title: Simultaneous dynamic T1 and T2* measurement for AIF assessment combined with DCE MRI in a mouse tumor model.
abstract: A double-delay SR-MGE-SNAP sequence allowing simultaneous T1 and T2* measurement was developed for integrating arterial input function (AIF) measurement into DCE MRI. Implemented on a 4.7-T animal MR system, this technique was applied to mice with colorectal tumor xenografts. AIF, measured in the mouse heart, was modeled by a bi-exponential function, whereas tumor K(trans) and v(e) parameter maps were obtained from analysis with a two- compartment model using an individually measured AIF. AIF analysis of T2*-corrected data yielded A1 = 9.2 +/- 4.3 kg/l, A(2) = 4.2 +/- 0.8 kg/l, m1 = 2.3 +/- 1.1 min(-1), and m2 = 0.05 +/- 0.02 min(-1). The mean initial plasma concentration C ( p )(t = 0) = 8.0 +/- 2.7 mM was compatible with estimated 8.6 mM. Without T2*-correction distribution phase parameters A1, m1, and C(p)(t = 0) were underestimated. In tumors, neglect of T2* effects yielded mean K(trans) values which were reduced by 14% (P < 0.05), whereas v(e) showed only a slight non-significant reduction. Simultaneous measurement of DeltaR1 and DeltaR2* studied in highly and poorly vascularized and (pre-)necrotic tumor regions revealed complementary behavior of both parameters with respect to vascular properties. In conclusion, the presented measurement technique is a promising tool for dynamic MRI applications studied in animal models at high field strengths and/or with CA of high relaxivities, as it combines classical DCE MRI integrating AIF assessment with dynamic T2* measurement.
authors.affiliation: U759 INSERM, Centre Universitaire, Bâtiment 112, 91405, Orsay, France. melanie.heilmann@curie.u-psud.fr
authors.forename: Melanie
authors.initials: M
authors.lastname: Heilmann
authors.forename: Christine
authors.initials: C
authors.lastname: Walczak
authors.forename: Julien
authors.initials: J
authors.lastname: Vautier
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Dimicoli
authors.forename: Carole D
authors.initials: CD
authors.lastname: Thomas
authors.forename: Mihaela
authors.initials: M
authors.lastname: Lupu
authors.forename: Joël
authors.initials: J
authors.lastname: Mispelter
authors.forename: Andreas
authors.initials: A
authors.lastname: Volk
mesh_terms: D000818:Animals; D015179:Colorectal Neoplasms / Q000473:pathology*; D004195:Disease Models, Animal; D006321:Heart / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D009206:Myocardium / Q000473:pathology; D009336:Necrosis