Medical Imaging Up Close

ECE leads the way in medical imaging, which seeks to expand diagnostic capabilities, increase patient safety, and enhance drug development.

If medical imaging were gold, Purdue would be sitting on a gold mine. That’s because the imaging field represents a core Midwest industry, placing the School of Electrical and Computer Engineering in an advantageous position.
    “The Midwest is the center for medical imaging in the world,” says ECE professor Charlie Bouman. First, several industry giants call the region home. GE Healthcare, for one, regularly turns to Purdue when recruiting team members-a plus for ECE students conversant in medical imaging. One 1987 graduate, John Chiminski, currently serves the company as vice president for global MR (magnetic resonance) business. Siemens and Philips also have strong ties to the region.
    Second, some of the top medical schools call the region home. Close proximity to these institutions, in addition to top healthcare companies, provides key opportunities for collaborative research.

From Diagnostics to Drug Development

Imaging plays a pivotal role in the healthcare industry. “Medical diagnostic imaging has a huge impact,” Bouman notes, explaining how exploratory surgeries have decreased due to imaging innovations. “It used to be that if you were sick-if there was something wrong-you might go in for exploratory surgery. You don’t hear about people going in for exploratory surgery anymore.”
    Scanners can provide internal images of patients, which is much more safe and cost-effective than the operation required by exploratory surgery. Systems like CT (computer tomography, one of the most common forms of imaging), make this possible, producing 3-D images of internal structures.
The diagnostic benefits of medical imaging are both varied and widespread, aiding in everything from cancer detection to determining whether or not a bone is broken to even improving auditory devices for the hearing-impaired. “One of the next big applications is going to be cardiac imaging,” Bouman says. “Right now if you believe you might have heart disease, they put you on a treadmill for a stress test, which isn’t very accurate.” Cardiac CT, for example, could help determine if an artery is clogged.  
    Extending beyond diagnostics, imaging’s applications could dramatically reduce the costs of developing new pharmaceuticals. “All of the top pharmaceutical companies have major efforts in imaging to reduce the cost of drug development,” Bouman says. For example, if a company can reduce a particular drug’s development costs by 5 percent, this can represent a $50 million savings.
    Drug companies can sometimes spend an exorbitant amount of time and money developing and testing drugs that ultimately fail. So, for instance, if a pharmaceutical company tests a drug on a large pool of people only to receive negative results, this can be quite costly. “If a large-scale drug test is going to cost $100 million and take five years,” Bouman says, “then you want to be pretty confident that it has a high likelihood of success before starting.”
    Medical imaging can help to identify drugs that will be unsuccessful early on and can also help to determine the appropriate dosage for a clinical trial. For example, if a candidate neurological drug does not pass through the blood-brain barrier, then it cannot be effective. Medical imaging can be used to establish this much earlier in the drug development process. In other cases, functional medical imaging modalities such as positron emission tomography (PET) can be used to determine the dosage required to achieve the desired
concentration of a drug in the brain.
    “You’re searching in the dark, you’re blind, but with imaging you can see where you are going. If Lilly doesn’t figure out how to do it cheaper, Pfizer will; if Pfizer doesn’t, some other drug company will,” Bouman says. “So if we want to keep the jobs in Indiana, we have to make Lilly more competitive with the technology we have here today. This can have an economic impact in the state and already does.”

Imaging Innovations

Biomedical imaging and sensing integrates multiple disciplines of electrical and computer engineering. Within this focused ECE research area, engineers seek solutions that lower imaging costs, improve the accuracy of imaging techniques and diagnostic capabilities, and enhance patient recovery and safety (e.g. eliminating exploratory surgeries).
    The school’s area chair for biomedical imaging and sensing, Bouman devotes considerable time to imaging initiatives. His far-reaching work covers a number of techniques:

- Positron Emission Tomography (PET), which produces 3-D images of functional processes in the human body.
PET provides improved visualization and comprehension of how the human brain functions, positioning this method for widespread impact-from drug development to an improved understanding of brain diseases like dementias. Oncology also benefits greatly from PET advancements as it aids in cancer detection and tumor imaging. By injecting a short-lived liquid radio tracer isotope into a patient (low exposure), you can produce a 3-D image of the radioactivity that lights up tumors. “You can see the tumors or the cancer, and you can go in and surgically remove it or use radiation treatment,” Bouman says. “This detects precisely, so then you have targeted therapies.”

- Optical Diffusion Tomography  (ODT), which has proven to be essential for imaging a highly scattering medium like tissue.
    An experimental technology, ODT is not a clinical imaging method at this time. This technique applies measurements of transmitted modulated light. Logically, it may not seem feasible to produce images of submerged tumors by using light. This is due to human tissue’s scattering nature, which makes it impossible to form images via conventional optical lenses. Yet it’s possible to form a volumetric image using surface measurements of the scattered light that passes through human tissue.
    In fact, by employing 3-D reconstruction, ODT’s deep-tissue imaging methods have proven capable of producing high-resolution images at centimeters of tissue depth. And like PET imaging, ODT is potentially valuable for tumor detection.

- Multi-slice helical CT, which provides clear advantages when used for routine diagnostic purposes.
This scanning technique promotes faster image acquisition and larger organ coverage through multi-slice detectors and quicker rotation speeds, plus increased spatial resolution. Benefits include dosage reduction and resolution increase. Bouman and his colleagues seek to enhance this technique further by applying iterative image reconstruction, which is capable of lowering patient dosage, increasing spatial resolution, and reducing reconstruction artifacts.