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Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights. 1281 EDUCATION EXHIBIT Christine M. Peterson, MD • John S. Anderson, MD • Amy K. Hara, MD Jeffrey W. Carenza, MD • Christine O. Menias, MD Volvulus of the gastrointestinal tract, a clinically relevant cause of acute or recurring abdominal pain in adults, remains a diagnostic di- lemma for radiologists in a large number of cases. The clinical symp- toms associated with volvulus are often nonspecifi c and include pain and nausea with vomiting. Yet referring clinicians often rely on radi- ologists to make the diagnosis; volvulus is rarely diagnosed clinically. Radiography, fl uoroscopy, and computed tomography are the imaging methods most often used for this purpose. Prompt diagnosis is critical to avoid life-threatening complications such as bowel ischemia and in- farction. Thus, it is useful for radiologists to be familiar with the vari- ous appearances of volvulus throughout the gastrointestinal tract. © RSNA, 2009 • radiographics.rsna.org Volvulus of the Gastrointestinal Tract: Appearances at Multi- modality Imaging 1 ONLINE-ONLY CME
LEARNING
OBJECTIVES After reading this article and taking the test, the reader will be able to: List the risk fac-
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ment of volvulus of the stomach, small bowel, and colon. Identify the most
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ing appearances of gastrointestinal volvulus. Describe common
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of the stomach and colon.
Abbreviation: GI = gastrointestinal RadioGraphics 2009; 29:1281–1293 • Published online 10.1148/rg.295095011 • Content Code: 1 From the Department of Radiology, Penn State College of Medicine, Penn State Milton S. Hershey Medical Center, 500 University Dr, H066, Her- shey, PA 17033-0850 (C.M.P.); Colorado Permanente Medical Group, Denver, Colo (J.S.A.); Department of Diagnostic Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.); Texas Radiology Associates, Plano, Tex (J.W.C.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.O.M.). Presented as an education exhibit at the 2006 RSNA Annual Meeting. Received January 15, 2009; revision requested February 11 and received June 16; accepted June 17. A.K.H. has license and research agreements with General Electric; all other authors have no fi nancial relationships to disclose. Address correspondence to C.M.P. (e-mail: cpeterson3@hmc.psu.edu). © RSNA, 2009 See last page TEACHING POINTS 1282 September-October 2009 radiographics.rsna.org Figure 2. Mesenteroaxial volvulus. Diagram shows the stomach twisting along its short axis. A = gastric antrum, GEJ = gastroesophageal junction.
the rotation of the stomach along its long axis. GC = greater curvature, LC = lesser curvature.
Volvulus of the gastrointestinal tract, a clinically relevant cause of acute or recurring abdominal pain in adults, often poses a diagnostic dilemma for radiologists. The clinical symptoms associ- ated with volvulus commonly are nonspecifi c and include pain, nausea, and vomiting. Because it is rarely diagnosed clinically, clinicians often con- sult radiologists for diagnostic evaluations; radi- ography, fl uoroscopy, and computed tomography (CT) are the modalities most frequently em- ployed. Prompt diagnosis is critical to avoid life- threatening complications of prolonged volvulus such as bowel ischemia and infarction. This ar- ticle highlights the different clinical features and common imaging fi ndings of volvulus throughout the gastrointestinal tract.
The stomach is a relatively uncommon site of volvulus. Patients with acute gastric volvulus typi- cally present with epigastric pain, nausea, and vomiting. A useful clinical triad for identifying gastric volvulus, the Borchardt triad consists of sudden epigastric pain, intractable retching, and inability to pass a nasogastric tube into the stom- ach (1). Gastric volvulus is usually divided into two main subtypes: organoaxial and mesenteroaxial. Organoaxial volvulus is far more common than mesenteroaxial volvulus and accounts for ap- proximately two-thirds of cases of gastric volvu- lus. Both are surgical emergencies and warrant prompt diagnosis and treatment. Organoaxial volvulus occurs when the stom- ach rotates along its long axis and becomes obstructed, with the greater curvature being dis- placed superiorly and the lesser curvature located more caudally in the abdomen (1–3). The antrum rotates anterosuperiorly, and the fundus rotates posteroinferiorly. In adults, organoaxial volvulus most commonly occurs in the setting of a post- traumatic or paraesophageal hernia that allows the stomach to move abnormally along its long axis (4). If the volvulus is severe or complete— meaning that the twist is greater than 180 °—gas-
tric outlet obstruction occurs, and the stomach becomes dilated and fi lls with fl uid. If positive oral contrast material is administered, it is re- tained in the stomach. However, many patients have a less severe, incomplete or partial volvu- lus—a rotation of less than 180 °. In these cases, ingested contrast material may pass through the stomach and into the duodenum. Patients with a redundant paraesophageal hernia are predisposed to developing a secondary rotation of the stom- ach along its long axis. These patients usually lack clinical symptoms of obstruction and exhibit no evidence of obstruction at imaging. In such cases, it is more accurate to describe the stomach as having an organoaxial position rather than an organoaxial volvulus, although an organoaxial position of the stomach predisposes it to future volvulus. It is unclear whether asymptomatic pa- tients should be treated or followed up clinically. In general, the acuity and severity of symptoms dictate management. In children, a large Boch- dalek hernia is a predisposing factor for gastric volvulus (Fig 1) (4).
