At last week’s RSNA conference in Chicago, we got a chance to learn about Seno Medical Instruments, a San Antonio, Texas company, and its imaging technology that combines conventional ultrasound with a new modality called optoacoustic imaging. We spoke with Dr. Tom Stavros, Medical Director at Seno.
The company’s Imagio system relies on a duplex probe that looks and acts like a regular ultrasound transducer, but that also emits laser light to simultaneously work as an optoacoustic imaging device. In optoacoustics, laser light is used to add energy to tissue, which is then released in the form of ultrasound waves. These waves can be detected, but unlike conventional ultrasound, they contain information about blood and its oxygenation. Ultrasound is pretty good at seeing the structures of tissues, and in this device, optoacoustics provides the functional view of blood oxygenation and improves the contrast, which can make it critically important for spotting tumors, as tumors eat up a lot more oxygen than nearby tissues.
The Imagio system is intended for breast cancer diagnostics rather than screening, and patients are expected to have been screened using ultrasound before being imaged by Seno’s system. Roughly 80% of breast biopsies turn out negative these days, a disturbingly high number, so anything to improve this would be highly beneficial for reducing costs, improving the emotional well being of patients, and getting the right people quicker from screening to treatment. To that effect, clinical trial data has just been released at RSNA that shows that the Imagio can reduce false positives breast exams and benign biopsies.
The system images at 30 frames per second using ultrasound and at 10 frames per second via optoacoustics. The optoacoustic component relies on shining two wavelengths (long and short) of light sequentially. The long wavelength is absorbed by oxygenated blood, while the shorter one is more readily absorbed by deoxygenated blood, providing a view of both and a contrast between regions of varying oxygenation.
We checked out a bunch of images of scans performed by the Imagio, which have red color showing deoxygenated blood and green color highlighting oxygenated regions. The images are created by sweeping the Imagio probe across the lesion, including a few centimeters around the lesion. By understanding the morphology of the vasculature that feeds a tumor and how it consumes oxygen, one can identify tumors in some cases while ruling them out in others with pretty good accuracy.
This is partially because unlike ultrasound, optoacoustics allows a unique view at the area around the tumor where a lot of the signature angiogenesis is taking place that points to the existence of the nearby tumor. In particular, oxygen being metabolized in specific ways differentiates a suspected lesion between a benign tissue and a cancerous tumor that needs treatment. Additionally, the orientation of the vessels leading up to a lesion can also indicate whether it’s probably cancerous or benign.
It does seem like it would require a good deal of training in order to perfect how one interprets the images that Seno Medical’s system produces. Nevertheless, being able to avoid unnecessary biopsies, which number in the millions every year, would be a major win for breast care generally. Seno still has to convince the FDA that its Imagio system merits being cleared for use in practice in the United States.
Here’s a video from Seno Medical explaining how optoacoustics works:
Link: Seno Medical…