Biopsy Technique – Lasers Replace Scalpels

Researchers have developed a new biopsy technique that uses pulses from two kinds of lasers to take pictures of microscopic biological structures.

The new biopsy technique, called ultraviolet-localized mid-infrared photoacoustic microscopy, or ULM-PAM, develops images of the microscopic structures found in a piece of tissue by bombarding the sample with both infrared and ultraviolet laser light.

A sample to be imaged is first hit with a pulse of ultraviolet laser light. This light causes the molecules inside the sample to vibrate. Sensors placed against the sample pick up those vibration signals and pass them along to a computer that processes them.

In the next step, the sample is hit with a pulse of infrared laser light. This pulse heats the sample slightly but not evenly. Some materials in the sample, like proteins or DNA, will heat up more than others because they absorb more energy from the laser.

Immediately after the heating pulse, the sample is again hit with a pulse of ultraviolet laser light. Just as before, the UV light causes molecules inside the sample to vibrate, and those signals are passed along to the computer. By comparing the signals from samples before and after they are heated, the computer creates an image in which structures can be identified by their heat signatures. Since cancerous cells express proteins and DNA differently than healthy cells, they can be differentiated this way.

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