RG ■ Volume 29 • Number 5 Peterson et al 1283 gastric volvulus, with both organoaxial and mes- enteroaxial components. Radiographic fi ndings of gastric volvulus in- clude herniation of a large portion of the stom- ach above the diaphragm, often with differential air-fl uid levels (5). An upper gastrointestinal (GI) series may be performed to evaluate the rotation of the stomach, as well as to detect passage of ingested oral contrast material into the duodenum. Multi–detector row CT often is performed in the setting of epigastric pain and vomiting and can help confi rm the rotation of the herniated stomach and the transition point (Figs 3–5). If a diagnosis is made and surgical repair is performed soon after the onset of symptoms, gastric ischemia usually can be avoided. However, if there is a delay in patient presentation, diagno- sis, or intervention, gastric ischemia may result, Figure 4. Primary organoaxial volvulus in a new- born. Upper GI image shows inversion of the greater (GC) and lesser (LC) curvatures of the stomach. Figure 5. Mesenteroaxial volvulus. Anteroposterior upper GI image shows displacement of the gastric an- trum (A) above the gastroesophageal junction (arrow). The gastric body (B) and pylorus (P) also are seen. Figure 3. Organoaxial volvulus. (a) Upper GI image shows an upward rotation of the stomach along its long axis, which results in inversion of the greater curvature (GC) above the lesser curvature (LC). Arrow = pylorus. (b) CT image shows the transverse lie of the stomach, which has herniated into the chest. Arrow = pylorus.
Mesenteroaxial volvulus is much less com- mon than organoaxial volvulus. It occurs when the stomach rotates along its short axis, with resultant displacement of the antrum above the gastroesophageal junction (1–3). Rotation is usu- ally partial (less than 180 °) and is not associated with an underlying diaphragmatic defect (Fig 2). However, some patients may have a complex Teaching Point 1284 September-October 2009 radiographics.rsna.org Figure 6. Perforated gastric volvulus in a 73-year-old man with abdominal pain. Scout radiograph (a) and coronal CT image (b) show gastric distention and pneumoperitoneum (arrows in a) due to a perforated gastric volvulus, the presence of which was confi rmed at surgery. Perforation of a gastric volvulus is an uncommon complication that re- sults from gastric ischemia. GC = greater curvature, LC = lesser curvature. Figure 7. Midgut volvulus in an infant. (a) Upper GI image shows that the small bowel lies in the right side of the abdomen and does not cross the midline. (b) Lateral upper GI image shows the typical twisting corkscrew-like appearance of a volvulus of the proximal jejunum. (c) Lateral up- per GI image obtained in a different pa- tient also shows the classic corkscrew-like appearance.
