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50.Schunk K, Kern A, Heussel CP, et al. [Assessment of inflammatory activity in Crohn disease with hydroMRI.] [German] Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2000;172:153–160.
51.Low RN, Francis IR, Politoske D, Bennett M. Crohn’s disease evaluation: comparison of contrast-enhanced MR imaging and single-phase helical CT scanning. J Magn Reson Imaging 2000;11:127–135.
52.Alonso JC, Lopez-Longo FJ, Lampreave JL, et al. Abdominal scintigraphy using 99mTc-HMPAO- labelled leucocytes in patients with seronegative spondylarthropathies without clinical evidence of inflammatory bowel disease. Eur J Nucl Med 1996;23: 243–246.
53.Challa S, Lyons KP, Broekelschen P, Milne N. Relative sensitivity of Tc-99m WBC versus In-111 WBC in a patient with Crohn disease and steroid use. Clin Nucl Med 1997;22:700–703.
54.Serrano J, Gomez A, Verdu J, et al. [Abdominal scintigraphy with 99MTc-HMPAO-labelled leukocytes. Utility of the quantification in the evaluation of the inflammatory activity of Crohn’s disease and ulcerative colitis.] [Spanish] Rev Esp Med Nucl 1999;18:356– 362.
55.Suh CH, Lee CH, Lee J, et al. Arthritic manifestations of inflammatory bowel disease. J Korean Med Sci 1998;13:39–43.
56.Zajac M, Engelhard K, Schuhmann R. [Spondylodiscitis with presacral abscesses caused by fistulization in Crohn’s disease of the small intestine.] [German] Rontgenpraxis 2000;52:340–342.
57.Sahai A, Belair M, Gianfelice D, Cote S, Gratton J, Lahaie R. Percutaneous drainage of intra-abdominal abscesses in Crohn’s disease: short and long-term outcome. Am J Gastroenterol 1997;92:275–278.
58.Cerro P, Scribano ML, Falasco G, Zannoni F, Spina C. [Ultrasonography in the diagnosis of enterocutaneous fistula in Crohn’s disease.] [Italian] Radiol Med 1998;96:214–217.
59.Kreisel W, Wolf LM, Grotz W, Grieshaber M. Renal tubular damage: an extraintestinal manifestation of chronic inflammatory bowel disease. Eur J Gastroenterol Hepatol 1996;8:461–468.
60.Fellermann K, Stahl M, Dahlhoff K, Amthor M, Ludwig D, Stange EF. Crohn’s disease and sarcoidosis: systemic granulomatosis? Eur J Gastroenterol Hepatol 1997;9: 1121–1124.
61.Lovat LB, Madhoo S, Pepys MB, Hawkins PN. Longterm survival in systemic amyloid A amyloidosis complicating Crohn’s. Gastroenterology 1997;112: 1362–1365.
62.Nordenholtz KE, Stowe SP, Stormont JM, et al. The cause of death in inflammatory bowel disease: a comparison of death certificates and hospital charts in Rochester, New York. Am J Gastroenterol 1995;90:927– 932.
63.Trommer G, Bewer A, Kosling S. [Mesenteric lymphadenopathy in Yersinia enterocolitica infection.] [German] Radiologe 1998;38:37–40.
64.Balthazar EJ, Charles HW, Megibow AJ. Salmonellaand Shigella-induced ileitis: CT findings in four patients. J Comput Assist Tomogr 1996;20:375–378.
65.Hoffmann H, Kawooya M, Esterre P, et al. In vivo and in vitro studies on the sonographical detection of
Ascaris lumbricoides. Pediatr Radiol 1997;27:226– 229.
66.Durand DV, Lecomte C, Cathebras P, Rousset H, Godeau P. Whipple disease. Clinical review of 52 cases. The SNFMI Research Group on Whipple Disease. Societe Nationale Francaise de Medecine Interne. [Review] Medicine 1997;76:170–184.
67.Olveira A, Sanchez Rancano S, Conde Gacho P, Moreno A, Martinez A, Comas C. [Gastrointestinal anisakiasis. Seven cases in three months.] [Spanish] Rev Esp Enferm Dig 1999;91:70–72.
