Dynamic T1-weighted monitoring of vascularization in XXXX carcinoma heterotransplants by magnetic resonance imaging.

@entity1 @entity39 @entity5 @entity19 @entity957 @entity7241
Studies on @entity5 angiogenesis and antiangiogenic therapies are commonly performed with @entity5 heterotransplants in @entity19 . To monitor therapeutic effects, improved noninvasive analyses of functional data are required, in addition to the assessment of @entity5 volume and histology. Here, we report on sequential monitoring of vascularization of @entity1 @entity957 growing as heterotransplants in @entity19 using MRI. Using a custom-developed animal coil in a conventional whole-body 1.5 T MRI scanner, dynamic T1w sequences were recorded after i.v. injection of @entity7241 in @entity5 grown for 17, 21, 25, 29 and 33 days. Amplitude and the exchange rate constant (k(ep)) were calculated according to a 2-compartment model, discriminating intravascular and interstitial spaces, and correlated with @entity5 size and histology. High-resolution imaging of small heterotransplants from 100 to 1,000 mm(3) was achieved, clearly discriminating @entity39 . Preceding the development of @entity39 , which were hyperintense in T2w images and confirmed with histology, a local decrease of amplitude and k(ep) values was observed. Significantly higher amplitudes were found in @entity5 periphery than in central parts, correlating well with the vascular pattern obtained by immunocytochemistry. @entity5 size correlated negatively with amplitude, probably as a result of increasing necrotic areas, whereas the reason for the observed increase of k(ep) value with @entity5 size remains unclear. These data demonstrate that dynamic MRI is an excellent method for noninvasive assessment of @entity5 vascularization in small animals using a clinical whole-body scanner with little technical modifications. This technique provides functional data characterizing essential features of @entity5 biology and is thus appropriate for monitoring antiangiogenic therapies.
