BioEngineering

Medical Imaging & Image-Guided Therapy

Contents

 

Faculty

Core Faculty

Other Faculty: Carter, Lewellen, Maravilla, Haynor, Rasey, Shimiedl, Stewart, and Yuan (radiology), Hannaford and Haralick (electrical engineering), Sheehan and Linker (cardiology), Fuller and Linker (medical education), Beach and Sinanan (surgery), Kliot and Silbergeld (neurological surgery), Matsen (orthopedics), Marsh (urology), Grimm (Seattle Prostate Institute), Wallner and Kalet (radiation oncology), Seibel (mechanical engineering).

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Description

The UW Department of Bioengineering has made significant contributions to medical imaging advances, particularly in diagnostic and therapeutic ultrasound. Imaging and Image-Guided Therapy within the Department spans many exciting research projects involving revolutionary new technologies and their clinical applications, ranging from image-guided surgery, high-intensity focused ultrasound (HIFU) and image analysis/segmentation/visualization to image computing for real-time support of various algorithms and applications and designing next-generation low-cost ultrasound machines.

During the last three decades of the 20th century, medical imaging, which for nearly 70 years had almost exclusively depended on conventional film/screen X-ray imaging, has experienced major technological growth resulting in the development and commercialization of a plethora of new imaging technologies. X-ray Computed Tomography, Magnetic Resonance Imaging, Digital Subtraction Angiography, ultrasound, and various imaging techniques based on nuclear emission (PET, SPECT, etc.) have all been valuable additions to the clinician's arsenal of imaging tools toward ever more reliable detection and diagnosis of disease.

In addition to the development of rapid and inexpensive computing capabilities, this era of accelerated change owes much of its success to the concurrent advances in the signal and image processing theories on which the development and maturation of many new technologies is based. Another important corollary to these developments is the relatively rapid development and deployment of methods for archiving and transmitting digital images, allowing hospitals to distribute the increasing number of images and associated diagnoses in a timely and cost-effective fashion. Medical imaging is still undergoing a very rapid change toward higher sensitivity and specificity, improved resolution and image quality, smaller equipment, cellular and molecular-level imaging, higher dimensions and real-time imaging, as well as new imaging modalities, e.g., optical coherence tomography and electrical impedance imaging.

The University of Washington is currently in an unusually strong position as a leader in medical image computing (Kim), medical image processing and analysis (Haralick, Haynor, Kim, Bassingthwaighte, Lewellen, Yuan), systems (Crum, Martin, Vaezy, Beach, Kim), therapeutic ultrasound (Crum, Martin and Vaezy), and applications (many researchers and clinicians). For example, with new, more powerful mediaprocessors, we can now tackle the whole ultrasound signal and image processing (about 30 to 50 billion operations per second) in a low-cost programmable fashion, rather than using multiple ASIC-based hardwired boards. When this is successful, it will change the research and development paradigm of medical ultrasound machines, which will result in smaller equipment and lower cost. This programmable medical image computing approach can be deployed in other medical imaging modalities, e.g., X-ray CT, MR, DSA, fluoroscopy, mammography, CR, and DR. New image analysis algorithms and innovative clinical applications developed by researchers and clinicians can be easily tested and quickly deployed and commercialized. For example, this kind of high-performance programmable image computing can be easily integrated into therapeutic ultrasound machines to support its unique real-time imaging and computing needs. It can also be applied to future laptop or palmtop ultrasound devices that require more customization and little training for individuals in nursing homes and individual homes for distributed diagnosis and home healthcare.

Image-guided surgery is one form of image-guided therapy and involves the use of medical images and the delivery of surgical treatment to the patient. The surgeon can use medical images not only for diagnosis and surgical planning before surgery, but also for visualization during surgery of target anatomy located deep within the organ of interest that cannot be directly visualized. Stereotactic systems use images obtained before surgery, e.g., MR and CT, for accurate guidance of the surgical tool to the target anatomy. A significant limitation of stereotactic systems is that they are based on the assumption that no changes in the anatomy of interest occur between the preoperative scan and the surgery. This is a reasonable assumption for the brain where the skull provides a rigid housing. However, it is not a valid assumption for soft and mobile organs, such as the pancreas and liver, which can shift and deform between the preoperative scan and the surgery. To overcome this limitation and provide a pathway for widespread clinical acceptance of image-guided surgery, ultrasound imaging can be used during the surgery to monitor the anatomy. Multimodality registration algorithms can be developed to combine intraoperative ultrasound with preoperative MR/CT images to overcome the limitation of current stereotactic systems. This image-guided surgery based on deformable anatomy, if it can be supported in real time, will enable the development of a new generation of image-guided surgical systems where treatment can be delivered in a minimally-invasive fashion with high spatial accuracy for organs in the abdominal area, e.g., pancreas, liver, prostate and kidney. Therefore, these systems will be applicable to a much wider range of clinical applications compared to the currently available stereotactic systems.

