Analysis of EUS Elastography to Differentiate Mass Forming Pancreatitis and Pancreatic Cancer By Using Strain Ratio

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Introduction: Recently, EUS elastography has been reported to supplemental information which can be applied for the diagnosis of pancreatic diseases. However, there is limit in evaluation only for color, and quantification by numerical value is required. Aim: The aim of our study was to evaluate the ability of EUS elastography and quantification by using strain ratio(non mass area/mass area: SR) in order to distinguish mass forming pancreatitis(MFP) from pancreatic cancer (PC). Patients and Methods: The subjects were 105 patients performed an endoscopic ultrasound (EUS) for pancreas in our hospital till September 2006 to November 2008. The disease were 6 with mass forming pancreatitis (MFP), 5 with chronic pancreatitis (CP), 61 with pancreatic cancer(PC), 6 with neuroendocrine carcinoma (PNET),4 with auto immune pancreatitis (AIP), 5 with SCN,2 with SPN,1 with Schwanoma,1 with GIST,1 with renal cell carcinoma pancreatic metastasis, 7 with IPMN,1 with malignant lymphoma and 5 with normal control. A histological diagnosis by surgery or endoscopic ultrasonography fine needle aspiration (EUS-FNA) was performed except normal control. The ultrasound was used the HITACHI HI VISION900, and EUS scope was PENTAX EG-3630UR, EG-3670URK and EG-3870UTK. Strain ratio was subsequently performed to choose a mass area and a non-mass area, and the ratio was measured by calculating in real time. Results: Elastography for all PC showed intense blue coloration, which indicated that the mass lesions had malignant aspects. While MFP presented the coloration pattern of mixed green, yellow and low intensity of blue. Normal control was an even application of green to red. The mean SR of MFP and PC were each 23.08 ± 12.65 and 39.08 ± 20.54, respectively, which was significant difference(p<0.05). Conclusion: EUS elastography is potentially capable of further defining the tissue characteristics of benign and malignant lesions. This study suggested that it was useful for the quantification by using strain ratio to characterize the tissue hardness of pancreatic disease and distinguish MFP from PC.