Csanad Gyorgy Varallyay MD, PhD, Presenter: Nothing to Disclose

Rochelle Fu, Abstract Co-Author: Nothing to Disclose

Joao Prola Netto MD, Abstract Co-Author: Nothing to Disclose

Bronwyn Elizabeth Hamilton MD, Abstract Co-Author: Nothing to Disclose

Edward Neuwelt MD, Abstract Co-Author: Nothing to Disclose

Contrast enhancement in central nervous system (CNS) MR imaging using gadolinium contrast agents visualizes the intravascular compartment and the disrupted blood brain barrier at the same time. Ferumoxytol is beneficial to assess vasculature early after injection, and the parenchymal enhancement peaks around 24h later. As shown previously, high resolution steady state cerebral blood volume (CBV) maps are feasible with ferumoxytol, and the late enhancement may improve the differential diagnosis. This study aimed to further explore the benefits of ferumoxytol MRI of brain tumors.

52 MRI studies of 21 patients with primary malignant brain tumors were analyzed to compare vascular visualization and parenchymal enhancement between ferumoxytol and gadoteridol. Each MR study included three days of MR imaging using gadoteridol on day1, 510mg or 2mg/kg iv. ferumoxytol on day2, and on day3 24h post ferumoxytol. Anatomical T1, T2 and high resolution T2*-weighted images pre- and post contrast were scored by 3 radiologists using a 3 point scale for visualization criteria: #1 contrast enhancement, #2 border delineation, #3 thickness of enhancement and #4 abnormal vascularity.

With one point non inferiority margin (suggested by the FDA), ferumoxytol was non inferior to gadoteridol in criteria #1-3 at 510mg and non inferior in criteria #2 and 3 at 2mg/kg. The mean differences in visualization scores between ferumoxytol at 510mg and gadoteridol were -0.47 (95%CI -0.85, -0.08), -0.31 (95%CI,-0.76, 0.13) and -0.17 (95%CI -0.58, 0.25) in criteria #1, 2 and 3 respectively. Further, ferumoxytol is superior to gadoteridol in visualizing abnormal vasculature, with a mean score of 1.35 point higher (95% CI 0.87,1.84; P<0.0001) at 510mg and 0.57 point higher (95% CI 0.20,0.93; P=0.0003) at 2 mg/kg.

Ferumoxytol can be used as an MR contrast agent in the CNS. The improved visualization of abnormal vasculature provides additional information to gadoteridol. A multicenter phase 3 clinical trial is being designed to support FDA market approval of ferumoxytol as an MR imaging agent in CNS neoplasms.

Ferumoxytol (Feraheme, approved for iv. iron replacement) is now clinically available for off label use as an MR imaging agent, with increasing CNS and non CNS applications.

Varallyay, C, Fu, R, Prola Netto, J, Hamilton, B, Neuwelt, E, Ferumoxytol MRI Improves Vascular Visualization of Brain Tumors—Aiming for FDA Market Approval.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045805.html