Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Gastrointestinal radiology Gastrointestinal radiology The field of gastrointestinal radiology encompasses the study of the: • gastrointestinal tract (pharynx, esophagus, stomach, duodenum, small bowel, and colon) • solid abdominal viscera (liver, gallbladder, biliary tract, pancreas and spleen) • peritoneal cavity (mesentery and omentum) • abdominal wall. Gastrointestinal radiology – the methods • Abdominal plain films (KUB) (KUB stands for Kidneys, Ureters and Bladder and is a common short term for an abdominal x-ray.) • Barium studies • Ultrasound • Computed Tomography • Nuclear medicine • Magnetic Resonance Imaging • Angiography and Interventional Radiology Plain Film of the Abdomen Plain Film of the Abdomen The prognostic value of an erect and supine abdominal X-ray was studied prospectively in 97 patients with an acute abdomen. Although 64 (66%) of the radiographs showed an abnormality, the surgical registrar altered his clinical diagnosis on only seven occasions and changed his management on four.... The investigation was of immediate clinical value in only 4% of the patients, and its use could probably be limited without detriment to patients. Evaluation of the plain abdominal X-ray in the acute abdomen. Stower MJ, Amar SS, Mikulin T, Kean DM, Hardcastle JD. J R Soc Med. 1985 Aug;78(8):630-3. Plain Film of the Abdomen • Often the starting point for the work up of abdominal problems • Upright abdominal x-rays are requested to look for pneumoperitoneum or fluid levels in obstruction or ileus. • Erect and supine films are used to confirm the diagnosis of intestinal obstruction. Plain Film of the Abdomen Indications for requesting abdominal films Bowel obstruction - abnormal gas pattern Free air - abnormal gas pattern Abscess - abnormal gas pattern Calculi or other abnormal intra-abdominal calcifications Radiopaque foreign bodies Plain Film of the Abdomen Erect abdominal x-ray The film is placed under the patient and the camera is positioned over the patient. Supine abdominal x-ray The film is placed in the back of the patient and the camera is positioned in front of the patient. The x-rays travel through the abdomen, revealing structures because they are surrounded by fat. Plain Film of the Abdomen The normal appearance of gas: • Gas is usually present in stomach • The small bowel may be partially filled with gas • Gas may also be seen throughout the entire colon Radiolucent fat which surrounds intraabdominal organs allows for visualization of the soft tissue: • Liver - posterior margin visible where outlined by retroperitoneal fat. • Spleen - often visible • Kidneys - outlines may not be seen in its entirety because of overlying gas and stool • Psoas muscles - margins usually visible but may not be seen in its entirety Plain Film of the Abdomen Small Bowel Large Bowel Distinguishing Features of Small and Large Bowel. Small Bowel Colon Location Central ‘Picture Frame’ Mucosal Folds Continuous (Plicae Circulares) Interrupted (Haustra) Diameter < 3cm < 6 cm (Cecum < 9 cm) Fecal Content Rarely Usually Plain Film of the Abdomen - the „normal” calcifications (with no clinical significance): Vascular - veins of the pelvis (phleboliths) Costal cartilage Mesenteric lymph nodes Injection sites Prostate gland Plain Film of the Abdomen - the „normal” calcifications (with no clinical significance): vascular - veins of the pelvis (phleboliths) Plain Film of the Abdomen - the „normal” calcifications (with no clinical significance): costal cartilage Plain Film of the Abdomen - the „normal” calcifications (with no clinical significance): lymph nodes Plain Film of the Abdomen - the „normal” calcifications (with no clinical significance): Injection sites Plain Film of the Abdomen - abnormal calcifications "Stones" - renal calculi, cholelithiasis, bladder calculi, appendiciolith Appendicitis fecalith Ureteral calculus Vascular - calcifications, aneurysm Atherosclerosis Abdominal Aortic Aneurysm Pancreatic - chronic pancreatitis Chronic Pancreatitis Leiomyoma (uterine fibroid) Leiomyoma Tumor calcification Other Plain Film of the Abdomen - abnormal calcifications renal calculi Plain Film of the Abdomen - abnormal calcifications ureteral calculus Plain Film of the Abdomen - abnormal calcifications appendicitis fecalith The flat plate reveals some round opacities which are calcified bile contents associated with the appendicitis. They are not always present with appendicitis but