Lihong Wang, Ph.D.

A Caltech-led team has developed a safe, effective, and painless breast imaging technique that incorporates machine learning to help differentiate between suspicious and healthy tissue. The method has now been tested on patients and performs as well as or better than other conventional breast imaging techniques.

For decades, X-ray mammography has been the gold standard of breast imaging for the early detection of breast cancer. While the technique remains valuable in terms of reducing cancer deaths, it does expose patients to small amounts of ionizing radiation, painfully squeezes breasts to allow X-rays to more easily pass through tissue, and, especially in the case of dense breast tissue, produces many false positive diagnoses… Continue reading.

Quantum imaging is a growing field that takes advantage of the counterintuitive and “spooky” ability of light particles, or photons, to become linked, or entangled, under specialized circumstances. If the state of one photon in the entangled duo gets tweaked, so does the other, regardless of how far apart the two photons might be.

Caltech researchers demonstrated last May how such entanglement could double the resolution of classical light microscopes while also preventing an imaging system’s light from damaging fragile biological samples. Now the same team has improved upon the technique, making it possible to quantum image whole organ slices and even small organisms… Continue reading.

Researchers in Caltech’s Andrew and Peggy Cherng Department of Medical Engineering have made a major step forward in medical imaging by taking inspiration from the field of astronomy.

The paper describing this research was published in Nature Photonics on January 23 and is titled “High-gain and high-speed wavefront shaping through scattering media.”

In astronomy, the light that reaches telescopes is distorted by the earth’s atmosphere, resulting in blurry images of planets, satellites, and other cosmic objects. The earth’s atmosphere is what’s known as a scattering medium; it scatters light, making images appear unfocused and cloudy. Wavefront shaping is a method of generating focused light by reversing the optical distortion caused by the atmosphere. In this method, a reflective device, like a mirror, “shapes” light waves to counterbalance distortion. It’s similar to a person wearing active noise-cancelling headphones to combat ambient noise… Continue reading.

Reach out right now and touch anything around you. Whether it was a key on your keyboard, the wood of your desk, or the fur of your dog, you felt it the instant your finger contacted it.

Or did you?

In actuality, it does take a bit of time for your brain to register the sensation from your fingertip, but it does still happen pretty darn fast, with the touch signal traveling through your nerves at over 100 miles per hour. Some nerve signals are even faster, approaching speeds of 300 miles per hour.

Now, scientists at Caltech have developed a new ultrafast camera that can record footage of these impulses as they travel through nerve cells. The camera can also capture video of other ultrafast phenomena, like the propagation of electromagnetic pulses in electronics… Continue reading.

Label-free intraoperative histology of bone tissue via deep-learning-assisted ultraviolet photoacoustic microscopyOf the many ways to treat cancer, the oldest, and maybe most tried and true, is surgery. Even with the advent of chemotherapy, radiation therapy, and more experimental treatments like bacteria that seek and destroy cancer cells, cancers, very often, simply need to be cut out of a patient’s body.

The goal is to remove all of the cancerous tissue while preserving as much of the surrounding healthy material as possible. But because it can be difficult to draw a clean line between cancerous and healthy tissues, surgeons often err on the side of caution and remove healthy tissue to make sure they have taken out all of the cancerous tissue… Continue reading.

In his quest to bring ever-faster cameras to the world, Caltech’s Lihong Wang has developed technology that can reach blistering speeds of 70 trillion frames per second, fast enough to see light travel. Just like the camera in your cell phone, though, it can only produce flat images.

Now, Wang’s lab has gone a step further to create a camera that not only records video at incredibly fast speeds but does so in three dimensions. Wang, Bren Professor of Medical Engineering and Electrical Engineering in the Andrew and Peggy Cherng Department of Medical Engineering, describes the device in a new paper in the journal Nature Communications… Continue reading.

Just about everyone has had the experience of blinking while having their picture taken. The camera clicks, your eyes shut, and by the time they open again, the photo is ruined. A new ultrafast camera developed at Caltech, were it aimed at your lovely face, could also capture you looking like a dunce with your eyes shut, except instead of taking just one picture in the time it takes you to blink, it could take trillions of pictures.

The new camera developed in the lab of Lihong Wang, Bren Professor of Medical Engineering and Electrical Engineering in the Andrew and Peggy Cherng Department of Medical Engineering, is capable of taking as many as 70 trillion frames per second. That is fast enough to see waves of light traveling and the fluorescent decay of molecules… Continue reading.

A little over a year ago, Caltech’s Lihong Wang developed the world’s fastest camera, a device capable of taking 10 trillion pictures per second. It is so fast that it can even capture light traveling in slow motion.

But sometimes just being quick is not enough. Indeed, not even the fastest camera can take pictures of things it cannot see. To that end, Wang, Bren Professor of Medical Engineering and Electrical Engineering, has developed a new camera that can take up to 1 trillion pictures per second of transparent objects. A paper about the camera appears in the January 17 issue of the journal Science Advances… Continue reading.

