Published in:
01-07-2009 | Diagnostic Neuroradiology
Temporal dependence of in vivo USPIO-enhanced MRI signal changes in human carotid atheromatous plaques
Authors:
T. Y. Tang, A. J. Patterson, S. R. Miller, M. J. Graves, S. P. S. Howarth, J. M. U-King-Im, Z. Y. Li, U. Sadat, V. E. Young, S. R. Walsh, J. R. Boyle, M. E. Gaunt, J. H. Gillard
Published in:
Neuroradiology
|
Issue 7/2009
Login to get access
Abstract
Introduction
Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced MRI has been shown to be a useful modality to image activated macrophages in vivo, which are principally responsible for plaque inflammation. This study determined the optimum imaging time-window to detect maximal signal change post-USPIO infusion using T1-weighted (T1w), T2*-weighted (T2*w) and quantitative T2* (qT2*) imaging.
Methods
Six patients with an asymptomatic carotid stenosis underwent high resolution T1w, T2*w and qT2* MR imaging of their carotid arteries at 1.5 T. Imaging was performed before and at 24, 36, 48, 72 and 96 h after USPIO (Sinerem™, Guerbet, France) infusion. Each slice showing atherosclerotic plaque was manually segmented into quadrants and signal changes in each quadrant were fitted to an exponential power function to model the optimum time for post-infusion imaging.
Results
The power function determining the mean time to convergence for all patients was 46, 41 and 39 h for the T1w, T2*w and qT2* sequences, respectively. When modelling each patient individually, 90% of the maximum signal intensity change was observed at 36 h for three, four and six patients on T1w, T2*w and qT2*, respectively. The rates of signal change decrease after this period but signal change was still evident up to 96 h.
Conclusion
This study showed that a suitable imaging window for T1w, T2*w and qT2* signal changes post-USPIO infusion was between 36 and 48 h. Logistically, this would be convenient in bringing patients back for one post-contrast MRI, but validation is required in a larger cohort of patients.