**9.5 Radiological parameters**

Functional clinical imaging, taking into account tumour vasculature or metabolic activity by utilising CT, MRI or PET scanning, either prior to commencing treatment or following brief exposure of patients to therapy, may be a useful tool for predicting response or resistance to anti-angiogenic therapy [102]. For conventional cytotoxic chemotherapy, imaging has been employed to assess therapy response based on change in tumour size, as defined by RECIST (Response Evaluation Criteria In Solid Tumours). However, biological agents, such as bevacizumab and TKIs, may be cytostatic in terms of their mechanism of action, thus size may not be the only parameter that needs to be considered when assessing response and outcome. Examination of various parameters such as blood flow and tumour morphology may provide additional important predictive information.
