An integrated RF-receive/B0-shim array coil boosts performance of whole-brain MR spectroscopic imaging at 7 T

Abstract Metabolic imaging of the human brain by in-vivo magnetic resonance spectroscopic imaging (MRSI) can non-invasively probe neurochemistry in healthy and disease conditions. MRSI at ultra-high field (≥ 7 T) provides increased sensitivity for fast high-resolution metabolic imaging, but comes with technical challenges due to non-uniform B0 field. Here, we show that an integrated RF-receive/B0-shim (AC/DC) array coil can be used to mitigate 7 T B0 inhomogeneity, which improves spectral quality and metabolite quantification over a whole-brain slab. Our results from simulations, phantoms, healthy and brain tumor human subjects indicate improvements of global B0 homogeneity by 55%, narrower spectral linewidth by 29%, higher signal-to-noise ratio by 31%, more precise metabolite quantification by 22%, and an increase by 21% of the brain volume that can be reliably analyzed. AC/DC shimming provide the highest correlation (R2 = 0.98, P = 0.001) with ground-truth values for metabolite concentration. Clinical translation of AC/DC and MRSI is demonstrated in a patient with mutant-IDH1 glioma where it enables imaging of D-2-hydroxyglutarate oncometabolite with a 2.8-fold increase in contrast-to-noise ratio at higher resolution and more brain coverage compared to previous 7 T studies. Hence, AC/DC technology may help ultra-high field MRSI become more feasible to take advantage of higher signal/contrast-to-noise in clinical applications.

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In Vivo Absolute Metabolite Quantification Using a Multiplexed ERETIC‐RX Array Coil for Whole‐Brain MR Spectroscopic Imaging

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.28028 ◽

2021 ◽

Author(s):

Bijaya Thapa ◽

Azma Mareyam ◽

Jason Stockmann ◽

Bernhard Strasser ◽

Boris Keil ◽

...

Keyword(s):

Spectroscopic Imaging ◽

Whole Brain ◽

Metabolite Quantification ◽

Mr Spectroscopic Imaging ◽

Array Coil

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Ultra-high-field 7-T MRI in multiple sclerosis and other demyelinating diseases: from pathology to clinical practice

European Radiology Experimental ◽

10.1186/s41747-020-00186-x ◽

2020 ◽

Vol 4 (1) ◽

Author(s):

Nicolo’ Bruschi ◽

Giacomo Boffa ◽

Matilde Inglese

Keyword(s):

Multiple Sclerosis ◽

High Field ◽

Neurological Diseases ◽

Lesion Detection ◽

Demyelinating Diseases ◽

Metabolic Imaging ◽

Central Vein ◽

Ultra High Field ◽

Functional Features

Abstract Magnetic resonance imaging (MRI) is essential for the early diagnosis of multiple sclerosis (MS), for investigating the disease pathophysiology, and for discriminating MS from other neurological diseases. Ultra-high-field strength (7-T) MRI provides a new tool for studying MS and other demyelinating diseases both in research and in clinical settings. We present an overview of 7-T MRI application in MS focusing on increased sensitivity and specificity for lesion detection and characterisation in the brain and spinal cord, central vein sign identification, and leptomeningeal enhancement detection. We also discuss the role of 7-T MRI in improving our understanding of MS pathophysiology with the aid of metabolic imaging. In addition, we present 7-T MRI applications in other demyelinating diseases. 7-T MRI allows better detection of the anatomical, pathological, and functional features of MS, thus improving our understanding of MS pathology in vivo. 7-T MRI also represents a potential tool for earlier and more accurate diagnosis.

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Effect of radiofrequency shield diameter on signal‐to‐noise ratio at ultra‐high field MRI

Magnetic Resonance in Medicine ◽

10.1002/mrm.28670 ◽

2021 ◽

Vol 85 (6) ◽

pp. 3522-3530

Author(s):

Bei Zhang ◽

Gregor Adriany ◽

Lance Delabarre ◽

Jerahmie Radder ◽

Russell Lagore ◽

...

Keyword(s):

High Field ◽

Signal To Noise Ratio ◽

Signal To Noise ◽

Ultra High Field ◽

High Field Mri ◽

Ultra High Field Mri ◽

Noise Ratio

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P1045 : Ultra-high-field MR-spectroscopy in NAFLD as non-invasive in-vivo tool for monitoring changes in fat and energy metabolism with potential identification of NASH and advanced fibrosis by saturation transfer technique

Journal of Hepatology ◽

10.1016/s0168-8278(15)31243-5 ◽

2015 ◽

Vol 62 ◽

pp. S739-S740 ◽

Cited By ~ 3

Author(s):

S. Traussnigg ◽

C. Kienbacher ◽

M. Gajdošík ◽

L. Valkovič ◽

H. Hofer ◽

...

