Mo1518 An Evaluation of Risk Factors for Inadequate Cytology Using Contrast-Enhanced Harmonic Endoscopic Ultrasound in Endoscopic Ultrasound-Guided Fine Needle Aspiration of Suspected Pancreatic Malignancy

An Evaluation of Risk Factors for Inadequate Cytology Using Contrast-Enhanced Harmonic Endoscopic Ultrasound in Endoscopic Ultrasound-Guided Fine Needle Aspiration of Suspected Pancreatic Malignancy Masahiro Itonaga*, Kazuki Ueda, Hiroko Terada, Takashi Tamura, Yasunobu Yamashita, Hiroki Maeda, Takao Maekita, Mikitaka Iguchi, Hideyuki Tamai, Jun Kato, Masao Ichinose Second Department of Internal Medicine, Wakayama Medical University, Wakayama City, Japan [OBJECTIVES] Contrast-enhanced harmonic endoscopic ultrasound(CH-EUS) is useful for differential diagnosis of pancreatic mass lesions, but risk factors for inadequate cytology using this modality in endoscopic ultrasound-guided fine needle aspiration(EUS-FNA) remain unclear. The present study aimed to evaluate the role of CH-EUS in EUS-FNA. [METHODS] Generally, CH-EUS is evaluated in the perfusion phase (60-90 s after contrast agent infusion), but we performed evaluations in the early phase (10-30s after contrast agent infusion) and categorized into two patterns: Pattern A, homogeneous enhancement; and Pattern B, heterogeneous enhancement with partial hypoenhancement. We selected typical Pattern A and Pattern B cases of pancreatic ductal adenocarcinoma that had undergone surgery and performed histopathological examinations with hematoxylin and eosin staining and immunohistochemical staining. Compared with Pattern A, the Pattern B case showed necrotic or fibrous lesions and fewer vessels. The Pattern A case showed tumor cells homogeneously, but the Pattern B case showed few tumor cells in the necrotic or fibrous regions and tumor cells were distributed heterogeneously. We thus hypothesized that accuracy of EUS-FNA would differ between Patterns A and B. From January 2009 to July 2012, a total of 61 patients with suspected pancreatic malignancy were included. After CH-EUS was performed, we performed EUSFNA at the center of each mass. Risk factors for inadequate cytology were evaluated retrospectively. [RESULTS] Male:female ratio was 36:25, mean ( standard deviation) age was 68.8 8.96 years, mean lesion size was 37.6 15.3 cm, head:body or tail ratio was 28:33; 19G/22G ratio was 37/24; number of passes was 2.77 1.28 and Pattern A:B ratio was 23:38. FNA was successfully performed in all cases and adequate samples for histological examination were obtained in 53 of the 61 cases (86.9%). Only Pattern B was identified as a significant risk factor for inadequate cytology (p 0.02) using the 2-test and Student’s t-test. [CONCLUSION] As expected, accuracy in EUS-FNA differed significantly between Patterns A and B. We expect CH-EUS to improve the diagnostic value of EUS-FNA if regions of hypoenhancement on CH-EUS are avoided.