Researchers know that cancer cells are generally much more metabolically active than healthy cells, and some insights into a cancer cell’s behavior can be gleaned by analyzing its metabolic activity. But getting an accurate assessment of these characteristics has proven difficult for scientists, they say, adding that several methods, including position emission tomography (or PET) scans, fluorescent dyes, and contrasts have been used, but each has drawbacks that limit their usefulness.

Caltech’s Lihong Wang, PhD, believes he can do better through the use of photoacoustic microscopy (PAM), a technique in which laser light induces ultrasonic vibrations in a sample. Those vibrations can be used to image cells, blood vessels, and tissues… Continue reading.

A laser-sonic scanner developed by researchers at California Institute of Technology detected tumors in a small cohort of patients in as little as 15 seconds by shining pulses of light into the breast, according to a study published in Nature Communications.

“This scanner is the only single-breath-hold technology that gives us high-contrast, high-resolution 3-D images of the entire breast without using ionizing radiation or contrast agent that can potentially cause harm,” Lihong Wang, PhD, Bren professor of medical engineering and electrical engineering at the Caltech Optical Imaging Laboratory at California Institute of Technology, said in a press release. “Our goal is to build a dream machine for breast screening, diagnosis, monitoring and prognosis without any harm to the patient… Continue reading.

Researchers from the California Institute of Technology (Caltech) in Pasadena have developed a single-breath-hold photoacoustic CT (SBH-PACT) system that can image a patient’s breast in 15 seconds and requires no ionizing radiation or contrast agents, sharing their findings in a new study published by Nature Communications.

Lihong Wang, PhD, a Caltech professor of medical engineering and electrical engineering, and colleagues scanned the breasts of eight women using SBH-PACT for their pilot study, identifying eight of the nine breast tumors present.

“SBH-PACT clearly identified eight of the nine breast tumors by delineation of angiographic anatomy,” the authors wrote. “These tumors were subsequently verified by ultrasound-guided biopsy. In addition, to improve on the interpretation of images, we developed an algorithm to highlight tumors automatically. Tumors were clearly revealed by SBH-PACT in all breasts even in radiographically dense breasts, which could not be readily imaged by mammography… Continue reading.

The Optical Society (OSA) is pleased to name Lihong Wang, California Institute of Technology, USA, the 2018 Michael S. Feld Biophotonics Award recipient. Wang is recognized for inventing the world’s fastest two-dimensional receive-only camera and enabling real-time imaging of the fastest phenomena such as light propagation and fluorescence decay.

“Lihong’s research crosses disciplines and impacts what we can see today with advanced imaging technologies,” remarked OSA Award Selection Committee Chair, Maria Angela Franceschini, Massachusetts General Hospital, USA. “We are honored to be able to present this year’s Feld award to Lihong for the broad impact of his work… Continue reading.

A team of scientists led by Lihong Wang at Washington University have more than doubled the resolution capabilities of the world’s fastest receive-only camera.

Now, the camera can take pictures of laser pulses that last just trillionths of a second as they travel through the air.

The new capabilities, which are detailed in the June 30 edition of Optica, have broad implications for researchers studying neuron activity and could help researchers learn more about how the brain works.

The camera, ultimately a series of devices combined to capture raw data, was developed by a team of Washington University engineers led by Wang, the Gene K. Beare Distinguished Professor of Biomedical Engineering, with $4 million in grant money from the National Institutes of Health.

The camera uses a technique developed at Washington University’s School of Engineering and Applied Science called compressed ultrafast photography (CUP) and could have major implications for scientists and researchers looking to acquire images from outside of the universe to reactions within the body, Wang said.

Using a high-tech imaging method, a team of biomedical engineers at the School of Engineering & Applied Science at Washington University in St. Louis was able to see early-developing cancer cells deeper in tissue than ever before with the help of a novel protein from a bacterium.

Lihong Wang, PhD, the Gene K. Beare Distinguished Professor of Biomedical Engineering at the School of Engineering; Junjie Yao, PhD, a postdoctoral researcher in Wang’s lab, and a team of engineers found that by genetically modifying glioblastoma cancer cells to express BphP1 protein, derived from the rhodopsuedomonas palustris bacterium, they could clearly see tens to hundreds of live cancer cells as deep as 1 centimeter in tissue using photoacoustic tomography.

The work, published Nov. 9 in advanced online publication of Nature Methods, is the first to combine deep-penetration, high-resolution photoacoustic tomography with a reversibly switchable, non-fluorescent bacterial phytochrome.

The migration of photoacoustic (PA) imaging technology from bench top to bedside, long expected thanks to its potential as an alternative to MRI and CT scanning in early-stage cancer detection, continues to take shape.

