Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1410_Библиотеки_им_академика_М_И_Перельмана
.pdf
6. Diagnostic Evaluations: Radiology, Nuclear Scans 101
Fig. 6.6. Plain fi lm of chronic burned out colitis.
mation regarding the extraintestinal manifestations of
IBD. Abnormalities of the skeletal system such as sacroiliitis, ankylosing spondylitis, and osteopenia secondary
to chronic steroid use can be seen.
• Another manifestation of colitis is pneumatosis where gas has
accumulated within the wall of the intestine. This may be a relatively benign process such as pneumatosis cystoides intestinalis
or it may represent the very grave situation of bowel infarction.
B. Contrast Studies
Contrast Enemas
• Barium studies of the colon are designed for the detection of
mucosal and intramural lesions.
• With the widespread use and availability of colonoscopy, the
role of single or double contrast barium studies has diminished.
102 The ASCRS Manual of Colon and Rectal Surgery
• The advantages of barium as a contrast medium are its ability
to coat and adhere to the mucosa.
• The indications for a barium study include screening and diagnosis of mucosal disease processes in the elective setting.
• The exposure of barium to the peritoneal cavity results in
an intense infl ammatory response that has a mortality rate
of approximately 50%. Therefore, the use of barium should
be avoided in urgent situations such as studying the integrity of an anastomosis, evaluating a large bowel obstruction,
examining acute colitis, or when there is concern for bowel
perforation. In these situations, a water-soluble contrast agent
should be used.
• Indications for a water-soluble study include evaluating the
integrity of a colonic anastomosis, evaluating colonic obstruction, the preoperative evaluation of the colon for evidence of
gross pathology, delineating colonic fi stulas, and therapeutic enema for fecal impaction. The peritoneal cavity tolerates
exposure of water-soluble contrast with very little reaction and,
therefore, it is the contrast agent of choice in urgent situations.
Cancer and Polyps
• The most common reason for ordering an air contrast barium
enema is for the screening and diagnosis of neoplastic lesions
of the colon and rectum, especially when screening for colorectal cancer in conjunction with fl exible sigmoidoscopy, when
colonoscopy is not possible.
• A barium enema can detect up to 90% of polyps and cancers
that are >1cm in size, but sensitivity decreases to 50% for
lesions <1cm in size.
• The size of the lesion is the most helpful indicator of malignancy, with lesions >2cm having a 50% chance of invasive
cancer.
• Sessile lesions when viewed in face take on a “bowlers hat”
appearance that project into the lumen (Fig. 6.7 ).
• Characteristic fi ndings implicating a malignant lesion include
destruction and irregularity of the overlying mucosa with shelflike, overhanging borders, and there is a sharp transition from
normal mucosa into the annular lesion.
• Benign strictures from ischemic colitis, diverticulitis, anastomotic strictures, or Crohn’s disease, in contrast, tend to have
smooth, tapering borders.
6. Diagnostic Evaluations: Radiology, Nuclear Scans 103
Fig. 6.7. ACE of polyp or early cancer.
• If a large bowel obstruction is suspected, barium should be
avoided and a water-soluble contrast agent should be used,
and only a single column contrast study is needed to defi ne the
pathology.
• A completely obstructing lesion will have an abrupt cutoff of
contrast at the level of the lesion. There will be shouldering or
evidence of mucosal destruction at the point of obstruction. If
the lesion permits some contrast to fl ow past the lesion, a “string
sign” may be seen (Fig. 6.8 ). This will be seen as a thin line of
contrast extending from the column of contrast at the level of
the obstruction. There is an abrupt cutoff of normal mucosa to
a shouldering, overhanging lesion. The “string” of contrast will
show irregular, destroyed mucosa along the length of the lesion.
Polyposis Syndromes: Familial Adenomatous Polyposis, Peutz-Jeghers,
Juvenile Polyposis
• It is not possible to distinguish between the sporadic adenomatous
polyps and these polyposis syndromes using contrast studies.
104 The ASCRS Manual of Colon and Rectal Surgery
Fig. 6.8. Contrast enema of apple-core cancer string sign.
Ulcerative Colitis
• Barium enema is used (1) to confi rm the diagnosis of UC and
differentiate it from Crohn’s disease, (2) to assess the extent
and severity of disease, and (3) for surveillance of the disease
and its complications.
• Radiographically, this appears as blunting or complete loss
of the haustral markings, a narrow tubular appearance to the
colon, and loss of the redundant course of the sigmoid and
transverse colon (Fig. 6.9 ).
• Barium contrast studies are also able to detect other colonic
complications of UC such as adenomatous polyps and cancers.
Crohn’s Disease
• Contrast studies help differentiate Crohn’s disease from UC,
defi ne the severity and extent of the colitis, and identify complications of the disease.
6. Diagnostic Evaluations: Radiology, Nuclear Scans 105
Fig. 6.9. Contrast enema of chronic UC.
• Contrast enemas are better than colonoscopy at identifying and
characterizing fi stulas, strictures, and the distribution of disease.
