Researchers have reported an approach to photoacoustic imaging that offers vastly improved resolution, setting the stage for detailed in vivo imaging of deep tissue. The technique is based on computational improvements, so it can be performed with existing imaging hardware, and thus could provide a practical and low-cost option for improving biomedical imaging for research and diagnostics.
After further refinements, the approach could offer the opportunity to observe the minute details of processes occurring in living tissue, such as the growth of tiny blood vessels, and therefore provide insights on normal development or disease processes such as cancer.
“Our main goal is to develop a microscope that can see the microvasculature and capillary vessels,” said Ori Katz, a researcher with the Hebrew University of Jerusalem, Israel, and senior author of the study. “It’s important to be able to watch these grow with nearby tumours, for example.”
The researchers describe overcoming the acoustic diffraction limit, a barrier that previously limited the resolution obtainable with photoacoustic imaging, by exploiting signal fluctuations stemming from the natural motion of red blood cells. Such fluctuations might otherwise be considered noise or viewed as detrimental to the measurements.
“With photoacoustic imaging you can see much deeper in tissue than you can with an optical microscope, but the resolution is limited by the acoustic wavelength,” Katz said. “What we have discovered is a way to obtain photoacoustic images with considerably better resolution, without any change in the hardware.”
Photoacoustic imaging combines optical illumination (which uses light waves) and ultrasound (which uses sound waves) to image biological samples in ways that would not be possible with either modality alone. Optical methods can provide excellent resolution but often only near the surface as light is highly scattered in tissue. Ultrasound can go much deeper but does not offer the same contrast as optical imaging. By integrating the two modalities, researchers have been able to overcome the drawbacks of each to advance a host of applications.
However, the imaging technique does have certain limitations. Photoacoustic imaging relies on acoustic detection, so the image resolution is determined by the acoustic wavelength. While optical microscopy, for example, can see objects on the scale of less than a micron, photoacoustic imaging is limited to tens of microns. This means that photoacoustic imaging cannot resolve small objects like microvessels or capillaries.
Katz devised the method for surpassing the acoustic diffraction limit in collaboration with Emmanuel Bossy, now at Université Grenoble Alpes in Grenoble, France. At the heart of their work is an advanced statistical analysis framework that they apply to images of red blood cells flowing through the vessels; the blood cells facilitate imaging by absorbing light at particular wavelengths. By increasing the resolution computationally, they avoided the need for any additional hardware, so the advances described can be attained using existing photoacoustic imaging systems.
 The tools needed to achieve super-resolution with photoacoustic imaging were described nearly a decade ago in a work in optical microscopy with the technique of super-resolution optical fluctuation imaging (SOFI). Katz and colleagues came to this work after grappling with the problem of the acoustic diffraction limit and discovered that the same mathematics used with SOFI could be used for improving photoacoustic imaging.
“Someone just needed to make the connection,” Katz said. “It’s the same equation—the wave equation. Mathematically, you could say it’s the same problem.”
Katz and his colleagues demonstrated the ability to surpass the acoustic diffraction limit using a SOFI-inspired photoacoustic imaging technique. That work had two main limitations. First, it required the use of a long-coherence laser, not a standard part of photoacoustic imaging systems, in order to form dynamic structured interference patterns called speckle to create the signal fluctuations. Second, due to their small dimensions, the use of speckles as dynamic illumination resulted in the fluctuations having a low amplitude with respect to the mean photoacoustic signal, which in turn made it difficult to resolve the specimen in question.
In the new study, the researchers showed that they could overcome these limitations by applying the statistical analysis framework to the inherent signal fluctuations caused by the flow of red blood cells—so the researchers didn’t need to rely on coherent structured illumination—and furthermore demonstrated experimentally that they could perform super-resolution photoacoustic imaging using a conventional imaging system.
The demonstration served as a proof of principle for the new technique. The researchers are now focused on developing it further, to fulfill its potential for in vivo applications.
Katz described two main challenges in reaching this goal. The first is the problem of motion artifacts. In their demonstration, the researchers imaged blood streaming through small tubes. In animal models and in humans, though, blood flow is only one of the motions they would have to consider. The technique would also need to account for the heartbeat, the changing volume of the vessels and even microscale movements of the tissue itself.
The other main challenge relates to signal levels. In recent experiments blood was the only absorber in play, but in real-world scenarios other absorbers would be present. The researchers are now working on ways to better see the signal originating from flow while suppressing any background signals.