Use of the technique in breast cancer screening has always been identified as a likely clinical success story – not least by PA pioneer Lihong Wang – as it could offer ways to improve upon the high levels of false-positive results or other uncertain conclusions that current testing methodologies can deliver.

Further proof of that suitability should come from a small-scale clinical trial carried out at the University of Florida, the initial findings of which have now been released. The study used a photoacoustic tomography (PAT) platform developed by the university and now licensed to a new company, Advanced fPAT Imaging Inc (AFPII).

Company CEO Michael Addley told Optics.org that the clinical trial had involved a modest group of between 20 and 25 patients. "This is a small proof-of-concept study, that has had amazing results," he said.

The trial used AFPII’s JBI-360 imaging system, a platform developed from the work of Huabei Jiang at the University of Florida and which employs a functional photoacoustic tomography – or fPAT – approach. In use, maps of total hemoglobin concentration (HbT) and oxygen saturation (O2%), two key indicators of the metabolic activity associated with cancerous and pre-cancerous tissues, are reconstructed using a finite element algorithm to give valuable information about tumor location and sizing.

A human skull, on average, is about 6.8 millimeters (0.3 inches) thick, or roughly the depth of the latest smartphone. Human skin, on the other hand, is about 2 to 3 millimeters (0.1 inches) deep, or about three grains of salt deep. While both of these dimensions are extremely thin, they present major hurdles for any kind of imaging with laser light. 

Why? The photons in laser light scatter when they encounter biological tissue. Corralling tiny photons to obtain meaningful details about tissue has proven to be one of the most challenging problems laser researchers have faced to date. 

However, researchers at Washington University in St. Louis (WUSTL) decided to eliminate the photon roundup completely and use scattering to their advantage. The result: an imaging technique that would peer right into a skull, penetrating tissue at depths up to 7 centimeters (about 2.8 inches). 

The approach, which combines laser light and ultrasound, is based on the photoacoustic effect, a concept first discovered by Alexander Graham Bell in the 1880s. In his work, Bell discovered that the rapid interruption of a focused light beam produces sound. 

To produce the photoacoustic effect, Bell focused a beam of light on a selenium  block. He then rapidly interrupted the beam with a rotating slotted disk. He discovered that this activity produced sound waves. Bell showed that the photoacoustic effect depended on the absorption of light by the block, and the strength of the acoustic signal depended on how much light the material absorbed.

"We combine some very old physics with a modern imaging concept," said WUSTL researcher Lihong Wang, who pioneered the approach. Wang and his WUSTL colleagues were the first to describe functional photoacoustic tomography (PAT) and 3D photoacoustic microscopy (PAM). [Listening with Lasers: Hybrid Technique Sees Into Human Body ]

The two techniques follow the same basic principles: When the researchers shine a pulsed laser beam into biological tissue, the beam spreads out and generates a small, but rapid rise in temperature. This produces sound waves that are detected by conventional ultrasound transducers. Image reconstruction software converts the sound waves into high-resolution images. 

Researchers have created the fastest imaging device of its type—a tool that may transform biomedicine, telecommunications, and more.

Strain as you might, some events happen too fast to perceive—the flap of a hummingbird’s wings, an atomic bomb’s instantaneous detonation, supersonic bullets carving a watermelon. Advances in optical technology have allowed humans to savor ephemera, extending visual perception beyond bodily bounds.

The latest innovation was announced on the cover of the scientific journal Nature in December. Lihong Wang, a professor of biomedical engineering at the University of Washington in St. Louis, and his team have developed a camera fast enough to image light as it’s propagating. The technique, called compressed ultrafast photography, can capture up to 100 billion frames per second—as much as 10,000 times faster than the next fastest camera of its type (single-shot, two dimensional, no extra illumination needed).

Wang and his team’s invention combines two well-known pieces of equipment: a streak camera (which takes a signal and spreads it sideways into a smear) and a digital micro-mirror device (the engine of many electronic projection displays). Together, the components are able to resolve images in two planes on the order tens of picoseconds. (A picosecond is one trillionth of a second.) Brian Pogue, an engineering professor at Dartmouth College and author of commentary accompanying the Nature paper, says he believes the device’s steep price could easily drop by an order of magnitude, to $10,000, if the streak camera finds a larger market.

In the Jan. 5 issue of Nature Communications, Wang, the Gene K. Beare Professor of Biomedical Engineering in the School of Engineering & Applied Science at Washington University in St. Louis, reveals for the first time a new technique that focuses diffuse light inside a dynamic scattering medium containing living tissue.
In addition, Wang and his team have improved the speed of optical focusing deep inside tissue by two orders of magnitude. This improvement in speed is an important step toward noninvasive optical imaging in deep tissue and photodynamic therapy.

