Fujifilm endoscopes

Reducing patient discomfort and enhancing imaging precision. Industry-leading Fujifilm innovations include the transnasal endoscope and double-balloon endoscope. More »

Fujinon EVE 590 series

With the pioneering 4400 endoscopy system, Fujinon is already meeting tomorrow’s standards in endoscopy today. More »

Fujifilm endoscopes 600 series

The leading-edge high resolution endoscopes, equipped with over megapixel customised CMOS image sensor, realize advanced observation and diagnosis. More »

Transnasal Endoscopy

In order to counter increasing cost pressure in modern endoscopy, Fujifilm has developed a complete product range for transnasal endoscopy (TNE). More »

 

This endoscope zaps tumors

To examine internal organs, doctors often use a tube with light and a tiny camera attached to it. The device, called an endoscope, helps detect cancer and other illnesses.

It may soon serve another purpose: zapping tumors.

The biomedical advancement, which is under development at the University at Buffalo, could make chemotherapy more efficient, reduce its side effects and improve how doctors treat some of the most deadly forms of cancer.

“We are developing a novel endoscopic device that will improve our ability to detect and destroy cancer cells,” says Ulas Sunar, PhD, a research assistant professor in UB’s Department of Biomedical Engineering and the principal investigator of a National Institutes of Health grant that supports the research.

Conventional endoscopic imaging has limitations. Its image contrast is distorted because light scatters and is absorbed by the body. This leads to blurred or low-contrast images of the tumor environment that limit doctors’ ability to visualize tumors.

To overcome these deficiencies, the new endoscope utilizes spatial frequency domain imaging. This new technique corrects the image contrast problem by projecting patterns of light at different frequencies on the cancer cells. This results in a high-contrast map of the tumor environment.

“We expect doctors in the operating room will greatly benefit from this device,” Sunar says.

The next step is to zap the tumors.

Chemotherapy drugs will be delivered intravenously. But unlike conventional treatment, the drugs will be encapsulated in tiny liposomes called nanoballoons. This technology – under development by Jonathan Lovell, PhD, UB assistant professor of biomedical engineering – carries the drugs to the tumor while shielding them from healthy cells, thus reducing side effects. Upon reaching the cancer cells, doctors strike the nanoballons with the endoscopic light beam, causing them to pop open and release the drug directly at the tumor.

To effectively target the nanoballoons, doctors need to control the light beam. Sunar is developing a “digital mask” that adjusts the beam’s intensity as well as manipulates its shape down to micron (one millionth of a meter) precision using a computer.

“The mask is sort of like the Bat signal from Batman movies. It alters the shape of the light,” he says. “At the same time, we’ll be able to control the strength of the light. The combination will allow us to manipulate the beam to target cancer cells with unprecedented accuracy.”

The system could be especially useful for treating ovarian cancer that has spread to the abdomen, as well as cancer in the lungs, gastrointestinal tract, mouth and other internal organs, he said.

Sunar will spend much of 2015 developing the system. He will then test it on animal models. Upon completion of the grant in 2016, he expects to begin a pilot study with Shashikant Lele, MD, clinical chief of gynecologic oncology at Roswell Park Cancer Institute, and professor of gynecology and obstetrics at the UB School of Medicine and Biomedical Sciences.

Virginia Mason sides with dead patient as endoscope scandal deepens

Richard Bigler had been fighting pancreatic cancer for nine months on Aug. 6, 2013, when his doctors at Virginia Mason hospital plunged an specialized endoscope into him.

The procedure was pitched to Bigler as low-risk, if not entirely routine. A surgeon operating a scope equipped with tiny tool would clear a blocked bile duct, a complication of his cancer. He’d feel a little better and be able to fight a little harder.

Bigler was dead nine days later. And it wasn’t the cancer that killed him.

Instead, Bigler, 57, died of an infection his family and Virginia Mason officials say was carried into him by the medical scope.

