News | Magnetic Resonance Imaging (MRI) | May 26, 2020

New Double-contrast Technique Picks Up Small Tumors on MRI

A new technique developed by researchers at UC Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The team created a probe that generates two magnetic resonance signals that suppress each other until they reach the target, at which point they both increase contrast between the tumor and surrounding tissue

A new technique developed by researchers at UC Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The team created a probe that generates two magnetic resonance signals that suppress each other until they reach the target, at which point they both increase contrast between the tumor and surrounding tissue. Image courtesy of Xiandoing Xue, UC Davis

May 26, 2020 — Researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work was published May 25 in the journal Nature Nanotechnology.

Chemical probes that produce a signal on magnetic resonance imaging (MRI) can be used to target and image tumors. The new research is based on a phenomenon called magnetic resonance tuning that occurs between two nanoscale magnetic elements. One acts to enhance the signal, and the other quenches it. Previous studies have shown that quenching depends on the distance between the magnetic elements. This opens new possibilities for non-invasive and sensitive investigation of a variety of biological processes by MRI.

The UC Davis team created a probe that generates two magnetic resonance signals that suppress each other until they reach the target, at which point they both increase contrast between the tumor and surrounding tissue. They call this two-way magnetic resonance tuning (TMRET).

Combined with specially developed imaging analysis software, the double signal enabled researchers to pick out brain tumors in a mouse model with greatly increased sensitivity.

"It's a significant advance," said senior author Yuanpei Li, associate professor of biochemistry and molecular medicine at the UC Davis School of Medicine and Comprehensive Cancer Center. "This could help detect very small early-stage tumors."

Two magnetic components

The probe developed by the UC Davis team contains two components: nanoparticles of superparamagnetic iron oxide (SPIO), and pheophorbide a-paramagnetic manganese (P-Mn), packaged together in a lipid envelope. SPIO and P-Mn both give strong, separate signals on MRI, but as long as they are physically close together those signals tend to cancel each other out, or quench. When the particles enter tumor tissue, the fatty envelope breaks down, SPIO and P-Mn separate, and both signals appear.

Li's laboratory focuses on the chemistry of MRI probes and developed a method to process the data and reconstruct images, which they call double-contrast enhanced subtraction imaging or DESI. But for expertise in the physical mechanisms, they reached out to Professors Kai Liu and Nicholas Curro at the UC Davis Department of Physics (Liu is now at Georgetown University). The physicists helped elucidate the mechanism of the TMRET method and refine the technique.

The researchers tested the method in cultures of brain and prostate cancer cells and in mice. For most MRI probes, the signal from the tumor is up to twice as strong as from normal tissue - a "tumor to normal ratio" of 2 or less. Using the new dual-contrast nanoprobe, Li and colleagues could get a tumor-to-normal ratio as high as 10.

Li said the team is interested in translating the research into clinical use, although that will require extensive work including toxicology testing and scaling up production before they could apply for investigational new drug approval.

For more information: www.ucdavis.edu

Related Content

New Module Creates a Warped MRI Scan that Matches Real-Time Ultrasound Results (Graphic: Business Wire)

New Module Creates a Warped MRI Scan that Matches Real-Time Ultrasound Results (Graphic: Business Wire)

News | Artificial Intelligence | May 07, 2021
News | Radiation Therapy | May 06, 2021
May 6, 2021 — Individuals living with severe...
3D aMRI not only provides a stunning look inside the "beating brain", but it can also measure this physiological motion in all directions. Here, the amplitude of brain motion is overlayed for each brain slice and orientation in 3D. Image credit: 3D aMRI method outlined in Abderezaei et al. Brain Multiphysics (2021); Terem et al. Magnetic Resonance in Medicine (2021).

3D aMRI not only provides a stunning look inside the "beating brain", but it can also measure this physiological motion in all directions. Here, the amplitude of brain motion is overlayed for each brain slice and orientation in 3D. Image credit: 3D aMRI method outlined in Abderezaei et al. Brain Multiphysics (2021); Terem et al. Magnetic Resonance in Medicine (2021).

News | Magnetic Resonance Imaging (MRI) | May 06, 2021
May 6, 2021 — Magnetic Resonance Imaging
Research finds that a commonly used risk-prediction model for lung cancer does not accurately identify high-risk Black patients who could benefit from early screening

Getty Images

News | Lung Imaging | May 05, 2021
May 5, 2021 — Lung cancer is the third most common cance
After radiosurgery concurrent with nivolumab in 59-year-old patient with melanoma BM (patient 1; Supplemental Tables 3 and 5), F-18 FET PET at follow-up 12 weeks after treatment initiation (bottom row) shows significant decrease of metabolic activity (TBRmean, ?28%) compared with baseline (top row), although MRI changes were consistent with progression according to iRANO criteria. Reduction of metabolic activity was associated with stable clinical course over 10 mo. CE = contrast-enhanced. Image created by

After radiosurgery concurrent with nivolumab in 59-year-old patient with melanoma BM (patient 1; Supplemental Tables 3 and 5), F-18 FET PET at follow-up 12 weeks after treatment initiation (bottom row) shows significant decrease of metabolic activity (TBRmean, ?28%) compared with baseline (top row), although MRI changes were consistent with progression according to iRANO criteria. Reduction of metabolic activity was associated with stable clinical course over 10 mo. CE = contrast-enhanced. Image created by N. Galldiks et al., Research Center Juelich, Juelich, Germany.

News | PET Imaging | May 05, 2021
May 5, 2021 — For patients with brain metastases, amino acid ...
The emergence of #therapeutic #radiopharmaceuticals and its adoption in #cancer care provide one more weapon in combating cancer

Getty Images

Feature | Radiation Oncology | May 04, 2021 | By Vinay Shivaprasad
The term nuclear medicine is associated with the diag
Despite receiving high radiation doses to their tumors, lung cancer patients treated with technique that spares a large part of the esophagus did not develop severe inflammation of the esophagus

Getty Images

News | Lung Imaging | April 30, 2021
April 30, 2021 — For many patients with localized lung cance...
News | Artificial Intelligence | April 30, 2021
April 30, 2021 — Canon Medical is bringing the power of accessible...