Endomicroscopy of the Pancreaticobiliary System

It is often difficult to accurately differentiate between benign and malignant pancreaticobiliary strictures, and some are interpreted as indeterminate despite ERCP, EUS, or radiological imaging techniques, thereby making it difficult for the clinician to make appropriate management decisions. Probe-based confocal laser endomicroscopy (pCLE) is an innovative imaging tool integrating real-time in vivo imaging of these difficult-to-interpret strictures in the pancreaticobiliary system during endoscopy. Recent studies of endomicroscopy have shown a promising role with improved accuracy in distinguishing these lesions, thus paving the way for future research addressing improving precise interpretation, training, and long long-term impact. 1. Introduction Over the past few years, advanced imaging techniques have improved the diagnosis of pancreaticobiliary disorders. While there have been improvements in technology involving procedures such as endoscopic retrograde cholangiopancreaticography (ERCP), endoscopic ultrasound (EUS), computed tomography (CT) scan, magnetic resonance imaging (MRCP), and direct cholangioscopy/SpyGlass, there have also been major advancements in not only diagnosis but also in tissue procurement combined with therapeutic potential. However, in spite of such progress, it remains difficult to accurately differentiate between benign and malignant lesions such as strictures, which are vital for decision-making and appropriate management [1] (Figure 1). Often, conventional methods such as intraductal biopsy, cytological brushings, or FNA remain inconclusive or indeterminate resulting in low diagnostic accuracy [2] (Figure 5). These scenarios lead to further testing or intervention; delay diagnosis is important for a potential candidate requiring surgical resection or palliative therapy. Probe-based confocal laser endomicroscopy (pCLE) is one innovative tool that allows for real-time in vivo imaging of these difficult-to-interpret strictures in the pancreaticobiliary system. Figure 1: ERCP images of biliary strictures. Current diagnostic modalities (biopsy, brush cytology, or fine needle aspiration (FNA) through ERCP or EUS guided routes) have their limitations in accurate diagnosis of biliary strictures, and the sensitivity of tissue sampling varies between 20% and 60% [3–5]. The sensitivity increases when two sampling methods are utilized such as combining brush cytology with forceps yielding a sensitivity ranging from 54% to 70.4% and specificity from 97% to 100% [6]. Adding EUS-guided FNA to these methods increased the sensitivity