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

Hangel, Gilbert; Hečková, Eva; Lazen, Philipp; Bednařík, Petr; Bogner, Wolfgang; Strasser, Bernhard

doi:10.1016/j.ab.2021.114479

Cited by 16 publications

(9 citation statements)

References 200 publications

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“…As our MRSI sequence was limited to a single 8-mm thick slice above the corpus callosum and bias due to partial volume effects had to be avoided, the number of included lesions was limited. To overcome the limitation of a single-slice acquisition, a 3D-MRSI version of this sequence, covering the majority of the brain, has recently been introduced and has provided promising results in brain tumors [6], [49]. In addition, we did not determine concentration estimates, as we could not avert changes in the T1 relaxation times due to MS pathology [50] and an additional water scan would have doubled our scan time for each slice.…”

Section: Discussionmentioning

confidence: 99%

“…For the analysis of lesion layers the influence of partial volume errors could not be fully extinguished, even though only every third lesion layer has been analyzed. To overcome these limitations of a single-slice acquisition, a 3D-MRSI version of this sequence, covering the majority of the brain, has recently been introduced and has provided promising results in brain tumors (Hangel et al, 2022; Hingerl et al, 2020). We did not determine concentration estimates (Kreis et al, 2021; Maudsley et al, 2021), as we could not avert changes in the T1 relaxation times due to MS pathology (Brief et al, 2010) and an additional water scan would have doubled our acquisition time (Kreis et al, 2021; Maudsley et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

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Metabolic Insights into Iron Deposition in Relapsing-Remitting Multiple Sclerosis via 7T Magnetic Resonance Spectroscopic Imaging

Lipka

Bogner

Dal‐Bianco

et al. 2023

Preprint

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Objective To investigate the metabolic pattern of different types of iron accumulation in multiple sclerosis(MS) lesions, and compare metabolic alterations within and at the periphery of lesions and newly emerging lesions in vivo according to iron deposition. Methods 7T MR spectroscopic imaging and susceptibility-weighted-imaging was performed in 31 RRMS patients(16female/15male;mean age,36.9+-10.3years). Mean metabolic ratio were calculated for regions of interest(ROI) of normal appearing white matter(NAWM), 'non-iron', and three distinct types of iron-laden lesions, and for lesion layers of 'non-iron' and 'rim' lesions. Furthermore, newly emerging 'non-iron' and 'iron' lesions were compared longitudinally. Results 52% of iron-containing lesions showed no distinct paramagnetic rim. Of these, 'area' lesions exhibited a 65% higher mIns/tNAA(p=0.035) than 'rim' lesions. Comparing lesion layers of both 'non-iron' and 'rim' lesions, a steeper metabolic gradient of mIns/tNAA('non-iron'+15%,'iron'+40%) and tNAA/tCr('non-iron'-15%,'iron'-35%) was found in 'iron' lesions, with the lesion core showing +22% higher mIns/tNAA(p=0.005) and -23% lower tNAA/tCr(p=0.048) in 'iron' compared to 'non-iron' lesions. In newly emerging lesions, 46% showed iron accumulation, with the drop in tNAA/tCr after lesion formation remaining significantly lower compared to pre-lesional tissue over time in 'iron' lesions(year0:p=0.013,year1:p=0.041) as opposed to 'non-iron' lesions(year0:p=0.022,year1:p=0.231). Conclusion 7T MRSI allows in vivo characterization of different iron accumulation types showing metabolic differences. Furthermore, the larger extent of neuronal damage in lesions with a distinct iron rim was reconfirmed, but with metabolic differences in lesion development between (non)-iron-containing lesions. This highlights the ability of MRSI to further investigate different types of iron accumulation and suggests possible implications for disease monitoring. Clinical relevance statement: The clinical importance of differentiating various types of iron accumulation in MS lesions was shown, as contrasting metabolic profiles are likely associated with different levels of tissue damage.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Metabolic Insights into Iron Deposition in Relapsing-Remitting Multiple Sclerosis via 7T Magnetic Resonance Spectroscopic Imaging

Lipka

Bogner

Dal‐Bianco

et al. 2023

Preprint

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“…Indeed the potential of UHF-MRS has been demonstrated in a multicenter study at 7T in the human brain using Semi-Localized by Adiabatic SElective Refocusing (sLASER) [87] and by using the STimulated Echo Acquisition Mode (STEAM) sequence [62]. Moreover, UHF is highly beneficial for MRSI applications, as it provides a high SNR that allows us to achieve a reliable metabolite map throughout the brain in a short scan time [88,89], which was demonstrated in comparison with 3T and 7T [90].…”

