Dose reduction is still key, but image quality, resolution, and improvements in workflow are gaining prominence too.
The global demand for CT scanners was valued at approximately USD 4924.0 million in 2017 and is expected to generate revenue of around USD 7126.0 million by end of 2024, growing at a CAGR of around 5.4 percent between 2018 and 2024. Hospitals will continue to invest in CT technology, as imaging use increases and CT is used as a first-line imaging device, especially in emergency departments. CT scanners are fast, continue to offer lower doses, and can prove to be total-cost-of-ownership solutions to providers. Dose reduction is still key, but image quality, resolution, and improvements in workflow are becoming more important to customers.
The biggest advances in CT scanners over the past few years have been the introduction of new dose-lowering technologies, easily upgradeable scanners to allow conversion to high-slice systems, and faster gantry speeds to freeze cardiac motion. Additionally, the concept of slices a scanner can image at once is less important today than the total anatomical coverage the scanner can image in one rotation. An issue with 64-slice scanners was that it usually took two rotations to image the heart, with the two images being stitched together, which can lead to stitching artifacts. Scanners with wider anatomical coverage capable of imaging the heart on one rotation without the need for stitching are ideal for CTA. All the major CT vendors — GE, Hitachi, Philips, Siemens, and Toshiba Medical (a Canon Group Company) — have introduced new CT systems in recent years with enhanced cardiac scanning capability.
Detector resolution is another area of research to increase the image sharpness, especially to better define smaller structures like plaque composition and stents inside coronary vessels. Toshiba is currently testing a new scanner with a resolution of 0.2 mm. The company also released in April 2017 the compact and economical Aquilion Lightning 80 system. The 80-detector row (160-slice) system is designed for full body imaging and routine volumetric scanning with the premium CT technology found on high-end systems so that providers can deliver a better patient experience. It delivers fast reconstruction speeds of up to 50 images per second at full resolution, and it optimizes workflow and patient comfort with thin slices at 0.5 mm and a 78-cm bore. It also utilizes Single Energy Metal Artifact Reduction (SEMAR) and SURESubtraction. It can be reconfigured from 40 to 80 to 160 slices without replacing hardware.
The University of Iowa Stead Family Children’s Hospital in Iowa City is the first facility in the United States to install Somatom Drive CT system from Siemens Healthineers. The new high-performance scanner joins the Somatom Force and Somatom Definition Flash in the dual-source segment of the company’s CT portfolio. It was designed to drive precision in diagnostic imaging across clinical disciplines, including cardiology. The Drive’s new Straton MX Sigma X-ray tube voltages are adjustable in 10 kV increments ranging from 70 kV to 140 kV, allowing clinicians to tailor the voltage and, therefore, the dose to each patient. It also offers extremely fast scanning speeds that support sedation-free pediatric exams and to freeze cardiac motion. The company claims cardiac imaging can be done in one heartbeat without the need for beta-blockers in some patients.
GE Healthcare has recently introduced its Whisper Drive technology, which is designed to take high-speed scans that allow full imaging of the heart in one heartbeat. This is accomplished using a high-speed X-ray tube, weighing about 100 pounds, that routinely reaches 70 Gs as it circles around the patient up to five times per second. This high speed is combined with intelligent motion correction. The gantry is constructed from aerospace-grade aluminum and includes a system of springs that absorb the acceleration, preventing movement of parts like the electronic board inside the detector. It uses contactless transmission to send power to the machine and collect the imaging signal from it. Older CT scanners use brushes to transmit power, but increasing the speed led to wear and reliability issues.
The latest configuration of the spectral CT from Royal Philips provides clinicians with advanced functionality that supports emergency and trauma department care. The new IQon Elite CT has faster reconstruction speeds and better visualization of bone marrow pathology. These faster reconstruction speeds have been shown to enable the imaging of up to 200 CT patients per day (under a protocol of 600 images per SBI, 3 conventional series per patient, and 1.5 SBI). The scanner’s ability to estimate electron density enhances tissue characterization, while a new radiation therapy planning couch and bariatric table permit larger patients to be scanned with increased positioning controls.
Indian market dynamics
The Indian CT scanners market in 2017 is estimated at Rs 1150 crore, translating to 944 units in quantity terms. While average unit prices remained steady, it is the 64–128 slice category which jumped from 48 units in 2016 to 100 units in 2017, an increase of 11 percent in value terms over 2016. The major contributor was a 22 units order received by GE from HLL. The >128 slice machines continue to constitute 5 percent of the market in value terms, with the Indian buyer in no hurry to invest in high-end technology, albeit dose reduction is the most important criteria when selecting a model. The 11 percent increase in share for 64–128 slice machines came from the two categories less than 64 slices. The market is dominated by GE and Siemens, with Philips a close second.
The portable CT scanners segment is gaining popularity at a rapid rate, which is a reflection of increasing number of device installations, lower switching costs provided by these portable products, and growing application horizons. Most of the makers are concentrating on developing portable products and increasing their geographical presence to strengthen their position in the market.
The evolution of CT scanners has advanced to the point where the number of slices per rotation is no longer the benchmark for performance. With the advent of high-speed and multi-slice CT scanners, healthcare providers have changed their approach to imaging, diagnosis, and treatment of patients as new ways for clinical applications in areas such as trauma, vascular, pediatric, and cardiac imaging are possible due to the higher speeds at which scanning can be done. CAD software has been pivotal in bringing new applications to CT, for example, making cancer detection possible with CT.