RG ■ Volume 29 • Number 5 Peterson et al 1285 Figure 8. Midgut volvulus in a patient with cardiovascular collapse. CT images (b is slightly more caudal than a) obtained emergently show bowel dilatation and mucosal hyperattenuation, fi ndings indicative of global small-bowel ischemia. There is a twist at the root of the small-bowel mesentery, and an abnormal relationship between the supe- rior mesenteric artery (long arrow) and the superior mesenteric vein (short arrow) is seen. which can lead to necrosis, perforation, medias- tinitis, and peritonitis (Fig 6). Midgut Volvulus Midgut volvulus is a different clinical entity and is most common in children; 60%–80% of those affected present with bilious vomiting in the 1st month of life (6). However, as the use of CT in emergency departments increases, midgut volvu- lus is increasingly being recognized in adults. Malrotation of the small bowel is the major predisposing factor for midgut volvulus. In a mal- rotation, there is abnormal fi xation of the small bowel mesentery, which results in an abnormally short mesenteric root. This allows the small bowel to twist around its mesentery, causing obstruction and possibly ischemia of the bowel. Midgut volvu- lus often occurs early in life, and in such cases sur- gery is performed to repair the malrotation. How- ever, volvulus also may occur in adulthood, and in some cases may manifest as chronic intermittent abdominal pain that resolves when the volvulus spontaneously reduces. If it does not spontane- ously reduce, patients at any age may present with abdominal pain, nausea, and vomiting (1,7). Conventional radiography usually yields non- specifi c fi ndings and is rarely helpful in making a diagnosis. On the other hand, fl uoroscopic upper GI and small-bowel examinations may reveal the characteristic abnormal position of most of the small bowel in the right abdomen and the resultant abnormal location of the ligament of Treitz. These are usually the preferred imaging tests when midgut volvulus is suspected. On upper GI images, the liga- ment of Treitz normally is located at or to the left of the left L1 pedicle. In patients with malrotation, the ligament of Treitz is abnormally positioned, usually below and to the right of the left L1 pedicle. In the presence of a midgut volvulus, the twisted segment (usually a proximal segment) of small bowel has a characteristic corkscrew-like appearance on fl uoro- scopic images (Fig 7) (6). Ultrasonography (US) is sometimes helpful in that an abnormal positional relationship between the superior mesenteric vein and artery may be appreciated, with the vein located to the left of the artery, which is the opposite of its usual ori- entation (6,8). However, US does not directly show the abnormal position of the bowel and is rarely used in this clinical setting. Familiarity with the CT fi ndings of midgut volvulus is important, because many patients present with nonspecifi c symptoms and are fi rst evaluated with cross-sectional imaging. At CT, a swirling of vessels in the mesenteric root may be seen at the site of the volvulus (6,7,9). The abnormal relationship between the superior mes- enteric artery and vein, an ectopic location of the majority of small bowel loops, and an abnormal position of the ligament of Treitz (which was de- scribed earlier) also may be seen (Fig 8).
1286 September-October 2009 radiographics.rsna.org Figure 10. Cecal volvulus in an elderly woman with abdominal pain. (a) Coronal reformatted CT image shows dilated cecum (arrow) in the left upper quadrant of the abdomen. The cecum is displacing the contrast material–fi lled stomach superiorly, and there is obstruction of the small bowel. (b) Axial CT image shows that the dilated cecal loop (arrow) has twisted on its mesentery and is located ectopi- cally in the upper abdomen. are less common and also may predispose pa- tients to cecal volvulus (1,10). As opposed to volvulus in other locations, colonic volvulus often has a characteristic ap- pearance at conventional radiography, which may be suffi cient for a diagnosis in a large percentage of patients. A dilated gas-fi lled viscus, usually located ectopically in the left upper quadrant or mid abdomen, is a radiographic feature of cecal volvulus. However, it is important to recognize that the cecum may be displaced anywhere in the abdomen (11). Proximal obstruction may or may Colonic Volvulus Cecum Cecal volvulus accounts for 25%–40% of all cases of colonic volvulus. Congenital anomalies of colonic fi xation usually are present and include an abnormal fi xation of the right colon to the ret- roperitoneum and abnormal motility of the right colon. Factors that result in dilatation of the right colon, such as pregnancy and recent colonoscopy, Figure 9. Cecal volvulus in a 74-year- old woman with abdominal pain. Ra- diograph shows dilated air-fi lled cecum (arrow) in the left upper quadrant. RG ■ Volume 29 • Number 5 Peterson et al 1287 Figure 12. Cecal volvulus in an elderly patient with abdominal cramps. (a) CT image shows dilated fl uid-fi lled cecum in the lower abdomen. The proximal small bowel also is dilated. (b) Image acquired in a contrast material enema study shows the classic beaklike appearance of the bowel at the twist (arrow).
