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Updated: Aug 14, 2026
Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring
Published on: December 9, 2010
Gradient echo acquisition for superparamagnetic particles with positive contrast (GRASP): sequence characterization
Venkatesh Mani1, Karen C Briley-Saebo, Vitalii V Itskovich
1Imaging Science Laboratories, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
Abstract:
Iron oxides are used for cell trafficking and identification of macrophages in plaque using MRI. Due to the negative contrast, differentiation between signal loss caused by iron and native low signal in tissue may be problematic. It is, therefore, preferable to achieve positive contrast. The purpose of this study was to test the efficacy of a new MRI sequence GRASP (GRe Acquisition for Superparamagnetic Particles) to generate a positive signal in phantoms containing iron. Membrane phantoms were constructed containing Ferumoxide at 7 concentrations. Standard GRE sequences were modified with user controlled z-gradient rephasing (+/- 100%). CNR values were determined as a function of echo time (TE) and % rephasing at 1.5T and 3T. T(2)* values were determined using multiple double-echo GRE. The GRASP sequence generated positive signal enhancement in phantoms containing iron. For all rephasing values