68.Chiu NT, Lee BF, Hwang SJ, Chang JM, Liu GC, Yu HS. Protein-losing enteropathy: diagnosis with (99m)Tclabeled human serum albumin scintigraphy. Radiology 2001;219:86–90.
69.Schmutz GR, Chapuis F, Morel E, N’Guyen D, Dion C, Regent D. [Drug-induced stenosis of the small bowel. Value of enteroclysis.] [French] J Radiol 1997;78:33– 39.
70.Zalcman M, Sy M, Donckier V, Closset J, Gansbeke DV. Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction. AJR 2000;175:1601–1607.
71.Kikuno M, Takahashi K, Shinozaki T, Nakazawa M, Sugawara T, Furuse M. [CT findings of the irradiated intestinal wall: comparison of early vascular phase and delayed equilibrium phase.] [Japanese] Nippon Igaku Hoshasen Gakkai Zasshi 1999;56:703–707.
72.De Backer AI, De Schepper AM, Vandevenne JE, Schoeters P, Michielsen P, Stevens WJ. CT of angioedema of the small bowel. AJR 2001;176:649– 652.
73.Nasnas R, Awky J, Aoun N, Haddad S, Slaba S, Atallah N. [Digestive manifestations of hereditary angioneurotic edema. Apropos of a case.] [French] J Radiol 1997;78:1167–1169.
74.Stevens RL, Jones B, Fishman EK. The CT halo sign: a new finding in intestinal lymphangiectasia. J Comput Assist Tomogr 1997;21:1005–1007.
75.Suzuki C, Higaki S, Nishiaki M, et al. 99mTc-HSA-D scintigraphy in the diagnosis of protein-losing gastroenteropathy due to secondary amyloidosis. J Gastroenterol 1997;32:78–82.
76.Vayre-Oundjian L, Boruchowicz A, Bloget F, Triboulet JP, Gosselin B, Colombel JF. [Pseudotumor nodular lymphoid hyperplasia of the ileum.] [Review] [French] Gastroenterol Clin Biol 1997;21:990–993.
77.Scafidi DE, McLeary MS, Young LW. Diffuse neonatal gastrointestinal hemangiomatosis: CT findings. Pediatr Radiol 1998;28:512–514.
78.Scarmato VJ, Levine MS, Herlinger H, Wickstrom M, Furth EE, Tureck RW. Ileal endometriosis: radiographic findings in five cases. Radiology 2000;214: 509–512.
79.Semelka RC, Marcos HB. Polyposis syndromes of the gastrointestinal tract: MR findings. J Magn Reson Imaging 2000;11:51–55.
80.DiSario JA, Burt RW, Vargas H, McWhorter WP. Small bowel cancer: epidemiological and clinical characteristics from a population-based registry. Am J Gastroenterol 1994;89:699–701.
81.Neugut AI, Jacobson JS, Suh S, Mukherjee R, Arber N. The epidemiology of cancer of the small bowel. [Review] Cancer Epidemiol Biomarkers Prev 1998;7: 243–251.
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82.Buckley JA, Siegelman SS, Jones B, Fishman EK. The accuracy of CT staging of small bowel adenocarcinoma: CT/pathologic correlation. J Comput Assist Tomogr 1997;21:986–991.
83.Chun HJ, Byun JY, Chun KA, et al. Gastrointestinal leiomyoma and leiomyosarcoma: CT differentiation. J Comput Assist Tomogr 1998;22:69–74.
84.Chan GS, Ng WK, Chua DT, Wu PC. Raised serum hCG in a male patient caused by primary jejunal choriocarcinoma. J Clin Pathol 1998;51:413–415.
85.Ledermann HP, Binkert C, Frohlich E, Borner N, Zollikofer C, Stuckmann G. Diagnosis of symptomatic intestinal metastases using transabdominal sonography and sonographically guided puncture. AJR 2001;176:155–158.
86.Elsayed AM, Albahra M, Nzeako UC, Sobin LH. Malignant melanomas in the small intestine: a study of 103 patients. Am J Gastroenterol 1996;91:1001–1006.
87.Strobel K. [Small intestine invagination in metastatic intestinal malignant melanoma.] [German] Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2001;173:768–769.
