Conventional Needle Biopsy
The diagnosis of diseases like cancer almost always needs a biopsy. Other tests can suggest that cancer or some kind of disease is present, but only a biopsy can make a diagnosis. A biopsy is a procedure to remove a piece of tissue or a sample of cells from the body to examine it, typically under a microscope.
Many areas of diagnostic medicine, especially cancer diagnostics, have seen huge advances in technology, with genetic sequencing, molecular biology and artificial intelligence all rapidly increasing doctors’ ability to work out what’s wrong with a patient.
However the technology of medical needles hasn’t changed dramatically in 150 years, and – in the context of cancer management – needles are struggling to provide adequate tissue samples for new diagnostic techniques.
Ultrasonic Vibrating Needles
Now researchers have shown a device that modifying the biopsy needle. The ultrasonic vibrating needles can house a conventional syringe with a fine needle. It can then vibrate the needle tip approximately 30,000 times per second.
The vibrations cause the tissue to behave more like a liquid and so more tissue can enter the fine needle. This procedure is also potentially less painful and less traumatic for patients.
“Biopsy yields – the amount of tissue extracted – are often inadequate, with some studies showing that up to a third of fine needle biopsies struggle to get enough tissue for a reliable diagnosis,” said Professor Heikki Nieminen, a researcher involved in the study, in an Aalto University announcement.
“A biopsy can be painful, and the wait for the results from a diagnostic test can be a highly distressing time for the patient and family, especially if diagnosis needs re-biopsies to be conclusive. We wanted to make the procedure more gentle for the patient, and increase the certainty that the test will be able to give us an answer on the first attempt.”
Researchers suggested that maybe the solution to the problem could be addressed with the help of ultrasound.
One of the least painful biopsy methods is called ‘fine needle biopsy’, which uses a needle the same thickness as in many other medical procedures.
However for more advanced diagnostic treatments – like those used in cancer – fine needles alone don’t get enough material routinely enough, so the current practice is often to use a much thicker needle, called a core needle.
“They are painful for the patient and can also cause bleeding – you don’t want to use a core needle unless you have to.” says Professor Kenneth Pritzker, a Pathologist at Mount Sinai Hospital.
“At body temperature, human tissue exists as something that behaves part-way between being a solid and a liquid. The breakthrough here is that by making the needle tip vibrate ultrasonically, we’re able to make the tissue flow more like a liquid, which allows us to extract more of it through a narrow needle.”
Ultrasonic Fine Needles Feels Like a Regular Needle
In a research, published in Scientific Reports, the team is sharing with the wider world how well these ultrasonic vibrating needles work.
“The vibrations provide energy to the tissue to make it more fluid like,” explains the first author of the paper, Emanuele Perra, who works in Aalto University.
“The vibrations are localised to just the tip, so it doesn’t affect any other tissue except a small region around the needle. We were able to show that the ultrasonic vibrations increase the biopsy yield by 3 to 6 times compared to the same needle without ultrasound, which was even greater than we hoped for.”
The vibrations are far above the hearing range for humans, and the amplitude of the waves is small enough that it shouldn’t feel much different to a normal blood test.
The big increase in the amount of tissue extracted in the biopsy means it is very useful for the growing trend for high tech cancer treatment. One such example is molecular diagnostics, which examine the chemical makeup of tumours, to allow doctors to target treatment more effectively to a specific cancer type.
“Molecular diagnostics is an expensive process, and it is an expensive waste of money to have it fail because the quality of the material gathered in the biopsy wasn’t previously good enough,” explains Pritzker.
The technology that powers the needle is non-linear acoustics, where vibrations passing through a material have such large amplitude that they interact with the material itself.
These interactions allowed the needle’s designers to focus all the energy to just the tip of the needle, and measure their effects.
“We’ve been able to characterise the vibrations at the end of the needle really well. We’ve used high speed cameras that have allowed us to study the physical effects of the vibrating needle on boundaries between fluids, solids and air in unprecedented detail,” says Nieminen.
“The rich understanding we’ve managed to get of the physics allowed us to design the medical device and understand how it could be used for different medical purposes.”
Ongoing Clinical Trials
The needle is expected soon to move into studies with real cancer patients, although for the time being only four legged ones. A specialist veterinary hospital in Canada is soon expected to be trialing the device on domestic pets with cancer, and if all goes as expected, the team hopes that their needles will be used in human patients soon after.
“Modern oncology doesn’t just take a biopsy at the beginning of treatment”, explains Nieminen. “Increasingly, oncologists want to be able to take multiple biopsies to track how the tumors are changing and responding over the course of the treatment. We want the tools for these biopsies to be as effective and painless as possible.”
While the team is preparing the needles for the real world biopsies, they are also excited about future applications that they are still researching.
“The effect that ultrasonic vibrations have on tissue might also be able to work the other way” explains Perra, “the vibrations might make it easier to deliver pharmaceuticals in a targeted way to tissue like the liver.
They might also be able to break up small hard objects in soft tissue, like kidney stones, or even small tumours – all minimally invasively.” By combining experts in acoustics physics with experts in medical technology, the team hopes that many more innovations will arise from their 21st century upgrade of the humble medical needle.
- Aalto University
- Ultrasonic actuation of a fine-needle improves biopsy yield. Emanuele Perra et. al. Sci Rep. 2021 Apr 15;11(1):8234. doi: 10.1038/s41598-021-87303-x.