Evidence based review of the impact of image enhanced endoscopy in the diagnosis of gastric disorders

Table 1 Summary of studies using magnification with white light

Use in stomach	Type of evidence	Description	Remarks
Identification of normal gastric mucosa	Descriptive study[7]; Cross-sectional study with comparison to histology[8]	Normal corpus: Regular honeycomb pattern Normal antrum: Coil-shaped network with rare collecting venules	Different descriptive classifications have been used, but all emphasize on regular and uninterrupted mucosal and vascular patterns
Diagnosis of H. pylori gastritis	Six prospective studies with histology as the comparator[8-13]	High sensitivities and specificities for diagnosis of H. pylori	Multiple and varied pattern classifications with different endoscopes. Inherent subjectivity in classifications is an issue
Characterization of EGC	Six prospective studies with histology as the comparator[15-20]	Better results as compared to the traditional white light endoscopy	Multiple classifications bring inherent subjectivity; the most prevalent classification is the “VS” classification[17] which describes: Differentiated EGC: Irregular microvessels with a demarcation line Undifferentiated EGC: Absent demarcation line and absent sub-epithelial capillary networks

H. pylori: Helicobacter pylori; EGC: Early gastric cancer.

Table 2 Summary of studies using narrow band imaging in stomach

Use in stomach	Type of evidence	Description	Remarks
Screening of focal lesions in stomach	Five prospective studies[35-39] studied screening with WLE followed by characterization of detected lesions with NBI Single randomized prospective study with bright-NBI[40]	WLE followed by characterization with NBI seems to increase confidence in taking targeted biopsies New generation “bright-NBI” appears promising to increase yield of FGL as single step examination in stomach	Majority of the detected FGLs are intestinal metaplasia Due to small sample sizes in these studies, it is unclear whether such strategy will improve detection of subtle malignant gastric lesions
Diagnosis of H. pylori gastritis	Two prospective trials[41,42] using M-NBI with histology as comparator	Subjective classifications of mucosal microvascular patterns showed high sensitivity and specificity for real-time diagnosis of H. pylori gastritis	Inherent subjectivity in the classification is an issue
Diagnosis of IM	Multiple prospective studies and one recent meta-analysis[44] using M-NBI for diagnosis of IM	Multiple patterns have been assigned for diagnosis of IM. The most prevalent is the “LBC” sign The pooled sensitivity and specificity of LBC for diagnosis of IM are 84% and 93% respectively	LBC sign with M-NBI appears easy to learn and reliable for real-time diagnosis of IM
Characterization of an EGC	Multiple prospective studies including two recent meta-analyses[52,53] using M-NBI for characterization of an EGC	Various pattern-classification systems with M-NBI have been used in different studies to characterize a lesion as EGC. The pooled sensitivity: 0.83-0.85 The pooled specificity: 0.96	Inherent subjectivities in a variety of classifications remain an issue Significant heterogeneity were observed in both meta-analyses
Prediction of histological differentiation of an EGC	At least two prospective studies[54,55]	Subjective pattern assignments were given; Only moderate sensitivities and specificities to determine histological differentiation of an EGC	Inherent subjectivities in the classification system. Currently, histology is still required to determine histological differentiation of an EGC
Determination of horizontal extent of an EGC	Few studies with small sample sizes	One study[58] showed better accuracy than indigo carmine chromoendoscopy	Real-time estimation of an EGC is useful before endoscopic resection. However, the histology still remains the gold-standard
Determination of depth of an EGC	Two prospective[61,62] studies	Subjective classifications but with excellent accuracy	Inherent subjectivities in the classification system. Currently, histology is still required to determine depth of an EGC

FGL: Focal gastric lesion; H. pylori: Helicobacter pylori; EGC: Early gastric cancer; M-NBI: Magnifying narrow band imaging; IM: Intestinal metaplasia; LBC: Light blue-crest; WLE: White light endoscopy.

Table 3 Summary of image-enhanced endoscopy in stomach

Technique	Use	Evidence	Remarks
High-definition WLE	Standard of care for initial examination of gastric mucosa	Not available
WLE with magnification	Helpful in describing normal mucosal patterns in corpus and antrum. Appears useful in predicting real-time diagnosis of H. pylori infection. Better than WLE for characterization of EGCs	Multiple prospective comparative studies for identifying H. pylori infection and for characterization of EGCs	A variety of classifications in describing the normal and abnormal mucosal pattern makes interpretation difficult for widespread use
Dye-based chromoendoscopy	Traditionally used for demarcation of EGC before resection	Few prospective studies are available, and more data will be needed	There are heterogeneity in the types of stain, technique of staining, classification in defining mucosal patterns
NBI	Good for characterization of a focal lesion detected on WLE May be useful for real-time diagnosis of H. pylori Appears reliable for diagnosis of intestinal metaplasia High specificity for characterization of EGCs May be useful for prediction of histological differentiation, prediction of depth of invasion, and in determination of horizontal extent of EGCs	Multiple prospective comparative study show good evidence in support of NBI for diagnosis of intestinal metaplasia and characterization of EGCs More evidence will be needed for other indications	Identifying intestinal metaplasia appears straightforward A variety of classifications for different mucosal pattern bring difficulty in generalization of NBI
FICE	May be useful for diagnosis of focal gastric lesions	Not much comparative prospective data is available
I-SCAN		No comparative data for use of I-SCAN in stomach
Blue-laser imaging	Is expected to be used in similar manner as NBI	Data mainly based on case series rather than comparative studies	Based on anecdotal experience it is similar to NBI and therefore would be expected to provide similar outcomes

WLE: White light endoscopy; EGC: Early gastric cancer; NBI: Narrow-band imaging; FICE: Flexible spectral imaging color enhancement; BNI: Narrow band imaging; H. pylori: Helicobacter pylori.