their presence imply a high risk for appendicitis. Plain Film of the Abdomen - abnormal calcifications atherosclerosis Plain Film of the Abdomen - abnormal calcifications chronic pancreatitis Plain Film of the Abdomen - abnormal calcifications leiomyoma Plain Film of the Abdomen - indications for requesting abdominal films Bowel obstruction - abnormal gas pattern Free air - abnormal gas pattern Abscess - abnormal gas pattern Calculi or other abnormal intra-abdominal calcifications Radiopaque foreign bodies Bowel obstruction - abnormal gas pattern Adynamic ileus - leads to increased gas throughout the Gl tract, multiple air-fluid levels, and gas in the rectum. There is gas in the small bowel, colon and distal bowel Case of adynamic ileus from pain medications - the bowel is not moving. The pathophysiology is that bowel has lost its motility. Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction – leads to a ladder-like arrangement of dilated small bowel loops, also termed a "stacked coin" appearance. There is very little or absent gas in the colon. supine When the small bowel dilates greater than 3 cm it is abnormal. Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction When we stand such a patient up in an upright view, we have appearance from air-fluid levels which is called „stair step” or „step latter”. The reason for the stair-step is because small bowel is fixed diagonally. upright view Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction – „stair step” or „step latter” sign Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction X-ray using a horizontal beam technique Supine abdominal x-ray Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction – „The string of pearls sign” can be seen on abdominal radiographs obtained with the patient in the upright position or on decubitus abdominal radiographs. Also commonly referred to as the "string of beads sign", the sign consists of a row or line of several small air bubbles obliquely or horizontally oriented in the abdomen left lateral decubitus Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction – String of pearls sign in a patient with small-bowel obstruction . Left lateral decubitus radiograph of the abdomen demonstrates a row of small air bubbles (arrows). The obliquely oriented row of air bubbles represents small amounts of air trapped between the valvulae conniventes along the superior wall of predominantly fluid-filled, dilated small-bowel loops. The meniscal effect of the surrounding fluid gives the trapped air an ovoid or rounded appearance. left lateral decubitus The appearance of the string of pearls sign depends on the combination of air, fluidfilled bowel loops, and peristaltic hyperactivity. Bowel obstruction - abnormal gas pattern Mechanical small bowel obstruction – „String of pearls sign” Air trapped at corners of valvulae conniventes (arrows) Almost always seen in obstructed fluid-filled small bowel loops Bowel obstruction - abnormal gas pattern Mechanical large bowel obstruction – leads to a distended colon but absence of gas in rectum and/or distal colon, +/- small bowel distension. supine Dilated colon (with haustra) upright Air-fluid levels Free air - abnormal gas pattern Free intraperitoneal air (pneumoperitoneum) - MUST have either an upright or left lateral decubitus view, will see a crescent of air under the diaphragm or outlining the liver. A pneumoperitoneum can be a normal finding in post op patients or patients on peritoneal dialysis; history is important. Free air - abnormal gas pattern Radiographic signs of free air: 1. Air under diaphragm 2. Rigler’s sign 3. Football sign UPRIGHT Free air - abnormal gas pattern Air under diaphragm Abdominal X-ray using a horizontal beam technique: pneumoperitoneum with free air between the liver and anterior abdominal wall (asterisk) If the patient cannot sit up, order a left lateral decubitus. This will allow air to accumulate over the edge of the liver Free air - abnormal gas pattern anteroposterior abdominal radiograph Rigler’s sign Extensive free intraperitoneal air is seen, which outlines the outer wall of multiple loops of air-filled bowel. Notice the discernible white stripe (arrows) of bowel wall between the intraluminal air and the free intraperitoneal air. Explanation: Gas normally outlines only the luminal surface of the bowel wall and not the serosal surface, which has a degree of opacity similar to that of adjacent peritoneal contents. When at least a moderate