Ultra high magnification endoscopy: Is seeing really believing?

Table 1 Comparison of endocytoscopy and confocal endomicroscopy

	ECS	CEM
Available systems
Probe based	Olympus (Japan)	Optiscan (Australia) endomicroscope integrated into Pentax (Japan) endoscope
Integrated	Olympus (Japan)	Cellvizio, Mauna Kea Technologies (France)
Max resolution	NA	1024 × 1024 pixels with integrated system (lower with probe based system)
Max magnification	1400 × (probe) 580 × (integrated)	1000 ×
Field of view	300 μm × 300 μm (450 x magnification)	475 μm × 475 μm
	120 μm × 120 μm (1125 x magnification)
Depth of imaging	Superficial mucosal layer only	Probe based: Different probes allow for different imaging depths
		Integrated system: Variable, up to 250 μm below surface (lamina propria)
Contrast agents	0.5%-1% methylene blue	Fluorescein sodium
	0.25% toluidine blue	Acriflavine
Commercially available?	No	Yes
Advantages	Higher magnification than CEM	Can visualize subsurface structures up to 250 μm
		Commercially available
Disadvantages	Cannot visualize subsurface structures	Lower magnification than ECS
	Requires mucolytic preparation of tissue	Two contrast agents required for optimal imaging
	Not commercially available

ECS: Endocytoscopy; CEM: Confocal endomicroscopy; NA: Not available.

Table 2 High magnification endoscopy and esophageal squamous cell cancer

Modality	Findings	Test characteristics
Endocytoscopy	Nuclear atypia	Sensitivity 81%-95%1
	Increased nucleus: Cytoplasm ratio	Specificity 84%-100%1
	Increase in cell density	Accuracy 82%-90%1
	Irregular cellular distribution
Confocal endomicroscopy	Dilated intraepithelial papillary capillary loops	Accuracy 85%-96%
	Abnormal cellular structures

¹Determination of malignant vs non-malignant.

Table 3 Confocal endomicroscopy and endocytoscopy findings of colonic architecture[33,34,36]

Feature	Normal	Malignant
Vessel Architecture	Hexagonal, honeycomb appearance of capillaries	Distorted, dilated capillaries with increased leakage
	Capillaries surround the stroma, which encircle the crypt openings	Irregular arrangement with no specific relationship to adjacent tissue
Crypts	Regular luminal openings and distribution	Heterogeneous distribution with irregular layer epithelial cells
	Crypts covered by uniform layer of epithelial cells (including Goblet cells)	Loss of crypts and goblet cells
Sensitivity		ECS: 79%-91%[6,35]
		CEM: 91%[37]
Specificity		ECS: 90%-100%[6,35]
		CEM: 76%[37]