enhanced CT image shows dilated, fl uid- and gas-fi lled cecum at the lower midline. Pneumatosis of the cecum (ar- rows) also is seen. The diagnosis was confi rmed at exploratory surgery. patients with suspected cecal volvulus proceed to CT if further imaging is required. At CT, the abnormally positioned cecum often appears in the upper mid and left abdomen and can be traced back to the level of the volvulus, which appears as an area of swirling of the bowel and its mesentery, a fi nding also known as the “whirl” sign (Figs 11–16) (12). Cecal bascule, fi rst described in the early 1900s, refers to abnormal location of the dilated cecum in the mid abdomen and results from up- ward folding of the cecum on itself, without as- sociated twisting. Cecal bascule occurs when the cecum is loosely attached to its mesentery. Some not be present, depending on the acuity of the volvulus (Figs 9, 10) (1). A diagnosis of cecal volvulus often is con- fi rmed with a contrast material enema study or CT. During the enema, the distal colon usually is decompressed, and there is a beaklike taper- ing at the level of the volvulus. It usually is not possible for much contrast material to pass beyond the volvulus into the more dilated proxi- mal colon and terminal ileum. For patients in whom cecal volvulus is suspected on the basis of radiographic fi ndings, a contrast material enema study may help confi rm the diagnosis. However, given the widespread availability of CT and the relative speed with which it can be performed compared with that of the enema study, most Teaching Point RG ■ Volume 29 • Number 5 Peterson et al 1287 Figure 12. Cecal volvulus in an elderly patient with abdominal cramps. (a) CT image shows dilated fl uid-fi lled cecum in the lower abdomen. The proximal small bowel also is dilated. (b) Image acquired in a contrast material enema study shows the classic beaklike appearance of the bowel at the twist (arrow).
enhanced CT image shows dilated, fl uid- and gas-fi lled cecum at the lower midline. Pneumatosis of the cecum (ar- rows) also is seen. The diagnosis was confi rmed at exploratory surgery. patients with suspected cecal volvulus proceed to CT if further imaging is required. At CT, the abnormally positioned cecum often appears in the upper mid and left abdomen and can be traced back to the level of the volvulus, which appears as an area of swirling of the bowel and its mesentery, a fi nding also known as the “whirl” sign (Figs 11–16) (12). Cecal bascule, fi rst described in the early 1900s, refers to abnormal location of the dilated cecum in the mid abdomen and results from up- ward folding of the cecum on itself, without as- sociated twisting. Cecal bascule occurs when the cecum is loosely attached to its mesentery. Some not be present, depending on the acuity of the volvulus (Figs 9, 10) (1). A diagnosis of cecal volvulus often is con- fi rmed with a contrast material enema study or CT. During the enema, the distal colon usually is decompressed, and there is a beaklike taper- ing at the level of the volvulus. It usually is not possible for much contrast material to pass beyond the volvulus into the more dilated proxi- mal colon and terminal ileum. For patients in whom cecal volvulus is suspected on the basis of radiographic fi ndings, a contrast material enema study may help confi rm the diagnosis. However, given the widespread availability of CT and the relative speed with which it can be performed compared with that of the enema study, most 1288 September-October 2009 radiographics.rsna.org Figure 14. The whirl sign of cecal volvulus. (a) Contrast-enhanced CT image shows a dilated, stool-fi lled cecum in the left upper quadrant of the abdomen (arrow). (b) Contrast-enhanced CT image shows that the twist involves the ileum, which lies in the right lower quadrant (arrow). Note the whorled appearance of the mesenteric vessels within the twist. Mesenteric stranding and edema also are seen. Figure 13. Cecal volvulus. (a) Topographic CT image shows a dilated air-fi lled viscus in the midline (arrow) and a small-bowel obstruction. (b) Contrast-enhanced CT image shows displacement of the dilated fl uid- fi lled cecum in the right upper quadrant (arrow), with resultant small-bowel obstruction.
20-year-old woman. Contrast-enhanced CT image shows a dilated cecum located high in the midline. Note the ring of gas in the cecal wall (arrows), a fi nding suggestive of pneuma- tosis. The diagnosis of an infarcted cecal vol- vulus was confi rmed at exploratory surgery.
