Evolution of CT technology has moved beyond low radiation dose to advanced functional imaging, iterative reconstruction techniques, novel spectral imaging, and multi-slice systems.

Computed tomography (CT) has evolved into a powerful diagnostic tool, with its widespread availability, ease of clinical applications, high sensitivity for the detection of coronary artery disease, and noninvasive nature. Advances in CT have focused in part on reduced radiation dose. Numerous technological advances have occurred, including dual-energy CT, spectral CT, and CT-based molecular imaging.

The evolution of CT scanners has progressed to the point where the number of slices per rotation is no longer the benchmark for performance. Market leaders in the higher-slice segments have proven superior image quality. They are under pressure to prove that they can incorporate effective dose-reduction techniques while maintaining image quality. High-end imaging modalities require advanced image management and archival systems. The diagnostic outcome of molecular imaging has been made available to clinicians, and healthcare IT and molecular imaging are exploiting the advantage of systems. Manufacturers are working on providing effective distribution of images to clinicians and integrating CT systems with electronic medical records. With the addition of high-speed multi-slice CT scanners, healthcare providers are thinking differently about imaging, diagnosis, and treatment of patients, as new pathways for clinical applications in areas such as trauma, pediatric, vascular, and cardiac imaging have opened up due to which scanning can be performed at higher speed.

Indian Market

In 2014, Indian CT scanners market is estimated at Rs.795 crore, a dip from the 2013 market. There was an 8-10 percent growth in the smaller machines, < 16 slices, with the sales of 360 units in <16 slices, and 120 units in 16-slice category. The three brands, GE, Philips, and Siemens, have a combined market share of 93 percent. In response to this trend, all the brands are offering models in the unit price range of Rs.20-80 lakh. The high-end cardiac scanners continue to constitute 11 percent of the market, in value terms.

With the launch of the Revolution ACT by GE in April 2015, the CT scanner market is seeing a major shift. The Made in India scan system is the result of the efforts of a 50+ team of Indians, working for four years and a development budget of USD 20 million. In the process GE engineers claimed 10 patents. Lower radiation dosage, special pediatric settings, and a smaller footprint are other features. GE is looking to market it worldwide starting with emerging markets - not just in India.

Global Scenario

The global market for computed tomography systems was valued at USD 4839 million in 2014 and is expected to grow to USD 6588.5 million by 2019 at a CAGR of 6.3 percent from 2015 to 2019, according to Research and Markets. Computed tomography scanner markets are driven by the trend toward multi-slice scanners, and the global market for CT scanners is expected to post a modest growth rate. This growth is driven in part by increasing popularity of independent diagnostic centers, which are increasing in number with patient demand and the relatively low set-up cost compared to a full, multi-disciplinary hospital.

Other growth drivers include the increasing demands from governments for high quality healthcare delivery that is supported with CT imaging.

Significant advances in imaging technologies promise to improve healthcare through earlier and more accurate detection of medical conditions. Increasing incidence of cardiovascular diseases has also increased market penetration of interventional CT systems along with diagnostic equipment. The CT market is shaped by instruments capable of high scanning speed. Systems offering high scanning speed have reduced examination time and radiation exposure for patients.

Technology Trends

Advances in cardiac CT. Worldwide demand for healthcare has created a need for screening and early diagnosis of cardiovascular disease and cancer conditions. By harnessing advances in technology, cardiac CT has advanced beyond the evaluation of coronary stenosis to an imaging tool that permits accurate plaque characterization, assessment of myocardial perfusion, and probing of molecular processes that are involved in coronary atherosclerosis. Novel innovations in CT contrast agents and pre-clinical spectral CT devices have paved the way for CT-based molecular imaging. Since the development of the CT scanner, clinicians have been interested in visualizing the beating heart. With the introduction of the multi-detector CT (MDCT), this possibility became a reality.

Dual-energy CT. Compared to conventional CT dual-energy and spectral CT distinguish more effectively tissues of different types, as well as urinary stones of differing chemical composition; enhance stroke evaluation through the improved detection of brain infarcts; help uncover lung cancer lesions by improving contrast-to-noise ratio, overall image quality, and tumor delineation; identify calcium-based plaques, even in the presence of iodinated contrast agents; and reduce artifacts with beam hardening. Selective energy CT also may, in some instances, reduce radiation dose to patients by reconstructing a virtual non-contrast CT image from the contrast-enhanced image by filtering out iodine in the contrast medium, thereby eliminating the need for a second CT scan. 

Dual energy, or spectral imaging, can help address the challenge of blooming artifacts. Additionally, dual energy has also been shown to reduce beam hardening, which can lead to overestimation of coronary artery calcium. There have been some initial investigations using dual-energy CT to help clinicians see in and around plaque, potentially to assist in the evaluation of in-stent restenosis. Dual energy CT has the potential to reduce the amount of contrast used in studies. This is an important consideration when imaging patients with renal dysfunction.