An investigation by the Seattle hospital later determined the Ballard-raised man was one of 39 patients there infected with the same strain of E. coli bacteria after surgeries involving the specialty endoscope manufactured by Olympus Corp. Eighteen of those patients – many of whom were critically ill before contracting E. coli – have since died of a variety of causes.

The Olympus scope – a doudenoscope, used in a small fraction of all endoscopic surgeries – has been the source of controversy in recent months as allegations surfaced that the manufacturer failed to notify medical providers that its design makes it very hard to clean. Olympus and federal health officials are reviewing the cleaning standards for the device.

Virginia Mason leaders opted to keep its investigation into problems with the scope secret, later claiming they were concerned about inciting “panic” by publicizing the fatalities. Bigler’s family didn’t learn he’d been infected by the scope until The Seattle Times published a report on the fatalities in January.

Acting on her late husband’s behalf, Theresa Bigler sued Virginia Mason and Olympus, contending that both were to blame for her husband’s death. In an unusual turn, though, she appeared Monday alongside Virginia Mason representatives to welcome the hospital’s newfound support in her lawsuit against Olympus.

Attorneys for Virginia Mason now claim the non-profit, Seattle-based medical provider and Bigler were both wronged by Olympus, which they say failed to provide hospitals with adequate cleaning protocols for the device. Virginia Mason has since overhauled its cleaning procedures for the devices and is urging other hospitals to do the same.

Speaking Monday, Bigler said she was upset Virginia Mason didn’t inform her that other patients had been stricken by the bacteria that killed her husband. But she said she understands the hospital’s reasoning and believes, with Virginia Mason’s help, her lawsuit will force Olympus to come clean.

“Hopefully other families won’t have to go through what we’ve gone through,” she said, flanked by her attorney John Gagliardi and Virginia Mason representatives.

In a statement late Monday, Olympus spokesman Mark Miller said the company is “continuing our investigation into the reports at Virginia Mason to be able to provide a more thorough and balanced perspective on the issues including potential causes of the infections.”

“Olympus expresses our sympathy to the patients who have experienced infections and to their families,” Miller said by email. “We are taking this matter extremely seriously.”

Recent months have seen a stream of “superbug” revelations related to the Olympus scope. According to the U.S. Food and Drug Administration, the scopes at issue, which are built to remove blockages in bile ducts, were used in about 668,800 procedures in 2014; Olympus scopes account 85 percent of the specialty endoscopes used in the United States.

The Los Angeles Times reported Monday that Olympus sent a warning to European hospitals after a 2012 outbreak related to its scopes at a Dutch hospital. That warning – apparently delivered in January 2013, eight months before Rick Bigler was infected – never made it to U.S. hospitals, according to the Times report.

Munhall woman sues endoscope maker over hospital superbug infection

A Munhall woman who contracted a highly resistant infection at Allegheny General Hospital has sued the manufacturer of a medical device doctors used to look inside her body, claiming it failed to provide the hospital with safe cleaning procedures.

Elsie Florian, 76, contracted the superbug when she was exposed to a contaminated endoscope at the North Side hospital between Feb. 23 and March 4, according to a civil lawsuit she filed Wednesday in Allegheny County Court of Common Pleas.

A spokesperson for Olympus, the manufacturer, which has headquarters near Allentown and in Japan, did not respond to requests for comment.

Endoscopes are flexible lighted tubes that can be threaded through the mouth, throat and stomach. They are used in more than 500,000 procedures in the United States each year, according to the Food and Drug Administration.

Florian claims Olympus, which redesigned its Q180V endoscope in 2014, should have included a label about proper cleaning and disinfecting procedures so the device could be used on other patients without risking contamination.

“Any patient who underwent a medical procedure with a contaminated scope was exposed to serious health risks, including severe infection and death,” the lawsuit states.

The lawsuit claims Olympus knew its product was difficult to clean but failed to provide disinfecting protocols so it could be reused, and committed fraud by claiming the devices were safe.

According to the lawsuit, the company was informed of infections in patients in Washington state involving similar models in 2013. At least four patients who were infected as a result of exposure to contaminated endoscopes died, the lawsuit states.

