Basic studies on the equivalent cross-relaxation rate imaging (equivalent CRI)--phantom studies.
We have studied saturation transfer in hydrophilic, cross-linked copolymer gels from irradiated polymer protons to observed water protons, using f2 (ppm) profiles of [1 - (I(infinity)/I(0))], [(I(0)/I(infinity)) - 1] or 1/T(IS)(H2O), where I(0) and I(infinity) are the longitudinal magnetization of the observed water protons before and after long-time-f2-irradiation on polymer protons, respectively, and 1/T(IS)(H2O) is the cross-relaxation rate. (A) [1 - (I(infinity)/I(0))] (magnetization transfer ratio, MTR) was used in magnetic resonance imaging (MRI) as the MTR imaging. 1/T(IS)(H2O) (cross-relaxation rate) was used in the imaging of the magnetization transfer rate constant. This method was quite time-consuming compared with MTR imaging. However, f2 (ppm) profiles of [(I(0)/I(infinity)) - 1] correlated well with corresponding profiles of 1/T(IS)(H2O), because [(I(0)/I(infinity)) - 1] is equal to 1/[T(IS)(H2O)/T1(H2O)]. These results lead us to the conclusion that [(I(0)/I(infinity)) - 1] might be applicable to cross-relaxation rate (CR)-like imaging, i.e. equivalent CRI. (B) W (%) (dry weight) profiles of [(I(0)/I(infinity)) - 1] and 1/T(IS)(H2O), obtained by near-resonance f2-irradiation, seem to indicate participation of molecular rigidity and an amount of bound water. However, those values, monitored with off-resonance f2-irradiation, seem to be independent of monomer composition and to indicate mainly participation of rigidity, i.e. W (%) of copolymer gels.
Sogami
M
M
Department of Physiology, School of Health Sciences, Fujita Health University, Toyoake 470-1192, Japan.
Era
S
S
Kinosada
Y
Y
Matsushima
S
S
Kato
K
K
Tomida
M
M
Hirabayashi
T
T
D003432:Cross-Linking Reagents; D005782:Gels; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D008280:Magnetics; D019047:Phantoms, Imaging; D011108:Polymers; D011522:Protons; D013997:Time Factors; D014867:Water
D003432:Cross-Linking Reagents; D005782:Gels; D011108:Polymers; D011522:Protons; D014867:Water