A University of Arizona is set to develop optical technology capable of peering deep into biological tissues, such as skin or soft tissue linings inside the body. The approach could be used to image skin cancers, the most prevalent malignancy worldwide, to help physicians assess tumor invasion and monitor treatment response.
The researchers are one of only four groups in the U.S. to receive funding through the "Advancing Non-Invasive Optical Imaging Approaches for Biological Systems" initiative.
The U of A research group will create a noninvasive approach based on synthetic wavelength imaging, or SWI, which uses two separate illumination wavelengths to computationally generate one virtual, "synthetic" imaging wavelength.
Due to the longer, synthetic wavelength, the signal is more resistant to light scattering inside tissue. At the same time, researchers can take advantage of the higher contrast information provided by the original illumination wavelengths.
"This project specifically focuses on nonmelanoma skin cancers, such as basal cell carcinoma or squamous cell carcinoma," states principal investigator and project lead Florian Willomitzer, an associate professor of optical sciences. "Those skin cancers can display significantly different imaging contrast properties than melanoma, which poses a unique challenge to the development of new 'deep' imaging technologies."
Current skin cancer imaging methods, such as confocal microscopy or optical coherence tomography, use optical light with wavelengths in the visible to near-infrared spectrum, according to Willomitzer. They offer superior contrast and resolution at shallow tissue depths, but their relatively short imaging wavelengths make them susceptible to light scattering deep inside biological tissue. Longer wavelength methods, like ultrasound or hybrid approaches, can image deeper layers, but they often lack resolution or sufficient contrast needed for certain cancer types.
Imaging tools must be versatile enough to accurately assess tumor margins at the time of diagnosis, while also being robust and reliable enough to monitor how lesions respond over the course of treatment.
To achieve this, medical technologists need tunable imaging capabilities that balance depth penetration with resolution and imaging contrast - something that current technologies cannot reliably provide.
The research seeks to overcome these and other limitations through technology development that will allow light to deeply image through tissue non-invasively at high resolution.
Enhanced imaging techniques can make possible earlier detection of health conditions, more precise evaluation of cellular and tissue health, and advancements in non-invasive procedures to replace surgery. The objective is to produce highly detailed images that can reveal structures ranging from individual cells to larger features of living tissues. The experiments also aim to record rapid biological processes, such as muscle contractions and pulse, with enough speed to capture them in real time.
"Synthetic wavelength imaging's resilience to scattering in deep tissue while preserving high tissue contrast at the optical carrier wavelengths is a rare combination," Willomitzer explains. "By pairing this property with advanced computational evaluation algorithms, our approach aims to break free from the conventional resolution-depth-contrast tradeoff."
The researchers state that if they can detect invasive lesions earlier, define tumour margins more precisely and monitor response to non-invasive treatments in real time, then they will be able to maximise the effectiveness of emerging therapeutic approaches.
It is also hoped the advancements will facilitate the first clinical demonstration of synthetic wavelength imaging in the critical, unmet need of assessing non-melanoma skin cancers.
The research team will receive nearly $2.7 million from the U.S. NIH's Common Fund Venture Program to advance next-generation imaging technologies that allow deeper, clearer views inside the body without the need for invasive procedures.