"Biopsy Without a Knife": A New Cancer Imaging Technique

To identify tumors or to determine if they’re malignant, surgical biopsies or the use of imaging techniques that rely on contrast dyes, are most commonly used. Researchers have now developed a high-powered imaging technique that doesn’t use dyes. The technique was published in the journal Biomedical Optics Express. It would not replace actual biopsies, at least not yet.

“Existing techniques are invaluable but suffer from low spatial resolution and often require the use of exogenous contrast agents,” stated Thomas Schnelldorfer from Lahey Hospital in Burlington, Massachusetts, co-leader of the research.

“This method utilized in this work identifies in a completely label-free manner cellular and tissue features at the microscopic level, essentially acting like a biopsy without a knife,” added Dimitra Pouli from Tufts University, lead author of the study.

The imaging system uses a multiphoton microscope with automated image and statistical analysis algorithms. They examined fresh biopsies from the peritoneal cavity. The approach evaluated both cellular and extracellular tissue at the microscopic levels, which allows the identification of cancer metastasis at an earlier stage. The algorithms help classify the tissues.

“This could ultimately help surgeons identify suspicious or diseased areas directly in the operating room in real-time, which in turn would directly affect patient management,” stated Schnelldorfer.

This research was the first time healthy and metastatic peritoneal tissue had been successfully studied by combining this microscopy technique with image texture analysis. Multiphoton microscopy delivers laser light to tissue. It is high-intensity, but delivered in very short pulses, which keeps the average power down and doesn’t cause tissue damage.

Different components of the tissue interact with the laser light, emitting signals that are picked up by the microscope to create an image. These are then analyzed with automated image processing algorithms. The details identified are not usually visible in the images typically picked up with standard imaging tools.

One of the key advantages is that it evaluates tissue directly. In standard contrast-dye imaging techniques, it’s the contrast in the tissues that is being analyzed, providing clues to the types of tissues. The algorithms also appear to provide more detailed analyses than is typical with standard imaging tools.

The research group plans to continue testing the technique in more image samples from a wider patient population. This particular method was optimized for detecting ovarian cancer that had metastasized in parietal peritoneal tissue, but it can be modified for other tissue and cancer types.

Although they used biopsies to evaluate the method, they say ultimately they hope to apply it directly to areas of the body where cancer is suspected without the need for biopsies or dyes. It could potentially be used for real-time tissue analysis during surgery, but the microscopy components would need to be miniaturized and integrated with surgical instruments.

“As the method exploits inherent tissue signals present almost ubiquitously in tissues, it can be applied to other types of cancer and other applications altogether, such as fibrosis and cardiovascular diseases when tissue structure and extracellular matrix remodeling are altered by the underlying diseases processes,” stated Irene Georgakoudi, research co-leader from Tufts University.