The use of contrast agents with fast field-cycling magnetic resonance imaging

Abstract

Fast field-cycling (FFC) MRI allows switching of the magnetic field during an imaging scan. FFC-MRI takes advantage of the T(1) dispersion properties of contrast agents to improve contrast, thus enabling more sensitive detection of the agent. A new contrast agent designed specifically for use with FFC was imaged using both a homebuilt FFC-MRI system and a 3 T Philips clinical MRI scanner. T(1) dispersion curves were obtained using a commercial relaxometer which showed large changes in relaxation rate between fields. A model of magnetization behaviour was used to predict optimum evolution times for the maximum T(1) contrast between samples at each field. Images were processed and analysed to create maps of R(1) values using a set of images at each field. The R(1) maps produced at two different fields were then subtracted from each other in order to create a map of ΔR(1) in which pixel values depend on the change in R(1) of the sample between the two fields. The dispersion properties of the agent resulted in higher contrast in a ΔR(1) image compared with a standard T(1)-weighted image.

Nuclear Magnetic Resonance with Fast Field-Cycling Setup: A Valid Tool for Soil Quality Investigation

“…FFC NMR relaxometry versatility makes the technique quite useful in many fields. As an example, it has been applied to monitor food quality [25,26], traceability [27][28][29], conservation [30], and transformation [31][32][33][34][35][36][37]; to evaluate the physical chemical characteristics of systems useful for drug delivery [38]; to design new contrast agents to be used in diagnostic imaging techniques [39][40][41]; to explore tumor development [42]; to monitor environmental quality [18,43,44], and many other different applications that can be found elsewhere [45,46]. The present review paper is intended to explore the suitability in soil science of FFC NMR relaxometry.…”

Transient versus Static Electron Spin Relaxation in Mn2+ Complexes Relevant as MRI Contrast Agents

“…9 Besides, the toxicity associated with the administration of some CAs based on Gd 3+ 10,11 has triggered a renewed interest in Mn 2+ agents. [12][13][14][15] Furthermore, the recent development of fast field-cycling MRI scanners has made it possible to improve image contrast by taking advantage of the high values and rapid variation of the relaxivity of Mn 2+ complexes below 0.5 T. 16 Scheme 1. Ligands Discussed in the Present Work.…”

Improved Contrast in Ultra-Low-Field MRI with Time-Dependent Bipolar Prepolarizing Fields: Theory and NMR Demonstrations

“…[12], Lee et al further generalized this approach. On the other hand, injection of contrast agents that exhibit T 1 dispersions has also been demonstrated to be suitable to enhance image contrast in prepolarized [13] or fast fieldcycling MRI [14]. Also nitrogen dips, which occur in the T 1 dispersion curves of tissues containing protein, have been demonstrated to offer means to improve image contrast in prepolarized MRI [15].…”