. Author manuscript; available in PMC: 2009 Sep 23.

Published in final edited form as: Proc IEEE Inst Electr Electron Eng. 2005 Apr 1;93(4):784–799. doi: 10.1109/JPROC.2005.844266

Table 1.

Summary of Vascular Parameters Derived From MRI of Different CAs, the Assumptions Made in the Derivations, and the Accompanying Limitations. Symbols and the Corresponding Parameters Are Listed in Table 2

T₁ CONTRAST AGENTS
Contrast Agent	Size	Extractable Vascular Parameters	Modeling Assumptions/Caveats
GdDTPA	≈550-600 Da	K^trans, k_ep, v_e [41, 131]	In general K^trans=FE=F(1-e^-PS/F)
			If PS»F, extraction is complete i.e. E=1 ⇒ K^trans≈ F
			If PS«F, E ≈ PS/F ⇒ K^trans≈ PS
		v_b, F	If E and mean transit time (MTT) can be estimated.
		λ	If tissue density (ρ) is known.
Gadomer-17	≈17kDa	v_b, K^trans [132]	PS-limited regime and the larger molecular weight of the CA must be taken into account, i.e. PS«F and K^trans ≈ PS
Albumin-GdDTPA	≈80 kDa	Same as above [56]	Primarily an intravascular tracer and K^trans ≈ ps as above
Antibody-conjugated Gd Liposomes	≈MDa	Receptor density on the luminal surface and turnover [11]	Requires high local concentration of the CA at target sites and high labeling efficiency of CA. Delivery to extravascular targets is challenging.
T₂ CONTRAST AGENTS
Contrast Agent	Size	Extractable Vascular Parameters	Modeling Caveats/Remarks
Gd-DTPA	≈500-600 Da	rCBV, rCBF, Time-to-peak, FWHM[133]	Using first-pass tracer kinetics and elimination of recirculation effects.
		≈MTT[134]	This is not the true first moment of the MRI concentration-time curve.
		Permeability or leakage [50]	Requires leakage correction for T1 enhancement due to extravasated CA.
		F[135]	Requires knowledge of the arterial input function to deconvolve the measured concentration-time curve.
		Vessel size index [50]	Requires simultaneous gradient- and spin-echo MRI.
MION/SPIO	≈0.775-1 MDa	rCBV, rCBF, time-to-peak, FWHM, F, Vessel size index [48]	Same as above.