TY - JOUR
T1 - Efficacy of positive contrast imaging techniques for molecular MRI of tumor angiogenesis
AU - Wolters, M.
AU - Oostendorp, M.
AU - Coolen, B.F.
AU - Post, M.J.
AU - Janssen, J.M.H.
AU - Strijkers, G.J.
AU - Kooi, M.E.
AU - Nicolay, K.
AU - Backes, W.H.
PY - 2012
Y1 - 2012
N2 - Superparamagnetic iron oxide particles (SPIOs) are promising contrast agents for molecular MRI. To improve the in vivo detection of iron-based contrast media, positive contrast imaging techniques have been developed. Here, the efficacy of two positive contrast techniques, white marker and susceptibility gradient mapping (SGM), were evaluated for molecular MRI of tumor angiogenesis and compared with conventional negative contrast gradient echo (GE) imaging. In vitro, cylindrical phantoms containing varying iron oxide concentrations were used to measure the response of positive contrast techniques. In vivo, tumor bearing mice were used as a model for tumor angiogenesis. Mice were injected with unlabeled SPIOs (n¿=¿5) or SPIOs labeled with cyclic NGR peptide (cNGR) (n¿=¿5), which homes specifically to angiogenic microvessels. Pre- and post-contrast GE and white marker images were acquired. Subsequently, SGM images and R2* maps were calculated. For image analysis, the contrast-to-noise ratio (CNR) and the percentage of enhanced voxels (EVs) in the tumor rim and core were calculated. In vitro, the linear increases in MRI signal response for increasing iron oxide concentration were much stronger for SGM than white marker. In vivo, the CNR of GE, white marker and SGM imaging was 5.7, 1.2 and 6.2, respectively, with equal acquisition times. Significant differences in the percentage of EVs between the tumor rim and core were found using R2* mapping, GE and SGM (p¿
AB - Superparamagnetic iron oxide particles (SPIOs) are promising contrast agents for molecular MRI. To improve the in vivo detection of iron-based contrast media, positive contrast imaging techniques have been developed. Here, the efficacy of two positive contrast techniques, white marker and susceptibility gradient mapping (SGM), were evaluated for molecular MRI of tumor angiogenesis and compared with conventional negative contrast gradient echo (GE) imaging. In vitro, cylindrical phantoms containing varying iron oxide concentrations were used to measure the response of positive contrast techniques. In vivo, tumor bearing mice were used as a model for tumor angiogenesis. Mice were injected with unlabeled SPIOs (n¿=¿5) or SPIOs labeled with cyclic NGR peptide (cNGR) (n¿=¿5), which homes specifically to angiogenic microvessels. Pre- and post-contrast GE and white marker images were acquired. Subsequently, SGM images and R2* maps were calculated. For image analysis, the contrast-to-noise ratio (CNR) and the percentage of enhanced voxels (EVs) in the tumor rim and core were calculated. In vitro, the linear increases in MRI signal response for increasing iron oxide concentration were much stronger for SGM than white marker. In vivo, the CNR of GE, white marker and SGM imaging was 5.7, 1.2 and 6.2, respectively, with equal acquisition times. Significant differences in the percentage of EVs between the tumor rim and core were found using R2* mapping, GE and SGM (p¿
U2 - 10.1002/cmmi.471
DO - 10.1002/cmmi.471
M3 - Article
C2 - 22434625
SN - 1555-4309
VL - 7
SP - 130
EP - 139
JO - Contrast Media and Molecular Imaging
JF - Contrast Media and Molecular Imaging
IS - 2
ER -