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Contrast Review

Contrast Review

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Contrast Review

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  1. Contrast Review

  2. CONTRAINDICATIONS • Two strict contraindications to contrast media studies of the intestinal tract are known: • Presurgical patients and patients suspected of having a perforated hollow viscus (intestine or organ) should not receive barium sulfate. Water-soluble, iodinated media should be used instead. With young or dehydrated patients, care must be taken when a water-soluble contrast medium is used. Because of these patients' hypertonic nature, they tend to draw water into the bowel, leading to increased dehydration. • Barium sulfate by mouth is contraindicated in patients with a possible large bowel obstruction. An obstructed large bowel should be ruled out first with an acute abdominal series and a barium enema.

  3. PATIENT AND ROOM PREPARATION FOR ESOPHAGRAM • Because the esophagus is empty most of the time, patients need no preparation for an esophagram unless an upper GI series is to follow. When combined with an upper GI, or if the primary interest is the lower esophagus, preparation for the UGI takes precedence. • For an esophagram only, all clothing and anything metallic between the mouth and the waist should be removed, and the patient should wear a hospital gown. Before the fluoroscopic procedure is performed, a pertinent history should be taken and the examination carefully explained to the patient.

  4. Foreign bodies • of which patients may ingest a variety, include a bolus of food, metallic objects, and other materials lodging in the esophagus. Their locations and dimensions may be determined during the esophagram. Radiolucent foreign bodies, such as fish bones, may require the use of additional materials and techniques for detection. Cotton may be shredded and placed in a cup of barium and drunk by the patient. The intent of this technique is to allow a tuft of the cotton to be suspended by the radiolucent foreign body and visible during fluoroscopy. Although this technique has been used for decades, most gastroenterologists prefer the use of endoscopy to isolate and remove these foreign bodies.

  5. Achalasia • also termed cardiospasm, is a motor disorder of the esophagus in which peristalsis is reduced along the distal two-thirds of the esophagus. Achalasis is evident at the esophagogastric sphincter because of its inability to relax during swallowing. The thoracic esophagus may also lose its normal peristaltic activity and become dilated (megaesophagus). Video and rapid digital fluoroscopy is most helpful in diagnosis of achalasia.

  6. Basic Positions • RAO (35° to 40°) • Lateral • AP (PA) • LAO

  7. Central Ray • CR perpendicular to IR • CR to level of T5 or T6 (2 to 3 inches [5 to 7.5 cm] inferior to jugular notch) • Minimum SID of 40 inches (100 cm) or 72 inches (180 cm) if erect

  8. UGI

  9. Hiatal hernia • Hiatal hernia is a condition in which a portion of the stomach herniates through the diaphragmatic opening. The herniation may be slight, but in severe cases, most of the stomach is found within the thoracic cavity above the diaphragm. • Hiatal hernia may be due to a congenitally short esophagus or weakening of the muscle that surrounds the diaphragmatic opening, allowing passage of the esophagus.This form of hiatal hernia may occur in both pediatric and adult patients.

  10. Diverticula • Diverticula are pouchlikeherniations of a portion of the mucosal wall. They can occur in the stomach or small intestine. Gastric diverticula generally range between 1 and 2 centimeters but may be as small as a few millimeters to 8 centimeters in diameter. Nearly 70% to 90% of gastric diverticula arise in the posterior aspect of the fundus. Consequently, the lateral position taken during an upper GI study may be the only projection that demonstrates gastric diverticula. Most gastric diverticula are asymptomatic and are discovered accidentally.

  11. Although benign, diverticula can lead to perforation if untreated. Other complications include inflammation and ulceration at the site of neoplasm formation. A double-contrast upper GI is recommended to diagnose any tumors or diverticula.

  12. The goal of patient preparation for an upper GI series is for the patient to arrive in the radiology department with a completely empty stomach. For an examination scheduled during the morning hours, the patient should be NPO from midnight until the time of the examination. Food and fluids should be withheld for at least 8 hours prior to the exam. The patient also is instructed not to smoke cigarettes or chew gum during the NPO period. These activities tend to increase gastric secretions and salivation, which prevents proper coating of barium to the gastric mucosa. The upper GI series is often a time-consuming procedure, so the patient should be forewarned about the time the examination may take when the appointment is made. This time is especially true if the UGI is to be followed by a small-bowel series. The importance of an empty stomach also should be stressed when the appointment is made so the patient arrives properly prepared both physically and psychologically

  13. Consider the body habitus of the patient. Remember that the stomach is high and transverse with the hypersthenic patient and low and vertical with the hyposthenic patient. The sthenic or average patient has the duodenum bulb near the L2 region. Usually, L2 is located 2.5 to 5 centimeters (1 to 2 inches) above the lower lateral rib cage margin. Centering points are designed for the average sthenic patient.

