TY - JOUR
T1 - Determination of the MRI contrast agent concentration time course in vivo following bolus injection
T2 - Effect of equilibrium transcytolemmal water exchange
AU - Landis, Charles S.
AU - Li, Xin
AU - Telang, Frank W.
AU - Coderre, Jeffrey A.
AU - Micca, Peggy L.
AU - Rooney, William D.
AU - Latour, Lawrence L.
AU - Vétek, Gábor
AU - Pályka, Ildikó
AU - Springer, Charles S.
PY - 2000/1/1
Y1 - 2000/1/1
N2 - For bolus-tracking studies, it is commonly assumed that CR concentration bears a linear relationship with the measured (usually longitudinal) 1H2O relaxation rate constant, R1/(*) ≡(T1/(*))-1. This requires that equilibrium transcytolemmal water exchange be in the fast exchange limit (FXL). However, though systems remain in fast exchange, the FXL will not usually obtain. Here, the consequences are considered: 1) the measurement of R1/(*) itself can be affected, 2) the resultant non-linear [CR]-dependence causes significant error by assuming FXL, 3) the thermodynamic [CR] (based on the space in which CR is actually distributed) can be determined, 4) transcytolemmal water permeability may be estimated, and 5) the pharmacokinetic parameters can be factored. For a 30-sec, 0.17 mmol/kg dose of GdDTPA2-, the FXL assumption underestimates the [CR] maximum in rat thigh muscle by a factor of almost two. Similar results are obtained for a rat brain GS-9L gliosarcoma tumor model.
AB - For bolus-tracking studies, it is commonly assumed that CR concentration bears a linear relationship with the measured (usually longitudinal) 1H2O relaxation rate constant, R1/(*) ≡(T1/(*))-1. This requires that equilibrium transcytolemmal water exchange be in the fast exchange limit (FXL). However, though systems remain in fast exchange, the FXL will not usually obtain. Here, the consequences are considered: 1) the measurement of R1/(*) itself can be affected, 2) the resultant non-linear [CR]-dependence causes significant error by assuming FXL, 3) the thermodynamic [CR] (based on the space in which CR is actually distributed) can be determined, 4) transcytolemmal water permeability may be estimated, and 5) the pharmacokinetic parameters can be factored. For a 30-sec, 0.17 mmol/kg dose of GdDTPA2-, the FXL assumption underestimates the [CR] maximum in rat thigh muscle by a factor of almost two. Similar results are obtained for a rat brain GS-9L gliosarcoma tumor model.
KW - Bolus-tracking
KW - Concentration
KW - Contrast reagent
KW - Transcytolemmal water exchange
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U2 - 10.1002/1522-2594(200010)44:4<563::aid-mrm10>3.0.co;2-%23
DO - 10.1002/1522-2594(200010)44:4<563::aid-mrm10>3.0.co;2-%23
M3 - Article
C2 - 11025512
SN - 0740-3194
VL - 44
SP - 563
EP - 574
JO - Magnetic Resonance in Medicine
JF - Magnetic Resonance in Medicine
IS - 4
ER -