Florian’s lawsuit claims Olympus failed to re-evaluate the safety and cleaning protocols developed for earlier models; develop new protocols for the redesigned model; recall the device; or update the cleaning procedures despite knowing that earlier models posed health risks to patients because they were hard to clean. She is seeking an unspecified amount in compensatory and punitive damages.

The FDA in February issued a general warning to health providers regarding the use of endoscopes for complex procedures in response to seven people becoming infected with a superbug bacteria at a Los Angeles hospital, two of whom died.

The FDA said it received 75 reports regarding the devices between January 2013 and December and recommended health facilities follow manufacturer instructions to minimize the risk of infection.

 

New superbug danger: Patients sickened by infected endoscopes

The use of contaminated endoscopes infected scores of patients in Pittsburgh, Seattle and Chicago hospitals with a deadly, drug-resistant infection, according to recent reports, underscoring the danger posed by the “looming global crisis” of such superbugs.

Carbapenem-resistant Enterobacteriaceae (CRE), the infection the patients contracted, has risen to prominence along with its superbug brethren due to the overuse of antibiotics. And at least one expert has said hospitals aren’t doing enough to screen for CRE, which can lead to infections in the lungs, urinary tract and blood, FierceHealthcare has reported.

The CRE outbreak, which began in 2012, spread among patients treated with a duodenoscope, a specialized endoscope that clinicians thread down patients’ throats to treat gallstones, cancers and other disorders of the digestive system, according to USA Today. The infection was transmitted from patient to patient because CRE can survive on the duoendocopes even after conventional cleaning.

Investigators have identified at least 35 cases of duodenoscope-related infections and 11 deaths through March 2014, the Seattle Times reports, though many of the patients were critically ill, making it difficult to definitively pin their deaths on CRE.

In addition, “there’s a likelihood that we’re just seeing a very small subset of the universe of infections from these types of scopes,” Jeffrey Duchin, M.D., head of communicable disease control at the Seattle and King County Public Health Department, told USA Today.

Despite the risk, the Food and Drug Administration hasn’t issued a warning about it or recalled the scopes, which are typically used in endoscopic retrograde cholangiopancreatography (ERCP) procedures, citing their importance in clinical care and the “low” risk of infection, according to the Seattle Times.

“The FDA feels that the lifesaving nature of ERCP, performed on more than 500,000 patients annually in the U.S., makes it important for these devices to remain available,” FDA spokeswoman Leslie Wooldridge told the newspaper.

But at least one Seattle hospital, Virginia Mason, has taken matters into its own hands, choosing to culture and quarantine each ERCP device for 48 hours after use to make sure it’s free of CRE and other infections, according to the article.

As more and more facilities look to reduce hospital-acquired infections, yet also fight antibiotic resistance, a recent study published in the Journal of the American Medical Association sheds some light on how to balance the sometimes-warring concepts. In examining the use of chlorhexidine to control infections in intensive care units, researchers found in the first trial that daily wipe-downs didn’t reduce infections, but the wipe-downs were effective when used every other day.

The study authors also note that such “universal decolonization strategies” don’t necessarily produce better infection-control results than “a simpler, less expensive approach that focuses on basic hygiene practices” such as hand-washing.

 

‘Clean as you go’ is the motto with endoscopes

If you just stack the dishes next to the sink and say you’ll get to them later, the gunk is going to be harder to get off by the time you get around to trying. And you may not get it all.

Same with endoscopes, which are flexible tubes used to see inside the digestive tract.

Better to clean them right away, which is what Rochester Regional Health System and UR Med do with the scopes that in some parts of the country have been linked to outbreaks of antibiotic resistance infections over the past several months.

No cases of CRE have been reported at either health system, according to representatives of each.

“It’s not for lack of looking,” said Dr. Mark Shelly, hospital epidemiologist and an infectious disease physician at UR Medicine’s Highland Hospital. “As soon as this happened, the first thing we did is look through our logs and asked,could this happen here and what should we be doing?”

