Living Systems

Functional Diagnostic Imaging

Technical Applications


High-resolution medical imaging techniques, including CAT scans, MRI and Ultrasound, are revolutionizing medical diagnosis and treatment. As a result, they have emerged as critical components of the nation's health system. Computer driven image processing (enhancement, comparison of episodic changes, quantitative analysis of absorption ratios) has held great promise and is becoming more clinically acceptable with better displays, faster processors, storage systems and networks. As the imaging parameters become more complex in modes such as MRI, decision support systems will become more valuable in making a differential diagnosis based on tissue response to the various excitation modalities available in MRI.


Functional MRI complements earlier methods of functional neurological imaging which used positron emitters carried in the blood stream. One method using labeled water allows the visualization of alterations of blood flow, labeled glucose allows visualization of altered regional metabolism. As astronomers learned that they could benefit from images registered from different parts of the electromagnetic spectrum, brain researchers and neuro-radiologists are beginning to utilize the multispectral perspective. Optical coherence tomography uses infrared radiation to provide cross-sectional images of biological tissues with 10 to 20 micron resolution. While its immediate applications will be in the eye for non-invasive detection of glaucoma and macular degeneration, the ability to analyze the top few millimeters of any biological structure should include arteries and mucosal tissue. As many pathologies such as skin cancers and atheroscelerosis begin on tissue surfaces, the use of various wavelengths may enable rapid, minimally invasive differential diagnosis. Incorporated in endoscopic procedures, it could provide real-time data on tissue hydration, oxygenation, and guidance for highly selective laser angioplasty.


Functional diagnostic imaging has the capability to improve early diagnosis and through earlier proper treatment, provide improved patient outcomes at lower costs. They also contribute to job creation and economic growth through global export of medical imaging systems. As the imaging chain becomes fully digitized, chemical wastes from film processing will be reduced, reducing the impact of medical technology on the environment. Techniques developed for clinical imaging are also being adapted to industrial quality control as they permit non-destructive testing and visualization of internal structures and flaws in complex metal and composite assemblies. Functional diagnostic imaging also makes a contribution to the nation's warfighting capabilities. Digital images can facilitate the medical decision making process in isolated or remote military environments, both ship-board and land based, not so much in the management of gross combat casualties, but in the daily experience of sick-bays and medical operating groups. In the event of large scale deployments, digital medical imaging could augment the interpretative capabilities on-site by using state-side radiology and pathology consultants linked to the forward areas.


The United States holds undisputed leadership in ultrasonic imaging of the heart and soft abdominal tissues. This is supported by an extensive technology base in ultrasonic transducer design, digital signal processing, and data display. Computerized tomography is also dominated by U.S. companies after a major marketing-based sorting out that occurred in the mid-1980s. While the initial invention was done at EMI in England, the mathematical reconstruction algorithms were derived from astronomy work and were ultimately dependent on both computer processing capabilities and low noise, high sensitivity detector technologies.