  14. High kV of 100 to 125 is required to penetrate adequately and increase visibility of barium-filled structures. A kV below 100 will not provide visibility of the mucosa of the esophagus, stomach, or duodenum. Short exposure times are needed to control peristaltic motion. With double contrast, reduction of the kV to the 90 to 100 range is common to provide higher-contrast images without overpenetrating the anatomy (determine departmental kV preferences). Iodinated water-soluble contrast studies often require a kV range of between 80 and 90 kV.

  15. Upper GI Series • RAO (recumbent) • PA (recumbent) • Right lateral (recumbent) • LPO (recumbent) • AP (recumbent)

  16. Respiration • Suspend respiration and expose on expiration Collimation and CR: • Collimation is seen along the four margins of the radiograph. • CR is centered to level of L1, with body of stomach and C-loop centered on radiograph. Exposure Criteria: • Appropriate technique is used to clearly visualize the gastric folds without overexposing other pertinent anatomy. • Sharp structural margins indicate no motion

  17. RAO

  18. PA

  19. LATERAL

  20. LPO

  21. Supine - Trandelenburg Supine

  22. LOWER GI

  23. Small Intestine

  24. Large Intestine The large intestine begins in the right lower quadrant, just lateral to the ileocecal valve. The large intestine consists of four major parts: cecum, colon, rectum, and anal canal.

  25. COLON VS. LARGE INTESTINE Large intestine and colon are NOT synonyms, although many technologists use these terms interchangeably. The colon consists of four sections and two flexures and does not include the cecum and rectum. The four sections of the colon are (1) the ascending colon, (2) the transverse colon, (3) the descending colon, and (4) the sigmoid colon. The right (hepatic) and left (splenic) colic flexures also are included as part of the colon.

  26. CONTRAST MEDIA A thin mixture of barium sulfate is used for most small bowel series. When perforated bowel is suspected, or when surgery follows the SBS, a water-soluble, iodinated contrast media may be given. If the patient exhibits hypomotility of the bowel, ice water or another stimulant may be provided to promote the transit of barium. Also, water-soluble, iodinated contrast media can be added to the barium to increase peristalsis and transit time of contrast media through the small intestine. UPPER GI–SMALL BOWEL COMBINATION For an upper GI–small bowel combination procedure, a routine upper GI series is done first. After the routine stomach study is performed, progress of the barium is followed through the entire small bowel. During a routine upper GI series, the patient generally should have ingested 1 full cup, or 8 ounces, of barium-sulfate mixture. For any small bowel examination, the time that the patient ingested this barium should be noted because timing for sequential radiographs frequently is based on ingestion of this first cup during the UGI procedure. Some departments, however, begin the timing upon ingestion of the second cup.

  27. After completion of fluoroscopy and routine radiography of the stomach, the patient is given 1 additional cup of barium to ingest. The time that this is done should be noted. Then, 30 minutes after the initial barium ingestion, a PA radiograph of the proximal small bowel is obtained. This first radiograph of the small bowel series (marked “30 minutes”) usually is obtained about 15 minutes after the UGI series has been completed. Radiographs are obtained at specific intervals throughout the small bowel series until the barium-sulfate column passes through the ileocecal valve and progresses into the ascending colon. For the first 2 hours in the small bowel series, radiographs usually are obtained at 15- to 30-minute intervals. If continuing the examination beyond the 2-hour time frame becomes necessary, then radiographs usually are obtained every hour until barium passes through the ileocecal valve.

  28. SMALL BOWEL ONLY SERIES The second possibility for study of the small intestine is the small bowel only series, for every contrast media examination, including the small bowel series, a radiograph of the abdomen should be obtained before the contrast media is introduced. For the small bowel only series, 2 cups (16 oz) of barium generally is ingested by the patient, and the time is noted. Depending on departmental protocol, the first radiograph is taken 15 or 30 minutes after completion of barium ingestion. This first radiograph requires high centering to include the diaphragm. From this point on, the examination is exactly like the follow-up series of the UGI. Half-hour radiographs generally are taken for 2 hours, followed by 1-hour radiographs thereafter, until barium reaches the cecum and/or ascending colon. Note: Some routines may include continuous half-hour imaging until the barium reaches the cecum. In the routine small bowel series, regular barium sulfate ordinarily reaches the large intestine within 2 or 3 hours, but this time varies greatly among patients. Fluoroscopy with spot imaging and use of a compression cone may provide options for better visualization of the ileocecal valve.

