Quantitative dynamic contrast-enhanced MRI in tumor-bearing rats and mice with inversion recovery TrueFISP and two contrast agents at 4.7 T.
OBJECTIVE
To characterize tumor vascularization by dynamic-contrast enhanced (DCE) MRI using low and medium molecular weight paramagnetic contrast agents (CA) and inversion recovery (IR) true fast imaging with steady state precession (TrueFISP) in tumor-bearing rats and mice.


METHODS
T(1) mapping was performed using IR True FISP in phantoms and in vivo at 4.7 T and validated with a segmented IR gradient-echo (IR GE) method. CA concentration in DCE-MRI studies in vivo was calculated from time-series T(1) maps using the CAs GdDOTA and P792 (low and medium molecular weight, respectively). Standard vascular input functions (VIFs) were measured in the jugular veins and were used for modeling of the CA kinetics with a two-compartment model. In rat breast tumors, vascular permeability (transfer constant K(trans)), fractional plasma volume v(p), and fractional leakage space v(e) were quantified and parametric maps were generated.


RESULTS
The IR TrueFISP T(1) was slightly underestimated in phantoms and overestimated in vivo (10%) with respect to IR GE. VIFs showed only small interindividual variation. Mean K(trans) values were 0.062 +/- 0.017 min(-1) for GdDOTA and 0.015 +/- 0.005 min(-1) for P792 (N = 12). Mean v(e) and v(p) values were 0.15 +/- 0.04 (0.09 +/- 0.03) and 0.04 +/- 0.01 (0.03 +/- 0.01) for GdDOTA (P792).


CONCLUSIONS
DCE-MRI with IR TrueFISP provided absolute values for K(trans), v(p), and v(e). Direct comparison between GdDOTA and P792 revealed significant differences in the VIF, model-fit-quality, permeability, leakage space, and plasma volume. The larger molecular weight CA P792 appears to be better for measuring tumor vascular parameters.
Weidensteiner
Claudia
C
Novartis Institutes for BioMedical Research, Basel, Switzerland. claudia.weidensteiner@roche.com
Rausch
Martin
M
McSheehy
Paul M J
PM
Allegrini
Peter R
PR
D000818:Animals; D003287:Contrast Media / Q000494:pharmacology*; D019786:Gadolinium DTPA / Q000494:pharmacology; D006571:Heterocyclic Compounds / Q000494:pharmacology; D007700:Kinetics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015674:Mammary Neoplasms, Animal / Q000098:blood supply / Q000175:diagnosis; D051379:Mice; D008809:Mice, Inbred C3H; D008819:Mice, Nude; D015233:Models, Statistical; D009942:Organometallic Compounds / Q000494:pharmacology; D019047:Phantoms, Imaging; D051381:Rats; D013997:Time Factors
D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate; D019786:Gadolinium DTPA