A new pen-sized microscope could revolutionize diagnostics.
Image credit: Dennis Wise/University of Washington
A surgeon operating on a brain tumor does not want to remove any more tissue than is completely necessary. The consequences of removing too much brain matter can be severe.
By the same token, the surgeon is eager to remove the entirety of the cancerous growth; the consequences of leaving a cancerous residue are equally severe.
As things stand, this balancing act can only be managed using the surgeon's senses. He must palpate the area and inspect it visually for remaining cells.
To fully and definitively ascertain whether a cell is cancerous, a sample must be sent to a pathology lab. There, the sample will be frozen, sliced, stained and mounted. Only then will it be inspected by a pathologist before the results are sent back.
The whole process can take days. A surgeon cannot leave a patient's skull open to the air for that amount of time, however.
The birth of the mini-microscope
A groundbreaking invention that has the potential to rid us of this waiting game is currently being perfected by the University of Washington. The device, not much bigger than a pen, will allow surgeons to observe their patient on a cellular level, there and then.
This incredible mini-microscope is being developed in collaboration with Stanford University, Memorial Sloan Kettering Cancer Center and the Barrow Neurological Institute. The ongoing work was recently published in Biomedical Optics Express.
Lead author Jonathan Liu explains the obvious benefits to the surgeon:
"Being able to zoom and see at the cellular level during the surgery would really help them to accurately differentiate between tumor and normal tissues and improve patient outcomes."
It is not just in the neurosurgeon's domain that this technological advance might come in useful. Dentists routinely come across a suspicious or unexpected lesion in a patient's mouth. In these situations, it is important to err on the side of caution, excise the tissue and send it for analysis.
These patients are subjected to procedures that, more often than not, turn out to be unnecessary; this also puts additional pressure on pathology labs.
A miniature microscope could remove the need for many superfluous procedures; in dermatological clinics, for instance, it could be used to quickly define which moles require further investigation.
The technology behind the new microscope
The smallest currently available microscopes are roughly the size of a hairdryer. Previous efforts at miniaturization have been to the detriment of some aspects of image quality, whether field of view, contrast or processing speed.
When it comes to balancing these tradeoffs, Liu feels "like this device does one of the best jobs ever." Below are some examples of the new microscope in action:
The slides on the left show samples of the miniature microscope's real-time images, compared with the results of a multi-day, clinical pathology lab on the right.
Image credit: University of Washington
The microscope carries out its magic using dual-axis confocal microscopy. This technology allows the operator to see through opaque tissue up to 0.5 mm deep. Liu explains the challenges of seeing at this depth:
"Trying to see beneath the surface of tissue is like trying to drive in a thick fog with your high beams on - you really can't see much in front of you. But there are tricks we can play to see more deeply into the fog, like a fog light that illuminates from a different angle and reduces the glare."
In standard microscopy, a physical slice of a tissue needs to be taken. Confocal microscopy, first developed in 1955, allows scientists to create a virtual slice many micrometers deep, giving extra detail. It has the added benefit of giving increased depth to the resultant image.
A technology called "line scanning" is also utilized to help speed up the image processing. Using micro-electrical-mechanical (MEMS) mirrors, the beam scans the tissue line by line and builds an image. Speed is of the essence with a handheld device, with a less than stationary operator, blurring is an obvious concern.
Initially, the microscope will be trialed as a cancer-screening tool; the team hopes that within 2-4 years it will be released to other clinical settings. If rolled out on a wide scale, this miniaturized microscope will see a reduction in unnecessary medical procedures and a higher success rate in tumor removal surgery.
In other optical news, Medical News Today recently covered the development of a smartphone microscope able to detect blood parasites quickly.