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Differential functional benefits of ultra highfield MR systems within the language network.

Geißler A, Matt E, Fischmeister F, Wurnig M, Dymerska B, Knosp E, Feucht M, Trattnig S, Auff E, Fitch WT, Robinson S, Beisteiner R - Neuroimage (2014)

Bottom Line: Improvement is expected from ultra highfield systems but studies on possible benefits for cognitive networks are lacking.During data acquisition and analysis we made particular efforts to minimize effects not related to static magnetic field strength differences.We conclude that functional UHF benefits are evident, however these depend crucially on the brain region investigated and the ability to control local artifacts.

View Article: PubMed Central - PubMed

Affiliation: Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Austria; High Field MR Center, Medical University of Vienna, Austria; Department of Neurology, Medical University of Vienna, Austria.

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EPI images for visualizing of ghosting artifacts (P7, 7 T data). Green: ROIs for detection of ghosting signals, blue: central reference ROI. The relation between the mean absolute signals within the ghosting ROIs and the reference ROIs was calculated.
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f0010: EPI images for visualizing of ghosting artifacts (P7, 7 T data). Green: ROIs for detection of ghosting signals, blue: central reference ROI. The relation between the mean absolute signals within the ghosting ROIs and the reference ROIs was calculated.

Mentions: Since patient motion leads to ghost-like artifacts in accelerated acquisitions (Skare et al., 2007) and parallel imaging was used at both field strengths (GRAPPA factor 2 (Griswold et al., 2002)), we evaluated 2 measures of image quality. The absolute ghost to signal ratio (GSRA) was calculated, and magnetic field gradients in Broca's and Wernicke's areas were assessed in a subgroup of patients. Ghost to signal ratio (GSRA) was calculated similar to the approach used in the EU COMAC-BME II project (Lerski and de Certaines, 1993). This measure is defined as the relation of the mean ghosting signal Sghost within 2 ghost contained ROIs and the mean signal within a homogenous white matter ROI SWM. ROI selection for this purpose was performed on the 3 central slices of the functional EPI dataset. The white matter ROI SWM was located in a central undisturbed white matter area. The 2 ghost ROIs were located anterior and posterior of the brain and comprised possible ghosting artifacts in the phase-encode direction (Fig. 2).


Differential functional benefits of ultra highfield MR systems within the language network.

Geißler A, Matt E, Fischmeister F, Wurnig M, Dymerska B, Knosp E, Feucht M, Trattnig S, Auff E, Fitch WT, Robinson S, Beisteiner R - Neuroimage (2014)

EPI images for visualizing of ghosting artifacts (P7, 7 T data). Green: ROIs for detection of ghosting signals, blue: central reference ROI. The relation between the mean absolute signals within the ghosting ROIs and the reference ROIs was calculated.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263528&req=5

f0010: EPI images for visualizing of ghosting artifacts (P7, 7 T data). Green: ROIs for detection of ghosting signals, blue: central reference ROI. The relation between the mean absolute signals within the ghosting ROIs and the reference ROIs was calculated.
Mentions: Since patient motion leads to ghost-like artifacts in accelerated acquisitions (Skare et al., 2007) and parallel imaging was used at both field strengths (GRAPPA factor 2 (Griswold et al., 2002)), we evaluated 2 measures of image quality. The absolute ghost to signal ratio (GSRA) was calculated, and magnetic field gradients in Broca's and Wernicke's areas were assessed in a subgroup of patients. Ghost to signal ratio (GSRA) was calculated similar to the approach used in the EU COMAC-BME II project (Lerski and de Certaines, 1993). This measure is defined as the relation of the mean ghosting signal Sghost within 2 ghost contained ROIs and the mean signal within a homogenous white matter ROI SWM. ROI selection for this purpose was performed on the 3 central slices of the functional EPI dataset. The white matter ROI SWM was located in a central undisturbed white matter area. The 2 ghost ROIs were located anterior and posterior of the brain and comprised possible ghosting artifacts in the phase-encode direction (Fig. 2).

Bottom Line: Improvement is expected from ultra highfield systems but studies on possible benefits for cognitive networks are lacking.During data acquisition and analysis we made particular efforts to minimize effects not related to static magnetic field strength differences.We conclude that functional UHF benefits are evident, however these depend crucially on the brain region investigated and the ability to control local artifacts.

View Article: PubMed Central - PubMed

Affiliation: Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Austria; High Field MR Center, Medical University of Vienna, Austria; Department of Neurology, Medical University of Vienna, Austria.

Show MeSH
Related in: MedlinePlus