Ayushman Bharat program is expected to provide a major impetus to this segment. The National Health Policy, 2017 has envisioned health and wellness centers as the foundation of India’s health system. Under this, 1.5 lakh centers will bring the healthcare system closer to the homes of people. These centers will provide comprehensive healthcare including diagnostic services, including the installation of CT scan facilities. An allocation of Rs 1200 crore has been made for this flagship program.
Trends and advances in CT technology
Artificial intelligence (AI) integration across vendors to aid quantification and workflow and advanced algorithms to pull more diagnostic data out of CT image datasets. Deep learning will maximize efficiency. This includes automatic iso-centering of patients on the scanner, automated identification of anatomy, specific coronary vessel segments, and plaque and calcium detection.
Use of CT to guide interventions. This includes use of CT imaging for structural heart procedure patient selection, planning access routes, device sizing and to guide the actual interventions. CT has become a gold standard for transcatheter aortic valve replacement (TAVR) and left atrial appendage (LAA) occlusion planning and guidance, but it plays an even more important role with the more complex transcatheter mitral valve replacement (TMVR) procedures coming into use. CT is also being used more to guide interventional procedures.
Fractional flow reserve CT (FFR-CT), which can non-invasively derive FFR blood flow readings for the entire coronary tree using computational fluid dynamics supercomputing algorithms. This can show if intermediate or significant coronary plaques are actually flow limiting or not to definitively screen a patient to be sent to the cath lab for an intervention, eliminating the need for diagnostic catheterizations.
CT perfusion, which maps the iodine contrast levels in the myocardium through the cardiac cycle, is starting to gain market traction thanks to validation studies showing its diagnostic accuracy compared with the gold standards of magnetic resonance imaging (MRI) and nuclear perfusion exams.
Spectral CT is likely going to become a standard part of CT imaging in the years to come. The ability to look at images at different kV energy levels allows cardiologists and radiologists to see different things than on average kV range images. This includes the ability to better image myocardial perfusion deficits, aid in metal artifact reduction to see restenosis inside stents, reduce metal blooming due to pacemaker leads or surgical clips, enhance plaque imaging, direct infarct imaging, and to better identify thrombus.
More sensitive CT detector technology that can reduce dose and increase image resolution. Two CT vendors now offer systems with resolutions down to 0.25 mm, when the standard today is 0.5. The newest generation detectors in development use computer power and photon counting to improve image quality beyond today’s generation of detectors.
Vendors will continue to develop solutions for lower dose, improved resolution, and improved workflow that will remain important in busy environments in which CT systems are typically found. Additionally, using big data and artificial intelligence, CT exams will continue to grow, and the market will see improvements on how big data is used to change clinical pathways and improve care.
Hybrid Imaging: The Future Ahead
A couple of decades back, nuclear medicine was referred to as a specialized imaging application, catering to a niche group of patients. In the last 10 years, by expanding and diversifying as hybrid imaging, facilitating direct fusion of morphologic and functional information with high-resolution single-photon emission computed tomography (SPECT) and positron emission tomography-computed tomography (PET CT), nuclear medicine is rapidly invading the arena of diagnostic imaging, especially in the field of oncology. Cancer diagnosis, treatment response evaluation, follow up, and surveillance, all can be accomplished to a large extent by undergoing this single imaging modality which combines at least five (sometimes more) regional CT scans and their functional information in one shot. In non-oncological setting, infection imaging, cardiovascular imaging, and functional imaging of neurodegenerative and neuroinflammatory conditions, are amongst few conditions where functional imaging often provides valuable information.
The technology has evolved side by side and starting from single detector gamma cameras, we have now multi-detector gamma cameras, with the facility of multimodality fusion in the form of SPECT-CT/MRI and high resolution multi detector CT scanners, intrinsically incorporated into the PET CT systems, capable of providing exquisitely detailed CT anatomy by providing very fine (mm sized) slices. PET MRI is another extension of the concept of hybrid imaging, which promises decreased radiation dose to the patient with better soft tissue resolution and allows for additional techniques like angiography, functional MRI, diffusion, spectroscopy, and perfusion techniques in one examination. Systems are being designed for low cost clinical applications to very high-resolution research applications with improved detector technologies.
Along with diagnostic applications, various radio-therapeutic molecules are also being developed which can help deliver targeted radiation dose to pathological sites. The nuclear medicine market is traditionally segmented into diagnostic and therapeutic products. The diagnostic segment comprising of SPECT and PET scanners, held the largest market share till 2016, while the therapeutics segment offering alpha emitters, beta emitters, and brachytherapy, is estimated to drive growth in the market during the coming years. An increasing incidence of cancer and cardiovascular disorders is contributing toward the growth of the global nuclear medicine market, the size of which was valued at USD 6.3 billion in 2016 and is expected to grow at a CAGR of 10.2 percent, fuelled by a growing demand for these diagnostic procedures.
In conclusion, the development of multi-modality hybrid imaging has revolutionized the practice of nuclear medicine and the number of mushrooming PET CT centres all over India is a direct evidence of the impact of this technology on the present medical investigation scenario.
Dr Ritu Verma
Consultant and Head, Department of Nuclear Medicine and PET CT,
Mahajan Imaging Center, Sir Ganga Ram Hospital