WG 1 — Final Report Part 4 — Technological Changes

Part 4: The Impact Of Changes In Technology On Medical Imaging

• The Status Quo
• Changes in Technology
• Magnetic Resonance Imaging and Spectroscopy
• Ultrasound
• CT
• Radiography: Plain X-Ray
• Computed Radiography/ Digital Radiography
• Information Display, Analysis, Transmission and Storage
• Computer-Aided Diagnosis
• Nuclear Medicine
• Optical Methods and Photonics
• Image-Guided Minimally Invasive Diagnosis, Intervention, and Therapy
• New Signals
• Multi-Modality Systems

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The Status Quo

The status quo is not reassuring ^{19, 20, 32}. Canada has 8.1 CT machines per million population while the Organization for Economic Cooperation and Development (OECD) average is 12.9. To reach the OECD level, Canada would need to install 144 CT machines. Additionally, Canada has 1.7 MRI machines per million population. To reach the OECD average of 4.3 per million population, 75 MRI machines would need to be installed nationwide. Canada has fewer than 3 percent of all PET detectors in the world, with 40 percent being found in the U.S., 40 percent in Europe and 11 percent in Pacific-rim nations. Taking this into account, one could suggest that Canada needs to install 6 PET machines. However, since most of the existing machines in Canada are "small aperture" (i.e. only able to image the head) and are only used for research, the correct number for clinical use is probably nearer 12. A recent Ontario analysis, admittedly by PET advocates, identifies a need for 9 to 12 units in that province alone. (See Appendix E for further information.)

The Fraser Institute has analyzed technology penetration in Canada, as has Rankin with respect to MRI ^{19, 20}. Both analysts find that Canada ranks lowest of the developed nations in imaging technology adoption. Indeed the deficit in technology is so great that Canada has fewer diagnostic machines than many underdeveloped nations.

It must be said that these analyses can be criticized. Accounts of the number of machines per capita tell nothing of their actual use. However, were this correction applied to Canada, the nation might look even worse because imaging machines, particularly MRI machines, are often funded by provinces for limited periods of operation. Equally, in the absence of a supply-and-demand scenario, it must be realized that no public policy has evolved world-wide to establish what is the optimum supply of high-technology imaging devices per capita of population. Nevertheless, there must be the presumption that because Canada is outstripped by nations that are both similarly developed as well as those that are much less developed, it is unlikely the optimum level has been achieved.

The 1997/98 OECD survey ³² of Canadian tertiary and quarternary hospitals showed that, not only does Canada have a deficit in the high-technology aspect of imaging, but that hospital clinical services have somewhat uniformly obsolescent machines. The data may contain a response bias; however, since the major regions (Maritimes, Quebec, Ontario, Prairies and West Coast) were all represented, this is unlikely to be a major factor. Survey results, obtained from eight institutions, reported the mean age of the machines and the number upon which the mean was based as well as the sizes of the capital inventories, the amount of capital reinvested and the reinvestment rate. In this fiscal year, all institutions fell short of, and many well short of, a 10 percent per annum reinvestment rate, which would be considered prudent in other industries. In fact, the mean reinvestment rate of the eight institutions was 5 percent, with two at 0 percent and the remainder ranging from 5 to 9 percent (see Appendix F for further information).

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Changes in Technology

The following is a list of changes in technology that are likely to occur over the next three to five years. The list is partly segregated by imaging method but some trends encompass more than one modality. Where this sort of overlap occurs, some new technologies are listed more than once.

In addition to the changes in specific instrumentation, some general themes are also apparent. These include:

• integration in the presentation of information and images from multiple modalities;
• a larger role for image-guidance and monitoring of interventional techniques;
• expansion of imaging beyond representations of anatomy to include functional, physiological, quantitative and dynamic information;
• integration with molecular biology technologies, e.g., detection of delivery of genetic probes, targeted delivery of genetic material, etc.;
• a general emphasis on faster, three-dimensional or volumetric imaging;
• faster and more detailed imaging of all types using more powerful computers; and
• the use of computers in image analysis and decision support.