Instead of tissue removal, we can use therapeutic ultrasound as a non-invasive, bloodless surgery tool, utilizing the surgical capability of HIFU. Image-guided therapy offers the potential to direct therapeutic action precisely to the point in the tissue where it is needed and not to other tissues. When this is possible, a higher dose can be administered with higher probability of a complete cure. A stronger dose may also accelerate recovery. Precision in delivery can produce less side effects and side-damage and allow more intricate treatment. Focused delivery requires the integration of three essential components: 1) Accurate and clear imagery to identify the offending tissue, 2) a therapy that can be accurately directed and controlled, and 3) a well-controlled means to guide the therapy to the imaged location. New methods in ultrasound and magnetic resonance (MR) provide higher resolution information in two and three spatial dimension, with acquisition and display occurring nearly in real time. Computer image processing methods offer ways of clarifying, highlighting, or detecting specific regions in tissue, e.g., pubic arch bone. It also allows assembling information from several sources or views to produce compound or panoramic images, e.g., SieScape or 3-Scape, which provides more complete depiction than single views. For example, cancer in the breast, prostate, liver and other organs can be imaged quite accurately with diagnostic ultrasound. If these carcinomas can be segmented, targeted and treated with therapeutic ultrasound, an entirely new non-invasive, bloodless approach to the treatment of such diseases can be developed.

The University of Washington is very close to have the critical mass in terms of the intellectual ability and key expertise needed in making image-guided therapy successful. This initiative will allow the Department of Bioengineering to have a major role in the development and clinical use of HIFU techniques, e.g., to treat uterine fibroids, to close wounds produced by catheters, and for various applications in cardiology, gene transfection, ocular drug delivery and fetal surgery.

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Areas of Research in Medical Imaging & Image-Guided Therapy

The UW Department of Bioengineering has made significant contributions to these medical imaging advances, particularly in ultrasound imaging in the last 35 years, ranging from spinning off start-up companies to developing enabling technologies, e.g., Doppler ultrasound and programmable ultrasound image processor. ATL (Bothell, WA), one of the world's largest manufacturers of medical ultrasound equipment, originated in the UW Department of Bioengineering. It was established nearly 30 years ago with a handful of UW Bioengineering researchers and others. Currently, ATL has approximately 2600 employees, most of them in the Seattle area. In 1996, Larry Crum and his group, in partnership with ATL, obtained a grant from DARPA to develop a hand-held portable ultrasound device for combat-casualty care. This project was so successful that ATL spun off a specialty company, SonoSite (Bothell, WA) which now manufactures and sells small 5-lb. portable diagnostic ultrasound scanners. Presently, SonoSite employs over 100 highly skilled workers and has a market capitalization over $250M.

Yongmin Kim has been working with Siemens Medical Systems Ultrasound Group since 1991. His group has successfully designed and implemented a high-performance programmable ultrasound image processor to fit within an ultrasound machine. It has revolutionized how new clinical ultrasound applications should be developed, deployed clinically, and supported. It provides a flexible platform for rapid deployment of new ultrasound applications via software and enables quick upgrades for future technologies. Current clinical applications include: SieScape (extended field of view), color SieScape, SieFlow gray scale flow imaging, 3-Scape real-time 3D ultrasound imaging, quantitative measurements, adaptive persistence, and speckle reduction. After obtaining an FDA clearance, it was introduced commercially in December 1996.

