Mesenteric Small Bowel (PBR 2) Flashcards
CT and MR enterography findings that suggest malignant small bowel lesions
- Solitary lesions
- Nonpedunculated lesions
- Long-segment lesions
- Presence of mesenteric fat infiltration
- Presence of enlarged mesenteric lymph nodes (>1-cm short-axis diameter)
Most common neoplasm of the small intestine
They are considered a low-grade malignancy that may recur locally or metastasize to the lymph nodes, liver, or lung
Carcinoid tumors
Accounting for about one-third of all small bowel tumors
They arise from endocrine cells (enterochromaffin or Kulchitsky cells) deep in the mucosa
In carcinoid tumors
Only 7%, those with liver metastases, present with carcinoid syndrome because the liver inactivates the vasoactive substances
What are clinical presentation of carcinoid syndrome?
Cutaneous flushing, abdominal cramps, and diarrhea
*Creator’s notes:
Heart failure can also be included
Complications of carcinoid tumors
Stricture Obstruction Bowel infarction (induced by fibrosis of the mesenteric vessels)
Can carcinoid tumor cause intussusception?
Yes
If they are pendunculated
Imaging signs of fibrosis and metastases of carcinoid tumors may resemble what disease?
Crohn disease
May overshadow primary tumor
Barium study findings of carcinoid tumor
- Luminal narrowing
- Thickened and spiculated folds
- Separation of bowel loops by mesenteric mass
- Bowel loops drawn together by fibrosis
- Primary lesion appearing as small (<1.5 cm) mural nodule or intraluminal polyp
CT and MR findings that are highly indicative of carcinoid tumor
- Sunburst pattern of radiating soft tissue density in the mesenteric fat due to mesenteric fibrosis
- Bowel wall thickening
- Primary lesion appearing as a small, lobulated soft tissue mass, occasionally with central calcification, usually in the distal ileum
- Marked contrast enhancement of the primary tumor mass
- Enlarged mesenteric nodes and liver masses due to metastatic disease
Adenocarcinoma of the small bowel is about half as common as carcinoid tumor
Where is it frequently seen in the small intestine?
Duodenum (50%) and proximal jejunum
Uncommon in distal ileum, where carcinoid is most common
Patients with what disease are at risk of small bowel carcinoma?
Adult celiac disease
Crohn disease
Peutz-Jeghers syndrome
Complications of small bowel adencarcinoma
Bleeding
Obstruction
Intussusception
What are the different tumor morphology of small bowel adenocarcinoma?
- Infiltrating producing strictures
- Polypoid producing filling defects
- Ulcerating
Most common location of infiltrating producing strictures of SB adenocarcinoma?
Jejunum
Most common location of polypoid producing filling defects of SB adenocarcinoma?
Duodenum
Barium study finding of SB adenocarcinoma
Typically show a characteristic “apple core” stricture of the small bowel
CT and MR findings of SB adenocarcinoma
- Solitary mass in the duodenum or jejunum (up to 8-cm diameter)
- An ulcerated lesion
- Abrupt irregular circumferential narrowing of the bowel lumen with abrupt edges to the wall thickening
Differential diagnosis of annular constricting lesions of the small bowel
- Small bowel adenocarcinoma
- Annular metastases
- Intraperitoneal adhesions
- Malignant gastrointestinal stromal tumors
- Lymphoma (rare)
Most common site for extranodal origin of lymphoma
GI tract
Small bowel is commonly involved
GI lymphoma involves what part of the small intestine?
