The purpose of this study is to measure and compare the difference of sound speed between pancreatic cancer and non-pancreatic cancer, and determine the critical value of sound speed for benign and malignant pancreatic cancer. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value for the diagnosis of pancreatic cancer are calculated, so as to evaluate the clinical application value of local sound speed measurement in the diagnosis of pancreatic cancer.

The investigators include patients who are found to have solid pancreatic mass on continuous imaging. All subjects are scanned by Fuji film su-9000 ultrasonic system. After the lesions are found, local sound velocity measurement technology will be used to measure the sound velocity in the lesions. Pathology diagnosis or clinical follow-up results will be regard as diagnostic gold standard to divide the patients into pancreatic cancer and pancreatic cancer group. The investigators will compare the sound velocity value if there is statistically significant difference between the two groups, build the receiver operating characteristic curve, calculation of pancreatic benign and malignant lesions of sound velocity threshold, and and the investigators will calculate the sensitivity, specificity, accuracy, positive predictive value and negative predictive value, to evaluate local sound velocity measurement in the diagnosis of pancreatic cancer clinical application value.

Inclusion Criteria:

1. Patients aged between 18 and 75, gender is not limited.
2. Evidence of solid pancreatic lesions have been found on imaging examination, including computed tomography, magnatic resonance imaging and endoscopic ultrasonography.
3. The lesion was greater 1cm.
4. The informed consent has been signed.

Exclusion Criteria:

1. Patients with serious cardiopulmonary diseases and poor general condition.
2. Patients with other contraindications to endoscopic ultrasonography.
3. Cannot or refuse to sign the informed consent.