Clinical translation of ferumoxytol-based vessel size imaging (VSI): Feasibility in a phase I oncology clinical trial population

PurposeTo assess the feasibility of acquiring vessel size imaging (VSI) metrics using ferumoxytol injections and stock pulse sequences in a multicenter Phase I trial of a novel therapy in patients with advanced metastatic disease. MethodsScans were acquired before, immediately after, and 48h after injection, at screening and after 2 weeks of treatment. R-2, , vessel density (Q), and relative vascular volume fractions (VVF) were estimated in both normal tissue and tumor, and compared with model-derived theoretical and experimental estimates based on preclinical murine xenograft data. Results R-2 and relaxation rates were still significantly elevated in tumors and liver 48h after ferumoxytol injection; liver values returned to baseline by week 2. Q was relatively insensitive to changes in , indicating lack of dependence on contrast agent concentration. Variability in Q was higher among human tumors compared with xenografts and was mostly driven by R-2. Relative VVFs were higher in human tumors compared with xenografts, while values in muscle were similar between species. ConclusionClinical ferumoxytol-based VSI is feasible using standard MRI techniques in a multicenter study of patients with lesions outside of the brain. Ferumoxytol accumulation in the liver does not preclude measurement of VSI parameters in liver metastases. Magn Reson Med 77:814-825, 2017. (c) 2016 International Society for Magnetic Resonance in Medicine