Ileum with its high concentration of lymphoid cells in 60 to 65% pf cases and jejunum in 20 to 25%
Other risk factors for GI lymphoma
Infections due to: H. pylori HIV Epstein-Barr virus Hepatitis B vurys
Presenting symptoms of lymphoma
Abdominal pain Weight loss Anorexia GI bleeding Bowel perforation
Morphologic pattern of involvement of GI lymphma
- Diffuse infiltration
- Exophytic mass
- Polypoid/nodular mass
- Multiple nodules
A feature of lymphoma which replaces the muscularis and destruction of the autonomic plexus by tumor without fibrosis
Aneurysmal dilation
As a result, obstruction is uncommon
Barium study fining of GI lymphoma
- Wall thickening with irregular, distorted folds due to submucosal infiltration of cells
- Fold thickening may be smooth and regular in early stages due to lymphatic blockage in the mesentery
- Folds become effaced in later stages with greater cell infiltration into the bowel wall
- Narrowed, widened, or normal lumen
- Cavitary lesions containing fluid and debris
- Polypoid masses that may cause intussusception
- Rare multiple filling defects that are larger than 4 mm, variable in size, and nonuniform in distribution
Shallow ulceration is common.
CT and MR finding of GI lymphoma
- Circumferential wall thickening involving a long segment of small bowel
- Effacement of folds
- Solid nodule, often polypoid
- Eccentric wall thickening
- Aneurismal dilation (lumen >4 cm)
- Stenosis of the lumen (rare)
Differentiating finding of lymphoma in comparison with GISTs and adenocarcinoma
Exophytic lymphoma is generally of uniform soft tissue density and enhances little, if any, with intravenous contrast administration
GISTs and adenocarcinoma usually enhance prominently
This refers to the sparing of rind of fat surrounding mesenteric vessels that are encased by lymphomatous nodes
“sandwich sign”
Lymphoma that usually presents with intestinal involvement, especially in the ileocecal area in children and young adults
The malignancy is aggressive, with rapid doubling time and poor prognosis
Imaging studies show bulky ileocecal mass
Burkitt lymphoma
This lymphoma is an aggressive high-grade non-Hodgkin lymphoma with poor prognosis
Extranodal involvement, including small bowel lymphoma, is common
Adenopathy may be caused by lymphoma, Kaposi sarcoma, or Mycobacterium avium-intracellulare infection
The radiographic findings are identical to those seen in immunocompetent patients
AIDS-relatd lymphoma
Difference of nodular lymphoid hyperplasia from lymphoma
By the uniform small size of the nodules (2 to 4 mm) and even distribution through the area of involvement
Location of lymphoid hyperplasia
Confined to the terminal ileum and proximal colon
May involve the entire small bowel
Usually considered incidental and may be related to recent viral infection
Associated disease of diffuse lymphoid hyperplasia
Hypogammaglobulinemia, especially low IgA
Metastases of the small bowel are less common then primary neoplasms
True or false
False
They are more common
Two most frequent routes of spread of to small bowel
Peritoneal seeding
Hematogenous spread
Peritoneal seeding involves what part of the small bowel?
Mesenteric border
Hematogenous spread implants on what part of the small bowel?
Antimesenteric border
Intraperitoneal implantation on the small bowel serosa is most commonly due to what cancers?
Ovarian carcinoma in women
Colon, gastric, and pancreatic carcinoma in men
Intraperitoneal implantation is most common at what part of the GI tract?
Terminal ileum, cecum, and ascending colon
Peritoneal implants on the parietal peritoneum, and omentum (omental cake), as well as in the pouch of Douglas, are demonstrated by CT
Hematogenous to the small bowel are seen in primary malignancies?