Shelly said the organism carbapenem-resistant Enterobacteriaceae, a family of germs with a high-level of resistance to antibiotics, aren’t common to begin with in this area.

“Perhaps we’re smarter with our antibiotics,” he said. “Maybe we’re using less antibiotics. Maybe we’re keeping things cleaner in general.”

The scopes associated with an outbreak CRE are not as frequently used at Rochester hospitals, according to reps at each. These specific instruments reach past the stomach to the duodenum, and have a more complex structure that may make them harder to clean. There is a standard protocol that requires used of an automated process. Even with steps in place, infection specialists at both systems are reviewing and where they think necessary, improving their practices.

Todd Schojan, manager of sterile processing for RRHS, said the protocol for several years has been to hand wash the scope soon after use and then use the automated system.

“They don’t wait till end of the day,” he said.

Like the dishes analogy.

“When you cook, you clean as you go so you don’t have a pile of dirty dishes at the end of the day.”

He said the process is done a second time.

The scopes have been used without causing problems, which Shelly led some to question whether a problem developed with the approved way of cleaning, or steps were being skipped.

Shelly said UR Medicine contacted places there were having trouble and asked about their protocols.

He said UR Medicine went to a buddy system, having two people clean each scope. Like RRHS, technicians do a prewash and then apply the automated process.

The Food and Drug Administration issued a warning in February, following an outbreak traced to a Los Angeles hospital, and this month issued recommendations to manufacturers on making safer reusable devices.

“We often talk about sterilization and high level disinfection,” Shelly said. “None of those mean taking it to zero germs. They mean reducing the amount of germs by X amount. Sterilization is taking a million and getting it down to one. The more you clean it out, get the gunk out, then you are dealing with less organisms to start with, (giving) the cleaning process a head start.”

FDA warns about medical scopes after ‘superbug’ bacteria hits UCLA hospital

The Food and Drug Administration on Thursday warned doctors and hospitals around the country that a commonly used medical scope could be difficult to clean and  “may facilitate the spread of deadly bacteria.”

The agency’s warning comes after seven patients were infected and two died from a drug-resistant “superbug” at UCLA’s Ronald Reagan Medical Center. Public health authorities are tracking down at least 179 other patients who might have been exposed to the dangerous bacteria through the use of contaminated medical scopes.

The affected patients suffered from a drug-resistant superbug known as CRE, or Carbapenem-Resistant Enterobacteriaceae, during “complex endoscopic procedures” to diagnose and treat diseases in the pancreas between October and January at the hospital, UCLA’s Health System said late Wednesday in an emailed statement.

In its warning on Thursday, the FDA noted that the medical scopes in question, known as duodenoscopes, are used in more than half a million procedures each year in the United States as the “least invasive way” of draining fluids from pancreatic and biliary ducts blocked by tumors, gallstones and other conditions. The light, flexible tubes are typically threaded through the mouth, throat, stomach, or into the top of the small intestine. Unlike other endoscopes, they have a movable “elevator” mechanism at one end that allows the instrument to treat problems with fluid drainage.

But that intricate design also can make the devices difficult to sterilize, the FDA said. Cleaning the scopes is “a detailed, multi-step process,” and meticulously following the manufacturer’s directions for disinfecting them “should reduce the risk of transmitting infection, but may not entirely eliminate it,” the agency said. The FDA also noted that recent medical publications and adverse event reports it had received had associated drug-resistant bacterial infections with patients who had undergone procedures using the scopes.

Officials: New sterilization process in place after ‘superbug’ exposure(1:11)

UCLA told the Los Angeles Times, which first reported the deadly infections, that it detected the bacteria last month while conducting tests on a patient and alerted both the California and Los Angeles County health departments. An internal investigation revealed that two medical endoscopes may have transmitted the infection, though the scopes had been sterilized in line with the manufacturer’s standards, it said.

‘Superbug’ kills two at UCLA hospital(0:52)
Two people have died, at least seven others are possibly infected and more than 100 might have been exposed to a drug-resistant “superbug” at UCLA’s Ronald Reagan Medical Center in Los Angeles. (Reuters)

Health officials sent out letters this week to 179 patients who were possibly exposed to the bacteria through one of the endoscopes, Los Angeles County Department of Public Health said in a statement.

