NONINVASIVE IN-VIVO MAPPING OF TUMOR VASCULAR AND INTERSTITIAL VOLUMEFRACTIONS

Non-invasive measurement of haemodynamic parameters and imaging of neo vasculature architecture is of importance in determining tumour progno sis, in directing tissue sampling and in assessing treatment efficacy. In the current research we investigated a dual tracer nuclear magneti c resonance (NMR) technique to map the tumour vascular (VVF) and inter stitial volume fraction (IVF) noninvasively in vivo. We hypothesised t hat a NMR signal emanating after intravenous administration of a vascu lar paramagnetic probe (MPEG-PL-GdDTPA) can be maximised so that addit ional signal after administration of a second interstitial probe (GdDT PA) would only reflect the IVF but not the VVF. The method and its ass umptions were verified and experimental conditions optimised both in p hantoms and in C6 glioma bearing rats. Data derived from in vivo studi es show tumoral VVF and IVF values that are consistent with histology data and literature values; the relative ranking order of values was t umour>muscle>brain. Image maps showed intratumoral and intertumoral he terogeneity of both parameters at submillimetre pixel resolution. The method is applicable to a wide variety of tumour models and can theore tically be performed repeatedly to study tumour growth or involution d uring therapy. (C) 1998 Elsevier Science Ltd. All rights reserved.