amount of free intraperitoneal air exists, however, this free air is more likely to accumulate between bowel loops, thus permitting visualization of the outer walls of the bowel. This is the classic appearance of the Rigler sign. supine A variant of the Rigler sign occurs when only the outside of the bowel wall is visible because the lumen is filled with fluid Free air - abnormal gas pattern Abdominal x-ray: 1. Pneumoperitoneum with a large oval lucency overlying the entire abdomen (football sign) 2. Visibility of both sides of the bowel wall (Rigler’s sign, white arrow) 3. Falciform ligament outlined by air on both sides (black arrow) supine view Free air - abnormal gas pattern supine position erect position Plain Film of the Abdomen Radiopaque foreign bodies Barium Studies of the GI Tract Upper GI and small bowel series = Barium swallow x-ray Small bowel enema = enteroclysis Lower GI series = Barium enema Barium Studies of the GI Tract Upper GI • An upper GI and small bowel series is a set of x-rays taken to examine the esophagus, stomach, and small intestine. • X-rays are taken after the patient has swallowed a barium suspension • This procedure is called "upper gastrointestinal tract radiography" when the esophagus, stomach and duodenum are evaluated or a "barium swallow" when only the pharynx and esophagus are evaluated. Barium Studies of the GI Tract Upper GI Barium Studies of the GI Tract Upper GI • The passage of the barium through the esophagus, stomach and duodenum is monitored on the fluoroscope. • Additionally, some patients are asked to swallow bakingsoda crystals to create gas and further improve the images; this procedure has the modified name of "aircontrast" or "double-contrast upper GI." The normal anatomy of the esophagus From: http://anatquest.nlm.nih.gov/xml-images/ The normal anatomy of the esophagus Esophagus containing contrast medium AP radiograph Arcus aortae Diaphragma Ostium cardiacum Fundus gastricus From Wolf-Heidegger’s Atlas of Human Anatomy, 4th Edition The normal anatomy of the esophagus Trachea Esophagus containing contrast medium Esophagus Lateral radiograph Hilum pulmonis From Wolf-Heidegger’s Atlas of Human Anatomy, 4th Edition Middle (aortic) esophageal constriction Diaphragma (distal to the plate), Cupula dextra Epiphrenic esophageal dilatation Diaphragma (close to the plate), Cupula sinistra Lower esophageal constriction Esophageal Foreign Body Esophageal Foreign Body Routine cervical and thoracic X-rays in the antero-posterior and lateral positions identify most of: metal objects, steak bones, and free mediastinal or peritoneal air Fish or chicken bones, wood, plastic, most glass, and thin metal objects are not readily seen. Most foreign bodies pass harmlessly through the GI tract and are eliminated in the stool. Retained foreign bodies may cause GI mucosal erosion, abrasion, local scarring, or perforation and should be removed within 24 hours. Any sharp object or battery in the esophagus must be removed immediately. Esophageal Foreign Body Imaging study: 1. If the swallowed object may be radiopaque, a single frontal radiograph that includes the neck, chest, and entire abdomen is usually sufficient to locate the object. 2. If the object is below the diaphragm, further radiographs are generally unnecessary. 3. If the object is in the esophagus, frontal and lateral chest radiographs are necessary to precisely locate and better identify the object and to be sure that the foreign body is not, in fact, 2 adherent objects. Esophageal Foreign Body Radiopaque foreign body – acoin, just below the cricopharyngeal muscle Biplane radiographs of the esophagus Esophageal Foreign Body Radiopaque foreign bodies – the metal buttons, Biplane radiographs of the esophagus just below the cricopharyngeal muscle Esophageal Foreign Body Radiopaque foreign body – a coin, just above the gastroesophageal junction Esophageal Foreign Body A pin in the pyriform sinus Esophageal Foreign Body Radiopaque foreign body – a piece of chicken bone just above the junction of the throat and the esophagus Esophageal Foreign Body Imaging study: 4. Radiolucent objects in the esophagus may be better visualized by repeating the study after having the patient drink a small amount of dilute contrast. This should not be done if endoscopy is planned. 5. Special care must be taken if the esophagus could possibly be obstructed or perforated. 