Abdominal CT

The purpose of abdominal CT examination is to understand whether there are infectious diseases in the abdominal organs, such as inflammation, tuberculosis, abscess, etc.; whether there are occupying places, such as benign, malignant tumors, metastatic tumors, etc.; whether there are abnormalities, stones, obstructions, Perforation, effusion, etc. Before the examination, the patient usually needs to drink 2% aqueous solution containing iodine contrast agent. One of the purposes is to let the contrast agent fill the entire intestinal lumen to reduce the artifacts generated by the intestinal gas accumulation under the X-ray. Artifacts affect the diagnostic effect. Basic Information Specialist classification: Digestive examination classification: CT Applicable gender: whether men and women apply fasting: fasting Tips: Inappropriate people: patients with severe heart and kidney failure and patients who are allergic to contrast agents. Normal value Normal CT performance: The CT image is a transected image of the abdomen and must be scanned according to the anatomy of each organ. (1) Liver: CT shows liver contour, size, density, and internal structure. Normal liver density is uniform, CT value is 40-70H, higher than spleen. At different levels, the size and shape of the leaves and segments of the liver are different. If the hilar is layered, an "H" shaped low-density band-like shadow can be displayed. The right longitudinal fissure is the gallbladder fossa, the left longitudinal fissure is the hepatic sacral ligament, and the middle is the hilar, which contains the hepatic artery, portal vein and hepatic duct. The left side of the left longitudinal fissure is the left lobe, and the right side of the right longitudinal fissure is the right lobe. (b) Gallbladder and biliary tract: The gallbladder is located in the gallbladder fossa, and the transverse diameter is 4cm. The capsule contains bile sweat, and its density is lower than that of adjacent liver tissue. It is oval-shaped, round, and has a clear boundary. In normal liver, the outer bile duct is not developed and is displayed when expanded. The dilated bile duct appears as a dendritic low-density shadow extending from the hepatic gate to the liver. (3) Pancreas: CT shows the contour, density, shape and size of the pancreas. The normal pancreas has a uniform density with a CT value of 40-50H, which is slightly lower than the surrounding organs. The pancreas is shaped like a silkworm, divided into three parts: the head, the body and the tail. The front and rear diameter heads are 3cm, the body is 2.5cm, and the tail is 2cm. (4) Spleen: It is crescent. The spleen has a uniform density and the CT value is lower than that of the liver, similar to the pancreas. No more than 5 rib units in size and length (one rib unit is equal to one rib or rib cross section). (5) Kidney and adrenal gland: The kidney is located on both sides of the spine and may have an elliptical shape and a horseshoe shape on different levels. The horseshoe-shaped opening points to the inner front and is caused by the low density of the renal pelvis and renal pelvis. The density of renal parenchyma is uniform. The adrenal gland is extremely "human" or triangular in the kidney. (6) Large blood vessels: The abdominal aorta is located in the left front of the spine and is round or round, with its sides connected to the iliac crest. The inferior vena cava is located in the right front of the spine and is oblate. The portal vein is located in front of the caudate lobe. Clinical significance The pancreas is a retroperitoneal organ, which is a difficult point for ordinary X-ray detection. CT can show the structure of the pancreas and its surrounding, so the diagnostic accuracy is high. (a) Pancreatic cancer: Direct signs are local enlargement of the mass or pancreas, equal density is common, and a few are low density. Indirect signs are distal expansion of the pancreatic duct due to tumor infiltration and compression. If the main pancreatic duct and the common bile duct expand simultaneously, the double duct sign is displayed. If the pancreatic cancer spreads, it infiltrates the surrounding fat layer and the outline is blurred. Lymphatic metastasis enlarges the lymph nodes around the pancreas and large blood vessels. Liver metastasis and retroperitoneal metastasis can cause ascites. (two) pancreatitis: Acute pancreatitis manifests as pancreatic enlargement, deformation, and blurred edges. Chronic pancreatitis shows atrophy or enlargement of the pancreas, deformation, calcification, and pseudocysts. Kidney