MRI is a useful imaging tool in prostate cancer management. It provides excellent soft tissue contrast and multidimensional information, does not involve exposure to ionizing radiation, and is non-invasive. However, like other imaging modalities such as computed tomography (CT), transurethral ultrasound (TRUS) and nuclear imaging, MRI cannot adequately detect small tumors.
The ability to accurately detect and locate small tumors is necessary for early detection of disease and for assessment of response to therapy in cancer patients. In recent years, the use of biomarker-targeted probes linked with nanoparticle-based contrast agents to enhance these imaging modalities has been a major area of research. Iron oxide magnetic nanoparticles (MNPs) are powerful contrast agents for MRI. Their superparamagnetic properties make them effective at reducing transverse (spin-spin) T2-relaxation time, causing negative contrast in magnetic resonance (MR) images. MNP-assisted MRI has the potential to improve the assessment of cell surface receptor expression on tumors, liver function (macrophage content and activity), inflammation, degenerative diseases, angiogenesis, perfusion and apoptosis.
This project evaluates the potential ability of MNPs to enhance MRI of prostate cancer by performing MRI on on mice with pre-established orthotopic LNCaP-luc tumors and intravenously injected with either MNPs alone or J591-MNPs. MR images of tumors from mice that received the J591-MNP conjugates show significant darkening at the prostate region, at the 2- and 24-h post-injection timepoints, as shown in the above image.
These observations have major clinical implications because tumor-targeting MNPs could potentially enable the early detection of tumors confined within the prostate by MRI. Based on its biocompatibility, stability, together with its ability to enhance MRI, PSMA-targeting MNPs have promise to be translated into the clinic to improve the management of prostate cancer.
Brian Wan-Chi Tse, Gary J Cowin, Carolina Soekmadji, Lidija Jovanovic, Raja S Vasireddy, Ming-Tat Ling, Aparajita Khatri, Tianqing Liu, Benjamin Thierry & Pamela J Russell
Tse, Brian Wan-Chi, et al. “PSMA-targeting iron oxide magnetic nanoparticles enhance MRI of preclinical prostate cancer.” Nanomedicine10.3 (2015): 375-386.