6. When a foreign body is strongly suspected on clinical grounds, visualization by endoscopy, which has the added advantage of allowing removal of the object, may be the most efficient method of management. Esophageal Foreign Body Radiolucent foreign body – a piece of meat Spot radiograph Esophageal Foreign Body Radiolucent foreign body – a piece of meat Esophageal Foreign Body Imaging study: 7. Radiolucent objects may be also visualized by repeating the esophagram after swallowing a bit of cotton wool. Esophageal Foreign Body Radiolucent foreign body – a fishbone A cotton pledget soaked in an opaque medium like barium should go down smoothly. If stucked anywhere in the esophagus – a presumptive diagnosis is made. Esophageal Foreign Body The foreign body was visualized on plain X-rays in only 27-48% of cases Negative radiological findings do not rule out the possibility of a foreign body in the crico-pharynx and esophagus. Persistence of symptoms even in the absence of positive clinical or radiological signs warrants an endoscopic examination. Anatomy of the stomach Anatomy of the stomach The stomach consists of the cardia adjacent to the gastroesophageal junction, fundus, body, antrum, and pylorus. The fundus is dome shaped and extends above and to the left of the cardia toward the left hemidiaphragm. The body extends from fundus to the lower end of the lesser curve, which is known as the incisura angularis. The antrum extends from the incisura to the pyloric canal. Cardiac Incisure Angular Incisure Antrum supine Anatomy of the stomach Upper GI double-contrast upper GI Anatomy of the stomach Barium Studies of the GI Tract In addition to the standard upper GI series, a physician may request a detailed small bowel follow-through (SBFT), which is a timed series of films. • After the preliminary upper GI series is complete, the patient will drink additional barium sulfate, and will be escorted to a waiting area while the barium moves through the small intestines. • X-rays are initially taken at 15-minute intervals until the barium reaches the colon (the only way to be sure the terminal ileum is fully seen is to see the colon or ileocecal valve). • The interval may be increased to 30 minutes, or even one hour if the barium passes slowly. Barium Studies of the GI Tract Small bowel follow-through • The passage of the barium through the esophagus, stomach, and small intestine is monitored on the fluoroscope. • The test usually takes around three to six hours. Barium Studies of the GI Tract Enteroclysis • Enteroclysis is a fluoroscopic (real-time) type of X-ray of the small intestine. • This test is done in a hospital radiology department. • A barium-based liquid contrast material (a mixture of barium and methylcellulose) is infused by a rate-controlled pump through a tube from the nose or mouth, through the esophagus, and through the stomach until the tip reaches the duodenum. • When in place, contrast medium is introduced and x-ray images are viewed on a fluoroscopic monitor to visualize how the contrast moves through the bowel structures. Barium Studies of the GI Tract Enteroclysis A tube is placed down through the stomach into the small intestine, often under endoscopic control. Barium Studies of the GI Tract Enteroclysis V a Jejunum Eneteroclysis study showing the jejnum The jejunum, has a feathery appearance due to the numerous folds, valvulae conniventes (plicae semi circulares) Barium Studies of the GI Tract Barium enema A barium enema is given in order to perform an x-ray examination of the large intestine This test may be done in an office or a hospital radiology department. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium is then allowed to flow into the colon. A small balloon at the tip of the enema tube may be inflated to help keep the barium inside. Barium Studies of the GI Tract Barium enema Barium Studies of the GI Tract Barium enema Single contrast barium enema Barium Studies of the GI Tract Barium enema The flow of the barium is monitored by radiologist on an x-ray fluoroscope screen. Air may be puffed into the colon to distend it and provide better images – a double contrast study The enema tube is removed after the pictures are taken. Double contrast barium enema Barium Studies of the GI Tract splenic flexure hepatic flexure sigmoid colon rectum Barium Studies of the GI Tract COLON Small bowel Small Bowel Colon Location Central ‘Picture Frame’ Mucosal Folds Continuous (Plicae Circulares) Interrupted (Haustra) Diameter < 3cm < 6 cm (Cecum < 9 cm) Fecal Content Rarely Usually