disease: (1) Kidney cyst: It occurs mostly in the renal parenchyma. CT appears as a single or multiple edge-clear round or round-like low-density area with a CT value of 6-18H. (2) Renal cell carcinoma: CT showed a mass unevenness in the renal parenchyma, in which calcium spots were common. When the cancerous tumor metastasizes to the aortic lymph node, CT is easy to display. (c) renal pelvic cancer: Most of them are transitional cell carcinoma. The main CT manifests as a mass in the renal pelvis. About 50% of patients have hydronephrosis. Adrenal tumors: Derived from the adrenal cortex and medulla. CT can detect tumors as small as 5 mm. When the adrenal gland is flat and convex, it is highly suspected of tumor presence. other: Other organs in the abdomen, such as the bladder, prostate, female genital tumors, and retroperitoneal lymph node metastasis can be diagnosed by CT. Patients with abdominal organ disease and injury who need to be examined. Precautions Taboo before inspection: 1. Before the test, fast for 4 hours, preferably on an empty stomach the night before. 2. CT scan of the lower abdomen was taken at 8:00, 10:00 on the previous day, and at the 6th and 8th of the day, 200-300 mL of contrast agent was taken. The bladder can be inspected after it has been filled. 3, the method of taking the contrast agent and the time of taking the radiology staff will be carefully explained to the patient. 4. Patients who need to enhance the scan, please ask the family to sign the instructions for the iodine contrast agent. If you have a history of drug allergy, history of heart, liver and kidney dysfunction, please inform the medical staff to prevent accidents. 5. Before the examination, the CT doctor should be informed of the detailed medical history and various examination results. If you have your own X-ray film, magnetic resonance film and previous CT film, you need to submit it to CT doctor for reference. 6, to explain to the doctor whether there is drug allergy, whether it has asthma, urticaria and other allergic diseases. 7, remove the inspection site clothing including underwear with metal materials and various items: such as headwear, hairpins, earrings, necklaces, jade, coins, belts and keys. 8, if the CT enhanced scan or children, unconscious, need to be accompanied by healthy people. 9, CT enhanced scan If you use ion contrast agent, you need to do intravenous injection of contrast agent iodine allergy test, no response after 20 minutes, before you can check. 10, 1 week, do not accept drugs containing heavy metals, do not check for gastrointestinal sputum. Patients who have been tested for expectorant need to wait for the sputum to empty; if they are eager to have a CT examination, they should be treated with a cleansing enema or oral laxative to sputum. Requirements for inspection: 1. Obey the instructions of the technicians during the inspection, keep the position and do not move, and cooperate with the examination to calmly breathe, hold your breath, do not swallow, and do not blink your eyes. 2. Follow the doctor's advice and drink the contrast agent regularly and quantitatively. 2. The CT machine is equipped with a walkie-talkie. If there is any discomfort during the examination or an abnormal situation occurs, the doctor should be informed immediately. Inspection process Before the examination, the patient usually needs to drink 2% aqueous solution containing iodine contrast agent. One of the purposes is to let the contrast agent fill the entire intestinal lumen to reduce the artifacts generated by the intestinal gas accumulation under the X-ray. The artifacts affect the diagnosis; the second is: the filling of the intestines facilitates the differential diagnosis of the disease to improve the accuracy of the diagnosis. Therefore, when you drink the contrast agent, you need a process. After the contrast agent reaches the intestine of the site to be examined, you can perform a CT examination. In the case of a small group of 100 cases of small liver cancer, only one case of liver cancer <3.0 cm in diameter showed less blood type, and there was no accumulation of iodine oil contrast agent on CT. Suspected to be stones, such as: gallstones, kidney stones, etc.; acute pancreatitis, intestinal obstruction, intestinal perforation usually do not need to drink contrast agents, this is to prevent contrast agents to cover up the condition or aggravate the condition. Not suitable for the crowd Inappropriate population: patients with severe heart and kidney failure and patients who are allergic to contrast agents.