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 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())
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.
is a (logical) multidimensional array that identifies the voxels to be analyzed.
is the vector of echo times (in seconds).
An optional list of control settings for nls.lm. See
nls.lm.control for the names of the settable control values and their
effect.
is a logical variable (default = FALSE) that allows
parallel processing via multicore.
is a logical variable (default = FALSE) that allows
text-based feedback during execution of the function.
is the vector of signal intensities as a function of echo times.
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
Scaling factor between signal intensity and T2 (proton density).
T2 relaxation time.
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.