Non-invasive in vivo mapping of tumour vascular and interstitial volume fractions

Non-invasive measurement of haemodynamic parameters and imaging of neovasculature architecture is of importance in determining tumour prognosis, in directing tissue sampling and in assessing treatment efficacy. In the current research we investigated a dual tracer nuclear magnetic resonance (NMR) technique to map the tumour vascular (VVF) and interstitial volume fraction (IVF) noninvasively in vivo. We hypothesised that a NMR signal emanating after intravenous administration of a vascular paramagnetic probe (MPEG-PL-GdDTPA) can be maximised so that additional signal after administration of a second interstitial probe (GdDTPA) would only reflect the IVF but not the VVF. The method and its assumptions were verified and experimental conditions optimised both in phantoms and in C6 glioma bearing rats. Data derived from in vivobrain. Image maps showed intratumoral and intertumoral heterogeneity of both parameters at submillimetre pixel resolution. The method is applicable to a wide variety of tumour models and can theoretically be performed repeatedly to study tumour growth or involution during therapy. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)