Photoacoustic imaging is a rapidly maturing imaging modality in biological research and medicine. This modality uses the photoacoustic effect (“light in, sound out”) to combine the contrast and specificity of optical imaging with the high temporal resolution of ultrasound. The primary goal of image-guided therapy, and theranostics in general, is to transition from conventional medicine to precision strategies that combine diagnosis with therapy. Photoacoustic imaging is well-suited for noninvasive guidance of many therapies and applications currently being pursued in three broad areas. These include the image-guided resection of diseased tissue, monitoring of disease states, and drug delivery. In this review, we examine the progress and strategies for development of photoacoustics in these three key areas with an emphasis on the value photoacoustics has for image-guided therapy.

The transmission of SARS‐CoV‐2 coronavirus has led to the COVID‐19 pandemic. Nucleic acid testing while specific has limitations for mass surveillance. One alternative is the main protease (M^pro) due to its functional importance in mediating the viral life cycle. Here, we describe a combination of modular substrate and gold colloids to detect M^pro via visual readout. The strategy involves zwitterionic peptide that carries opposite charges at the C‐/N‐terminus to exploit the specific recognition by M^pro. Autolytic cleavage releases a positively charged moiety that assembles the nanoparticles with rapid color changes (t<10 min). We determine a limit of detection for M^pro in breath condensate matrices <10 nM. We further assayed ten COVID‐negative subjects and found no false‐positive result. In the light of simplicity, our test for viral protease is not limited to an equipped laboratory, but also is amenable to integrating as portable point‐of‐care devices including those on face‐coverings.

The etiology of peri-implant crestal bone loss is today better understood and certain factors proposed in the past have turned out to not be of concern. Regardless, the incidence of crestal bone loss remains higher than necessary and this paper reviews current theory on the etiology with a special emphasis on traditional and innovative methods to assess the level of crestal bone around dental implants that will enable greater sensitivity and specificity and significantly reduce variability in bone loss measurement.

The gold-standard periodontal probe is an aging tool that can detect periodontitis and monitor gingival health but is highly error-prone, does not fully characterize the periodontal pocket, and causes pain. Photoacoustic imaging is a noninvasive technique that can address these limitations. Here, a range of ultrasound frequencies between 16-40 MHz were used to image the periodontium and a contrast medium based on cuttlefish ink was used to label the pockets. A 40 MHz ultrasound frequency could spatially resolve the periodontal anatomy, including tooth, gum, gingival margin, and gingival thickness of tooth numbers 7-10 and 22-27. The photoacoustic-ultrasound measurements were more precise (0.01 mm) than those taken with physical probes by a dental hygienist. Furthermore, the full geometry of the pockets could be visualized with relative standard deviations of 10% (n = 5). This study shows the potential for non-invasive monitoring of periodontal health with photoacoustic-ultrasound imaging in the dental clinic.