RG ■ Volume 29 • Number 5 Peterson et al 1289 Figure 16. Cecal volvulus. Axial (a) and coronal (b) reformatted CT images show the distended cecum in the left upper quadrant of the abdomen (* in a). The mesenteric twist, which in this case involves the terminal ileum, is most easily seen within the circled area in b. have argued that cecal bascule is a form of cecal adynamic ileus that may lead to perforation, de- pending on duration of symptoms (13). Transverse Colon The transverse colon is the rarest site of colonic volvulus (
woman with a 7-year history of intermittent abdominal pain and a 30-year history of laxative use. (a, b) CT images (b is slightly more caudal than a) show a whirl sign adjacent to the transverse colon (arrow). (c) Image acquired during an en- ema shows classic beaklike narrowing of the transverse colon at the volvulus (arrow). with the highest mortality. It occurs in the setting of abnormal fi xation of a long transverse colon. Conventional radiography is seldom helpful in diagnosing this entity. As in cases of cecal volvu- lus, a contrast material enema study shows the characteristic beaklike tapering of the colon at the level of the twist. However, because volvulus of the transverse colon is rare and not usually ex- pected, the diagnosis is often made at CT, which shows bowel obstruction and the classic mesen- teric twist (Fig 17). 1290 September-October 2009 radiographics.rsna.org Figure 19. Sigmoid volvulus. (a) Supine radiograph shows the sigmoid colon arising from the pelvis, with its apex in the left upper abdomen. The interposed loops produce the white-stripe sign (arrow). (b) Image acquired in a contrast material enema study shows abrupt termination of the contrast material column in a beaklike point. cause of large-bowel obstruction in the absence of neoplasm and diverticular disease. However, in developing countries, sigmoid volvulus causes a majority of bowel obstructions and is presumably caused by relatively high-fi ber diets. It is also the most common cause of bowel obstruction during pregnancy. Because patients usually present with nonspe- cifi c abdominal pain and symptoms of obstruc- tion, conventional radiography often is performed as part of the initial work-up. Radiographic fi nd- ings that may be diagnostic of sigmoid volvulus include a large air-fi lled bowel loop, which rep-
The sigmoid is the most common site of colonic volvulus and accounts for 60%–75% of all cases of colonic volvulus. It is generally considered to be an acquired condition because its prevalence increases among those with chronic constipation and sigmoid colonic redundancy due to a high- fi ber diet, pregnancy, hospitalization or institu- tionalization, or Chagas disease (1,10,14). In de- veloped countries, sigmoid volvulus is a common Figure 18. “Northern exposure” sign in a 52-year-old man with abdominal pain. Erect radiograph shows the displacement of the sig- moid colon (arrow) above the transverse colon (Tr). This sign was fi rst observed as extension of the apex of the sigmoid colon cephalad to the transverse colon on supine radiographs.
RG ■ Volume 29 • Number 5 Peterson et al 1291 Figure 21. Sigmoid volvulus. Coronal CT images obtained with soft-tissue (a) and lung (b) window settings show the whirl sign (arrow in a) and the classic beak sign (arrow in b) at the level of the twist. The diagnosis was confi rmed at endoscopy.
air-fi lled, dilated viscus (arrow) arising from the pelvis. (b) Coronal CT image shows the whirl sign in the sigmoid mesocolon (arrow). A contrast material enema study helped confi rm the diagnosis. resents the sigmoid colon, arising from the pelvis and extending cranially beyond the level of the transverse colon (the “northern exposure” sign) (Figs 18–23) (10,15). Other useful radiographic features include the “coffee bean” sign, which re- fers to the coffee bean–like shape that the dilated sigmoid colon may assume (10,16). Similarly, the “closed-loop” and “three-line” or “white-stripe”
1292 September-October 2009 radiographics.rsna.org Figure 23. Sigmoid volvulus. (a) Radiograph shows a dilated viscus arising from the pelvis and ascending above the transverse colon. (b) CT image shows the site of the twist (arrow). Figure 22. Sigmoid volvulus. (a) Radiograph shows a dilated sigmoid colon arising from the pelvis, with its apex in the right upper quadrant of the abdomen (arrow). (b) Coronal CT image shows the characteristic whirl sign at the level of the volvulus (arrow).
1292 September-October 2009 radiographics.rsna.org Figure 23. Sigmoid volvulus. (a) Radiograph shows a dilated viscus arising from the pelvis and ascending above the transverse colon. (b) CT image shows the site of the twist (arrow). Figure 22. Sigmoid volvulus. (a) Radiograph shows a dilated sigmoid colon arising from the pelvis, with its apex in the right upper quadrant of the abdomen (arrow). (b) Coronal CT image shows the characteristic whirl sign at the level of the volvulus (arrow).