The Optical Societyhttps://tinyurl.com/ybrr85l8

Investigators at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MGH) have used magnetoencephalography (MEG) – a technology that measures brain activity by detecting the weak magnetic fields produced by the brain’s normal electrical currents – to measure levels of the iron-based mineral called magnetite in the human brain. While magnetite is known to be present in the normal brain and to accumulate with age, evidence has also suggested it may play a role in neurodegenerative disorders like Alzheimer’s disease.
“The ability to measure and localize magnetite in the living brain will allow new studies of its role in both the normal brain and in neurodegenerative disease,” says David Cohen, PhD, of the Martinos Center, corresponding author of the report published in Human Brain Mapping. “Studies could investigate whether the amount of magnetite in the hippocampal region could predict the development of Alzheimer’s disease and whether treatments that influence magnetite could alter disease progression.”
Cohen was the first to measure the magnetic fields generated by currents within the brain when he was at the University of Illinois in 1968. After he moved to the Massachusetts Institute of Technology in 1969, the development of highly sensitive magnetic detectors – along with the availability of a room well shielded from external magnetic fields – significantly improved detection of the magnetic fields produced by the brain, as well as the heart and lungs. Since then, MEG has developed into a valuable tool for research – particularly for its ability to precisely measure when a brain signal occurs, in contrast to functional MRI that can reveal where it takes place – and to guide surgical treatment of brain tumours and epilepsy.
While magnetite particles were first reported in the human brain in 1992, until now their presence could only be studied in post-mortem brains. Previous studies found higher levels of magnetite in the brains of older individuals – implying age-associated accumulation of the particles – and suggested that magnetite may play a role in neurodegenerative diseases. For example, magnetite particles have been associated with the characteristic plaques and tangles in the brains of patients with Alzheimer’s disease. The current study came out of Cohen’s investigation of MEG signals produced by direct current (dc) magnetic fields, rather than the better understood alternating current fields.
The earliest dcMEG mapping studies found only a single source of dc magnetic fields of the head, produced when healthy hair follicles over the scalp were lightly pressed. The availability of an advanced dcMEG system at the Martinos Center has allowed the detection of new phenomena, including for the first time, fields produced by magnetic material within the head. This observation led Cohen, who joined the Martinos Center in 2001, and lead author Sheraz Khan, PhD, to investigate the ability of dcMEG to measure the amount and the location of magnetite in the brains of healthy volunteers.
The study enrolled 11 male participants aged 19 to 89 – all with little or no hair, to avoid interference from the hair-follicle signal – who underwent an initial baseline dcMEG scan before being placed in a powerful MRI scanner, both to acquire an MR image and to magnetize any magnetite particles within their brains. A second dcMEG scan taken several minutes later revealed changes in the magnetic field that reflect the size and shape of magnetite particles, as well as other factors. Alignment of the MEG and MRI images allowed precise localization of the magnetic signals.
The results found greater accumulation of magnetite in the brains of the oldest volunteers, primarily in and around the hippocampus – the structure in which memories are encoded – replicating the findings of post-mortem studies. The rate at which the magnetic signal dissipated, which could reflect the size of magnetite particles, was measured by subsequent dcMEG scans taken from hours to several days later. The authors note that this new tool will be valuable for determining whether and how magnetite can be used in the diagnosis and potentially the treatment of Alzheimer’s disease and other disorders.
Massachusetts General Hospital
www.massgeneral.org/about/pressrelease.aspx?id=2315

