Low field T1rho imaging of myositis.
The purpose of this study was to evaluate 1/T1rho in relation to 1/T1 and 1/T2 in characterizing normal and diseased muscle. We measured the muscle relaxation rates 1/T1 and 1/T2 at 0.1 T and 1/T1rho at on-resonance locking fields B1 between 10 and 160 microT in myositis patients and normal volunteers. 1/T2 and 1/T1rho of muscle were lower in the patients than in the volunteers, whereas there was no difference in the 1/T1 values. The lower relaxation rates 1/T2 and 1/T1rho in the diseased muscle may be due to fat and connective tissue infiltrations and edema. 1/T1rho contrast between muscle and subcutaneous fat was higher than 1/T2 and 1/T1 contrast. This may be explained by the different B1 dispersion behavior of these two tissue types. 1/T1rho of fat is B1 field independent, whereas 1/T1rho of muscle decreases clearly with increasing B1 field. In conclusion, 1/T1rho provides a useful tool in manipulating contrast in magnetic resonance imaging of diseased muscle.
Department of Diagnostic Radiology, University of Turku, Finland. anevir@codon.nih.gov
A
A
Virta
M
M
Komu
N
N
Lundbom
S
S
Jääskeläinen
H
H
Kalimo
A
A
Airio
A
A
Alanen
M
M
Kormano
D000273:Adipose Tissue / Q000473:pathology; D000368:Aged; D003238:Connective Tissue / Q000473:pathology; D004487:Edema / Q000175:diagnosis; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology; D009220:Myositis / Q000175:diagnosis* / Q000503:physiopathology