Second sight – next-generation imaging probes

Among the yellow fields of eastern England’s flat countryside, there is a high-tech but unobtrusive laboratory. Here, a group of researchers are discovering new ways to help improve public health diagnostics around the world.

The uneven and sometimes flawed process of diagnosing tumours, heart conditions, problems related to brain injuries and a host of other illnesses can often come down to a hit-or-miss, trial-and-error system. This leaves doctors unable to find specific evidence for definitive answers and patients anxious throughout an already stressful process.

New research undertaken by the team at The Technology Partnership (TTP), a technology and product development company with a team of business innovators who work with the healthcare industry to come up with new devices, may have uncovered a way of improving this procedure and helping patients worldwide.

These researchers have made advances in elastography imaging technology to give better vision to surgeons. This imaging technique maps the elastic properties of soft tissue to provide vital diagnostic information during surgery, and they have managed to get it into a handheld probe.

False alarms

Diagnosis of internal tumours and other problems – without reverting to surgery or invasive biopsies – has always been an issue. False positives and negatives are an ongoing problem.

A 2015 report by leading US pathologists and family medicine specialists published in the Journal of the American Medical Association reported a match-rate of an initial diagnosis through screening and end result of a definite tumour of around 75%. This means that 25% of the 1.5 million American women who have discovered lumps or other issues after a screening for breast cancer every year are being unnecessarily sent for biopsies and further treatments because the equipment they are being tested with isn’t giving clear enough images and clues. Lumps and blotches on images that could be, and sometimes are, nothing to worry about, are being mistaken for malignant masses.

Obviously, this is extremely upsetting for the patient and family, time consuming for the doctor and expensive for the medical services. It is an outdated and often extremely inefficient way of testing.

This, also, is just for one type of cancer. Many other types of tumours grow in parts of the body – such as the pancreas – where procedures would be invasive and complicated and, one would hope, a last resort due to the extended healing time. If such cases are added to the figures for suspected breast cancer, as well as the other types of illnesses and diseases that are hard to visualise due to the depth of certain body parts, then you end up with millions of preliminary diagnoses every year that are being unnecessarily made and are often no more than a hunch.

Elastographic imaging

Elastography is a medical imaging modality that maps the elastic properties of soft tissue. The main idea is that, depending on whether the tissue is hard or soft, diagnostic information about the presence or status of a disease can be gleaned, and this is what the team at TTP have used to adapt into a tool.

They are using a new probe that is more sensitive and provides feedback to a colour monitor for better patient accuracy, and it is the elastographic imaging technology that provides this improved vision to surgeons.

This technique maps the elastic properties of soft tissue to provide diagnostic information during surgery. The adapted elastography imaging probe created by the team at TTP can be used inside blood vessels to investigate cardiovascular health or outside the body to visualise major organs.

The technique also gives surgeons better vision while performing treatments with endoscopic tools, killing or removing cancerous or damaged tissue, or simply navigating around the body during an operation.

When surgeons perform these procedures under normal circumstances, they are working with an instrument that is ‘blind’, so to speak, so they cannot see into lesions and have to rely on their skills to avoid damaging nearby organs during processes such as resection or ablation. The elastographic imaging technique could change all of this.

Paul Galluzzo, chief researcher at TTP, is adamant that they are on to something, even if they are, at times, unsure of its exact application. He and his team have been working for nearly three years on the probe, and believe that it could be a great tool for the improvement of patient care and public health. Drawing from his engineering background, Galluzzo and a team of physicists and other scientists put their heads together to work out what they can do.

“There are a lot of things in the body that have changes in stiffness,” Galluzzo says. “If you have cancer in the breast – cancer is stiffer in the breast – you can palpate. Or, if you are doing an ablation procedure, where you are killing tissue, you are trying to create a necrotic zone of higher stiffness.”

Galluzzo explains it as follows: the cancer (in other words, the stiff tissue) is killed by the ablation, plus a bit of skin and tissue around it. “You can feel the effect but you cannot really see it on the ultrasound, and that was the whole driver behind developing this easily integrated elastography probe; it is making some things more visible where you would otherwise be blind.”

The technique works by mapping soft tissue to provide vital diagnostic information during surgery – this is good for the patient, no doubt, as it finds more damaged tissue that needs to be removed, or tested. Galluzzo likens it to cooking a steak.

“Suppose you have Barrett’s oesophagus, a common result of prolonged acid exposure; then there is a much higher chance of developing oesophageal cancer,” Galluzzo says.“Barrett’s oesophagus is a pre-cursor to oesophageal cancer and the common (but quite new) treatment for it is to go in and ablate the tissue to kill it. The problem is that you do not know how far you have burnt because it is a blind procedure. It is like frying a steak – you do not know how deeply you have fried into it; you do not know how deep the pink section is and how much is brown; so the exact same process applies, but instead of burning it on an oven, you are using a 500kHz current and it heats up the tissue.”

The heat needs to reach a certain depth for a clear image, but at the same time, you don’t want it to go too deep. “Imagine it is ill-controlled, blind and subjective – you are just taking operating parameters, meaning voltage, time, temperature, heat, and electrical impedance, and you are trying to keep them all within a window, because that is your recipe. This actually gives you the ability to see, instead of just frying it on high heat with enough oil to get a decent thermo contact and hoping that you get the right result.”

He continues this metaphor, saying that some organs are fairly simple to ‘cook’, but the beauty of elastography imaging is that by distinguishing between levels of mechanical stiffness, you would be able to see right through your steak and say which parts are burnt, stiff, damaged or untouched.

Greater precision

The team is certain that there are advantages for patients here: radio frequency ablation is surprisingly inconsistent without it. “The ablation equipment will always keep you within the ‘recipe’ parameters but that doesn’t always help. You can just end up doing a much less successful job than you thought you had. Actually monitoring it, I am very surprised that the technique has had as much success as it has in the past without proper monitoring. I think we have been honestly quite surprised by how poor it is; this is not just a minor ‘it would be nice’, it is an ‘it doesn’t work’.”

Elastography normally works by sending out from the ultrasound probe a pulse generated with a high voltage that pushes the tissue and causes it to distort. Doctors can then view the distribution. The difference now is that TTP can hold it in place and, using a very adaptable set of algorithms, can adjust the system over a wide range of sensitivities. The device can look at the heart and have it view the full range of motion, or it can be set such that if you hold it as still as you possibly can you can see the strain image emerging clearly. Working on this basis of the body’s natural motion means it doesn’t send out a push pulse and is applicable to a number of cases.

This technology is designed to be used in conjunction with existing ablation instruments or probes, and aims to enable surgeons to visualise work that would otherwise be done blind or where the end-point of a procedure is uncertain but can determine both the efficacy and safety of the treatment.

What this means is that the new elastography probe will provide a safer and more efficient way of sensing which tissue is healthy and which is not, enabling biopsies, tumour removals and a host of other procedures to be carried out not just because of the surgeon’s instincts or gut feelings but by a much more exact form of in-depth imaging and therapy assessment.

Galluzzo concludes that it is important to note how often things do not go as planned even when you think you know what you are doing. This is the case for surgeons who are following the ‘recipe’ but are still performing blind. “If you have a way of monitoring what you are doing as you follow the recipe, it is far more exciting.”

Elastography is here to stay and will hopefully enable surgeons to provide better patient care, reduce unnecessary operations and allow operations that do go ahead to be done with a much greater level of precision.