Parametric imaging of tumor perfusion using flow- and permeability-limited tracers

Abstract

Purpose: To quantitatively evaluate the spatial distribution of flow- and permeability-limited perfusion in MCF7 human breast cancer tumors orthotopically implanted in CD1-NU mice. Materials and Methods: Flow-limited perfusion was derived from 2H-MRI recorded before and after infusion of deuterated water. Permeability-limited perfusion was evaluated from GdDTPA-enhanced 1H-MRI. Results: The dominant processes in tumor perfusion, namely blood flow and capillary permeability, were mapped in orthotopically implanted MCF7 human breast cancer tumors. The dynamic data were processed according to physiological models, yielding parametric maps of intravascular volume fraction, water perfusion rate, GdDTPA permeability rate constant, and extracellular volume fraction accessible to GdDTPA. The maps exhibited the heterogeneous distribution of each perfusion parameter. Most of the tumor tissue (≥95%) was perfused with HDO, while Gd-DTPA was perfused in only about 50% of it. In most loci the perfusion rate was limited by capillary permeability to Gd-DTPA. Conclusion: The results demonstrated the instructive value of tracers with different properties used in conjunction to achieve a deeper understanding of tumor perfusion capacity. This study offers tools for the accurate, noninvasive evaluation of drug delivery efficacy. © 2002 Wiley-Liss, Inc.