Recently, a study found that clinicians use SieScape panoramic imaging techniques in 27% of all cases, about as frequently as they employ standard color Doppler imaging. All of these applications are enabled and commercialized by our software and the UW-designed supercomputer board embedded in the ultrasound machine, as well as UW-held patents & copyrights. This is a significant step in the evolution of ultrasound machines toward more flexible and generalized systems, bridging the gap between many innovative ideas and their clinical use in ultrasound machines. This ultrasound supercomputer board was made possible by the UW's pioneering work with Texas Instruments in creating the world's fastest image processor, TMS320C80 Multimedia Video Processor (MVP), in the early and mid 1990s. Even though this chip was being targeted for consumer electronics products, the UW team was the first to adapt it for use in medical imaging due to our understanding and experience in both high-performance microprocessors and medical imaging. For example, in 1996, an interactive 3D ultrasound application was developed by developing efficient volume reconstruction and visualization algorithms for the Texas Instruments TMS320C80 MVP, making it possible for our 3D ultrasound (US) to provide the same immediate feedback as current 2D US technologies, with the added advantage of presenting information in three dimensions. For example, for acquired sequences of 512 x 512 US images, volumes can be reconstructed using six degree-of-freedom position measurements at 11.4 frames/s and rendered via shear-warp factorization and maximum intensity projection at 10 frames/s. It was integrated into the Siemens US machines and commercialized in 1998. Due to our unique expertise in high-performance mediaprocessors and their programming, many other companies are using UW's hardware and software, e.g., Sony, Tektronix, GE, 3M, Mercury Computer Systems, Xerox and Canon.

The Kim group has also been working on developing enhancements for current transrectal ultrasound (TRUS) technology that will improve the effectiveness of TRUS in diagnosis and treatment of prostate diseases. By having these improved (and ideally low-cost) diagnostic/treatment techniques routinely available in the clinic, it will facilitate their use in practice. These tools will help to more effectively address an increase in the reported incidence of prostate diseases (both benign and malignant) due to longer life expectancy, and enhanced patient and physician awareness. Transperineal prostate brachytherapy employs TRUS as the primary imaging modality to accurately preplan and subsequently execute the placement of radioactive seeds into the prostate. Under TRUS guidance, a needle (preloaded with radioactive seeds) is inserted via a template guidance through the perineum and into a predetermined prostate target. The pubic arch, formed by the central union of pelvic bones, is a potential barrier to the passage of these needles in the prostate. A critical aspect, therefore, in the planning and execution of the brachytherapy procedure is the accurate assessment of pubic arch interference (PAI) in relation to the prostate. Traditionally, the evaluation of PAI has involved X-ray CT scanning. A new method of assessing PAI by detecting the pubic arch via image processing and analysis on the TRUS images was developed. The PAI detection algorithm first uses a technique known as "sticks" to selectively enhance the contrast of linear features in ultrasound images. Next, the enhanced image is thresholded via percentile thresholding. Finally, a parabola (to model for the pubic arch) was fit recursively to the thresholded image before overlaying the parabola to a TRUS prostate image with the largest cross-sectional area. This algorithm was tested in 46 patients. The Type 2 error (inaccurate prediction of bone as soft tissue) occurred in only 30 out of 1030 coordinates, i.e., 2.9%, and the probability of our algorithm failing to predict a clinically significant PAI is 0.58%. This small error is, according to our urology and radiation oncology collaborators, clinically acceptable and the patient does not have to wait a week for the CT scan result to find out whether he can have a prostate brachytherapy procedure or not. Furthermore, the TRUS-based PAI detection is inexpensive compared to a CT scan. This invention with its patents has been licensed to a company for commercializing this more effective and less costly solution to be deployed to many urology clinics performing prostate brachytherapy.

Recently, there has been significant progress in the use of ultrasound to enhance drug delivery. EKOS (Bothell, WA), a new start-up company, has been working with UW researchers to explore this therapeutic approach, test the clinical viability, and develop the necessary technology for commercial exploitation. EKOS currently has 25 employees and is undertaking clinical trials of an ultrasound radiating catheter for dissolving blood clots. Also, UW ultrasound researchers, in collaboration with UWEB, are working to develop an implantable, synthetic-membrane-covered insulin reservoir that, when irradiated with ultrasound, will release insulin on demand. This example typifies the UW Bioengineering's tradition and clear strength in that both groups (ultrasound and UWEB) are leaders in their academic fields, but when two groups work together with the sincere collaborative spirit pervasive in the Department of Bioengineering they can formulate new ideas and create a unique intellectual frontier and a set of new applications and opportunities. Another example is that by collaborating with the Department of Neurological Surgery, it was found that ultrasound can be used to transiently open the blood brain barrier, which could permit many diseases, such as Parkinsons, epilepsy, and Alzheimers to potentially be treated with therapeutic drugs.

