Quantification and localization of contrast agents using delta relaxation enhanced magnetic resonance at 1.5 T.

OBJECT: Delta relaxation enhanced magnetic resonance (dreMR) is a new imaging technique based on the idea of cycling the magnetic field B (0) during an imaging sequence. The method determines the field dependency of the relaxation rate (relaxation dispersion dR (1)/dB). This quantity is of particular interest in contrast agent imaging because the parameter can be used to determine contrast agent concentrations and increases the ability to localize the contrast agent.
MATERIALS AND METHODS: In this paper dreMR imaging was implemented on a clinical 1.5 T MR scanner combining conventional MR imaging with fast field-cycling. Two improvements to dreMR theory are presented describing the quantification of contrast agent concentrations from dreMR data and a correction for field-cycling with finite ramp times.
RESULTS: Experiments demonstrate the use of the extended theory and show the measurement of contrast agent concentrations with the dreMR method. A second experiment performs localization of a contrast agent with a significant improvement in comparison to conventional imaging.
CONCLUSION: dreMR imaging has been extended by a method to quantify contrast agent concentrations and improved for field-cycling with finite ramp times. Robust localization of contrast agents using dreMR imaging has been performed in a sample where conventional imaging delivers inconclusive results.