TABLE 2

FROM:

Model selection in magnetic resonance imaging measurements of vascular permeability: Gadomer in a 9L model of rat cerebral tumor

James R Ewing, Stephen L Brown, Mei Lu, Swayamprava Panda, Guangliang Ding, Robert A Knight, Yue Cao, Quan Jiang, Tavarekere N Nagaraja, Jamie L Churchman and Joseph D Fenstermacher

Table 2. Symbols, with units of measure

Symbol	Use (units)
C p(t)	Plasma concentration as a function of time (mL tracer/mL plasma)
C R	Relaxivity of the contrast agent in units of (ms-1 per unit concentration)
C t(t)	Tissue concentration as a function of time (mL tracer/mL tissue)
Hct	Hematocrit as a fraction of blood volume (mL erythrocytes/mL blood)
k b	Transvascular unidirectional (inward) transfer constant (min-1)
K i	Transvascular unidirectional (outward) transfer constant (min-1)
R 1a, R 1p	Arterial, erythrocyte, and plasma (respectively) longitudinal relaxation rates (ms-1)
R 1a, R 1t	The change, due to the injection of contrast agent, in the arterial (subscript a) and tissue (subscript t) longitudinal relaxation rates (ms-1)
R 1tiss, R 1	Tissue, cellular, and extravascular extracellular (respectively) longitudinal relaxation rates (ms-1)
S e, S p, S f	Summed-squared residuals between the model and the data: extra, partial, and full, respectively
t	Time (min)
(Greek tau)	Dummy variable of integration of time-varying quantities
d	Fractional volume of rapidly equilibrating reversible space (mL/mL tissue)
a	Fractional volume of plasma (mL/mL tissue)
D=v d+v a	Combined fractional volume of plasma and rapidly equilibrating non-plasma spaces (mL/mL tissue)
v e	Extravascular, extracellular volume fraction (mL EES/mL tissue)
V D'	The y-axis intercept of the linear portion of the Patlak plot in the event that an initial portion of the arterial input function is not measured
e, p, f (Greek nu)	Degrees of freedom for extra, partial, and full summed-squares
(1-Hct)R 1tiss(t)/R 1a(t)	Patlak plot ordinate
	Patlak plot abscissa
	Efflux-corrected Patlak plot abscissa