Melonoma
Lung, breast, colon carcinoma
Embryonal cell carcinoma of the testes
Imaging finding of small bowel metastases
Mural nodules of uniform or varying size anywhere in the small bowel
They may appear as target lesions, or ulcerate or cavitate
Direct extension to involve the small bowel is seen with malignancies of the pancreas and colon
Clinical presentation of GISTs of the small bowel
Obstruction or intestinal bleeding
Barium study findings of GISTs of the small bowel
Well-defined submucosal mass with smooth mucosa
Tumors that exceed 2 cm in size tend to ulcerate whether they are benign or malignant
CT findings of GISTs of the small bowel
Benign GISTs are homogeneous with attenuation similar to muscle
Malignant GISTs tend to be larger (>5 cm) and heterogeneous with prominent areas of low attenuation necrosis and hemorrhage
Nodal metastases are uncommon
Calcification is infrequent
Location of small bowel adenoma
It is more common in the duodenum than in the mesenteric small intestine
The tumor is a benign proliferation of glandular epithelium, and has the potential for malignant degeneration
Most common location of lipoma in small bowels
Ileum
The tumor arises from the fat of the submucosa
Lipomas account for about 17% of benign small bowel tumors
Most are asymptomatic incidental findings, although some cause bleeding or intussusception
Presentation of hemangioma in the small bowel
Solitary and submucosal, projecting into the lumen as polyp
Tumors are located predominantly in the jejunum
About two-thirds present with occult bleeding and anemia
This finding is occasionally seen in small bowel hemagioma and it suggest the diagnosis
Calcified phlebolith
Syndromes that cause multiple polypoid lesions of the small bowel
Polyposis syndromes
Differential diagnosis for polyposis syndrome
Metastases Lymphoma Nodular lymphoid hyperplasia Kaposi sarcoma Carcinoid tumors
This is an autosomal dominant inherited condition consisting of multiple hamartomatous polyps in the small intestine (most common), colon, and stomach associated with melanin freckles on the facial skin, palmar aspects of the fingers and toes, and mucous membranes
Peutz-Jeghers syndrome
Polyps that are nonneoplastic, abnormal proliferation of all three layers of the mucosa, epithelium, lamina propria, and muscularis mucosae
Hamartomatous polyps
Polyps of Peutz-Jeghers syndrome are commonly located where?
Jejunum
Usually pedunculated, and are variable in size up to 4 cm
Patients with Peutz-Jeghers syndrome are at risk of what diseases?
Intussusception
GI tract adenocarcinoma
Extraintestinal malignancy (breast, pancreas, ovary)
Barium study finding of Peutz-Jeghers syndrome
Myriad polyps in involved areas of small intestine, separated by normal bowel segments
This is an inherited adenomatous polyposis coli usually includes a few adenomatous polyps in the small bowel
Gardner syndrome
*Creator’s notes:
Characterize by:
Familial adenopolyposis
Multiple osteomas: especially of the mandible, skull, and long bones
Epidermal cysts
Fibromatoses
Desmoid tumours of mesentery and anterior abdominal wall
Ascaris lumbricoides mature where in the GI tract?
Worms mature in the small bowel, especially in the jejunum, and may reach 15 to 35 cm in size
New generations of infective ova are excreted in feces
Barium study finding of ascariasis
Barium studies demonstrate worms as long linear filling defects
Barium ingested by the worms may be seen in their intestinal tract as a long, string-like white line
Normal mesenteric lymph nodes diameter
Less than 5 mm in short-axis diameter
Most common meseneteric mass
It causes bulky adenopathy
Lymphoma
Confluent adenopathy surrounds mesenteric vessels and fat producing the “sandwich sign”
Adenopathy is commonly present in the retroperitoneum and elsewhere
The sandwich sign is specific to mesenteric lymphomas
True or false
True
These are lymphangiomas that arise in the root of the small bowel mesentery
Most are thin walled and multiloculated with internal fluid that may be chylous, serous, or bloody
Mesenteric cysts
Imaging findings of mesenteric cysts
US demonstrates a well-defined cyst with internal debris, and fluid-debris or fluid-fat levels
CT shows a cystic mass, displacing loops of small bowel anteriorly and laterally
On MR, cyst contents are hyperintense on T2WI and hypointense on T1WI when serous, or hyperintense on T1WI when chylous or hemorrhagic
*Creator’s note:
Remember chylous component
This is a congenital, partial, or complete replica of the small bowel
Most arise from the distal small bowel and may communicate with the normal intestinal lumen at one or both ends, or not at all
They are lined by intestinal epithelium.