Endoscopes linked to outbreak of drug-resistant E. coli

An outbreak of a novel Escherichia coli (E. coli) strain resistant to antibiotics has been linked to contaminated endoscopes in a Washington state hospital. The study indicates that industry standard cleaning guidelines, which were exceeded by hospital staff, may not be sufficient for sterilizing endoscopes adequately. The research was published online in Infection Control & Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.

“Although the endoscopes had been reprocessed according to industry standards, we identified contaminated endoscopes that might have facilitated the transmission of the multidrug-resistant organism,” said Kristen Wendorf, MD, MS, lead author of the study. “In the wake of the recent outbreak of CRE due to contaminated endoscopes, we suspect endoscope-associated transmission of bacteria is more common than recognized and not adequately prevented by current reprocessing guidelines.”

During a period of November 2012-August 2013, a hospital in Washington state experienced an outbreak of the rare E. coli bacteria, initially identified through molecular testing of isolate bacteria by the Washington State Public Health Laboratory. Testing identified a cluster of carbapenem-resistant E. coliwith distinct genetic markers, suggesting a common source.

Researchers collaborated with hospital staff to conduct a public health investigation to determine the extent of the outbreak, identify potential sources of transmission and design, and implement infection control measures to prevent future cases.

The investigation identified 32 patients with the specific bacteria. All patients had severe pancreatic or biliary disease and had undergone endoscopic retrograde cholangiopancreatography (ERCP). A manufacturer review of the endoscope cleaning procedures found the hospital’s process to be above industry standards. However, the review found serious defects in the endoscopes that were not apparent during hospital testing. While testing the scopes for bacteria, researcher also found half of the reprocessed scopes harbored bacteria, including the two used in ERCP procedures that tested positive for the specific E. coli bacteria. Even after an overhaul by the manufacturer, these scopes harbored bacteria in the elevator channel.

More than 30 percent of patients infected with the bacteria died during the investigation and seven of the deaths occurred during hospitalization within 30 days of the date the E. coli isolate was obtained, although it is not possible to determine whether an infection contributed to the deaths. The primary diagnoses for the patients who died included pancreatic cancer, colon cancer, primary sclerosing cholangitis, and renal/pancreatic transplant.

“The outbreak was detected through a public health surveillance program that was enhanced with the addition of molecular testing, and would likely have gone undetected otherwise,” said Wendorf. “Routine surveillance is crucial for promptly recognizing outbreaks and monitoring and responding to the ongoing threat from multidrug-resistant organisms in healthcare facilities.”

As a result of this outbreak, the hospital has undertaken costly and extraordinary measures to minimize risk for endoscope-related infection transmission. The facility now quarantines ERCP scopes after cleaning and does not release them for use until cultures are negative at 48 hours. Despite these additional safeguards, the hospital’s scopes continue to show signs of bacteria after cleaning and require additional cleaning before the next use.

While there are industry standards for cleaning these devices, maintenance guidelines are not available from the manufacturers. The researchers note the need to include evaluation and maintenance schedules in the approval processes of these devices in moving forward to ensure adequate cleaning processes.

WATCHDOG CALLS FOR TESTING ENDOSCOPES TIED TO SUPERBUG

A Plymouth Meeting-based healthcare safety organization issued a “high priority safety hazard” report today, detailing steps to reduce infections from a drug-resistant bacteria.

The ECRI Institute said the risk of infection from CRE (carbapenem-resistant enterbacteriaceae)is inherent in the devices, and most, if not all models are “susceptible.”

Over the past 7 years, at least 7 hospitals have reported outbreaks of CRE associated with endoscopes for procedures used to treat and diagnose a variety of conditions of the gall bladder and pancreas.

Two weeks ago, UCLA’s Ronald Reagan Medical Center revealed that 7 people were infected, 2 may have died, and another 180 people may have been exposed to CRE through contaminated scopes.