CT Perfusion and CT FFR. Functional imaging with CT - both CT perfusion and CT fractional flow reserve (FFR) - is another emerging technology that shows promise in helping address the issue of overestimation of stenosis in patients with calcified plaque. Various studies have shown CT perfusion to be at least equal to SPECT or invasive angiography for detecting ischemia and infarct. A multi-center, multi-vendor study of myocardial perfusion imaging comparing CT perfusion to SPECT found a comparable diagnostic accuracy of CT perfusion to SPECT. CT perfusion can detect myocardial ischemia and adds incremental value to CT angiography, improving the diagnostic accuracy with improved specificity and positive predictive value.

Major companies are working toward expanding their product portfolio with the goal of allowing clinicians to perform both anatomical and physiological, or functional imaging such as CT perfusion on the same system, providing a one-stop shop approach to cardiac CT. While the dose was an issue with CT perfusion, now, with iterative reconstruction (IR), clinicians can reduce the dose and acquire data in a single rotation. Dose recording software developed by manufacturers have enabled hospitals to build a more robust radiation safety program and re-evaluate their radiation safety practices. Empirical data from these systems offer justification for changing imaging protocols and revision of workflows in both radiology exams and interventional procedures.

”Make in India means much more than local manufacturing for us at GE Healthcare. It is a 360 degree thrust starting with designing and developing relevant solutions in partnership with our users; robust engineering of technologies; developing a world-class supply chain, advanced manufacturing, expert user training and developing a network for distribution as well as maintenance of these solutions in the remotest parts of the country and world. It represents our commitment to work toward making quality healthcare truly accessible and affordable for India as well as the world."

John Flannery
President and CEO,
GE Healthcare

"We are proud that our first ever locally designed CT technology - Revolution ACTs is developed by the people of India, for the people of India. It is a testament to India's intellectual, design, and advanced manufacturing capabilities."

Terri Bresenham
President & CEO,
GE Healthcare South Asia

Fractional flow reserve CT has also shown promise for calculating flow dynamics. FFR CT provides high diagnostic accuracy and discrimination for the diagnosis of hemodynamically significant CAD with invasive FFR as the reference standard. When compared with anatomic testing by using coronary CTA, FFR CT led to a marked increase in specificity and positive predictive value. While the technology appears promising, the main disadvantage is delay in diagnosis. Currently the images must be sent to the manufacturer for analysis. For the technique to become more widely adopted, the calculation of CT FFR need to take place ideally on the clinicians' workstations so it does not impede workflow.

System enhancements. Though the majority of CT scanners are still used as general systems, some are being customized for specific purposes such as cardiovascular studies or bone densitometry. CAD software has been instrumental in bringing new applications such as cancer detection to the table with CT. On average, the CT market has been a growth market in the last five years. The multi-slice feature has moved CT from simply a diagnostic tool to an interventional modality.

Today's modern scanners - boasting from 64 to 320 detectors - are capable of generating sub-millimeter slices with gantry rotation times as low as 0.25 seconds, collimation as narrow as 0.24 mm, and reconstruction times as fast as 0.020 seconds or shorter. Many systems can image the heart in a single gantry rotation and enable free-breathing CTA exams. The CT segment most in demand, particularly in the growth sector, is the 16-detector-row scanner. Unless a center plans to offer coronary imaging, it will settle for 16-slice CT. This affirms that the switch from 16-slice to 64-slice CT was motivated primarily by coronary imaging. Cardiac CT substitutes catheter angiography for stable coronary artery disease. With time, it is likely that 64-detector-row CT will disappear from the Indian market and imaging centers interested in coronary imaging will opt for higher-end CT. At the same time, 16-detector-row CT will be the workhorse and likely to become less expensive as it penetrates further.

Second Opinion
CBCT- A Paradigm Shift

Digitization has caused facelift of the world. Medical engineering has reached its apex and has given the medical world precise and easy-to-use diagnostic equipment and tools. Digital radiology is helping diagnosticians like never before. Three-dimensional studies are now possible with CT scans that give accurate diagnosis and help in proper treatment planning thus bettering the prognosis. A specially designed CT technique for head, neck, and face region was introduced worldwide in 2001 known as cone beam computed tomography (CBCT). CBCT offers several additional advantages like 50-500 times reduced radiation dosage to the patient, reduced metal artifacts, reduced scan time, reduced cost of the unit, varying fields of view, submillimeter resolution, precision, and better patient compliance as compared to CT. Several biggies have come up in this field and buyers now have several options to choose units. While the core concept remains the same, the companies offer different image acquisition software and varying fields of view.