3. Eisenberg R, Levine M. Miscellaneous abnormali- ties of the stomach and duodenum. In: Gore RM, Levine MS, eds. Textbook of gastrointestinal radiol- ogy. 2nd ed. Philadelphia, Pa: Saunders, 2000; 675. 4. Godshall D, Mossallam U, Rosenbaum R. Gastric volvulus: case report and review of the literature. J Emerg Med 1999;17(5):837–840. 5. Menuck L. Plain fi lm fi ndings of gastric volvulus herniating into the chest. AJR Am J Roentgenol 1976;126(6):1169–1174. 6. McAlister WH, Kronemer KA. Emergency gastro- intestinal radiology of the newborn. Radiol Clin North Am 1996;34(4):819–844. 7. Bernstein SM, Russ PD. Midgut volvulus: a rare cause of acute abdomen in an adult patient. AJR Am J Roentgenol 1998;171(3):639–641. 8. Shimanuki Y, Aihara T, Takano H, et al. Clockwise whirlpool sign at color Doppler US: an objective and defi nite sign of midgut volvulus. Radiology 1996;199(1):261–264. 9. Fisher JK. Computed tomographic diagnosis of volvulus in intestinal malrotation. Radiology 1981; 140(1):145–146. 10. Ott DJ, Chen MY. Specifi c acute colonic disorders. Radiol Clin North Am 1994;32(5):871–884. 11. Freeny PC, Stevenson GW, eds. Margulis and Burhenne’s alimentary tract radiology. 5th ed. St. Louis, Mo: Mosby-Year Book, 1994; 362–365, 2059–2061. 12. Frank AJ, Goffner LB, Fruauff AA, Losada RA. Cecal volvulus: the CT whirl sign. Abdom Imaging 1993;18(3):288–289. 13. Fazel A, Verne GN. New solutions to an old prob- lem: acute colonic pseudoobstruction. J Clin Gas- troenterol 2005;39(1):17–20. 14. Jones IT, Fazio VW. Colonic volvulus: etiology and management. Dig Dis 1989;7(4):203–209. 15. Javors BR, Baker SR, Miller JA. The northern ex- posure sign: a newly described fi nding in sigmoid volvulus. AJR Am J Roentgenol 1999;173(3):571– 574.
16. Burrell HC, Baker DM, Wardrop P, Evans AJ. Signifi cant plain fi lm fi ndings in sigmoid volvulus. Clin Radiol 1994;49(5):317–319. 17. Baker SR. The abdominal plain fi lm. East Norwalk, Conn: Appleton & Lange, 1990; 185–188. signs describe the U-shaped closed-loop appear- ance of the colon, which is dilated between the two points of obstruction at the site of the volvu- lus; and the obliquely oriented vertical white lines that represent the opposed walls of the dilated bowel loop (the center line) and the outer walls of the bowel loop on either side (11,17). In cases in which the diagnosis is uncertain, a water-soluble contrast material enema study or CT may be performed. In an enema study, a beak-shaped area often is seen at the level of the distal aspect of the twist in the sigmoid, beyond which no contrast material passes. In addition to providing diagnostic information, the enema may help achieve reduction of the volvulus. At CT, the abnormal position of the sigmoid colon and swirling of the mesentery at the level of the volvu- lus are visible. As with cases of volvulus involving other sites in the GI tract, coronal and sagittal reformations may be useful for locating the mes- enteric swirl and evaluating the orientation of the rotated bowel segment.
Volvulus may involve any portion of the GI tract from the stomach to the colon and is an impor- tant cause of acute or recurring abdominal pain. Because a delay in diagnosis can have devastating consequences, including bowel ischemia and in- farction, prompt diagnosis is essential. The clini- cal symptoms of volvulus often are nonspecifi c, and radiologists often are consulted for diagnos- tic evaluations. This article describes the vari- ous radiologic imaging appearances of volvulus throughout the GI tract, emphasizing strategies for achieving an accurate diagnosis.
1. Feldman M, Scharschmidt BF. Sleisenger and Fordtran’s gastrointestinal and liver disease: pathophysiology/diagnosis/management. 6th ed. Philadelphia, Pa: Saunders, 1998; 324–328. 2. Yamada T, Alpers DH, Owyang C, Powell DW, Silverstein FE, eds. Textbook of gastroenterology. Philadelphia, Pa: Lippincott, 1991; 1404–1407. This article meets the criteria for 1.0 AMA PRA Category 1 Credit TM . To obtain credit, see www.rsna.org/education /rg_cme.html. Yüklə 93,26 Kb. Dostları ilə paylaş:
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