Characterizing Breast Cancer Mouse Xenografts with T1ρ-MRI
Previously three imaging methods, dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), T1ρ -MRI, and low temperatureNADH/Fp (reduced nicotinamide adenine dinucleotide/oxidized flavoprotein) fluorescence imaging (redox scanning)were reported to differentiate themouse xenografts of a lessmetastatic human melanoma cell line A375P and a more metastatic line C8161. The more metastaticmelanoma is characterized by less blood perfusion/permeability andmore oxidized mitochondrial redox state in the tumor core and lower T1ρ relaxation time averaged across the tumor section. These featuresmay be useful for identifying imaging biomarkers for cancer metastatic potential. Here, we have employed T1ρ - and T2-weightedMRI to image mouse xenografts of two human breast cancer lines (more metastatic MDA-MB-231 and less metastatic MDA-MB-468) on a vertical bore 9.4- T Varian MR system. The preliminary results indicated that the more metastatic MDA-MB-231 tumors had shorter Txρ relaxation constants on average than the less metastaticMDA-MB-468 tumors, and Txρ relaxationmight be a potential biomarker of breast tumor metastatic potential. Distinct ring-like structures were observed on Txρ -weightedMR images of the breast tumors, indicating tumor core and rim difference. This observation appears to be consistent with the tumor core-rim difference previously observed by DCE-MRI and redox scanning on aggressive melanoma xenografts.
KeywordsMouse Xenograft Dynamic Contrast Enhance Magnetic Resonance Imaging Relaxation Constant Relaxation Time Constant Tumor Core
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