Keyword(s):

Energy Metabolism ◽

Mr Spectroscopy ◽

High Field ◽

Advanced Fibrosis ◽

Saturation Transfer ◽

Ultra High Field ◽

Non Invasive ◽

High Field Mr

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Emerging methods and applications of ultra-high field MR spectroscopic imaging in the human brain

Analytical Biochemistry ◽

10.1016/j.ab.2021.114479 ◽

2021 ◽

pp. 114479

Author(s):

Gilbert Hangel ◽

Eva Heckova ◽

Philipp Lazen ◽

Petr Bednarik ◽

Wolfgang Bogner ◽

...

Keyword(s):

Human Brain ◽

High Field ◽

Spectroscopic Imaging ◽

Ultra High Field ◽

High Field Mr ◽

Mr Spectroscopic Imaging

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In vivo manganese tract tracing of frontal eye fields in rhesus macaques with ultra-high field MRI: Comparison with DWI tractography

NeuroImage ◽

10.1016/j.neuroimage.2018.06.072 ◽

2018 ◽

Vol 181 ◽

pp. 211-218 ◽

Cited By ~ 7

Author(s):

David J. Schaeffer ◽

Kevin D. Johnston ◽

Kyle M. Gilbert ◽

Joseph S. Gati ◽

Ravi S. Menon ◽

...

Keyword(s):

High Field ◽

Rhesus Macaques ◽

Frontal Eye Fields ◽

Tract Tracing ◽

Ultra High Field ◽

High Field Mri ◽

Ultra High Field Mri

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Improved MR Thermometry to Measure Brain Temperatures

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192017 ◽

2008 ◽

Author(s):

Devashish Shrivastava ◽

Lance DelaBarre ◽

Timothy Hanson ◽

J. Thomas Vaughan

Keyword(s):

High Field ◽

Core Body Temperature ◽

Temperature Response ◽

Time History ◽

Rf Heating ◽

Mr Thermometry ◽

Ultra High Field ◽

High Fields ◽

Rf Safety

An MR thermometry technique with sub-degree celsius accuracy is needed to measure in vivo temperatures vs. time in porcine brains at ultra-high fields. Porcine models are used to study thermoregulatory temperature response of the ultra-high field radiofrequency (RF) heating. The porcine hot critical temperature limit is comparable to and lower than that of humans. Also, porcine thermoregulatory mechanisms are similar to humans. Thus, conservative porcine thermoregulatory temperature responses can help develop new RF safety thresholds for ultra-high field human MRI. Sub-degree C temperature accuracy is needed since RF safety guidelines limit the maximum in vivo head temperature change due to RF heating to 1 °C over the core body temperature. Three-dimensional temperature maps over time are required since non-uniform RF power deposition at ultra-high fields and blood flow produce non-uniform in vivo temperatures with local hot spots. Thermogenic hazards are related to in vivo temperatures and temperature-time history — and not to the typically measured whole head average specific absorption rate.

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P.063 Stereotactic targeting of hippocampal substructures using ultra-high field magnetic resonance imaging: Feasibility study in patients with epilepsy

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/cjn.2018.165 ◽

2018 ◽

Vol 45 (s2) ◽

pp. S32-S33

Author(s):

JC Lau ◽

J DeKraker ◽

KW MacDougall ◽

H Joswig ◽

AG Parrent ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Dentate Gyrus ◽

High Field ◽

Longitudinal Axis ◽

The Body ◽

7 Tesla ◽

Resonance Imaging ◽

Ultra High Field

Background: The hippocampus can be divided longitudinally into the head, body, and tail; and unfolded medial-to-laterally into the subiculum, cornu ammonis (CA) sectors, and the dentate gyrus. Ultra-high field (≥ 7 Tesla; 7T) magnetic resonance imaging (MRI) enables submillimetric visualization of these hippocampal substructures which could be valuable for surgical targeting. Here, we assess the feasibility of using 7T MRI in conjunction with a novel computational unfolding method for image-based stereotactic targeting of hippocampal substructures. Methods: 53 patients with drug-resistant epilepsy were identified undergoing first-time implantation of the hippocampus. An image processing pipeline was created for computationally transforming post-operative electrode contact locations into our hippocampal coordinate system. Results: Of 178 implanted hippocampal electrodes (88 left; 49.4%), 25 (14.0%) were predominantly in the subiculum, 85 (47.8%) were in CA1, 23 (12.9%) were in CA2, 18 (10.1%) were in CA3/CA4, and 27 (15.2%) were in dentate gyrus. Along the longitudinal axis, hippocampal electrodes were most commonly implanted in the body (92; 51.7%) followed by the head (86; 48.3%). Conclusions: 7T MRI enables high-resolution anatomical imaging on the submillimeter scale in in vivo subjects. Here, we demonstrate the utility of 7T imaging for identifying the relative location of SEEG electrode implantations within hippocampal substructures for the invasive investigation of epilepsy.

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