GI duplication cyst
US, CT, and MR reveal a thick-walled cyst with usually serous contents
Malignancies, primarily adenocarcinoma, may arise within duplication cysts
This is an uncommon inflammatory condition affecting the root of the mesentery with variable inflammation, fat necrosis, and fibrosis
Lesions may be solitary or multifocal within the mesentery
Cause is unknown but the disease is associated with
other idiopathic inflammatory disorders including retroperitoneal fibrosis and sclerosing cholangitis
Mesenteric panniculitis (sclerosing mesenteritis)
Patients commonly present with abdominal pain
CT shows localized increase in fat density in the mesentery
This finding is known as what?
“misty mesentery”
Cause of misty mesentery
Mesenteric infiltration by edema, inflammatory cells, neoplastic cells, or fibrosis
Mesenteric panniculitis can be diagnosed as the cause of misty mesentery if other causes are excluded
Mesenteric edema may occur in what processes?
Portal hypertension
Cardiac or renal failure
Hypoproteneimia
*Creator’s note:
Like any other cause of edema
What are the 5 rules of diffuse small bowel disease
#1 Dilation of the small bowel lumen means small bowel obstruction or dysfunction of small bowel muscle #2 Thickening of small bowel folds means infiltration of the submucosa #3 Uniform, regular, straight thickening means infiltration by fluid (edema or blood) #4 Irregular, distorted, nodular thickening means infiltration by cells or nonfluid material #5 The specific diagnosis requires matching the small bowel pattern with clinical data
This disease affects the small bowel in 60% of patients producing atrophy of the muscularis by the process of progressive collagen deposition resulting in flaccid, atonic, often greatly dilated small bowel
The valvulae conniventes are normal or thinned
Scleroderma
A “hide-bound” appearance of thinned folds tethered together is produced by contraction of the longitudinal muscle layer to a greater extent than the circular muscle layer
This is seen on what disease?
Scleroderma
Excessive contraction of the mesenteric border of the small bowel results in formation of mucosal sacculations along the antimesenteric border
In scleroderma, what part of the small bowels are more severely involved?
The jejunum and duodenum are more severely involved than the ileum
How is scleroderma diagnose?
The diagnosis is confirmed by skin changes and characteristic involvement of the esophagus
Malabsorption eventually occurs
High-resolution chest CT is required to document pulmonary involvement
Also known as nontropical sprue
This disease presents with malabsorption, steatorrhea, and weight loss
Gluten, an insoluble protein found in wheat, rye, oats, and barley, acts as a toxic agent to the small bowel mucosa
The mucosa becomes flattened and absorptive cells decrease in number; villi
disappear
Adult celiac disease
The submucosa, muscularis, and serosa remain normal
Findings and symptoms resolve with a strict gluten-free diet
Complications of celiac disease
Intussusception Lymphoma Ulcerative jejunoileitis Cavitating lymphadenopathy sydrome Pneumotosis intestinalis
Classic radiographic findings of celiac disease
- Dilated small bowel
- Normal or thinned folds
- Decreased number of folds per inch in the jejunum
- An increased number of folds per inch in the ileum (≥5)
Findings are best demonstrated by standard or CT enteroclysis
Five or more folds per inch in the jejunum make the diagnosis unlikely
CT enterography findings of celiac disease
- Reversed jejunoileal fold pattern with loss of folds in the jejunum and increased number of folds in the ileum
- Small bowel dilation
- Increased separation of small bowel folds
- Mesenteric lymphadenopathy
- Engorgement of mesenteric vessels
*Creator’s notes:
All appears to be nonspecific except for #1
This disease has similar clinical and radiographic findings as nontropical sprue but is confined to India, the Far East, and Puerto Rico
Tropical sprue
Illness starts with acute diarrhea, fever, and malaise and transitions to chronic steatorrhea, weight loss, malaise, and nutrient and vitamin deficiencies
The cause is unknown but the disease responds to administration of folate and antibiotics
Secondary lactase deficiency may develop in what cases?
Alcoholis, Crohn disease, and drugs such as neomycin
The nondigested lactose in the small bowel causes increased intraluminal fluid and dilated small bowel with normal folds
Disease that may result from embolism or thrombosis of the superior mesenteric artery or vein
Patients may present with an acute abdomen or vague symptoms
Intestinal ischemia
In intestinal ischemia:
What are the causes of arterial occlusion?
