When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
A PEEK (polyaryletherketone) polymer capsule, the size of a grain of rice and containing a water-based cobalt salt solution, is lighting up possibilities for magnetic resonance imaging (MRI) scans.
The What and How
During an MRI, the ability to visualize the internal structures is greatly increased when using a contrast agent. This technology is excellent for focusing on certain areas of the body. The agents are usually taken orally or administered intravenously. Current standard contrasting agents include intravenous gadolinium, which is used for boosting visualization of vessels or brain tumors, and oral gadolinium, which is used for the gastrointestinal tract.
The MRI creates a very strong magnetic field while a radio frequency is pulsed, causing some atoms to spin and then to relax when the pulse stops. The relaxed state sends out a signal that the scanner mathematically translates into an image. The image itself can use varying weights to give a higher or lower signal.
Making High-Tech Even High-Techier
In his research on prostate cancer at the University of Texas’ MD Anderson Cancer Center, Steve Frank, M.D., was trying to improve the process of MRI scans in brachytherapy. The brachytherapy procedure includes the implantation of radioactive seeds in the treatment of prostate cancer. Up to 100 seeds are directly implanted into the prostate and held in place by inserting a spacer on each side of the seeds. This procedure is standard for prostate cancer treatment as it is successful, accessible, and minimally invasive, as well as having a low occurrence of erectile dysfunction. Radiation released from the seeds is confined to the area within the prostate, penetrating the tissue.
The use of the MRI to identify the seeds accurately illustrates certain parts of the prostate but cannot identify the implanted seeds. This inadequacy is due to the paramagnetic titanium shell of the seed, which shows a void or “black hole” in the MRI image. The void makes the seeds indistinguishable from the surrounding vessels.
In his research, Frank developed the first permanently implantable MRI contrast agent. This technology can be used when a specific place of interest in the body needs to be observed — for example, a biopsy site. The PEEKcapsules, which Frank calls Sirius capsules, have been in development since 2006. However, because the original beads he used contained titanium, Frank had a hard time finding a coating that could stop the “black hole” created by the MRIs.
He began working with Karen Martirosyan, Ph.D, a bioengineer at the University of Texas. Together they discovered a new contrasting agent that they refer to as “cobalt-chloride complex contrasting agent” or C4. Cobalt’s paramagnetic properties were clearly visible using an MRI. Moreover, they decided that instead of using standard spacers to hold the seeds in place, they would use plastic capsules filled with a droplet of C4. Frank said:
‘To be able to take a novel contrast agent and place it inside a polymer tube for visualization, it provides the potential for additional applications that may have not been thoroughly thought through. It’s exciting on that side, too.’
PEEK was chosen for its standard use in medical equipment and its low degradation rate with exposure to radiation. While micromolding and extrusion were both considered in regards to fabrication, extrusion was chosen based on reproducibility.
The capsules are 5.5 mm long, with a diameter of 0.8 mm; the walls are 0.1 mm thick.
Frank and Martirosyan started C4 Imaging to develop Sirius capsules and won FDA 510(k) approval for Sirius in late 2013. They now have an undisclosed contract ramping up to start production next month. Andrew Bright, the former vice president of sales and marketing at GE Healthcare’s Oncura business, joined C4 Imaging as its CEO in 2010.
When it comes to MRI scans, it seems that PEEK has helped in giving us a visually enhanced peek into the human body.
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