Ultrasmall superparamagnetic iron oxide nanoparticle uptake as noninvasive marker of aortic wall inflammation on MRI: proof of concept study

Objective: Radiation therapy for cancer can lead to atherosclerosis by inducing inflammatory changes in the vascular wall. It is difficult to quantitatively measure inflammation on CT and MRI studies. The purpose of this study was to assess the use of ferumoxytol, an ultrasmall superparamagnetic iron oxide nanoparticle, as a noninvasive marker of vessel wall inflammation secondary to radiation therapy in pancreatic cancer patients in comparison with healthy volunteers. Methods: MRI of upper abdomen (T1, T2, multi echo T2* weighted imaging) was performed on 3 T magnet before and 48 h after intravenous administration of ferumoxytol in pancreatic cancer patients who underwent radiation therapy (n = 8) and in healthy volunteers (n = 8). R2* value was obtained by drawing regions of interest outlining the aortic wall directly on the T2* medic image and subsequently transposed to the R2* image using Amira software (v. 5.3.2, FEI, Bordeaux, France). The change in R2* values was analyzed by student’s t-test. Results: The average change in R2* value of the pancreatic cancer patients was determined to be 216.1 ms−1. The average change R2* value of the control patients was determined to be 54.6 ms−1. Thus, pancreatic cancer patients following radiation therapy had a greater uptake of ferumoxytol (p = 0.0082) in their aortic wall as compared to healthy controls. Conclusion: This proof of concept study suggests that greater uptake of ferumoxytol in the aortic wall in cancer patients without visible atherosclerosis may be the expression of increased inflammation. Advances in knowledge: Ultrasmall superparamagnetic iron oxide enhanced MRI can offer an imaging biomarker for quantitative estimation of aortic inflammation preceding atherosclerosis.