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Magnetic Resonance Imaging and Spectroscopy

A greater variety in choices of equipment and a broader range of magnets and systems will be developed, generating opportunities for developing and marketing devices, accessories, and image processing software. New MRI contrast agents for dynamic and functional studies will emerge, increasingly coupled with molecular biologicals. MRI will develop major clinical roles in the guidance and monitoring of minimally-invasive interventional techniques and there will be opportunities for the development and manufacture of MRI-compatible devices and equipment ³³.

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Ultrasound

Major developments are anticipated in ultrasound imaging based on the development of new contrast agents. Innovative and complicated operating modes will be developed to exploit these new contrast agents. In general, instrumentation is becoming more specialized, utilizing higher frequencies and more complex transducers, with emphasis on miniaturization for intravascular and interstitial imaging. Systems will continue to become more portable ³⁴.

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CT

Emphasis will be placed on faster imaging methods, creating a need to develop new x-ray tubes, detectors, image reconstruction display methods, etc. Special purpose machines will be developed such as trauma CT, low-cost C-arm and mobile units. There will be opportunities for the development of accessories and devices, particularly for dynamic studies ^{35, 36}.

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Radiography: Plain X-Ray Imaging

There will be major developments in digital technologies for both detectors and display. Image-processing software will find increasing clinical applications. There will be emphasis on smaller, mobile systems and there will continue to be developments in x-ray tubes and other innovative x-ray sources.

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Computed Radiography/Digital Radiography

The film-screen combination currently used to capture radiographic images will soon be replaced by digital acquisitions, so that the entire array of imaging modalities can be part of the electronic patient record. The advent of digital detectors will likely play a major role in acquisition of static (digital radiography) as well as dynamic (digital fluoroscopy) images ³⁷.

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Information Display, Analysis, Transmission and Storage

Once plain x-rays and fluoroscopy have been converted to digital acquisition, all medical imaging modalities will be read off computer monitors, transmitted instantly wherever they are needed, and archived electronically. The continuous progress made in network communication and computer technology will allow development of new organizational models for imaging departments with a trend towards large global networks, decentralization and globalization of the medical imaging business ³⁷.

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Computer-Aided Diagnosis

Computer-aided diagnosis will be a side benefit of the migration towards a totally electronic format. Specialized software will be developed in order to support radiologists and clinicians in the diagnosis process. The capability for convenient multi-modality image registration and display will accelerate this trend ³¹.

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Nuclear Medicine

One key technology for nuclear medicine remains the development of radiopharmaceuticals and here molecular imaging techniques are anticipated to have great impact ¹². Developments in instrumentation will continue to focus on special purpose systems, e.g., economical PET imaging, as well as high resolution gamma cameras ³⁸.

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Optical Methods and Photonics

Visible light techniques (including ultraviolet and infrared) will play bigger roles in medical imaging in the future. Molecular biology techniques will develop specific labels (e.g., fluorescent proteins) which will be detectable with interstitial probes for local measurements of tissue function and disease, with the potential for in vivo biopsy. Transillumination and optical computed tomography techniques will undergo further development ³⁹.

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Image-Guided Minimally Invasive Diagnosis, Intervention, and Therapy

Interventional techniques will increasingly exploit imaging technologies that will enable improved and new interventional technologies to be developed. Minimally invasive, day-surgery techniques to avoid or reduce hospital stays will involve various imaging tools and specialized operating-room equipment. Thermal therapy techniques for tumour ablation will evolve, and robotic technologies will be increasingly used, to bridge imaging and interventional technologies. Interstitial probes will be increasingly applied as sensors for diagnosis and monitoring and for guiding and assessing delivery of agents for diagnosis and therapy ⁴⁰.

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New Signals

There are still some observational windows into the body which can be developed. Likely candidates are electrical impedance tomography and magnetoencephalography (MEG), as well as high-resolution optical imaging.

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Multi-Modality Systems

Exciting combinations of technologies will be developed. For example, the combination of the rotational technologies of CT and SPECT will be more powerful than either alone. X-ray angiography techniques will be combined with ultrasound, CT or MRI to provide better definition of the vascular system for diagnosis, treatment and interventions. Magnetoencephalography (MEG) will gain power when combined with simultaneous PET or fMRI imaging.