As a result of another $10M grant from DARPA, Larry Crum and his group have developed a device that combines the imaging capability of diagnostic ultrasound with the surgical capability of High-Intensity Focused Ultrasound (HIFU). This combination of imaging and therapeutic modalities may ultimately permit revolutionary advances in healthcare. In its imaging mode, the device is used to locate the region of interest through the use of a proper transducer, which, when used correctly, can generate images of most tissue and/or organs in the human body. This same device, switched to therapy mode, can then be used to focus high-intensity ultrasound into the region of interest, causing local and rapid elevations in temperature and mechanical activity.

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Career Opportunities in Medical Imaging & Image-Guided Therapy

Graduates are in great demand in both academia and industry. With the increasing power and information content of imaging modalities, and the resurgence of interest in non-invasive treatment, new programs and initiatives are being established across the world. In addition to commercial companies involved in the large-scale development of imaging equipment and algorithms, new companies involved in the development of imaging and image-guided therapy systems form a solid employment basis for graduates trained in this area. The research and educational initiatives set forth by National Institute of Health, and National Science Foundation also play a strong role in encouraging active academic program development in imaging and image-guided therapy.

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Degree Programs

Course credit requirements for MS and PhD degrees are those listed for the department. These will be more or less evenly spread among bioengineering courses, engineering courses offered by other departments, biological courses offered by other departments, and medical courses offered by the school of medicine. Bioengineering courses will aim at conveying in detail some specific areas of research and expose the students to a variety of state of the art, current enabling technologies (i.e. software and hardware; typically, more than one).

The thesis and research topics might be in any area related to the expertise of the faculty, and will most likely be among currently funded research areas.

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Sample Programs

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Subspecialty Areas & Suggested Coursework

To provide our students with a solid foundation for their research and future industrial and academic careers, we have established a well-integrated systems-oriented educational program in Medical Imaging & Image-Guided Therapy within the Department of Bioengineering (See Figure Below). It will start out with two senior elective courses, BIOEN 420 (Medical Imaging) and BIOEN 470 (Systems Engineering and Electronic Medicine). At the graduate level, BIOEN 568 (Image Processing Algorithms and Systems) will be a core course for students in the Medical Imaging & Image-Guided Therapy thrust area. This is a very rigorous course with an individual project requirement in addition to homework and laboratory assignments. Students interested in medical imaging and computing can take BIOEN 599 (Advanced Mediaprocessors and Programming) for high-performance algorithm development, students in biomedical lasers and microscopy can take BIOEN 561 (Biomedical Optics and Microscopy), and students pursuing image-guided therapy can take courses on ultrasound and MRI, ultimately leading to a new course, BIOEN 585, on Image-Guided Therapy for in-depth analysis, system design, and applications. These Bioengineering courses will be supplemented by courses in other departments, e.g., computer vision, image compression, statistical signal processing, and other signal/image/video processing/analysis topics in Electrical Engineering, Computer Science & Engineering, and Statistics. This integrated systems-oriented curriculum will not only benefit our graduate students who will receive solid training in Medical Imaging and Image-Guided Therapy, but will also benefit many imaging research programs on campus by educating the students in a structured setting in principles, algorithms, systems and clinical applications for advanced research in their thesis/dissertation topic. Many courses in this thrust will have laboratory and individual project components to provide our students with hands-on experience.

The Medical Imaging and Image-Guided Therapy curriculum (See Figure Below) trains students through two senior courses in medical imaging and systems engineering and electronic medicine. After learning about the algorithms and systems that support image processing in BIOEN 568, the students can branch into modalities such as ultrasound, MRI or optics & microscopy, take the ultrasound and MRI courses followed by an in-depth course on image-guided therapy, or concentrate on high-performance processors and their programming.

diagram of imaging curriculum

In addition to the above courses, the Bioengineering student can enjoy a wealth of courses in engineering, biology, and medicine. These courses can potentially provide a custom-designed program for each student, to pursue an interest in a specific area of imaging and image-guided therapy.

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Summary

University of Washington, and particularly the Department of Bioengineering, is an exciting place to be, if you are interested in imaging and image-guided therapy. To obtain more information about our program, we encourage you to contact us. We would love to hear from you.

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