Endoscopic imaging: How far are we from real-time histology?

Table 1 Overview of the currently available high-resolution imaging technologies

Technology	Contrast	Field of view	Lateral resolution	Clinical results
				Trial	Patients(n)	No. of examined areas	Results
Confocal laser endoscopy (Pentax-eCLE)	IV fluorescein	475 μm	0.7 μm	Kiesslich et al[36]	63	156	Barrett’s: Sensitivity 98.1%; Specificity 94%
	Topical acriflavine 0.05%						Esophageal neoplasia: Sensitivty 92.9%; Specificity 98.4%
Confocal laser endoscopy (Mauna Kea-pCLE)	IV fluorescein	240-600 μm	1 μm	Bajbouj et al[51]	39	670	Specificity: 97% (blinded), 95% (on-site);
	Topical acriflavine 0.05%						Sensitivity: 28% (blinded), 12% (on-site)
Endocytoscopy (Olympus)	Absorptive contrast (i.e. Methylene Blue or Toludine Blue)	< 0.5 mm	1.7-4 μm	Pohl et al[33]	16	166	PPV/NPV (HGIN or cancer in Barrett’s patients)-0.29/0.87 (× 450)-0.44/0.83 (× 1125)
				Sasajima et al[35]	6	7	93.3% accuracy in colon cancer detection
HRME	Topical proflavine 0.01%	750 μm	< 4 μm	N/A→Currently going to clinical trial
Optical coherence tomography	None		Traditional systems: 7-20 μm	Poneros et al[52	121	288	Diagnosis of intestinal metaplasia: 97% sensitive, 92% specific
			Catheter-based: 1-2 μm

HRME: High resolution magnification endoscopy; PPV: Positive predictive value; NPV: Negative predictive value.