Early detection of metastases can greatly impact the prognosis and treatment of cancer. A recent study conducted at Radboud university medical center shows that, using a powerful MRI scanner and a new contrast agent, lymph node metastases of prostate cancer can be detected at an earlier stage.
It is important to know if cancer has metastasized as it determines the patient's prognosis and treatment. The new approach used in the study, visualizes very small metastases in lymph nodes of patients with prostate cancer, allowing for earlier detection of metastatic prostate cancer. The study was conducted on twenty patients and led by Tom Scheenen, Professor of Biomedical Magnetic Resonance at Radboudumc.
Imaging one-millimeter metastases
Scheenen explains the new approach: ‘For the first time, we have combined two recently developed techniques: an MRI scan of the lower abdomen using a scanner with a magnetic field strength of seven Tesla and the use of magnetic iron oxide nanoparticles as a contrast agent. The high field strength – normal clinical scanners use one and a half or three Tesla - allows for much sharper MRI images. The iron oxide particles accumulate in normal healthy lymph nodes, reducing their MRI signal. In nodes with metastases, this accumulation does not occur, so the MRI signal remains strong. This allows us to distinguish lymph nodes suspected of having metastases from normal nodes. Using this combination of the contrast agent and the powerful scanner, we can detect metastases as small as one millimeter in size. None of other currently available techniques can do this, the minimum size they can typically detect is five millimeters.’
The study was conducted in cooperation with the University of Duisburg-Essen, where the advanced scanner is located at the Erwin L. Hahn institute for MRI. This scanner is typically used to scan the head and limbs. Scanning the lower abdomen, where the prostate and surrounding lymph nodes are located, was technically challenging. Scheenen states: ‘We solved all technical issues together with our German colleagues. The contrast agent is also unique. It is not yet approved for routine clinical diagnosis, but we can already use it in specific patients in research settings.’
Early detection and personalized irradiation
What does this mean for patients? ‘We can give these men more clarity about their disease course and provide earlier and more targeted treatment," says radiologist Ansje Fortuin, the first author of the publication. "In case of metastatic cancer, treatment by surgical removal of the prostate is not sufficient and radiation therapy might be the better option. Using the powerful MRI scanner and the iron oxide contrast agent allows for early detection of small lymph node metastases and their exact location. Radiotherapists use this information in their radiation treatment plan. They subsequently perform highly focused irradiation of the prostate and the metastatic nodes, providing optimized personalized treatment for the individual patient.’ In the future, this new approach may also be applicable to other types of cancer. Studies are already underway on esophageal, pancreatic and head/neck tumors.
About the publication
This study was published in European Urology: Small suspicious lymph nodes detected on ultrahigh-field Magnetic Resonance Imaging (MRI) in patients with prostate cancer with high risk of nodal metastases: the first in-patient study on Ultrasmall Superparamagnetic Iron Oxide-enhanced 7T MRI. A. Fortuin, J. van Asten, A. Veltien, B. Philips, T. Hambrock, S. Johst, S. Orzada, B. Hadaschik, H. Quick, J. Barentsz, M. Maas, T. Scheenen. DOI: 10.1016/j.eururo.2023.01.002.
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