May be due to embolus, vasculitis, trauma, or adhesions
In intestinal ischemia:
What are the causes of venous thrombosis?
Hypercoagulability states (neoplasms, oral contraceptives)
Inflammation (pancreatitis, peritonitis, abscess)
Stasis (portal hypertension, congestive heart failure)
Radiograph findings of intestinal ischemia
Gaseous distention
Thickened mucosal folds (thumbprinting)
Intramulra or portal venous gas (in some cases)
Diagnostic imaging method of choice for intestinal ischemia
MDCT with intravenous contrast
CT findings of intestinal ischemia
- Diffuse thickening of the bowel wall, usually to 8 to 9 mm, rarely exceeding 15 mm
- Thinning of the bowel wall may occur in acute arterial occlusion caused by loss of intestinal muscle tone and tissue volume loss with vessel constriction
- Low attenuation of the bowel wall is caused by edema
- High attenuation of the bowel wall is caused by intramural hemorrhage
- Lack of or decreased bowel wall enhancement is highly specific for acute ischemia
- Pneumatosis of the thickened bowel wall may indicate transmural infarction
- Dilation of the bowel wall occurs with adynamic ileus; 8. Mesenteric vessels with emboli or thrombi fail to enhance following intravenous contrast administration
- Mesenteric fat stranding and ascites are commonly present
*Creator’s notes
Already discussed on Acute Abdomen
This occurs when large doses of radiation are give to adjacent organs
Radiation enteritis
The small bowel is the most sensitive organ in the abdomen
Pathological process of radiation enteritis
Long segments of bowel may be involved, with thickening of folds and bowel wall
Peristalsis is impaired
Progressive fibrosis leads to tapered strictures commonly involving long segments
The bowel may be kinked and obstructed by adhesions
Fistulas to the vagina or other organs may also result
*Creator's notes: In short: Thickened wall of log segments of the bowel with possible strictures and adhesions Impaired peristalsis Fistulas
CT findings of radiation enteritis
Wall thickening and increased density of the mesentery, and fixation of bowel loops
Diagnosis is confirmed by researching the radiation field and dose
This refers to gross dilation of the lymphatic vessels in the small bowel mucosa and submucosa
The primary form is a congenital lymphatic blockage, often associated with asymmetric edema of the extremities
Lymphangiectasia
Despite being congenital, symptoms often do not occur until young adulthood
Patients present with protein-losing enteropathy, diarrhea, steatorrhea, and recurrent infection
Causes of secondary lymphangiectasia
Lymphatic obstruction due to radiation, congestive heart failure, or mesenteric node involvement by malignancy or inflammation
How is lymphangiectasia diagnosed?
Jejunal biopsy
Barium study findings of lymphangiectasia
Diffuse fold thickening that is most pronounced in the jejunum, increased intraluminal fluid, and groups of tiny (1 mm) nodules due to distended villi
Pattern closely resembles Whipple disease
CT helps the differentiation by revealing thickening of the bowel wall and mesenteric adenopathy in secondary lymphangiectasia
This is a disease complex associated with extracellular infiltration of an amorphous protein material in body tissues
The disease may be primary or associated with multiple myeloma (10% to 15%), rheumatoid arthritis (20% to 25%), or tuberculosis (50%)
Amyloidosis
Most cases are systemic, but 10% to 20% are localized
The small bowel is the most common site of GI involvement of amyloidosis
True or false
True
Amyloid deposits are seen throughout the wall of the small bowel, especially within the walls of small blood vessels resulting in ischemia and infarction
Deposits in the muscularis impair motility. Diffuse, irregular thickened folds may be seen throughout the small bowel
Nodules are sometimes present
CT finding of small bowel amyloidosis
CT demonstrates symmetric wall thickening of affected bowel without luminal dilation or hypersecretion
Small mesenteric lymph nodes may be evident
Diagnosis is confirmed by biopsy
This is s a myeloproliferative neoplasm characterized by infiltration of mast cells in the skin, bones, lymph nodes, liver, spleen, and GI tract
Systemic mastocystosis
