Endoscopic ultrasound-guided fine needle aspiration: from the past to the future

Abstract

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a technique which allows the study of cells obtained through aspiration in different locations near the gastrointestinal tract. EUS-FNA is used to acquire tissue from mucosal/submucosal tumors, as well as peri-intestinal structures including lymph nodes, pancreas, adrenal gland, gallbladder, bile duct, liver, kidney, lung, etc. The pancreas and lymph nodes are still the most common organs targeted in EUS-FNA. The overall accuracy of EUS is superior to computed tomography scan and magnetic resonance imaging for detecting pancreatic lesions. In most cases it is possible to avoid unnecessary surgical interventions in advanced pancreatic cancer, and EUS is considered the preferred method for loco-regional staging of pancreatic cancer. FNA improved the sensitivity and specificity compared to EUS imaging alone in detection of malignant lymph nodes. The negative predictive value of EUS-FNA is relatively low. The presence of a cytopathologist during EUS-FNA improves the diagnostic yield, decreasing unsatisfactory samples or need for additional passes, and consequently the procedural time. The size of the needle is another factor that could modify the diagnostic accuracy of EUS-FNA. Even though the EUS-FNA technique started in early nineteen's, there are many remarkable progresses culminating nowadays with the discovery and performance of needle-based confocal laser endomicroscopy. Last, but not least, identification and quantification of potential molecular markers for pancreatic cancer on cellular samples obtained by EUS-FNA could be a promising approach for the diagnosis of solid pancreatic masses.

Keywords: confocal laser endomicroscopy; endoscopic ultrasound; fine needle aspiration.

Figure 1

Initial designs of the endoscopic ultrasound-guided fine needle aspiration needle (Vilmann-Hancke needle).

Figure 2

Endoscopic ultrasound (EUS)-guided fine needle aspiration consisting of a linear EUS scope with the FNA needle exiting the biopsy channel in the plane of the ultrasound image.

Figure 3

Initial thesis was considered a landmark study and published as a book on endoscopic ultrasound (EUS) using curved linear array transducer with description and development of the biopsy needle and the EUS-guided fine needle aspiration procedure.

Figure 4

Endoscopic ultrasound-guided fine needle aspiration performed with a 22-G needle on the side of a hypoechoic pancreatic tumor mass, with both cytology and microhistology performed after at least 3 passes. Cytology showed a clump of malignant cells, while microhistology confirmed the diagnosis of adenocarcinoma.

Figure 5

Needle based confocal laser endomicroscopy (nCLE) image of pancreatic tissue using fluorescein as a systemic contrast agent, presenting grey lobular structures of tissue with thin white lines crossing representing fibrosis in a patient with chronic pancreatitis. Another nCLE image of pancreatic tissue, demonstrating dark lobular structures and large vessels obtained in a patient with pancreatic ductal carcinoma.