Fig. 4.

63-year-old man with recurrent metastatic lung cancer within right frontal lobe. Example of time-dependent signal changes observed with ferumoxytol-enhanced MRI. Baseline unenhanced MRI (left) shows T2-hyperintense mass with susceptibility along resection cavity margin and absence of intrinsic T1 shortening. Gadolinium-based contrast agent (GBCA)-enhanced T1-weighted image (second from left) shows typical masslike enhancement consistent with recurrent disease. Early intravascular phase ferumoxytol (Fe)-enhanced imaging (second from right) performed immediately after infusion shows negligible T1 and T2 change within brain parenchyma. However, T2*/susceptibility-weighted imaging (SWI) shows marked intravascular susceptibility effect (star, second from right) within cerebral vasculature. This forms basis for steady-state cerebral blood volume map calculation (not shown). Delayed extravascular phase ferumoxytol imaging (right) shows marked T1 shortening, similar to that with GBCA. This highlights noninferiority of ferumoxytol as alternative contrast agent for detection of primary and metastatic brain parenchymal foci. T2-weighted image shows hypointensity (arrow) similar in distribution to that on T2*/SWI. Persistence of intravascular signal (star, right) in delayed phase contaminates assessment of brain parenchyma. This forms basis for segregation and extravascular localization of ferumoxytol (SELFI) map calculation (not shown).