Optimizing acquisition and fitting conditions for 1 H MR spectroscopy investigations in global brain pathology.

Höfemann, Maike Svenja; Adalid López, Víctor Javier; Kreis, Roland (2019). Optimizing acquisition and fitting conditions for 1 H MR spectroscopy investigations in global brain pathology. NMR in biomedicine, 32(11), e4161. Wiley Interscience 10.1002/nbm.4161

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PURPOSE

To optimize acquisition and fitting conditions for nonfocal disease in terms of voxel size and use of individual coil element data. Increasing the voxel size yields a higher signal-to-noise ratio, but leads to larger linewidths and more artifacts. Several ways to improve the spectral quality for large voxels are exploited and the optimal use of individual coil signals investigated.

METHODS

Ten human subjects were measured at 3 T using a 64-channel receive head coil with a semi-LASER localization sequence under optimized and deliberately mis-set field homogeneity. Eight different voxel sizes (8 to 99 cm3 ) were probed. Spectra were fitted either as weighted sums of the individual coil elements or simultaneously without summation. Eighteen metabolites were included in the fit model that also included the lineshapes from all coil elements as reflected in water reference data. Fitting errors for creatine, myo-Inositol and glutamate are reported as representative parameters to judge optimal acquisition and evaluation conditions.

RESULTS

Minimal Cramér-Rao lower bounds and thus optimal acquisition conditions were found for a voxel size of ~ 70 cm3 for the representative upfield metabolites. Spectral quality in terms of lineshape and artifact appearance was determined to differ substantially between coil elements. Simultaneous fitting of spectra from individual coil elements instead of traditional fitting of a weighted sum spectrum reduced Cramer-Rao lower bounds by up to 17% for large voxel sizes.

CONCLUSION

The optimal voxel size for best precision in determined metabolite content is surprisingly large. Such an acquisition condition is most relevant for detection of low-concentration metabolites, like NAD+ or phenylalanine, but also for longitudinal studies where very small alterations in metabolite content are targeted. In addition, simultaneous fitting of single channel spectra enforcing lineshape and coil sensitivity information proved to be superior to traditional signal combination with subsequent fitting.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology > DCR Magnetic Resonance Spectroscopy and Methodology (AMSM)
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR)
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Forschungsbereich Pavillon 52 > Abt. Magnetresonanz-Spektroskopie und Methodologie, AMSM

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Höfemann, Maike Svenja; Adalid López, Víctor Javier and Kreis, Roland

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0952-3480

Publisher:

Wiley Interscience

Language:

English

Submitter:

Maria de Fatima Henriques Bernardo

Date Deposited:

29 Aug 2019 15:39

Last Modified:

15 Aug 2020 02:30

Publisher DOI:

10.1002/nbm.4161

Related URLs:

PubMed ID:

31410911

Uncontrolled Keywords:

artifacts lineshape modeling signal acquisition spectral quality

BORIS DOI:

10.7892/boris.132756

URI:

https://boris.unibe.ch/id/eprint/132756

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