88.Seppala R, Prefontaine M, Mikhael NZ. Mesenteric small-bowel polyposis: a diagnostic radiographic sign of neurofibromatosis. AJR 1997;168:434–436.
89.Sugimoto E, Lorelius LE, Eriksson B, Oberg K. Midgut carcinoid tumours. CT appearance. Acta Radiol 1995; 36:367–371.
90.Bader TR, Semelka RC, Chiu VC, Armao DM, Woosley JT. MRI of carcinoid tumors: spectrum of appearances in the gastrointestinal tract and liver. J Magn Reson Imaging 2001;14:261–269.
91.Hoegerle S,Altehoefer C, Ghanem N, et al. Whole-body 18F dopa PET for detection of gastrointestinal carcinoid tumors. Radiology 2001;220:373–380.
92.Jadvar H, Segall GM. False-negative fluorine-18–FDG PET in metastatic carcinoid. J Nucl Med 1997;38:1382– 1383.
93.Hennigs S, Jager H, Gissler M, et al. [Small intestinal transit with radio-opaque markers to localize intermittent small bowel obstruction.] [German] Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2000;172:1000–1005.
94.Lappas JC, Reyes BL, Maglinte DD. Abdominal radiography findings in small-bowel obstruction: relevance to triage for additional diagnostic imaging. AJR 2001;176:167–174.
95.Assalia A, Schein M, Hashmonai M. Barium contrast study converts partial small-bowel obstruction into a complete one. Report of 2 cases. S Afr J Surg 1993;31: 102–103.
96.Miyazaki O. [Efficacy of abdominal plain film and CT in bowel obstruction.] [Japanese] Nippon Igaku Hoshasen Gakkai Zasshi 1995;55:233–239.
97.Maglinte DD, Reyes BL, Harmon BH, et al. Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction. AJR 1996;167: 1451–1455.
98.Makanjuola D. Computed tomography compared with small bowel enema in clinically equivocal intestinal obstruction. Clin Radiol 1998;53:203–208.
99.Jabra AA, Eng J, Zaleski CG, et al. CT of small-bowel obstruction in children: sensitivity and specificity. AJR 2001;177:431–436.
100.Harisinghani MG, Wittenberg J, Lee W, Chen S, Gutierrez AL, Mueller PR. Bowel wall fat halo sign in patients without intestinal disease. AJR 2003;181: 781–784.
101.Matter I, Khalemsky L, Abrahamson J, Nash E, Sabo E, Eldar S. Does the index operation influence the course and outcome of adhesive intestinal obstruction? Eur J Surg 1997;163:767–772.
102.Hentel KD, Gollub MJ. Contrast enema before bypass surgery for small-bowel obstruction in the oncologic patient: is it necessary? AJR 2003;181:1361–1364.
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104.Gurleyik E, Gurleyik G. Small bowel volvulus: a common cause of mechanical intestinal obstruction in our region. Eur J Surg 1998;164:51–55.
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5
Colon and Rectum
Technique
Barium Enema
Contrary to the opinion of some computed tomography (CT) and magnetic resonance imaging (MRI) enthusiasts, a double-contrast barium enema continues to be a viable option in a setting of suspected colitis, colorectal cancer screening and detection, and follow-up after therapy. Similarly, it is a sad reflection on medical practice that occasionally a statement still appears in print that barium sulfate is toxic to the colon (1).
One of the present indications for a barium enema is failed colonoscopy, although in some centers CT colonography is gaining ground and magnetic resonance (MR) virtual colonoscopy is on the horizon. An obvious concern in performing any enema shortly after failed colonoscopy is risk of perforation. Contrary to the experience of some investigators, the author has found barium enemas performed on the same day as colonoscopy to be mostly unsatisfactory; invariably the patient is “tired out”from the colonoscopy, has difficulty cooperating, excessive colonic spasm is often encountered, and residual fluid interferes with mucosal coating. A formal air contrast barium enema, performed a week or so later, tends to be of superior quality.
