Synergistic enhancement of iron oxide nanoparticle and gadolinium for dual-contrast MRI.
OBJECTIVE
The use of MR contrast agents allows accurate diagnosis by exerting an influence on the longitudinal (T(1)) or transverse (T(2)) relaxation time of the surrounding tissue. In this study, we combined the use of iron oxide (IO) particles and nonspecific extracellular gadolinium chelate (Gd) in order to further improve the sensitivity and specificity of lesion detection.


METHODS
With a 7-Tesla scanner, pre-contrasted, IO-enhanced and dual contrast agent enhanced MRIs were performed in phantom, normal animals, and animal models of lymph node tumor metastases and orthotopic brain tumor. For the dual-contrast (DC) MRI, we focused on the evaluation of T(2) weighted DC MRI with IO administered first, then followed by the injection of a bolus of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA).


RESULTS
Based on the C/N ratios and MRI relaxometry, the synergistic effect of coordinated administration of Gd-DTPA and IO was observed and confirmed in phantom, normal liver and tumor models. At 30 min after administration of Feridex, Gd-DTPA further decreased T(2) relaxation in liver immediately after the injection. Additional administration of Gd-DTPA also immediately increased the signal contrast between tumor and brain parenchyma and maximized the C/N ratio to -4.12±0.71. Dual contrast MRI also enhanced the delineation of tumor borders and small lesions.


CONCLUSIONS
DC-MRI will be helpful to improve diagnostic accuracy and decrease the threshold size for lesion detection.
Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health (NIH), Bethesda, MD 20892, USA.
Fan
F
Zhang
Xinglu
X
Huang
Chunqi
C
Qian
Lei
L
Zhu
Naoki
N
Hida
Gang
G
Niu
Xiaoyuan
X
Chen
D000818:Animals; D001932:Brain Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D003287:Contrast Media; D005260:Female; D005290:Ferric Compounds; D019786:Gadolinium DTPA; D008099:Liver / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D051379:Mice; D008807:Mice, Inbred BALB C; D019047:Phantoms, Imaging
D003287:Contrast Media; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; C000499:ferric oxide; D019786:Gadolinium DTPA