In the new research, the team built on a technique it developed in 2010 to improve the focusing speed of time-reversed ultrasonically encoded (TRUE) optical focusing for applications in living tissue. To focus light, the engineers use a virtual internal guide star at the targeted location. By detecting the wavefront of light emitted from the guide star, they can determine an optimum phase pattern that allows scattered light moving along different paths to focus at the targeted location.

When light is shined into living biological tissue, breathing and blood flow changes the optical interference, or speckle pattern, which can cause previous methods to focus diffuse light inside scattering media to fail. Scientists have to act quickly to get a clear image.

The new TRUE technology combines two techniques: focused ultrasonic modulation and optical phase conjugation. Researchers use a type of mirror to record then time-reverse the ultrasound-modulated light emitted from the ultrasonic focus to achieve the best focus.

​A team of biomedical engineers at Washington University in St. Louis, led by Lihong Wang, PhD, the Gene K. Beare Distinguished Professor of Biomedical Engineering, has developed the world’s fastest receive-only 2-D camera, a device that can capture events up to 100 billion frames per second.

That’s orders of magnitude faster than any current receive-only ultrafast imaging techniques, which are limited by on-chip storage and electronic readout speed to operations of about 10 million frames per second.

Using a technique developed at the School of Engineering & Applied Science called compressed ultrafast photography (CUP), Wang and his colleagues have made movies of the images they took with single laser shots of four physical phenomena: laser pulse reflection, refraction, faster-than light propagation of what is called non-information, and photon racing in two media. While it’s no day at the races, the images are entertaining, awe-inspiring and represent the opening of new vistas of scientific exploration.

The research appears in the Dec. 4, 2014, issue of Nature.

“For the first time, humans can see light pulses on the fly,” Wang said. “Because this technique advances the imaging frame rate by orders of magnitude, we now enter a new regime to open up new visions. Each new technique, especially one of a quantum leap forward, is always followed a number of new discoveries. It’s our hope that CUP will enable new discoveries in science — ones that we can’t even anticipate yet.”

Lihong Wang, PhD, the Gene K. Beare Distinguished Professor of Biomedical Engineering in the School of Engineering & Applied Science at Washington University in St. Louis, has received a prestigious BRAIN Initiative Award from the National Institutes of Health (NIH).

Wang’s three-year, $2.7 million award, is one of 58 grants totaling $46 million announced Sept. 30 by Francis S. Collins, MD, PhD, director of the NIH, in Washington, D.C.

The award is part of the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, a national research effort launched by President Barack Obama last year to revolutionize the understanding of the human mind and uncover new ways to treat, prevent and cure brain disorders such as Alzheimer’s disease, schizophrenia, autism, epilepsy and traumatic brain injury.

With the new grants, more than 100 investigators in 15 states and several countries will work to develop new tools and technologies to understand neural circuit function and capture a dynamic view of the brain in action. These new tools and this deeper understanding will ultimately catalyze new treatments and cures for devastating brain disorders and diseases that are estimated by the World Health Organization to affect more than 1 billion people worldwide.

Biomedical engineer Lihong Wang, PhD, and researchers in his lab work with lasers used in photoacoustic imaging for early-cancer detection and a close look at biological tissue. But sometimes there are limitations to what they can do, and as engineers, they work to find a way around those limitations.
Wang, the Gene K. Beare Distinguished Professor of Biomedical Engineering in the School of Engineering & Applied Science at Washington University in St. Louis, and Junjie Yao, PhD, a postdoctoral research associate in Wang’s lab, found a unique and novel way to use an otherwise unwanted side effect of the lasers they use — the photo bleaching effect — to their advantage.

The results were published online Jan. 10 in Physical Review Letters.

The researchers use an optical microscopy method called photoacoustic microscopy to take an intensely close look at tissues. The laser beam is a mere 200 nanometers wide. However, the center of the laser beam is so strong that it bleaches the center of the tissue sample. When researchers pulse the laser beam on the tissue, the molecules no longer give signals packed with information.

Wang will receive the James B. Eads Award, which recognizes a distinguished individual for outstanding achievement in engineering or technology.

Wang and his lab were the founders of a type of medical imaging that gives physicians a new look at the body’s internal organs, publishing the first paper on the technique in 2003. Called functional photoacoustic tomography, the technique relies on light and sound to create detailed, color pictures of tumors deep inside the body and may eventually help doctors diagnose cancer earlier than is now possible and to more precisely monitor the effects of cancer treatment — all without the radiation involved in X-rays and CT scans or the expense of MRIs.
A leading researcher on new methods of cancer imaging, Wang has received more than 30 research grants as the principal investigator with a cumulative budget of more than $40 million. In 2013, Wang received a Transformative Research Award from the National Institutes of Health.

The Academy of Science of St. Louis aims to foster the advancement of science and encouragement of public interest in and understanding of the sciences. The awards will be given April 9 at the Chase Park Plaza Hotel