The promising but yet controversial effect of bevacizumab have been recently reported by Keunen et al.[20], whose data strongly suggest that vascular remodeling induced by anti- VEGF treatment may lead LDK378 molecular weight to a more hypoxic tumor microenvironment and, consequently,

to enhanced tumor cell invasion into the normal brain. Studies combining imaging with molecular biomarkers will probably make a substantial contribution to a better understanding of the complex cellular mechanisms by which bevacizumab temporarily corrects the abnormal vasculature of tumors [9, 19]. Anti-hypoxia inducible factor-1α (HIF−1α) have recently been shown to have a link with perfusion imaging. Yopp et al.[19] analyzed a group of patients with primary liver cancer treated with floxuridine and bevacizumab and found that reductions in tumor perfusion were greater in tumors expressing HIF−1α. To our knowledge, this is the first investigation using FK506 datasheet PCT to evaluate the response to anti-angiogenic therapies in patients with brain tumors. Data on CT perfusion, as a biomarker in oncology, for the response to therapy are to date insufficient [8], in spite of the advantage of PCT for providing

absolute perfusion data, thanks to the linear relationship between CT enhancement and contrast agent concentration compared to MR perfusion. Although the to feasibility

of PCT for routine diagnosis is mainly limited for the use of ionizing radiation, selecting a low kVp X-ray beam and optimizing the scanning protocol, i.e. image interval and scanning duration, it is possible to reduce the radiation dose to the patient to acceptable levels of total effective dose. There are some limits to our study. The 4-cm coverage of PCT in cranio-caudal direction precluded us from investigating, in some patients, the entire tumor volume and, in these cases, only the central portion of the lesion was examined. Furthermore, two different MR systems were used to evaluate the VT1 and VFLAIR changes, which represents a potential bias of the study because the magnetic field intensity affects the signal to noise ratio and may have an impact on the dimensional measurement of the VT1 and VFLAIR. However, this bias is attenuated by the fact that only relative measurements (volume variations expressed as percentages) were correlated with the different perfusion metrics, and the same MR system was used, before and at first follow-up, for the each patient. Due to the low statistical power of the analyzed patient group, a few correlations were found between the observed perfusion changes and clinical endpoints, i.e. PFS and OS (only a tendency of correlation emerged between changes in V=0 and PFS).