Photoacoustic PET takes imaging inside GI tract

A novel, non-invasive molecular imaging technique uses nanotechnology to allow clinicians a view into the gastrointestinal track without having to resort to invasive procedures, according to a study published July 6 in Nature Nanotechnology.

“There is a need for safer and improved methods for non-invasive imaging of the gastrointestinal tract,” wrote Weibo Cai from the University of Wisconsin-Madison and colleagues. Such a procedure could one day be used to diagnose and track gastrointestinal illness such as bacterial overgrowth and irritable bowel syndrome.

More conventional imaging such as x-ray and MR imaging provide limited access and contrast, while functional imaging would provide a comprehensive understanding of the dynamics of the GI tract.

Researchers leveraged the hydrophobicity of naphthalocyanine dyes to create frozen micelles about 20 nanometers in size with impressive absorption values and resilience in the GI environs. The researchers took to calling them “nanonaps” and conducted preclinical photoacoustic imaging to test the functionality of the technique. The nanonaps were radiolabeled with Cu-64, and PET was conducted successfully to provide whole-body imaging as the nanonaps traversed the GI tract.

“Unlike conventional chromophores, nanonaps exhibit non-shifting spectra at ultrahigh optical densities and, following oral administration in mice, passed safely through the gastrointestinal tract,” wrote the authors of the study.

The non-ionizing photoacoustic technique revealed “remarkable resolution” and low background. The method provided a means of functional imaging of the intestines in real time with ultrasound co-registration.

More research is needed to develop this technique before it could be used in clinical practice.