SYSTEM AND METHOD FOR IMAGING MACROPHAGE ACTIVITY USING DELTA RELAXATION ENHANCED MAGNETIC RESONANCE IMAGING
A magnetic resonance imaging (MRI) system is provided for imaging immune response of soft tissue to therapy by, prior to therapy, administering a contrast agent to the soft tissue; imaging a region of interest using delta relaxation enhanced magnetic resonance (DREMR) to define a functional section; selectively sampling local cells in the functional section; conducting immuno-assay analysis on the sampled local cells; and following therapy, further imaging said region of interest using DREMR to assess immune response of said cells to therapy.
1 . A method of imaging soft tissue comprising:
administering a contrast agent comprising superparamagnetic iron oxide (SPIO) nanoparticles to soft tissue; and
imaging a region of interest associated with the soft tissue using DREMR imaging to obtain positive contrast images due to the presence of SPIO nanoparticles, possessing T 1 dispersion.
2 . The method of claim 1 , wherein the contrast agent is selected from the group consisting of ferumoxytol, ferucarbotran, ferumoxide, FeRex, and Ferumoxtran-10.
3 . The method of claim 2 , wherein an amount of contrast agent in the region of interest is determined by comparison to a reference standard having imaging properties that mimic the region of interest.
4 . The method of claim 3 , further comprising:
placing at least one reference standard in an imaging field of view prior to the imaging of the region of interest.
5 . The method of claim 2 , wherein an amount of contrast agent in the region of interest is determined by using a double inversion recovery (DIR) DREMR imaging method using the R 1 relaxivity of the contrast agent and the R 1 relaxivity of the tissue in the region of interest or by fast field-cycling relaxometric imaging.
6 . The method of claim 1 , wherein the contrast agent is ferumoxytol.
7 . The method of claim 6 , wherein the imaging comprises ultra-short time to echo (UTE) imaging sequences.
8 . The method of claim 7 , wherein said UTE imaging sequences are selected from the group consisting of fast spoiled-gradient recalled-echo or radial/spiral imaging sequences.
9 . The method of claim 7 , wherein the main field strength B 0 used in said imaging is from 0.01 T to 0.4 T or ≥1.0 T.
10 . The method of claim 6 for use in active labelling of cells, wherein the method comprises incubating cells in vitro with ferumoxytol to form incubated cells, injecting the incubated cells into a subject, and tracking the distribution of the incubated cells in vivo using the DREMR imaging.
11 . The method of claim 6 for use in passive labelling of cells, wherein the method comprises injecting ferumoxytol into a subject and tracking the distribution of ferumoxytol in vivo using the DREMR imaging.
12 . The method of claim 1 , wherein the contrast agent is ferucarbotran,
13 . The method of claim 12 , wherein the main field strength B 0 used in said imaging is from 0.01 T to 1.0 T.
14 . The method of claim 13 , wherein B 0 is about 0.5 T.
15 . A contrast agent selected from the group consisting of ferumoxytol, ferucarbotran, ferumoxide, FeRex, and Ferumoxtran-10 for use in generating positive contrast images using DREMR imaging due to T 1 dispersion of the contrast agent.
16 . The contrast agent of claim 15 , selected from ferumoxytol and ferucarbotran.
17 . The contrast agent of claim 15 , wherein the contrast agent is ferumoxytol.