ECRI’s report says the infection risk from the scopes is a hazard that requires immediate action, and that investigations of earlier infection outbreaks have tagged the cause as either poor cleaning techniques or damaged scopes.

It says the risk can be reduced, however, there’s no way now to completely eliminate it.

Among the institute’s recommendations:

1.) Doing a baseline culture of all the scopes currently in use, to see if they are harboring the CRE or other bacteria.

2.) If the scopes are now being cleaning with a liquid germicide, flush them, with alcohol, and dry them with filtered forced air.

3.) Consider doing regular culturing of the scopes, and not putting them back into service until the tests are back and negative. ECRI points out that regular testing is standard in Australia and some other countries.

However, it says no single solution will work for every hospital or medical facility.

ECRI is an independent institute which assesses healthcare technology and studies technology-related incidents and risks.

Second Hospital Reports Superbug Infections Linked to Endoscopes

Four patients at Cedars-Sinai Medical Center in Los Angeles were sickened by a ‘superbug’ that has been linked to a type of medical scope, the Los Angeles-based hospital said Wednesday.

Just two weeks ago, Ronald Regan UCLA Medical Center in Los Angeles announced that seven patients were infected with the superbug after undergoing endoscopic procedures. Two died.

The news from Cedars-Sinai came the same day as ABC News reported that the U.S. Food and Drug Administration said the endoscopes linked to the superbug infections at UCLA had been redesigned by the maker and were sold without approval.

In total, 179 patients may have been exposed to the CRE superbug at UCLA, according to the hospital.

Those cases were traced to two duodenoscopes, which are inserted into the mouth to access patients’ small intestine, pancreas and liver. The scopes had only been in use since June and were cleaned according to manufacturer guidelines, hospital officials said.

Both scopes were made by Olympus Corp. The FDA says Olympus changed the design of the scopes and sold them without seeking permission to do so, ABC News reported.

Companies must notify the FDA of design changes 90 days before marketing redesigned devices, the FDA website says.

The FDA did not clarify what changes were made to the scopes or whether they could have increased the chances the scopes would be more difficult to clean or more likely to harbor bacteria, ABC News reported.

Officials at Cedars-Sinai said the hospital stopped all procedures using the endoscopes in question after learning about the UCLA outbreak and began its own investigation. The superbug may have been transmitted through a duodenoscope made by Olympus Corp., hospital officials said.

One patient died, but hospital officials said the cause was an underlying medical condition and not the superbug infection.

Cedars Sinai said that, as a precaution, it sent home-test kits to 71 patients who had procedures there to diagnose pancreatic and bile-duct problems.

Stanford engineers develop high-resolution endoscope as thin as a human hair

Engineers at Stanford have demonstrated a high-resolution endoscope that is as thin as a human hair with a resolution four times better than previous devices of similar design. The so-called micro-endoscope is a significant step forward in high-resolution, minimally invasive bio-imaging, with potential applications in research and clinical practice. Micro-endoscopy could enable new methods in diverse fields ranging from study of the brain to early cancer detection.

The new endoscope was developed by a team under the direction of Joseph Kahn, professor of electrical engineering at the Stanford School of Engineering. The resultswere published recently in the journal Optics Express and showcased in the Optical Society of America’s “Spotlight on Optics.”

Their prototype can resolve objects about 2.5 microns in size, and a resolution of 0.3 microns is easily within reach. A micron is one thousandth of a millimeter. By comparison, today’s high-resolution endoscopes can resolve objects only to about 10 microns. The naked eye can see objects down to about 125 microns.

Light paths

Kahn is best known for his work in fiberoptic communications – the ultra-fast data pipes essential to the Internet and large-scale data centers. His work on endoscopy began two years ago when he and a fellow Stanford electrical engineer, Olav Solgaard, were discussing biophotonics – a field of light-based technologies used in studying biological systems.

“Olav wanted to know if it would it be possible to send light through a single hair-thin fiber, form a bright spot inside the body and scan it to record images of living tissue,” said Kahn.

