Trial Information

A Randomized Study Comparing Endoscopic Video-Autofluorescence Imaging Followed by Narrow Band Imaging With Standard Videoendoscopy for the Detection of High Risk Lesions of Stomach

Gastric cancer remains one of the leading causes of cancer deaths worldwide. Early detection
and diagnosis of gastric cancer improves the outcomes of treatment. However, most of gastric
cancers detected in Singapore are late and advanced in stages.

Videoendoscopy is the standard tool for examination of gastrointestinal tract. Despite the
improvement of technology, early gastric cancers can be easily missed by routine
examination, because there are few morphological changes. Therefore, a functional imaging
modality, that can distinguish abnormal lesion from surrounding normal mucosa may complement
the current videoendoscopy.

Autofluorescence Imaging (AFI) based on the presence of natural tissue fluorescence on the
gastrointestinal tract. When the mucosa was exposed by an excitation light, certain
endogenous molecules (fluorophores) will emit fluorescence light of longer wavelength. The
fluorescent light can be detected and spectrally analyzed. By computation of the difference
in the reflecting images, the system can specify lesions, including malignancies from the
adjacent mucosa, and can reveal early cancers that are not detectable by standard endoscopy.

Narrow band imaging (NBI) is another novel optical imaging technique based on high
resolution imaging, which aims at enhancing the fine structure of the mucosa. In NBI, the
band widths of the red, blue, green components of the excitation light are narrowed to
certain wavelength ranges, which allow better contrast of the superficial mucosa and the
vascular structure. NBI has a maximum zoom capacity of 115 times. Abnormal lesions are
detected by the presence of abnormal mucosal and vascular patterns.

Recent studies suggested that these AFI and NBI systems can be complementary to each other.
The resolution of AFI is low but it can be used as a 'red flag' technique to screen any
suspicious lesions from the normal mucosa. On the other hand, NBI produces high resolution
images which allows detailed examination and subsequent target biopsy of the suspicious
lesions based on AFI. Preliminary reports from Japan and the Netherlands suggested this
combined imaging method improves the detection of early esophageal and gastric cancers.
Recently, a new endoscopy system has been developed that incorporates standard
videoendoscopy system with both AFI and NBI modes. By pressing a switch, the endoscopy
system can switch from normal white light to either a narrow band light or autofluorescence
mode. This novel system reduces the convenience and discomfort for the patients to avoid
repeated intubation. The purpose of this study is to prospectively evaluate this combined
imaging modality for detection of high risk gastric lesions and early cancers by comparing
it with standard videoendoscopy in a randomized fashion.