EARLY DETECTION OF TREATMENT RESPONSE BY DIFFUSION-WEIGHTED H-1-NMR SPECTROSCOPY IN A MURINE TUMOR IN-VIVO

Nuclear magnetic resonance (NMR) non-invasively measures the apparent diffusion coefficient (ADC) of water, which is sensitive to the biophy sical characteristics of tissue. Because anti-cancer treatment alters tumour pathophysiology, tumour ADC may be altered by treatment. In ord er to test this hypothesis, ADC was measured in s.c. implanted murine RIF-I rumours before and up to 9 days after treatment with cyclophosph amide. A dose-dependent, reversible increase in tumour ADC was observe d after cyclophosphamide treatment, which is consistent with an increa se in the fraction of interstitial water due to treatment-induced cell death. Because tumour water ADC is increased substantially at a lime when there is no change in tumour volume for a dose which produces min imal cell kill, its measurement could provide a novel means for early detection of response to anti-cancer therapy. If The changes in ADC ob served in the present study are evident for commonly used anti-cancer therapies in different tumour types and specific to a therapeutic resp onse, this approach could be broadly applicable as a response predicto r since magnetic resonance imaging can be used to measure ADC in human tumours.