Basic studies on the equivalent cross‐relaxation rate imaging (equivalent CRI)—phantom studies

Abstract

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.

Saturation transfer in human red blood cells with normal and unstable hemoglobin

“…2 10 (see references therein) and is designated as the action spectrum for the saturation transfer from irradiated protein protons to observed water protons. In this manuscript, unless otherwise stated, we refer to f 2 -profile of MTR as the action spectrum (see Table 1 in Sogami et al 25 ). †In our previous reports, 11,19,24 we called the 1/T IS (H 2 O) vs f 2 (ppm) plot cross-relaxation spectrum.…”

“…are the longitudinal magnetization before and after long-time f 2 -irradiation on the S-spin system, respectively, and 1/T Action spectra* {[1 À(I ? /I 0 )] vs f 2 (ppm)} 10,11,24,25 and intermolecular cross-relaxation rate (CR) spectra † [CR spectra; 1/T IS vs f 2 (ppm)] 11,19,25 for the saturation transfer from irradiated protein protons to observed water protons were obtained using eqn (2) and 1/T Ã 1 = 1/T IS 1/T 1 relation with f 2 -irradiation from À 100 to 100 ppm except for the region of water signal AE 1.5 ppm at gH 2 /2p of 69 or 250 Hz for 5 Â T 1 .…”

“…38 The patient with Hb Koeln was a 22-year-old male, but he showed few hematological features (Hb level, 13.3 g/dl; Ht, 45.3%). The substitution of a methionine for a valine at position 98 of the b-chain was determined by Ohba et [11][12][13][14][15][16][17][18][19]25 In this section, unless otherwise stated, the following abbreviations were used: T 1 , T 1 (H 2 O) and T IS , T IS (H 2 O). Actual strength of f 2 -power at the sample position, calibrated using partially hydrolyzed BSA gel (BSA* gel), [11][12][13][14][15][16][17][18][19]25 was chosen to be in the range of 69 or 250 Hz in gH 2 /2p units.…”

“…13,[15][16][17][18][19] These results seem to suggest that changes in T IS (H 2 O) are related to not only water (bound water) content but also physical characteristics of macromolecules, such as molecular rigidity and aggregation. [8][9][10][12][13][14][15][16][17][18][19][24][25][26][27] Thus we have studied T IS [28][29][30][31][32] formaldehyde 33 or phenylhydrazine 3,5,[34][35][36][37] which exhibit Met-Hb formation with or without cross-linking.…”

“…Intermolecular cross-relaxation times [T IS (H 2 O)] from irradiated protein protons to observed water protons were introduced and applied to elucidate protein-water and proteinprotein interactions. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] We found that spin-lattice relaxation times [T 1 (HDO)], spin-spin relaxation times [T 2 (HDO)] and T IS (HDO) values from irradiated protein protons to observed water protons became greatly reduced, with the strongest effect being on T IS (HDO), in the solution → gel transition of bovine serum albumin (BSA) in D 2 O. [11][12][13][14] We also found that T IS (H 2 O) values for tissues exhibit significant changes with pathophysiological states of living tissues.…”