The opportunity and the challenge, Kahn and Solgaard knew, rested in multimode fibers in which light travels via many different paths, known in optics as modes; hence the name, multimode fiber. Light is very good at conveying complex information through such fibers – whether computer data or images – but it gets scrambled potentially beyond recognition along the way.

Kahn devised a way to undo the scrambling of information by using a miniature liquid crystal display called a spatial light modulator. To make this possible, Kahn and his graduate student Reza Nasiri Mahalati developed an adaptive algorithm – a specialized computer program – by which the spatial light modulator learned how to unscramble the light. Several years before, Kahn had set world records for transmission speeds using a similar trick to unscramble computer data transmitted through multimode fibers.

Research on the micro-endoscope took an unexpected and fortunate turn when Nasiri Mahalati mentioned seminal work in magnetic resonance imaging (MRI) done by John Pauly, another Stanford electrical engineer. Pauly had used random sampling to dramatically speed up image recording in MRIs.

“Nasiri Mahalati said, ‘Why not use random patterns of light to speed up imaging through multimode fiber?’ and that was it. We were on our way,” said Kahn. “The record-setting micro-endoscope was born.”

Confronting the laws of physics

In Kahn’s micro-endoscope, the spatial light modulator projects random light patterns through the fiber into the body to illuminate the object under observation. The light reflecting off the object returns through the fiber to a computer. The computer, in turn, measures the reflected power of the light and uses algorithms developed by Nasiri Mahalati and fellow graduate student Ruo Yu Gu to reconstruct an image.

Kahn and his students were stunned to discover their endoscope could resolve four times as many image features as the number of modes in the fiber.

“Previous single-fiber endoscopes were limited in resolution to the number of modes in the fiber,” said Kahn, “So this is a fourfold improvement.”

The result, however, raised a scientific conundrum for the team.

“This meant that, somehow, we were capturing more information than the laws of physics told us could pass through the fiber,” said Kahn. “It seemed impossible.”

The team wrestled with the paradox for several weeks before they came up with an explanation. The random intensity patterns mix the modes that can propagate through the fiber, increasing the number of modes fourfold and producing four times as much detail in the image.

“Previous research had overlooked the mixing. The unconventional algorithm we used for image reconstruction was the key to revealing the hidden image detail,” said Kahn.

The ultimate endoscope

Kahn and team have created a working prototype. The main limiting factor at this point is that the fiber must remain rigid. Bending a multimode fiber scrambles the image beyond recognition. Instead, the fiber is placed in a thin needle to hold it rigid for insertion.

Rigid endoscopes – those used frequently for surgeries – are common, but they often use relatively thick, rod-shaped lenses to yield good images. Flexible endoscopes on the other hand – the kind used in colonoscopies and ureteroscopies – usually employ bundles of tens of thousands of individual fibers, each conveying a single pixel of the image. Both types of endoscopes are bulky and have limited resolution.

A single-fiber endoscope such as Kahn’s would be the ultimate minimally invasive imaging system, and has been the focus of intense research in optical engineering over the past few years.

Kahn is not the first to develop a single-fiber endoscope, but in boosting the resolution it is possible now to conceive of a fiber endoscope about two-tenths of a millimeter in diameter – just thicker than a human hair – that can resolve about 80,000 pixels at a resolution of about three-tenths of a micron. Today’s best flexible fiber endoscopes, by comparison, are about a half-millimeter in diameter and can resolve roughly 10,000 pixels with a resolution of about 3 microns.

The future

A rigid single-fiber micro-endoscope could enable myriad new procedures for microscopic imaging inside living organisms. These range from analyzing neuronal cellular biology in brain tissue to studying muscle physiology and disease to the early detection of various forms of cancer.

Looking ahead, Kahn is excited about the potential of working with biomedical researchers to pioneer these applications, but being a physicist and an engineer at heart, he is most enthralled by the technical challenges of creating a flexible single-fiber endoscope.

“No one knows if a flexible single-fiber endoscope is even possible, but we’re going to try,” said Kahn.