Osteoblastic bone changes are found in 70% of cases Lymphadenopathy and hepatosplenomegaly are often present
The bowel wall and mucosal folds are thickened, and mucosal nodules up to 5 mm size are often evident
Characteristic skin manifestation of systemic mastocytosis
Urticaria pigmentosa
This is an uncommon systemic disorder affecting the GI tract, joints, central nervous system, and lymph nodes
The disease is caused by Whipple bacilli, gram-positive, rod-shaped bacteria that are found within macrophages in many organs and tissues
Whipple disease
Patients may present with arthritis, neurologic symptoms, or steatorrhea
Generalized lymphadenopathy is usually present
Imaging findings of Whipple disease
Irregularly thickened folds most prominent in the jejunum
Demonstration of tiny (1 mm) sand-like nodules spread diffusely over the mucosa or in small groups is strong evidence of the disease
Increased luminal fluid is usual
CT reveals thick folds especially in the jejunum without significant dilation
Low-density or fat density nodes in the mesentery are characteristic
*Creator’s notes:
Remember sand-like nodules
Infectious agents that appears in AIDS enteritis
Cryptosporidium and Isospora belli
Cytomegalovirus
Mycobacterium avium-intracellulare
Candida, Amoeba histolytica, Gardia, Strongyloides, herpes simplex, and Campylobacter may also occur in AIDS patients
This is a common inflammatory disease of uncertain etiology that may involve the GI tract from the esophagus to the anus
The disease is characterized by erosions, ulcerations, full-thickness bowel wall inflammation, and formation of noncaseating granulomas
Crohn disease
Patients present, usually in their teens, 20s, and 30s, with diarrhea, abdominal pain, weight loss, and often fever
Patterns if GI involvment of Crohn disease
Colon and terminal ileum (55%)
Small bowel alone (30%)
Colon alone (15%)
Proximal small bowel without terminal ileum (3%)
Imaging hallmarks of Crohn disease
- Aphthous erosions
- Confluent deep ulcerations
- Thickened and distorted folds
- Fibrosis with thickened walls, contractures, and stenosis
- Involvement of the mesentery
- Asymmetric involvement both longitudinally and around the lumen
- Skip areas of normal intervening bowel between disease segments
- Fistula and sinus tract formation
These are shallow, 1- to 2-mm depressions usually surrounded by a well-defined halo
Aphthous ulcers
What produces the “cobblestone pattern” in Crohn disease?
Deep ulcerations - forming fissures between nodules of elevated edematnous mucosa
What produces the “string sign” in Crohn disease
Fibrosis and progressive thickening of the bowel wall narrow the lumen, particularly the terminal ileum
Mesenteric involvement is best demonstrated by CT or MR.
What are the mesenteric findings in Crohn disease?
Ulceration along the mesenteric border may extend between the leaves of the mesentery
The mesenteric fat is infiltrated; the mesentery is thickened and retracted
Crohn disease:
What are the findings indicative of active inflammation?
- Wall thickening (>3 mm)
- Layered pattern of wall enhancement
- The “comb sign” of fibrofatty proliferation around inflamed bowel segments with engorged mesenteric vessels forming the comb
- On MR high signal intensity of the thickened bowel wall on T2WI with fat saturation
Diffusion- weighted MR enterography shows restricted diffusion in acutely inflamed small bowel
Complications of Crohn disease
Obstruction
Fistulae (MC ileocolonic and ileocecal) and sinus tract formation
Abscess and phlegmon formation
Perforation
Carcinomas
Derangement of intestinal absorption - Megaloblastic anemia (Vit B12 deficiency)
Increased incidence of gallstones and renal stones
20% of patients have arthritis or spondylitis that mimics ankylosing spondylitis
This is caused by infection with the gram-positive bacilli, Y. enterocolitica, or Y. pseudotuberculosis
Infection causes acute enteritis with abdominal pain, fever, and often bloody diarrhea that mimics acute appendicitis or acute Crohn disease
Children and young adults are most often affected
Yersinia enterocolitis
Children and young adults are most often affected. The infection runs a self-limited course of 8 to 12 weeks
Diagnosis is confirmed by stool culture
Imaging findings of Yersinia enterocolitis are most pronounced at what part of the small intestine?