  29. ENTEROCLYSIS–DOUBLE-CONTRAST SMALL BOWEL PROCEDURE A third method of small bowel study is the enteroclysis procedure, which is a double-contrast method that is used to evaluate the small bowel. Enteroclysis describes the injection of a nutrient or medicinal liquid into the bowel. In the context of a radiographic small bowel procedure, it refers to a study wherein the patient is intubated under fluoroscopic control with a special enteroclysis catheter that passes through the stomach into the duodenum to the region of the duodenojejunal junction (ligament of Treitz). With fluoroscopy guidance, a duodenojejunal tube is placed into the terminal duodenum. First, a high-density suspension of barium is injected through this catheter at a rate of 100 ml/minute. Fluoroscopic and conventional radiographs may be taken at this time. Then, air or methylcellulose is injected into the bowel to distend it, providing a double-contrast effect. Methylcellulose is preferred because it adheres to the bowel while distending it. This double-contrast effect dilates the loops of small bowel, while enhancing visibility of the mucosa. This action leads to increased accuracy of the study. Disadvantages of enteroclysis include increased patient discomfort and the possibility of bowel perforation during catheter placement

  30. METHOD OF IMAGING Imaging for any overhead radiograph during a small bowel series is done with 35 × 43-centimeter (14 × 17-inch) IRs for visualization of as much of the small intestine as possible. Spot imaging of selected portions of the small bowel is done with smaller IRs. The prone position usually is used during a small bowel series, unless the patient is unable to assume that position. The prone position allows abdominal compression to separate the various loops of bowel, creating a higher degree of visibility.Asthenic patients may be placed in the Trendelenburg position to separate overlapping loops of ileum. For the 30-minute radiograph, the IR is placed high enough to include the stomach on the radiograph. This placement often requires longitudinal centering to the duodenal bulb and side-to-side centering to the midsagittal plane. Approximately three-fourths of the IR should extend above the iliac crest. Because most of the barium is in the stomach and proximal small bowel, a high-kV (100 to 125 kV) technique should be used on this initial radiograph. All radiographs after the initial 30-minute exposure should be centered to the iliac crest. For the 1-hour and later radiographs, medium-kilovoltage techniques may be used because barium is spread through more of the alimentary canal and is not concentrated in the stomach. Spot imaging of the terminal ileum usually completes the examination.

  31. PATIENT PREPARATION Preparation of the patient for a barium enema is more involved than is preparation for the stomach and small bowel. The final objective, however, is the same. The section of alimentary canal to be examined must be empty. Thorough cleansing of the entire large bowel is of paramount importance for a satisfactory contrast media study of the large intestine. CONTRAINDICATIONS TO LAXATIVES (CATHARTICS) Certain conditions contraindicate the use of very effective cathartics or purgatives needed to thoroughly cleanse the large bowel. These exceptions include (1) gross bleeding, (2) severe diarrhea, (3) obstruction, and (4) inflammatory conditions such as appendicitis.

  32. CONTRAST MEDIA • Barium sulfate is the most common type of positive-contrast medium used for the barium enema. The concentration of the barium sulfate suspension varies according to the study performed. A standard mixture used for single–contrast media barium enemas ranges between 15% and 25% weight-to-volume (w/v). The thicker barium used for double-contrast barium enemas has a weight-to-volume concentration between 75% and 95% or higher.

  33. Contrast Media Preparation • The mixing instructions as supplied by the manufacturer should be followed precisely. • A debate has evolved over the temperature of the water used to prepare the barium sulfate suspension. Some experts recommend the use of cold water (40°F to 45°F) in the preparation of contrast media. Cold water is reported to have an anesthetic effect on the colon and to increase the retention of contrast media. Critics have stated that the use of cold water may lead to colonic spasm. • Room temperature water (85°F to 90°F) is recommended by most experts for completion of a more successful examination with maximal patient comfort. • The technologist should NEVER use hot water to prepare contrast media. Hot water may scald the mucosal lining of the colon.

  34. After the fluoroscopic room and the contrast media have been completely prepared, the patient is escorted to the examination room. Before insertion of the enema tip, a pertinent history should be taken and the examination carefully explained. Because complete cooperation is essential and this examination can be somewhat embarrassing, every effort should be made to reassure the patient at every stage of the exam. • Previous radiographs should be made available to the radiologist. The patient is placed in Sims' position before the enema tip is inserted.

