Rise and impact of advanced imaging technology

Technology has taken the world of healthcare to a new level which looks promising and supports a wide scope for innovation.

Medical technology is undoubtedly indispensable to the health and improved quality of life of people. It has revolutionised healthcare over almost the past three decades, allowing doctors to find disease earlier and improve patient outcomes.

In a utopian world, it would have been possible to diagnose, treat and cure patients without causing any harmful side effects. Since this is not possible, the efficacy of medical imaging cannot be overstated considering it has enabled doctors to see inside a patient without having to cut them open. It has ensured the early detection and treatment for cases such as lung, breast cancers etc. The chances of medico–legal issues to have been reduced due to delayed or incorrect diagnosis.

There is some downside to the rise of imaging technology too. In the present era, the deterioration of skills in physical examination has become much more evident. Poor clinical skills in new doctors or even senior doctors losing their touch with clinical skills have made meticulous examination extinct.

Conventional ultrasound imaging relies on good contact between the transducer and the skin, using acoustic coupling gel. Without this, the ultrasound beam encounters a large acoustic impedance mismatch between the transducer and the air in front of it, which prevents beam transmission. This limits the use of ultrasound in some clinical scenarios, including imaging of open wounds and during surgery, where sterile conditions are required.

Now, researchers in Japan have demonstrated non-contact ultrasound imaging, where the transducer is separated from the skin by air. “The project is in its infancy, but the results to date have been very encouraging,” claims Gregory Clement, physicist and lead author of the study conducted at the University of Electro-Communications in Tokyo.

The non-contact technique exploits the greater focusing potential of ultrasound in air, in which focal diameters one-quarter of that possible in tissue can be achieved. High beam intensity in air compensates for the low transmission of the beam across the air–skin boundary. The group’s approach uses a bowl-shaped transducer to focus an ultrasound beam onto a 5 mm spot at the skin surface. The spot generates a point source of ultrasound that, when scanned over the surface of an object, can be used to perform diffraction tomography. “The method treats the skin surface as a ‘virtual’ transducer, allowing for a large effective number of sources and receivers, thus opening the potential for large regions to be imaged,” claims Clement. “Current medical probes can’t conform to the body, thereby limiting where they can be placed.”The team simulated and constructed 40 kHz transducer prototype, comprising 400 elements arranged in a hemispherical array.

Using a low, suboptimal frequency for imaging, elements capable of emitting40 kHz that are commercially available at low cost the researchers ‘have provided proof-of-principle. After beam characterization and transmission measurements, they acquired images using the transducer and a broadband microphone receiver. In vivo, non-contact imaging of a hand was demonstrated with a conventional C-mode approach, which produces images with a fixed depth below the skin. The low-res scan showed the varying contrast between the anatomy containing mainly bone and that containing only soft tissue.

Clement says that the group will continue the development and clinical testing of the non-contact imaging technique over the next few years. Ongoing work in the lab includes optimising the receiver to increase technique sensitivity and investigating faster acquisition techniques to reduce scan times.

The ability to visualise processes that take place in the brain during the development and progression of Alzheimer’s disease also provides a powerful aid for diagnosing the condition, monitoring treatments and testing preventive and therapeutic agents. Taut angles are not only an important marker of neurodegeneration in Alzheimer’s disease but also a hallmark of other neurodegenerative disorders that do not involve amyloid-beta plaques. And while imaging technologies have been developed to observe the spread of amyloid-beta plaques in patients’ brains, tau tangles have previously not been easily monitored in living patients.

There are other some latest cutting-edge imaging techniques that may become popular in the near future. Pocket-sized hand-held ultrasound devices are predicted to replace the 200-year-old stethoscopes in near future. They can diagnose heart, lung and other problems more accurately than traditional stethoscopes.

Similarly, hyperspectral imaging may provide a non-invasive diagnostic method that allows determination of pathological tissue with high reliability. There are chances that this would also lessen doctor’s liability and reduce indemnity insurance premiums. This technology is in use in the defence sector and is now finding applications in the healthcare imaging Industry.

Research is also on in the field of stem cell migration and immune cell trafficking, as well as in the areas of targeted iron oxide nanoparticles for molecular imaging studies. Another study that is under focus is that on the ultra small superparamagnetic iron oxide particles that are being researched as blood pooling agents for angiography, tumour permeability and tumour blood volume or steady-state cerebral blood volume and blood vessel size index measurements.

Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D-bioprinted tissue models for research, drug discovery and toxicology.

A new technique has been developed by researchers at Philips that determines blood flow velocity. Philips has applied or a patent for it. The method uses ultrasound pulse at one location and the pulse is detected at a second location by an ultrasound receiver. The calculation is then done for a flow velocity of blood in a blood vessel between the first and second locations.

 This article has been authored by Dr Rajeev Boudhankar, CEO, Bhatia Hospital