resolutions. Extension of the proposed 2D approach to 3D stack-of-spirals is desirable as benefits of 3D VASO acquisitions was previously shown[8]. Even though spiral sampling allows efficient and flexible acquisition of fMRI data, implementation is more challenging and reconstruction is slow compared to conventional Cartesian sampling. The latter will be overcome by further advances in reconstruction hardware and techniques, not least the highly promising DL/ML based approaches that attract a lot of attention lately.

Modeling and Analysis Methods:

Activation (eg. BOLD task-fMRI) 2
Methods Development 1

Novel Imaging Acquisition Methods:

BOLD fMRI
Non-BOLD fMRI

Keywords:

fMRI CONTRAST MECHANISMS
FUNCTIONAL MRI
HIGH FIELD MR
MRI

1|2Indicates the priority used for review

My abstract is being submitted as a Software Demonstration.

No

Please indicate below if your study was a "resting state" or "task-activation” study.

Task-activation

Healthy subjects only or patients (note that patient studies may also involve healthy subjects):

Healthy subjects

Was any human subjects research approved by the relevant Institutional Review Board or ethics panel? NOTE: Any human subjects studies without IRB approval will be automatically rejected.

Yes

Was any animal research approved by the relevant IACUC or other animal research panel? NOTE: Any animal studies without IACUC approval will be automatically rejected.

Not applicable

Please indicate which methods were used in your research:

Functional MRI

For human MRI, what field strength scanner do you use?

7T

Which processing packages did you use for your study?

AFNI
SPM
FSL
Other, Please list  -   LAYNII

Provide references using author date format

[1] Lu H et al. 2003. 'Functional Magnetic Resonance Imaging Based on Changes in Vascular Space Occupancy.' Magnetic Resonance in Medicine 50: 263–74. http://www.ncbi.nlm.nih.gov/pubmed/12876702
[2] Setsompop K et al. 2011. 'Blipped-controlled aliasing in parallel imaging for simultaneous multislice echo planar imaging with reduced g-factor penalty'. Magnetic Resonance in Medicine. 67(5), 1210–1224. doi:10.1002/mrm.23097
[3] Engel M et al. 2018. 'Single-shot spiral imaging at 7 T'. Magnetic Resonance in Medicine 80(5), 1836–1846. doi:10.1002/mrm.27176
[4] Kasper L et al. 2019: 'Advances in Spiral fMRI. A High-resolution Study with Single-shot Acquisition'. In bioRxiv. DOI: 10.1101/842179.
[5] Kurban D et al. 2019. 'Dual-echo simultaneous multi-slice spiral acquisition for concurrent CBF and BOLD fMRI at 7T'. Proceedings of ISMRM, Montreal, Canada
[6] Huber L et al. 2014. 'Slab-Selective, BOLD-Corrected VASO at 7 Tesla Provides Measures of Cerebral Blood Volume Reactivity with High Signal-to-Noise Ratio'. Magnetic Resonance in Medicine 72(1): 137–48. https://doi.org/10.1002/mrm.24916.
[7] Liberman G et al. 'Minimal Linear Networks for Magnetic Resonance Image Reconstruction'. NatSciRep (accepted; SREP-19-06395B)
[8] Huber L et al. 2018. 'Techniques for blood volume fMRI with VASO: From low-resolution mapping towards sub-millimeter layer-dependent applications'. NeuroImage, 164, 131–143. doi:10.1016/j.neuroimage.2016.11.039