Advanced endoscopic imaging of indeterminate biliary strictures

Table 1 Potential etiologies of indeterminate biliary stricture

Benign

Primary sclerosing cholangitis

IgG4-associated cholangiopathy

Postoperative stricture (anastomotic, ischemic, cholecystectomy-related)

Ischemia (e.g., hepatic artery thrombosis)

Infections (HIV cholangiopathy, parasites)

Pancreatitis (acute, chronic, autoimmune)

Choledocholithiasis

Mirizzi syndrome

Eosinophilic cholangitis

Vasculitis

Radiation

Portal biliopathy

Malignant

Pancreatic adenocarcinoma

Cholangiocarcinoma

Hepatocellular carcinoma

Lymphoma

Metastatic adenocarcinoma (e.g., compressive lymphadenopathy)

HIV: Human immunodeficiency virus.

Table 2 Comparison of advanced endoscopic imaging modalities

	Advantages	Disadvantages
ERCP	Widely available	Procedural risks
	Workhorse technique with numerous accessories	Fluoroscopic (and endoscopic) images only
	Facilitates other diagnostic modalities (e.g., biliary brushing, biopsy, endomicroscopy) as well as therapy	Low sensitivity of conventional cytology and intraductal biopsies
EUS	Provides staging information	Limited views of the intrahepatic biliary tree (and non-visualization of the right intrahepatic ductal system)
	Permits FNA	Generally nondiagnostic in and of itself without FNA
	Can facilitate difficult biliary cannulation	Risk of tumor seeding if FNA primary tumor
IDUS	Can help direct ERCP-guided tissue acquisition	Limited depth of imaging
		Infrequently used in routine practice
Cholangioscopy	Excellent visualization of the biliary mucosa (with digital cholangioscopes)	High cost (disposable system $2000 per case)
	May improve sensitivity, specificity, and overall accuracy compared to ERCP alone	Likely higher rates of pancreatitis, cholangitis, and perforation compared to ERCP alone
		Time-consuming
		Not widely available
CLE	Excellent sensitivity and negative predictive value	Marginal interobserver agreement
	Provides imaging at a cellular and sub-cellular level (lateral resolution of 3.5 μm)	Contact imaging of a very limited regional surface
		Time-consuming
		Not widely available
OCT	High resolution	Suboptimal sensitivity
	Improved sensitivity compared to ERCP-guided tissue acquisition	Resolution not as high as CLE
	Highly specific	Not widely available
	Permits larger surfaces areas to be examined compared to CLE	Not well-validated

ERCP: Endoscopic retrograde cholangiopancreatography; EUS: Endoscopic ultrasound; IDUS: Intraductal ultrasound; CLE: Confocal laser endomicroscopy; OCT: Optical coherence tomography; FNA: Fine needle aspiration.