Question: How to diagnose Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) ?
Answer: Lab tests and imaging tests are used to detect (find) and diagnose pancreatic NETs. The following tests and procedures may be used: - Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patients health habits and past illnesses and treatments will also be taken. - Blood chemistry studies : A procedure in which a blood sample is checked to measure the amounts of certain substances, such as glucose (sugar), released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease. - Chromogranin A test: A test in which a blood sample is checked to measure the amount of chromogranin A in the blood. A higher than normal amount of chromogranin A and normal amounts of hormones such as gastrin, insulin, and glucagon can be a sign of a non-functional pancreatic NET. - Abdominal CT scan (CAT scan): A procedure that makes a series of detailed pictures of the abdomen, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography. - MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI). - Somatostatin receptor scintigraphy : A type of radionuclide scan that may be used to find small pancreatic NETs. A small amount of radioactive octreotide (a hormone that attaches to tumors) is injected into a vein and travels through the blood. The radioactive octreotide attaches to the tumor and a special camera that detects radioactivity is used to show where the tumors are in the body. This procedure is also called octreotide scan and SRS. - Endoscopic ultrasound (EUS): A procedure in which an endoscope is inserted into the body, usually through the mouth or rectum. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. This procedure is also called endosonography. - Endoscopic retrograde cholangiopancreatography (ERCP): A procedure used to x-ray the ducts (tubes) that carry bile from the liver to the gallbladder and from the gallbladder to the small intestine. Sometimes pancreatic cancer causes these ducts to narrow and block or slow the flow of bile, causing jaundice. An endoscope is passed through the mouth, esophagus, and stomach into the first part of the small intestine. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. A catheter (a smaller tube) is then inserted through the endoscope into the pancreatic ducts. A dye is injected through the catheter into the ducts and an x-ray is taken. If the ducts are blocked by a tumor, a fine tube may be inserted into the duct to unblock it. This tube (or stent) may be left in place to keep the duct open. Tissue samples may also be taken and checked under a microscope for signs of cancer. - Angiogram : A procedure to look at blood vessels and the flow of blood. A contrast dye is injected into the blood vessel. As the contrast dye moves through the blood vessel, x-rays are taken to see if there are any blockages. - Laparotomy : A surgical procedure in which an incision (cut) is made in the wall of the abdomen to check the inside of the abdomen for signs of disease. The size of the incision depends on the reason the laparotomy is being done. Sometimes organs are removed or tissue samples are taken and checked under a microscope for signs of disease. - Intraoperative ultrasound : A procedure that uses high-energy sound waves (ultrasound) to create images of internal organs or tissues during surgery. A transducer placed directly on the organ or tissue is used to make the sound waves, which create echoes. The transducer receives the echoes and sends them to a computer, which uses the echoes to make pictures called sonograms. - Biopsy : The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. There are several ways to do a biopsy for pancreatic NETs. Cells may be removed using a fine or wide needle inserted into the pancreas during an x-ray or ultrasound. Tissue may also be removed during a laparoscopy (a surgical incision made in the wall of the abdomen). - Bone scan : A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the blood. The radioactive material collects in bones where cancer cells have spread and is detected by a scanner. Other kinds of lab tests are used to check for the specific type of pancreatic NETs. The following tests and procedures may be used: Gastrinoma - Fasting serum gastrin test: A test in which a blood sample is checked to measure the amount of gastrin in the blood. This test is done after the patient has had nothing to eat or drink for at least 8 hours. Conditions other than gastrinoma can cause an increase in the amount of gastrin in the blood. - Basal acid output test: A test to measure the amount of acid made by the stomach. The test is done after the patient has had nothing to eat or drink for at least 8 hours. A tube is inserted through the nose or throat, into the stomach. The stomach contents are removed and four samples of gastric acid are removed through the tube. These samples are used to find out the amount of gastric acid made during the test and the pH level of the gastric secretions. - Secretin stimulation test : If the basal acid output test result is not normal, a secretin stimulation test may be done. The tube is moved into the small intestine and samples are taken from the small intestine after a drug called secretin is injected. Secretin causes the small intestine to make acid. When there is a gastrinoma, the secretin causes an increase in how much gastric acid is made and the level of gastrin in the blood. - Somatostatin receptor scintigraphy: A type of radionuclide scan that may be used to find small pancreatic NETs. A small amount of radioactive octreotide (a hormone that attaches to tumors) is injected into a vein and travels through the blood. The radioactive octreotide attaches to the tumor and a special camera that detects radioactivity is used to show where the tumors are in the body. This procedure is also called octreotide scan and SRS. Insulinoma - Fasting serum glucose and insulin test: A test in which a blood sample is checked to measure the amounts of glucose (sugar) and insulin in the blood. The test is done after the patient has had nothing to eat or drink for at least 24 hours. Glucagonoma - Fasting serum glucagon test: A test in which a blood sample is checked to measure the amount of glucagon in the blood. The test is done after the patient has had nothing to eat or drink for at least 8 hours. Other tumor types - VIPoma - Serum VIP (vasoactive intestinal peptide) test: A test in which a blood sample is checked to measure the amount of VIP. - Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease. In VIPoma, there is a lower than normal amount of potassium. - Stool analysis : A stool sample is checked for a higher than normal sodium (salt) and potassium levels. - Somatostatinoma - Fasting serum somatostatin test: A test in which a blood sample is checked to measure the amount of somatostatin in the blood. The test is done after the patient has had nothing to eat or drink for at least 8 hours. - Somatostatin receptor scintigraphy: A type of radionuclide scan that may be used to find small pancreatic NETs. A small amount of radioactive octreotide (a hormone that attaches to tumors) is injected into a vein and travels through the blood. The radioactive octreotide attaches to the tumor and a special camera that detects radioactivity is used to show where the tumors are in the body. This procedure is also called octreotide scan and SRS.