Areas of hypoxia, or low oxygen in tissue, are hallmarks of fast-growing cancers and of blockages or narrowing in blood vessels, such as stroke or peripheral artery disease. Researchers have developed a way to find hypoxic spots noninvasively in real time. The researchers developed an oxygen-sensitive molecular beacon that emits ultrasound signals in response to light, a process called photoacoustic imaging.

Source: Molecular beacon signals low oxygen with ultrasound