Proctography
Evacuation proctography, a dynamic imaging modality, evaluates functional and morphologic abnormalities of the anorectal region. This examination, also called dynamic proctography or defecography, requires specially adopted fluoroscopic equipment, including rapid filming, that is not available in many radiology departments. It has a role in evaluating unexplained constipation, incontinence, rectal prolapse, and rectal pain. It evaluates the presence or absence of a sigmoidocele, rectocele, rectal prolapse, puborectalis muscle contraction, anal canal opening, changes in anorectal angle, and rectal emptying. Resultant findings appear to be independent of contrast agent viscosity used.
Preand postproctography questionnaires by referring clinicians revealed that clinicians found this study of major benefit in 40% and of moderate benefit in 40% (2); the primary diagnosis was changed in 18% of patients, intended surgical management became nonsurgical in 14%, intended nonsurgical therapy became surgical in 4%, and type of surgery contemplated changed in 10%.
Although detailed and precise anatomic measurements are possible with this study, their clinical relevance is still not clear. In particular, the borderland between normal and abnormal is poorly defined. Lack of confidence in some
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of the findings becomes evident after patient symptoms persist following surgical correction of an alleged abnormality.
Computed tomographic proctography is feasible, but rarely performed. The study is performed with the patient seated; coronal images aid in outlining perineal floor muscles. Sagittal reconstruction allows comparison with conventional proctography.
An open configuration MR system allows image acquisition with the patient in a vertical position. Anorectal angle changes, anal canal function, puborectalis muscle configuration, and pelvic floor dynamics are evaluated at rest and during straining (3). Even if an open MR unit is not available, conventional proctography is gradually being replaced by pelvic floor MRI using an endoanal coil. Suspected fistulas, sphincter lacerations, rectoceles, tumor invasion by low rectal carcinomas, and other pelvic floor disorders are imaged in detail with this technique. Currently this is considered to be the most accurate imaging test of distal perirectal structures, especially the external sphincter.
Two approaches are possible for MR rectal studies: either rectal distention with fluid and use of a surface coil or no distention and use of a rectal MR coil. More studies have addressed the latter technique, but advances in hardware and software design make it difficult to predict which path will be superior. One technique consists of opacifying the rectum with 200mL of an ultrasonography (US) gel and obtaining a single sagittal T2-weighted gradient echo sequence through the rectum (4); with a 1.5-T MR unit, a temporal resolution of 1.1 second is obtained, allowing imaging at rest and during straining and evacuation.
Using a surface coil in the anal canal, endorectal MRI appears superior to endorectal US in visualizing the external sphincter, although internal sphincter lesions are better evaluated with endorectal US (5).
Colonoscopy
Conventional
The prevalence of incomplete colonoscopy varies considerably among endoscopists and institutions, ranging from several percent up to one third of studies. A majority of incomplete
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colonoscopies are in women. A prior abdominal hysterectomy is associated with a higher rate of incomplete colonoscopy.
Complete colonoscopy consists in visualizing cecal landmarks, an elusive task in some patients. Attempts to provide photographs of cecal landmarks have met with limited success. Experienced endoscopists display considerable disparity in deciding whether complete colonoscopy had been performed when reviewing photographs of cecal landmarks (6).
The polyp miss rate of colonoscopy was estimated by performing two consecutive back-to- back colonoscopies on the same day (7); overall polyp miss rate was 24%, being 27% for polyps £5mm, 13% for lesions 6 to 9mm, and 6% for those ≥1cm. The miss rates for small polyps occurred among essentially all endoscopists.
Polyp size is routinely estimated by endoscopists. Because of endoscopic lens system limitations, apparent measurements tend to be smaller than actual. Lesions in the periphery of the field of view are smaller than in the center. Likewise, size varies with depth of view. Comparing magnified radiographic polyp measurements (which are magnified due to inherent focus-object-film geometry) with the minified endoscopic appearance results in considerable discrepancy.
Laser fluorescence spectroscopy performed during colonoscopy has detected colonic dysplasia with a claimed sensitivity and specificity of over 90% (8).
