CPMG-methods: Quantitative T2 Methods
In dcemriS4: A Package for Image Analysis of DCE-MRI (S4 Implementation)

Description Usage Arguments Value Author(s) References See Also

The regional blood volume is found by integrating of the tissue concentration curve and the artieral input funciton (AIF). In order to avoid reperfusion effects on the rCBV measurements, the tissue and arteiral concentration curves must first be reduced to their first-pass versions.

T2.fast(cpmg, ...)

## S4 method for signature 'array'
T2.fast(cpmg, cpmg.mask, TE,
  control = minpack.lm::nls.lm.control(maxiter = 150), multicore = FALSE,
  verbose = FALSE)

T2.lm(signal, TE, guess, control = minpack.lm::nls.lm.control())

`cpmg`	is a multidimensional array of signal intensities. The last dimension is assumed to be a function of the echo times, while the previous dimenions are assued to be spatial.
`...`	Additional variables defined by the method.
`cpmg.mask`	is a (logical) multidimensional array that identifies the voxels to be analyzed.
`TE`	is the vector of echo times (in seconds).
`control`	An optional list of control settings for `nls.lm`. See `nls.lm.control` for the names of the settable control values and their effect.
`multicore`	is a logical variable (default = `FALSE`) that allows parallel processing via multicore.
`verbose`	is a logical variable (default = `FALSE`) that allows text-based feedback during execution of the function.
`signal`	is the vector of signal intensities as a function of echo times.
`guess`	is the vector of initial values for the parameters of interest: rho and T2.

A list structure is produced with (all or some of the) parameter estimates

`rho`	Scaling factor between signal intensity and T2 (proton density).
`T2`	T2 relaxation time.

Brandon Whitcher bwhitcher@gmail.com

Kennan, R.P. and J\"ager, H.R. (2004) $T_2$- and $T_2^*$-w DCE-MRI: Blood Perfusion and Volume Estimation using Bolus Tracking, in Quantiative MRI of the Brain (P. Tofts ed.), Wiley: Chichester, UK, pp. 365-412.

R1.fast, R10.lm

dcemriS4 documentation built on May 1, 2019, 9:23 p.m.