Chronic pancreatitis (CP) is pathologically characterized by the loss of exocrine pancreatic parenchyma, irregular fibrosis, cellular infiltration, and ductal abnormalities. Diagnosing CP objectively is difficult because standard diagnostic criteria are insufficient. The change of parenchymal hardness is the key factor for the diagnosis and understanding of the severity of CP. The ultrasonography (US) or endoscopic ultrasonography (EUS) elastography have been used to diagnose pancreatic diseases. Both strain elastography (SE) and shear wave elastography are specific diagnostic techniques for measuring tissue hardness. Most previous studies were conducted with SE. There are three methods of interpreting SE; the method of recognizing the patterns in SE distribution images in the region of interest, the method of using strain ratio to compare the hardness of adipose tissue or connective tissue with that of the lesion, and the method of evaluating the hardness distribution of a target by histogram analysis. These former two methods have been used primarily for neoplastic diseases, and histograms analysis has been used to assess hardness distribution in the evaluation of CP. Since the hardness of the pancreas increases with aging, it is necessary to consider the age in the diagnosis of pancreatic disorders using US or EUS elastography.

Case 1 is a 70-year-old male. He has a history of cholelithiasis and left inguinal hernia. A preoperative examination of the inguinal hernia showed the enlargement of the mediastinal shadow, and he was referred to our department. A close examination revealed a right-sided aortic arch, a right descending aorta, and a descending aortic diverticulum. No subjective symptoms, intracardiac malformations, or other cardiovascular diseases were observed. The surgery was scheduled for descending aorta replacement including a diverticulum with right posterior lateral 4th intercostal thoracotomy and lower body partial extracorporeal circulation. However, due to aortic intima injury at the proximal end, hypothermic cerebral circulatory arrest and proximal anastomosis were performed by the open proximal method. There was no problem with the postoperative course, and he was discharged 19 days after surgery. Case 2 is a 51-year-old female. Born in China, she has lived in Japan for 15 years. No notable history. An abnormal shadow was shown on chest Xp performed in a medical examination, and aortic malformation was suspected on chest CT. She was referred to our department. The diagnosis was right-sided aortic arch, right descending aorta, aberrant left subclavian artery, and Kommerell diverticulum. There were no subjective symptoms and no intracardiac malformations. The operation was a two-stage operation. As the initial surgery, median sternotomy was performed, total arch replacement with intrathoracic reconstruction of the left subclavian artery, and open stent graft insertion, and the Kommerell diverticulum was covered with an open stent graft. We did not treat the diverticulum because it was located on the dorsal side. At 15 days after surgery, we performed embolization of the origin of the left subclavian artery from the Kommerell diverticulum. There was no problem with the postoperative course, and she was discharged 19 days after the initial surgery.