New views of esophageal cancer by MAGIC

08 May 2024

Johns Hopkins gastrointestinal imaging capsule offers screening, diagnosis, treatment.

A project at Johns Hopkins University has developed a multifunctional ablative gastrointestinal imaging capsule (MAGIC) for esophagus surveillance and interventions.

Described by the project as "a groundbreaking advancement in gastrointestinal health," the MAGIC device is described in the AAAS partner journal BMEF.

"A clinically viable technology for comprehensive esophagus surveillance and potential treatment is lacking," commented the MAGIC team in its paper. "MAGIC technology could also facilitate the clinical translation and adoption of the tethered capsule endomicroscopy (TCE)."

TCE devices, designed to be swallowed by the patient and deliver imaging data back up an attached tether before being either withdrawn or allowed to pass onward, can already carry a number of different imaging technologies. The incorporation of OCT is particularly attractive for surveillance of Barrett’s esophagus and esophageal cancer without the need to sedate patients.

Building OCT into a TCE module was part of work for which Andreas Wartak at Massachusetts General Hospital was a winner of the SPIE-Franz Hillenkamp Postdoctoral Fellowship in 2019 (pdf from SPIE Photonics West). Speaking at the time Wartak said that merging specialized high-end equipment and customized components for a high-speed and high-resolution instrument was the key hurdle for TCE.

The current Johns Hopkins project commented that "it remains challenging with the current TCE technology for detecting early lesions and clinical adoption due to its suboptimal resolution, imaging contrast, and lack of visual guidance during imaging."

MAGIC was designed to tackle these problems, by incorporating not only dual-wavelength OCT imaging operating at 800 and 1300 nanometers and an ultracompact endoscope camera, but also an ablation laser. This should allow surveillance, guidance and tissue marking of the esophagus from the same capsule.

Faster clinical translation for esophagus treatment

"The 800 nm OCT images would allow for differentiating fine histopathological changes in mucosal layers with better resolution and enhanced contrast, while the 1300 nm OCT images enable monitoring the depth of lesion invasion," said the project. "An ablation laser facilitates laser marking for precise biopsies, and thus can improve diagnostic yield and accuracy."

Two particular challenges to implementation were minimizing chromatic aberration over a broad spectral bandwidth, particularly at the shorter 800 nm wavelength range; and dealing with astigmatism in the device optics. The latter was tackled by incorporating a customized curved mirror for beam scanning, with the curvature of the mirror optimized to prefocus the imaging beam and compensate for the astigmatism effect of the capsule shell.

MAGIC was tested by imaging swine esophagus both ex vivo and in vivo. The dual-wavelength OCT system successfully revealed fine tissue microarchitecture as well as the deeper tissue details required for treatment selection, while the ablation laser enabled precise marking of areas for subsequent biopsies.

Although direct laser ablation of tissues for therapy was not examined in this initial study, the potential for the MAGIC device to ablate early-stage esophageal lesions itself via laser treatment clearly holds promise and points to the device's versatility, according to the Johns Hopkins team.

"By fully utilizing the critical functions in a single device, the MAGIC system can offer a comprehensive and effective solution for endoscopic screening, diagnosis, and potential ablation treatment of the esophagus," said the project. "This advancement holds a strong promise in accelerating the clinical translation and adoption of the TCE technology."