The tumor microenvironment and its assessment with DCE-MRI and DW-MRI

Abnormal characteristics of the tumor microenvironment, such as hypoxia, high fluid pressure, and a dense extracellular matrix, significantly influence cancer progression and therapeutic response. Hence, to provide each patient with the optimal treatment, methods to non-invasively characterize the tumor microenvironment are needed. The current work explored the potential of two functional MRI methods – DCE-MRI and DW-MRI – to assess the microenvironment in solid tumors. In both cervical and pancreatic tumor xenografts, the DCE-MRI parameter Ktrans was strongly related to the fraction of hypoxic tissue. Moreover, the parameter ADC – derived from DW-MR images – was sensitive to the amount of extracellular collagen in cervical cancer xenografts. Therapy to modify the tumor vasculature has been proposed as a means to increase the supply of oxygen to tumors and enhance the effect of other cancer therapies. However, the present work demonstrates that so-called antiangiogenic therapy may increase the amount of hypoxia in cervical and pancreatic tumor xenografts. It was further revealed that DCE-MRI is a promising method to monitor the effect of antiangiogenic therapy on tumor oxygenation