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Derived Parameters
Other parameters:
• Extraction fraction (
E
): average volume of contrast media allowable in the
extravascular-extracellualr space (EES):
,
if BF>>PS (like for tumors) we can write:
, dimensionless.
• k
trans
: constant of transfer from intravascular space to EES. It is closely related to PS,
and often given instead of it, under the assumption BF>>PS.
Unit of measure
Tofts: “Modeling Tracer Kinetick in Dynamic Gd-DTPA MR Imaging”
JMRI
7(1)
, 92-101 (1997)