The Multilinear Reference Tissue Model

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Description

The multilinear reference tissue model (MRTM) estimates the binding potential from an observed time activity curve without the need for arterial sampling. Instead, a second time activity curve must be provided from a suitable reference region where there is negligible binding.

Usage

1
multilinearReferenceTissueModel(tac, ref, time, tstar, MRTM2 = TRUE, k2prime = NULL)

Arguments

tac

a vector corresponding to the time activity curve from the tissue (in Bq/mL).

ref

a vector corresponding to the time activity curve from the reference region (in Bq/mL).

time

a vector of average frame times (in minutes).

tstar

the time (in minutes) where the linear relationship between the response and covariates may be assumed to be true.

MRTM2

a logical value that selects the three-parameter model (MRTM) or the two-parameter model (MRTM2), where k2prime is fixed.

k2prime

the value of k2prime that has been fixed.

Details

See the references.

The numeric integration required to construct the design matrix is performed by interpolating the time activity curves, both for the tissue and reference region, to one-second resolution and then performing the cumsum operation on them.

Given the nonlinear relationship between binding potential and the regression parameters, the deltamethod is used to approximate its standard error.

Value

BP

Binding potential

BP.error

Approximate standard error of the binding potential

R1

Ratio of the volumes of distrubution for the tissue and reference region (assumes a one-tissue model is valid)

R1.error

Approximate standard error for the ratio

k2

Clearance rate constant from the tissue to plasma (assumes a one-tissue model is valid)

k2.error

Approximate standard error for k2

X

Design matrix used in the linear regression

beta

Regression coefficients

Author(s)

Brandon Whitcher bwhitcher@gmail.com

References

Ichise, M., Ballinger, J.R., Golan, H., Vines, D., Luong, A., Tsai, S. and Kung, H.F. (1996) Noninvasive quantification of dopamine D2 receptors with iodine-123-IBF SPECT, Journal of Nuclear Medicine, 37, 513-520.

Ichise, M., Liow, J.-S., Lu, J.-Q., Takano, A., Model, K., Toyama, H., Suhara, T., Suzuki, K., Innis, R.B., Carson, R.E. (2003) Linearized reference tissue parametric imaging methods: Application to [11C]DASB positron emission tomography studies of the serotonin transporter in human brain, Journal of Cerebral Blood Flow \& Metabolism, 23, 1096-1112.

See Also

cumsum, deltamethod