Section: Advantages Of Uhf-mrs To Assess Cerebral Metabolismmentioning

confidence: 99%

Multinuclear Magnetic Resonance Spectroscopy at Ultra-High-Field: Assessing Human Cerebral Metabolism in Healthy and Diseased States

Veeraiah

Jansen

2023

Metabolites

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The brain is a highly energetic organ. Although the brain can consume metabolic substrates, such as lactate, glycogen, and ketone bodies, the energy metabolism in a healthy adult brain mainly relies on glucose provided via blood. The cerebral metabolism of glucose produces energy and a wide variety of intermediate metabolites. Since cerebral metabolic alterations have been repeatedly implicated in several brain disorders, understanding changes in metabolite levels and corresponding cell-specific neurotransmitter fluxes through different substrate utilization may highlight the underlying mechanisms that can be exploited to diagnose or treat various brain disorders. Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure tissue metabolism in vivo. 1H-MRS is widely applied in research at clinical field strengths (≤3T) to measure mostly high abundant metabolites. In addition, X-nuclei MRS including, 13C, 2H, 17O, and 31P, are also very promising. Exploiting the higher sensitivity at ultra-high-field (>4T; UHF) strengths enables obtaining unique insights into different aspects of the substrate metabolism towards measuring cell-specific metabolic fluxes in vivo. This review provides an overview about the potential role of multinuclear MRS (1H, 13C, 2H, 17O, and 31P) at UHF to assess the cerebral metabolism and the metabolic insights obtained by applying these techniques in both healthy and diseased states.

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“…MRSI enables the in vivo mapping of brain metabolites, whose alterations have been associated with various cancer types, multiple sclerosis, epilepsy, and other diseases that affect brain metabolism. 1,2 MRSI data quality benefits from higher magnetic field strengths through increases of the chemical shift dispersion and SNR. 3 This provides high-field MRSI with more sensitivity to distinguish low-SNR metabolite peaks and facilitates increased spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

A silent echo‐planar spectroscopic imaging readout with high spectral bandwidth MRSI using an ultrasonic gradient axis

Versteeg,

Nam,

Klomp

et al. 2024

Magnetic Resonance in Med

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PurposeWe present a novel silent echo‐planar spectroscopic imaging (EPSI) readout, which uses an ultrasonic gradient insert to accelerate MRSI while producing a high spectral bandwidth (20 kHz) and a low sound level.MethodsThe ultrasonic gradient insert consisted of a single‐axis (z‐direction) plug‐and‐play gradient coil, powered by an audio amplifier, and produced 40 mT/m at 20 kHz. The silent EPSI readout was implemented in a phase‐encoded MRSI acquisition. Here, the additional spatial encoding provided by this silent EPSI readout was used to reduce the number of phase‐encoding steps. Spectroscopic acquisitions using phase‐encoded MRSI, a conventional EPSI‐readout, and the silent EPSI readout were performed on a phantom containing metabolites with resonance frequencies in the ppm range of brain metabolites (0–4 ppm). These acquisitions were used to determine sound levels, showcase the high spectral bandwidth of the silent EPSI readout, and determine the SNR efficiency and the scan efficiency.ResultsThe silent EPSI readout featured a 19‐dB lower sound level than a conventional EPSI readout while featuring a high spectral bandwidth of 20 kHz without spectral ghosting artifacts. Compared with phase‐encoded MRSI, the silent EPSI readout provided a 4.5‐fold reduction in scan time. In addition, the scan efficiency of the silent EPSI readout was higher (82.5% vs. 51.5%) than the conventional EPSI readout.ConclusionsWe have for the first time demonstrated a silent spectroscopic imaging readout with a high spectral bandwidth and low sound level. This sound reduction provided by the silent readout is expected to have applications in sound‐sensitive patient groups, whereas the high spectral bandwidth could benefit ultrahigh‐field MR systems.

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

Cited by 16 publications

References 200 publications

Metabolic Insights into Iron Deposition in Relapsing-Remitting Multiple Sclerosis via 7T Magnetic Resonance Spectroscopic Imaging

Metabolic Insights into Iron Deposition in Relapsing-Remitting Multiple Sclerosis via 7T Magnetic Resonance Spectroscopic Imaging

Multinuclear Magnetic Resonance Spectroscopy at Ultra-High-Field: Assessing Human Cerebral Metabolism in Healthy and Diseased States

A silent echo‐planar spectroscopic imaging readout with high spectral bandwidth MRSI using an ultrasonic gradient axis

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