• Aphthous ulcerations are the earliest mucosal lesions seen in
Crohn’s disease. Barium accumulates within the lesions and
they appear as small, shallow, or punctate collections with a
surrounding radiolucent halo (Fig. 6.10a ). These lesions occur
more frequently in the colon than the small intestine, and they
help to distinguish Crohn’s disease from UC.
• The transmural nature of the infl ammation allows the ulcerations
to extend into the musculature of the bowel wall and even lead
to fi stulization. The result is deep longitudinal and transverse
fi ssuring with edematous mucosa in between that gives the colon
a cobblestone appearance. Barium deposits in the deep fi ssures
and appear as multiple irregular white stripes (Fig. 6.10b ).
106 The ASCRS Manual of Colon and Rectal Surgery
a
b
Fig. 6.10. ( a ) Contrast enema of Crohn’s disease showing ulcers. ( b ) Contrast
enema of Crohn’s with fi ssures, and long linear ulcers.
6. Diagnostic Evaluations: Radiology, Nuclear Scans 107
Fig. 6.11. Contrast enema of Crohn’s disease showing a stricture.
• Also, the identifi cation of skip lesions or areas of normal mucosa
in between areas of active colitis distinguish Crohn’s disease
from UC.
• Another signifi cant feature of Crohn’s disease is the development of strictures. Crohn’s strictures are a result of transmural
fi brosis. Radiographically, the strictures are asymmetric, have
irregular borders, and are not circumferential (they are centered on the mesenteric edge) (Fig. 6.11 ).
Diverticulitis
• Air contrast barium enemas are more sensitive than single contrast
studies at detecting diverticula because of better colonic distension and mucosal detail.
• Diverticula can be distinguished from polyps and small cancers because they project away from the lumen as compared
with neoplasms that project into the lumen.
108 The ASCRS Manual of Colon and Rectal Surgery
Fig. 6.12. Air contrast enema of severe diverticulosis.
• The combination of a shortened, thickened colon and extensive diverticula can disrupt the symmetric appearance of the
haustral clefts, giving the mucosal outline an irregular zigzag
appearance (Fig. 6.12 ).
• In the acute setting, a water-soluble contrast agent should be
used rather than barium to avoid the highly morbid case of
barium peritonitis.
Submucosal and Extracolonic Lesions
Lipoma
• On double contrast barium enema, lipomas can appear as a
submucosal mass or a polypoid lesion.
• Lipomas are soft and pliable, so during fl uoroscopic examination, compression can change the confi guration of the lesion;
this is called the “pillow sign.”
Lymphoma
• There are three basic radiographic morphologies that primary
colonic lymphomas can demonstrate.
– First, they can appear as discrete polypoid lesions.
– Second, the mass can infi ltrate the mesentery resulting in
cavitation of the lesion into the mesentery.
– Finally, disseminated lymphoma appears as multiple, long
segments of nodular, narrowed colon.
6. Diagnostic Evaluations: Radiology, Nuclear Scans 109
Endometriosis
• The fi ndings on barium enema in the patient with endometriosis are
consistent with an extracolonic process, because the mucosa
remains smooth and intact. Scaring occurs on the serosal surface which contracts the serosa causing the normal mucosa to
bunch into what is called mucosal pleating.
Colonic Intussusception
• The classic appearance of an intussusception on contrast enema
is the spring coil appearance or crescent sign.
Anastomotic Assessment
• Contrast enema studies are frequently used postoperatively to
examine a colocolic, colorectal, coloanal, or ileal-anal anastomosis. The studies are used to evaluate for anastomotic leak in
a septic patient, before closure of a diverting stoma, or to rule
out an anastomotic stricture in patients with defecation diffi culties.
• When testing the integrity of an anastomosis, a water-soluble
contrast agent should be used.
• In the early postoperative period when evaluating for an anastomotic leak, water-soluble contrast enema is more sensitive
than CT with rectal contrast.
• Radiographic fi ndings of an anastomotic dehiscence include
the extravasation of contrast freely into the peritoneal cavity or
into a contained cavity (Fig. 6.13a , b ).
• Finally, the postevacuation fi lms are the most important because
they identify any residual contrast outside of the lumen, which
may be the only fi nding that a leak is present.
Small Bowel Series and Enteroclysis
• Radiologic studies of the small bowel are often used to fi nish
an examination of the GI tract for the sake of completeness.
• Indications for small bowel studies include unexplained GI bleeding, evaluation for small bowel tumors, SBO, Crohn’s disease,
and malabsorption.
• Barium follow-through and enteroclysis are the principle methods for examining the small bowel. During a small bowel follow through (SBFT), the patient drinks a large volume of dilute
110 The ASCRS Manual of Colon and Rectal Surgery
a
b
Fig. 6.13. ( a ) Contrast enema showing a contained anastomotic leak. ( b ) Contrast
enema showing a free-fl owing leak.
Соседние файлы в папке Библиотека им академика М.И. Перельмана