Computed Tomographic Colonography
The introduction of multidetector CT opened possibilities for complex three-dimensional (3D) colon studies, allowing the entire abdomen and pelvis to be covered with a slice thickness of <3mm in under 30 seconds, allowing single breath-hold scanning. An effective slice thickness approaching 1mm should, in theory, detect all relevant polyps. Once lumen distention is introduced, one is well on the road toward CT detection of colon neoplasms. Yet although multiple publications have established the feasibility of screening CT colonography, its role remains undefined.
The terms CT colonography, CT colonoscopy, and virtual colonoscopy have often been used interchangeably to describe a global examination designed to detect colonic tumors regardless of specific images obtained. Computed
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tomographic colonography appears to better describe this procedure, but virtual colonoscopy is ingrained in the literature, although a trend has developed to use CT colonography for a global examination consisting of narrow collimation data reconstructed to various combinations of 2D multiplanar reformatting and 3D images and to limit the term virtual colonoscopy to specific colonoscopy-like images. Hydro-CT is a less often used term to describe colonic distention with fluid during a CT study.
Currently CT colonography is a viable alternate after failed or incomplete conventional colonoscopy. Residual colonic distention is adequate in many patients when CT is performed shortly after incomplete colonoscopy, but additional air insufflation is often helpful. Indications for CT colonography have expanded considerably and in some centers it has mostly replaced conventional colonoscopy for polyp detection, leaving the latter modality for therapy of detected polyps.
Technique
Although CT colonography is generally regarded as a technically easy study, interpretation requires a steep learning curve. Data evaluation time and number of false positive findings decrease with experience. Similar to a barium enema, a colon-cleansing regimen is required with most current CT colonography techniques. Numerous false positives ensue if residual stool is present, thus emphasizing the importance of a colon-cleansing regimen, a difficult task in most practices. One study achieved ideal bowel preparation in only 19% of 200 patients (9). The two bowel preparations commonly employed are a polyethylene glycol electrolyte (“wet”) solution or a phospho-soda (“dry”) preparation, both given the day prior to CT colonography. Polyethylene glycol electrolyte solution results in considerably more bowel residual fluid.
Current limitations of CT colonography include fluid retention and inadequate luminal distention due to spasm. Similar to a barium enema, polyps tend to be missed if the lumen is not distended. Spasm is minimized by judicious use of an antispasmodic agent. Problems inherent with fluid retention are partly overcome by performing the study with the patient both prone and supine, at the expense of doubling the radiation dose. Nevertheless, acquisition and
review of supine and prone images significantly increase polyp detection sensitivity (10), and the trend is to use both positions.
Ingestion of oral contrast agents is generally considered inadequate preparation for CT cancer detection. In practice, colonic lavage combined with oral barium contrast for stool tagging and oral iodinated contrast for electronic fluid marking are useful techniques. A viable option consists of oral contrast combined with laxatives in frail, elderly patients who do not tolerate more vigorous CT colonography or a barium enema, realizing that this technique detects only more bulky tumors.
Air is commonly used to distend the lumen. Carbon dioxide is an alternative agent but the relative merits of one over the other are arguable. Adequacy of distention is evaluated with a CT scout image.With newer CT scanners, if a study is being performed for suspected colitis, especially ischemic colitis, some authors find little advantage for intraluminal contrast.
As an aside, a tap-water enema is often administered if colon visualization is desired during abdominal CT examination. Comparing water, methylcellulose, and ultrasound gel as multislice CT rectal contrast agents, methylcellulose was significantly superior to ultrasound gel in differentiating normal from diseased bowel (11); although better rectal distention was achieved with methylcellulose and ultrasound gel, superior more proximal colon distention was obtained with water. Of these three agents, the authors recommend rectal methylcellulose.
Computed tomographic colonography with multidetector CT results in significantly better colonic distention and yields fewer respiratory artifacts compared to single-detector CT.
Computed tomographic colonography is a viable alternate after failed or incomplete conventional colonoscopy. A prospective study of patients performed within 2 hours of incomplete colonoscopy found that although residual colonic distention was adequate in most patients, additional air insufflation significantly increased colon distention (12).
Once patient scanning is completed, the data are transferred to a workstation for analysis. These are complex examinations, and hundreds of images are generated in transverse, multiplanar reformatted, and 3D endoluminal modes. The relative advantages of axial, coronal, 2D, and 3D display techniques are still evolving;