Introduction of CBCT in dentistry has helped dentists better their success rates. CBCT provides primary data for surgical stent fabrication and has therefore improved surgical ease. Decisions regarding re-root canal treatment over extractions, size of implants, need of grafting, sinus elevation, and access to the impacted tooth can easily be made. If a preoperative scan is shot and studied well then there are no last minute surprises left during dental procedures. Predictable results can then be obtained. Research is simplified as human cadaveric studies are largely replaced by CBCT assisted studies with comparable accuracy. With high precision and definite diagnostics CBCT has truly been a boon to dental fraternity and has caused a paradigm shift in healthcare.

Dr Alok Ashok Lathi
Director and Consultant,
Wave CBCT Imaging, Pune

Second Opinion
Reducing Radiation Dose- Need of the Hour

The big focus area today is to reduce radiation doses as awareness in clinicians and general public growing rapidly. The vendors are focusing on developing newer hardware and algorithm to ensure minimum radiation per scan without compromising on image quality or in fact with improvement of CT images.

The routine use of iterative reconstruction algorithm is becoming the standard practice with high-end new-generation scanners for the last 2-3 years. But there are newer algorithm developed continuously which can virtually remove noise from the image with simultaneous reduction in radiation dose. These are called model-based iterative reconstruction as general terminology where image noise reduces dramatically and actually one can visualize small pathologies better and able to differentiate them.

The major CT manufacturing companies offer product solution mainly for performance in the premium segment.  Image quality at lower radiation levels and advanced applications are key customer criterion in this segment.

IMR sets a new direction in CT image quality with virtually noise-free images with low-contrast resolution, which has been long associated with MRI. This improvement in low-contrast resolution is a breakthrough made possible through iterative reconstruction built on a knowledge-based model in addition to image quality benefits. For the first time physicians are also able to combine these improvements simultaneously with lower doses.  Kinetic motion of any nature is detrimental toward the image quality output. IMR is the first knowledge-based solution that overcomes the motion-sensitivity associated with traditional model-based solutions, allowing it to be used in even the most advanced acquisitions, such as Cardiac CTA. Enabled by next-generation reconstruction hardware and reconstruction algorithm innovation, reconstruction speed allows IMR to be used in even the most time demanding applications, such as trauma.

There is another area where big improvement is taken up by all vendors is to make detectors more sensitive where imaging can be performed even with lower X-ray power. The complex detector electronics is getting miniaturized improving signal quality at lower radiation level.

The newer lower power protocol can be applied for imaging with this new generation of detector system.

Every vendor is also working on reducing complexity in scanner operations and making them more efficient. This also allows users to optimize dose and image quality without much intervention.

Dual energy and spectral imaging are of great interest and curiosity for all users where newer techniques are developing which will make routine use of these techniques. Clinicians are really expecting from vendors more deliverables than promises in this area.

May be in the near future the CT imaging will be able to characterize the pathology rather than just finding size and location. Different approaches in terms of technology adopted by all vendors are to get spectral reading as kV switching, dual source, and spectral detectors. Thus, multiple images of tissue can be achieved from various energies.

Dual source CT scanners make use of two X-ray tubes and the detector system. Cardiac, imaging, evaluation of calculi and imaging at various energy levels can be performed for extracting more data as related to the constituents of a lesion.

Another interesting and important area where vendors are introducing more value based system at entry-level CT scanner is by making it more affordable and viable. Thus taking care in remote areas, smaller towns, and villages, such systems do not compromise diagnostic image quality.

Currently, Philips, Siemens, and GE are the major players producing low dose scanners. The workstations and the software produced by multiple vendors including other companies such as Terarecon score over each other by providing extra and better information.

The future trend has to be development of contrast medias suitable at low dose energy systems, thus giving the metabolic basis on CT, which is currently only on MRI.

Dr TBS Buxi
Sir Ganga Ram Hospital, New Delhi


The market for top-of-the-range CT scanners includes large corporate and flagship hospitals that leverage new technologies to assert their international brand and tap into the burgeoning medical tourism industry. As the screws on new technology are tightened in the developed markets, hospitals in India will use same technology to further their healthcare infrastructure. Major academic centers funded by the government will also vie for new high-end technology to establish their academic credential and research potential. The original equipment manufacturers continue to make specific technological developments enabling customers to better manage patient care, including lung cancer screening, dose guidance and regulation, spectral and multi-energy imaging, and expansion of cardiac and brain imaging. The future of CT will be scanners that are faster, more automated, and easier to use, with the goal of transitioning from a good interpretation tool to something with more quantification for speedy and direct diagnosis.

10 Diagnostic Imaging Trends for 2018



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