Utility of EUS: Elastography in the Diagnosis of Pancreatic Diseases

Abstract

Clinical usefulness of real-time tissue elastography (EG: Hitachi, Japan) that visualizes elastic information of tissue using transabdominal ultrasonography (US) is reported mainly in the diagnosis of a superficial organ disorders such as thyroid and breast. EG is the technology that images the difference of distortion between hard tissue and soft tissue in real time. With the cooperation of Hitachi and Pentax, clinical use of EUS-elastography (EUS-EG) became possible. We investigated utility of EUS-EG in the diagnosis of pancreatic diseases. Methods: Subjects consist of 38 patients with 45 lesions: 11 solid tumors (10 pancreatic cancer, 1 pancreatic endocrine tumor), 19 cystic lesions (10 IPMN (intraductal papillary mucinous neoplasm), 6 pseudocyst, 1 mucinous cyst adenoma, 1 solid pseudo-papillary tumor, 1 simple cyst), 13 chronic pancreatitis and 2 autoimmune pancreatitis. We observed target lesions in EUS-EG after depiction in B-mode EUS and compared both images. In this system, both B-mode and EUS-EG images are represented on dual screen at the same time, we can compare both images of same scan plane precisely. In EUS-EG, the tissue elasticity in ROI (region of interest) is expressed in difference of colors, that is, from hard to soft tissue, it is displayed continually from blue to red. We compared EUS-EG images with B-mode images of pancreatic diseases. EUB-8500 (Hitachi) as an ultrasound diagnostic machine and EG-3630UR (Pentax) as an endosonoscope were used in this study. Results: As for 11 solid tumors, in 8 cases of cancer, the sizes of tumor images on EUS-EG corresponded to those of B-mode EUS and in remaining 2 cases, EUS-EG images were revealed slightly wider in range than those of B-mode EUS. The hardness of one endocrine tumor was represented as the same degree as the pancreatic parenchyma. For cystic lesions, usually no color signals were displayed in the cysts. The parenchyma of chronic pancreatitis (including autoimmune pancreatitis) was shown as the image that various colors coexisted from hard to soft tissue. Conclusion: EUS-EG needs attention for the interpretation to show relative value of the hardness in setting ROI. EUS-elastography may be useful diagnostic modality in the diagnosis of pancreatic diseases to offer different information from that of conventional diagnostic imaging methods and be more useful technique in future if absolute evaluation of EUS-elastography become possible. Clinical usefulness of real-time tissue elastography (EG: Hitachi, Japan) that visualizes elastic information of tissue using transabdominal ultrasonography (US) is reported mainly in the diagnosis of a superficial organ disorders such as thyroid and breast. EG is the technology that images the difference of distortion between hard tissue and soft tissue in real time. With the cooperation of Hitachi and Pentax, clinical use of EUS-elastography (EUS-EG) became possible. We investigated utility of EUS-EG in the diagnosis of pancreatic diseases. Methods: Subjects consist of 38 patients with 45 lesions: 11 solid tumors (10 pancreatic cancer, 1 pancreatic endocrine tumor), 19 cystic lesions (10 IPMN (intraductal papillary mucinous neoplasm), 6 pseudocyst, 1 mucinous cyst adenoma, 1 solid pseudo-papillary tumor, 1 simple cyst), 13 chronic pancreatitis and 2 autoimmune pancreatitis. We observed target lesions in EUS-EG after depiction in B-mode EUS and compared both images. In this system, both B-mode and EUS-EG images are represented on dual screen at the same time, we can compare both images of same scan plane precisely. In EUS-EG, the tissue elasticity in ROI (region of interest) is expressed in difference of colors, that is, from hard to soft tissue, it is displayed continually from blue to red. We compared EUS-EG images with B-mode images of pancreatic diseases. EUB-8500 (Hitachi) as an ultrasound diagnostic machine and EG-3630UR (Pentax) as an endosonoscope were used in this study. Results: As for 11 solid tumors, in 8 cases of cancer, the sizes of tumor images on EUS-EG corresponded to those of B-mode EUS and in remaining 2 cases, EUS-EG images were revealed slightly wider in range than those of B-mode EUS. The hardness of one endocrine tumor was represented as the same degree as the pancreatic parenchyma. For cystic lesions, usually no color signals were displayed in the cysts. The parenchyma of chronic pancreatitis (including autoimmune pancreatitis) was shown as the image that various colors coexisted from hard to soft tissue. Conclusion: EUS-EG needs attention for the interpretation to show relative value of the hardness in setting ROI. EUS-elastography may be useful diagnostic modality in the diagnosis of pancreatic diseases to offer different information from that of conventional diagnostic imaging methods and be more useful technique in future if absolute evaluation of EUS-elastography become possible.