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Titolo:
Sensitivity and performance time in MRI dephasing artifact reduction methods
Autore:
Wadghiri, YZ; Johnson, G; Turnbull, DH;
Indirizzi:
NYU, Sch Med, Skirball Inst Biomol Med, New York, NY 10016 USA NYU New York NY USA 10016 kirball Inst Biomol Med, New York, NY 10016 USA NYU, Sch Med, Dept Radiol, New York, NY USA NYU New York NY USANYU, Sch Med, Dept Radiol, New York, NY USA NYU, Sch Med, Dept Pathol, New York, NY USA NYU New York NY USANYU, Sch Med, Dept Pathol, New York, NY USA
Titolo Testata:
MAGNETIC RESONANCE IN MEDICINE
fascicolo: 3, volume: 45, anno: 2001,
pagine: 470 - 476
SICI:
0740-3194(200103)45:3<470:SAPTIM>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
GRADIENT-ECHO; FIELD INHOMOGENEITIES; COMPENSATION;
Keywords:
susceptibility artifacts; field homogeneity; high field MRI; functional MRI;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
20
Recensione:
Indirizzi per estratti:
Indirizzo: Wadghiri, YZ NYU, Sch Med, Skirball Inst Biomol Med, 550 1St Ave,5th FloorLab 13, New York, NY 10016 USA NYU 550 1St Ave,5th Floor Lab 13 New York NY USA 10016 16 USA
Citazione:
Y.Z. Wadghiri et al., "Sensitivity and performance time in MRI dephasing artifact reduction methods", MAGN RES M, 45(3), 2001, pp. 470-476

Abstract

Although shimming can improve static field inhomogeneity, local field imperfections induced by tissue susceptibility differences cannot be completelycorrected and can cause substantial signal loss in gradient echo images through intravoxel dephasing, Dephasing increases with voxel size so that onesimple method of reducing the effect is to use thin slices. Signal-to-noise ratio (SNR) can then be increased by averaging over the subslices to formthe final, thick slice. We call this method subslice averaging or SSAVE. Alternatively, a range of different amplitude slice select rephase gradientscan be used to compensate for different susceptibility induced gradient offsets, The final image can then be formed by combining individual images ina variety of ways: summation, summation of the squares of the images, forming the maximum intensity projection of the image set, and Fourier transformation followed by summation. We show here that, contrary to previous claims, the theoretical sensitivity (i.e., SNR divided by the square root of theimaging time) of all these alternative methods is very similar. However, performance time (i.e., minimum-imaging time) of the simplest method, SSAVE,is much shorter than that of alternatives. This is confirmed experimentally on phantoms and anesthetized mice. (C) 2001 Wiley-Liss, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/01/20 alle ore 21:19:32