  35. ENEMA TIP INSERTION • Before the enema tip is inserted, the opening in the back of the patient's gown should be adjusted to expose only the anal region. The rest of the patient should be well covered when the rectal tube is inserted. The patient's modesty should be protected in any way possible during the barium enema examination. The right buttock should be raised to open the gluteal fold and expose the anus. The patient should take in a few deep breaths before actual insertion of the enema tip. If the tip will not enter with gentle pressure, the patient should be asked to relax and assist if possible. The tip should NEVER be forced in a manner that could cause injury to the patient. Because the abdominal muscles relax on expiration, the tip should be inserted during the exhalation phase of respiration.

  36. SUMMARY OF SAFETY CONCERNS • Review Patient's Chart: Note any pertinent clinical history on the exam requisition, and inform the radiologist about whether the patient underwent a sigmoidoscopy or colonoscopy before the barium enema was given, especially if a biopsy was performed. Determine whether the patient has any known allergies to the contrast media or the natural latex products. Diabetic patients shall not be given glucagon prior to or during procedure unless ordered by physician. • Never Force Enema Tip Into Rectum: This action may lead to a perforated rectum. The radiologist inserts the enema tip under fluoroscopic guidance, if needed. • Height of Enema Bag Does Not Exceed 24 Inches (60 cm) Above Table: This distance should be maintained before the procedure is begun. The radiologist may wish to raise bag height during the procedure based on rate of flow of the contrast media. • Verify Water Temperature of Contrast Media: Water that is too hot or too cold may injure the patient or compromise the procedure. • Escort Patient to the Restroom After Completion of the Study: A barium enema can be stressful for some patients. Patients have been known to faint during or after evacuation.

  37. Diverticulum • A diverticulum(di′-ver-tik′-u-lum) is an outpouching of the mucosal wall that may result from herniation of the inner wall of the colon. Although this is a relatively benign condition, it may become widespread throughout the colon but is most prevalent in the sigmoid colon. It is most common among adults over 40 years of age. The condition of having numerous diverticula is termed diverticulosis. If these diverticula become infected, the condition then is referred to as diverticulitis. Inflamed diverticula may become a source of bleeding, in which case surgical removal may be necessary. A patient may develop peritonitis if a diverticulum perforates the mucosal wall.

  38. Intussusception • Intussusception is a telescoping or invagination of one part of the intestine into another. It is most common in infants younger than 2 years of age but can occur in adults. A barium enema or an air/gas enema may play a therapeutic role in reexpanding the involved bowel. Radiographically, the barium column terminates into a “mushroom-shaped” dilation with very little barium/gas passing beyond it. This dilation marks the point of obstruction. Intussusception must be resolved quickly so it does not lead to obstruction and necrosis of the bowel. If the condition recurs, surgery may be needed.

  39. Polyps • Polyps are saclike projections similar to diverticula except that they project inward into the lumen rather than outward, as do diverticula. Similar to diverticula, polyps can become inflamed and may be a source of bleeding, in which case they may have to be surgically removed. Barium enema, endoscopy, and computed tomography colonography (CTC) are the most effective modalities used to demonstrate neoplasms in the large intestine.

  40. Volvulus • Volvulus is a twisting of a portion of the intestine on its own mesentery, leading to a mechanical type of obstruction. Blood supply to the twisted portion is compromised, leading to obstruction and necrosis, or localized death of tissue. A volvulus may be found in portions of the jejunum or ileum or in the cecum and sigmoid colon. Volvulus is more likely to occur in men than in women and is most common between the ages of 20 and 50 years. The classic sign is called a “beak” sign, a tapered narrowing at the volvulus site as demonstrated during a barium enema. A volvulus will produce an air-fluid level, as is well demonstrated on an erect abdomen projection.

  41. PA PROJECTION: SMALL BOWEL SERIES Pathology Demonstrated • Inflammatory processes, neoplasms, and obstructions of the small intestine are shown Respiration Suspend respiration and expose on expiration.

  42. Barium Enema • PA and/or AP • RAO • LAO • LPO and RPO • Lateral rectum and ventral decubitus • R lateral decubitus • L lateral decubitus • PA (AP) postevacuation • AP or LPO axial (butterfly) • PA or RAO axial (butterfly)

  43. PA AND/OR AP PROJECTION: BARIUM ENEMA Pathology Demonstrated Obstructions, including ileus, volvulus, and intussusception, are demonstrated. Double-contrast media barium enema is ideal for demonstrating diverticulosis, polyps, and mucosal changes. Radiographic Criteria Structures Shown: • The transverse colon should be primarily barium-filled on the PA and air-filled on the AP with a double-contrast study. • Entire large intestine, including the left colic flexure, should be visible.