Relaxation effects in the quantification of fat using gradient echo imaging.
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.
Bydder
Mark
M
MR3 Research Building, University of California-San Diego, San Diego, CA 92103-8226, USA. mbydder@ucsd.edu
Yokoo
Takeshi
T
Hamilton
Gavin
G
Middleton
Michael S
MS
Chavez
Alyssa D
AD
Schwimmer
Jeffrey B
JB
Lavine
Joel E
JE
Sirlin
Claude B
CB
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
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide