title: Relaxation effects in the quantification of fat using gradient echo imaging.
abstract: Quantification of fat has been investigated using images acquired from multiple gradient echoes. The evolution of the signal with echo time and flip angle was measured in phantoms of known fat and water composition and in 21 research subjects with fatty liver. Data were compared to different models of the signal equation, in which each model makes different assumptions about the T1 and/or T2* relaxation effects. A range of T1, T2*, fat fraction and number of echoes was investigated to cover situations of relevance to clinical imaging. Results indicate that quantification is most accurate at low flip angles (to minimize T1 effects) with a small number of echoes (to minimize spectral broadening effects). At short echo times, the spectral broadening effects manifest as a short apparent T2 for the fat component.
authors: MR3 Research Building, University of California-San Diego, San Diego, CA 92103-8226, USA. mbydder@ucsd.edu
authors: Mark
authors: M
authors: Bydder
authors: Takeshi
authors: T
authors: Yokoo
authors: Gavin
authors: G
authors: Hamilton
authors: Michael S
authors: MS
authors: Middleton
authors: Alyssa D
authors: AD
authors: Chavez
authors: Jeffrey B
authors: JB
authors: Schwimmer
authors: Joel E
authors: JE
authors: Lavine
authors: Claude B
authors: CB
authors: Sirlin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003287:Contrast Media / Q000008:administration & dosage; D003911:Dextrans; D017352:Echo-Planar Imaging / Q000379:methods*; D005234:Fatty Liver / Q000473:pathology*; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007501:Iron / Q000008:administration & dosage; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D010087:Oxides / Q000008:administration & dosage; D019047:Phantoms, Imaging
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide