Endoscopic ultrasound (EUS) guided fine needle aspiration (FNA) biopsy using radial scanning endosonography: Results of diagnostic accuracy

Background: EUS has been accurate in staging gastrointestinal (GI) malignancies. Recently, FNA has been reported to be useful in obtaining tissue for diagnosis of both submucosal and extramural GI lesions. Some centers use curved array EUS to guide the FNA, but the cost of having both curved array (for FNA) and radial scanning (for diagnosis) EUS can be prohibitive. We report our experience with EUS-guided FNA using a radial scanning echoendoscope. Methods: 45 consecutive patients over a 1-year period (Nov. 1995 - Nov. 1996) (20M/25F, mean age 62, age range 25-89), referred for EUS evaluation of submucosal or extramural GI masses, underwent EUS-guided FNA using a radial scanning echoendoscope (GF-UM20, Olympus, Melville, NY). We used either a Wilson-Cook prototype FNA needle (23 gauge, 40mm) or a Millrose transbronchial needle (22 gauge, 13mm). Data collected included lesion types sampled, # of passes performed, complications and cytological accuracy of FNA. Cytological accuracy was defined by cytological evidence of malignant cells or target tissue (e.g. pancreatic acinar cells or submucosal tissue). FNA samples were immediately processed by a cytologist in the endoscopy suite. All histological diagnoses were reviewed with a single cytologist. Results: A total of 45 lesions were targeted (mean passes = 2.95). No complications were reported. Lesion type # Pts # Passes Proc. Time Cyto. Yield Submucosal 20 2.83 89 min 6/20 = 30% Pancreatic cyst 5 3.00 87 min 3/ 5 = 60% Pancreatic masses 15 2.92 95 min 7/15 = 47% Other extramural 5 3.40 98 min 1/ 5 = 20% Radial scanning EUS FNA had diagnostic cytology in 38% (17/45). Conclusions: EUS FNA with a radial scanning echoendoscope is technically feasible and safe but appears to have a very low cytological yield even in experienced hands. This may be due to (1) inability visualizing the FNA needle during its entire track to the lesion; and (2) technical problems with a workable stylet and in producing adequate suction to obtain sufficient samples with the FNA needles, which are being addressed. Other EUS systems, such as curved array or mechanical longitudinal rotating, appear to be more suitable for FNA.