Distal 20 cm of the ileum
Aphthous ulcers, nodules up to 1 cm in size, wall thickening, and thickened folds that become effaced with increasing edema
Nodular lymphoid hyperplasia may appear during the resolution stage
*Creator’s note
Not very specific except for the location
This disease is a multisystem disease due to a small vessel vasculitis that affects eyes, joints, skin, central nervous system, and the intestinal tract
Prominent clinical features include relapsing iridocyclitis, mucocutaneous ulcerations, vesicles, pustules, and mild arthritis
Behcet disease
Intestinal disease most commonly involves the ileocecal region, where Crohn disease is closely mimicked with aphthous erosions, deep ulceration, stenosis, and fistula formation
Complications include bowel perforation and peritonitis
The cause is unknown and there is no cure
The disease is most common in the Middle East, especially Turkey, and Asia
General presentation of GI tuberculosis
Presents as peritonitis or focal infection of the gut, most commonly involving the ileocecal area, closely mimicking Crohn disease
Less than half of the patients have concurrent evidence of pulmonary tuberculosis
Imaging finding of GI tuberculosis
Barium studies:
Inflamed mucosa with transverse and stellate ulcers
The affected bowel becomes rigid and narrowed with nodular mucosa
The ileocecal valve is stiff and gaping with narrowed terminal ileum and cecum
CT:
Mesenteric adenopathy, high- density ascites, and peritoneal thickening and enhancement accompanying the bowel wall thickening
Most common location of small bowel diverticula
Jejunum along the mesenteric border
They are outpouchings of mucosa through the bowel wall and between the leaves of the mesentery
They are commonly multiple and often asymptomatic
Complications of small bowel diverticula
Malabsorption
Vit B12 absorprtion - Megaloblastic anemia
Obstruction, acute diverticulitis, hemorrhage, and volvulus
Imaging findings of small bowel diverticula
Conventional radiographs:
Featureless ovoid collections of air
Barium study:
Outpouchings, most with a neck smaller in diameter than the outpouching itself
The diverticulum lacks mucosal folds and does not contract because of the lack of muscle within its wall
CT:
Discrete, round or ovoid, structures outside the expected lumen of the small bowel
They may be filled with air, fluid, or contrast and have a thin smooth wall
Most common congenital anomaly of the GI tract
Meckel diverticulum
Length and location of Meckel diverticulum
2 to 8 cm in length
Located on the antimesenteric border of the ileum up to 2 m from the ileocecal valve
The tip of the diverticulum may be attached to the umbilicus by what vestigial structure?
A remnant of the vitelline duct
Ectopic gastric mucosa is present in up to 62% of cases
Complications of Meckel diverticulum
Ulceration and bleeding (ectopic gastric mucosa, peptic secretion)
Other complications:
Intussusception, volvulus, and perforation
Test of choice for Meckel diverticulum
Radionuclide (Tc-99m pertechnetate) scanning for ectopic gastric mucosa is the test of choice but is less reliable in adults than in children, and is negative when the diverticulum does not contain gastric mucosa
Enteroclysis is then the best method to demonstrate the diverticulum, which appears as a blind sac attached to the antimesenteric border of the ileum
CT:
Meckel diverticulitis appears as a blind-ending pouch of variable size and wall thickness with inflammatory changes in adjacent mesentery
These are outpouchings along the antimesenteric border of the small bowel that result from disease of the small bowel
They occur most commonly in association with Crohn disease or scleroderma
Pseudodiverticula or sacculations
With fibrosis and contraction of the mesenteric border of the bowel, the unsupported antimesenteric border becomes pleated and forms sacculations
