New microscope technique sees samples in three dimensions

A new technique to see inside tissues in three dimensions, so doctors can make better and much faster diagnoses during surgery, has been invented by scientists in the US.

Traditionally, tissue samples collected from patients are sent to a laboratory where they are prepared onto microscope slides so that a pathologist can inspect them under a microscope.

The process usually takes hours, which means that if a surgeon has not managed to achieve a complete resection of a cancer, for instance, then a patient might require a repeat trip to the operating theatre for further intervention.

In other circumstances, to spare a patient the risk of a repeat surgery, more radical treatment may be administered, "just in case".

Although procedures do exist to take samples during a surgical procedure, quickly freeze, cut and study them, these techniques work reliably with only certain tissue types.

Now a team from the University of Washington, in Seattle, have developed a new microscopy technique that can image large or small pieces of tissue straight out of a patient.

"We can basically visualise the material immediately," says inventor Jonathan Liu who is senior author on the Nature biomedical engineering paper where the work is published.

"You can think of it as a bit like a flatbed scanner for tissue," says Liu. "The material is placed on the try on top, and the light source and camera are beneath."

The new system generates a flat sheet of light about 2 millimetres wide and 7 micrometres (millions of a metre) thick, which penetrates at a 45 degree angle to illuminate a thin slice through the tissue.

Light issuing from within the specimen, also at 45 degrees, is then captured by a camera.

The supporting tray moves in an s-shaped pattern to illuminate and photograph similar slices throughout the tissue block.

The images are captured with a computer and reassembled digitally into a three-dimensional representation of the specimen, and the whole process is totally non-destructive, leaving the tissue undamaged or unchanged for other analyses.

"The 3D micro-architecture of the tissue should allow them to understand the tissue, to understand the disease and to guide patient treatments ultimately more accurately," says Liu.

"We've shown in our paper that there are much more accurate diagnoses that can be made, based on the 3D information."