The 34th Korea International Medical and Hospital Equipment show held in Seoul last March gathered 1,313 exhibiting companies from 34 countries, including 649 domestic Korean manufacturers over 40,122 sq m of exhibition space. The 4-day  event attracted over 73,000 visitors from 92 countries. About 30,000 items of medical equipment, including high tech devices, medical information systems, rehabilitation equipment and healthcare supplies were presented at the show. Over the years, KIMES has succeeded in establishing itself as the leading technology-oriented and most prominent medical exhibition in the whole of the South East Asian region.
In tune with this year‘s theme ‘Think the Future’, a number of exhibitors, mostly domestic,  were involved in robotic solutions applied to healthcare, showing a variety of robotic medical devices, for example medical sterilization robots, artificial joint orthopedic surgery robots, walking assistance robots as well as robotic rehabilitation systems. There was even a special rehabilitation robot booth in Hall B.
For the third consecutive edition of the show, the Global Bio & Medical Plaza organized by KOTRA (Korea Trade Investment Promotion Agency) provided extra business opportunities for domestic exhibitors by helping to develop commercial and business relationships between foreign and overseas guests and Korean companies.
KIMES is a definite must for international buyers interested in the latest product developments from the particularly dynamic and innovative Korean medical device industry as well as for foreign companies keen to boost their market share in the Korean growing healthcare industry fuelled by increasing consumer demand. KIMES 2019 will take place in Seoul from 14 to 17 March of next year.

KIMESwww.kimes.kr

Hologic, Inc. opened on March 21, 2019 its first Learning and Experience Centre in Zaventem, Belgium (a municipality neighboring Brussels). The state-of-the-art facility provides comprehensive training for customers, healthcare professionals and employees across Hologic’s Europe, Middle East and Africa (EMEA) region, centralizing the education experience for Hologic’s technologies.
Radiologists, lab technicians, obstetrician-gynecologists and many other healthcare professionals count on Hologic solutions to perform when lives are at stake. The 1,500m2 Learning and Experience Centre contains fully equipped training labs with demonstration capabilities for technologies from all four of Hologic’s divisions (Breast & Skeletal Health, Diagnostic, Gynecological Surgical and Medical Aesthetics) to ensure the highest level of understanding and provide hands-on experience.
“The opening of our new Hologic Learning and Experience Centre in Brussels is a significant milestone in our company’s history and reflects our deep commitment to providing unparalleled training and support to our customers,” said Jan Verstreken, Regional President EMEA and Canada at Hologic. “Hologic is a global champion for women’s health and brings leading-edge technology to healthcare systems around the world. The patient is our greatest priority and when their health is in question, nothing is more important to us than providing the most accurate, effective, and timely diagnosis or treatment. As Hologic continues to gain recognition as a leader in women’s health, we commit to supporting the healthcare systems and their patients by ensuring the absolute best use of our truly unique technologies, for the direct benefit of millions of patients in the region.”
For the first time, Hologic will bring training and education for all its products under one roof – located at the heart of Europe – to offer the most cohesive, convenient and interconnected experience. Products featured at the Hologic Learning and Experience Centre include:
3Dimensions™, a mammography system that delivers the fastest, highest resolution 3D™ images and is clinically proven to be more comfortable and enhance workflow; Panther Fusion^®, a fully automated, integrated molecular testing platform with true sample-to-result automation, adaptable workflow options, and a consolidated testing menu; NovaSure®, a minimally invasive, one-time, five-minute endometrial ablation procedure to reduce or stop abnormal uterine bleeding; PicoSure^®, a laser workstation to remove tattoos and revitalize skin by reducing the appearance of wrinkles, acne scars and pigment-like freckles, sunspots and discoloration.
The creation of Hologic’s European hub and the consolidation of key European functions, including customer service, will create up to 60 new jobs in Belgium over the next 12 months. Each year, the new Learning and Experience Centre is expected to welcome several thousand visitors including healthcare professionals, key opinion leaders, current and prospective customers, distributor partners, and employees.