Imaging in Abdominal
Presenter : Dr. NavniModerator : Dr. Ravi
• Tuberculosis can affect any organ system, particularly in immunocompromised individuals.
• Can be divided into Pulmonary TB (85-90 %) Extrapulmonary TB (10-15% )
• Genitourinary TB (MC)• Bone and joint TB• Miliary TB• Meningeal TB• Gastrointestinal ( abdominal ) TB : 3-4%
• Defined as tuberculosis infection of the abdomen involving the peritoneum and its reflections, gastrointestinal tract, abdominal lymphatics and solid visceral organs.
• Causative organisms : M. tuberculosis hominis, M. bovis, Atypical mycobacterium (MAIC)
Routes of infection
• Ingestion of milk • Swallowing of sputum in active PTB• Hematogenous spread from active pulmonary
lesion, miliary tuberculosis to submucosal lymph nodes
• Contiguous spread from infected foci like fallopian tubes, mesenteric lymph node
• Very rarely as a consequence of peritoneal dialysis
Only 15 % of patients with abdominal TB have pulmonary disease !!!!
• Disease of young• Slight female preponderance• Children : more gastrointestinal disease• Adults : adhesive peritoneal and lymph nodal
disease• Can present as acute, chronic, acute on
chronic• Most patients have constitutional symptoms
Classification of Abdominal Tb
1.Peritoneal tuberculosis and Tuberculosis of the mesentery and its contents
2.Lymph node tuberculosis3.Gastrointestinal tuberculosis4.Tuberculosis of the solid viscera : Liver ,
1. Tubercular peritonitis
• Originate primarily as result of reactivation of latent TB foci in the peritoneum or secondary to a ruptured lymph node or due to tubercular salpingitis
• The condition is subdivided into three main types—
Wet ascitic typeFibrotic fixed typeDry /plastic type
Wet ascitic type
• Most common type ( 90%)• Large amounts of free or loculated ascitic fluid
• USG: fine, multiple ,complete or incomplete, mobile strands of fibrin and debris in ascitis
Wet ascitic type
• CT : usually slightly hyperattenuating (20–45 HU) relative to water due to its high protein and cellular content
• Ascites (arrows) that ishyperattenuating relative to urine within the bladder(arrowheads).
Fibrotic fixed type
• Large omental and mesenteric cake like masses with matting of bowel loops.
• Occasionally ascitis may be present
• CT :Omental thickening (arrows) and ascitis (*)
Dry/ Plastic type
• Mesenteric thickening, fibrous adhesions, and caseous nodules.
• The omentum appears smudged, caked, or thickened (arrow heads)
• Peritoneal thickening with associated enhancement occurs
• Omental thickening seen in both TB and peritoneal carcinomatosis
• TB : thin omental line ( fibrous wall covering the infiltrated omentum )
• Peritoneal carcinomatosis : Irregularly thickened outer contour of the infiltrated peritoneum
Small bowel mesentry
• Mesentric nodular lesions ( solid or cystic nodules , lymph node or abscess )
• Mesentric thickening ( > 15mm )• Loss of normal mesentric configuration
STELLATE SIGN• Fixed loops of bowel
and mesentry standing out as spokes radiating out from the mesentric root
CLUB SANDWICH SIGN• Due to localised or focal
ascites radially oriented bowel loops due to local exudation from inflamed bowel or ruptured lymph nodes
CTLarge volume of high density ascitic fluid (*). It is also visible pronounced
peritoneal andmesenteric thickening and enhancement (arrows).
Mesenteric thickening, with loss of normal mesenteric architecture and increasedvascularity (arrows). Thickened mesentery also shows contrast enhancement. Small
volume of ascites in the left parietocolic gutter is also visible in this section (*).
Sclerosing encapsulating peritonitis( Abdominal cocoon)
• Small bowel loops congregated to the centre of abdomen encased by a soft tissue density mantle
2. Tubercular lymphadenitis
• Abdominal lymphadenopathy is the most common manifestation of abdominal tuberculosis.
• Involvement of periportal, anterior pararenal,upper paraaortic and lesser omental lymph nodes.
• The characteristic pattern is mesenteric and peripancreatic lymph node group enlargement, with multiple groups affected simultaneously .
Isolated retroperitoneal LN involvement highly uncommon !!!!
Dorfman et al Radiology,1991 (29)
• Discrete or conglomerate masses
• Mixed heterogeneous echotexture with central hypoechoic area
• FIG : enlarged hypoechoic nodes (arrows) in a thickened hyperechoic mesentery
• D/D : Lymphoma : homogeneous hypoechoic nodes
• Caseation and calcification : highly suggestive of TB , uncommon in lymphoma
• Biliary obstruction due to direct ductal compression by infected nodes
• PV thrombosis and portal hypertension due to involvement of hepatic hilar LN
• Renovascular hypertension due to vascular compression by nodes
Caroli et al. j clin Gastroenterol 1997;25:541-43
Patterns of nodal enhancement on CECT
1. Peripheral rim enhancement with low attenuation centre
• D/D : metastasis from testicular tumors, head and neck squamous cell cancers,lymphoma, whipples disease, Crohns ds.
2. Homogeneous enhancement
Seen in patients with MAIC infection and HIV positive patients
3. Inhomogeneous enhancement : less necrosis
4. Non enhancing low attenuation nodes
Multiple mesenteric lymphadenopathy forming a conglomerate mass (arrows) Most enlarged nodes have central hypoenhancing areas due to necrosis.
A variety of patterns of contrast enhancement on CT even within the same nodal group may be seen in tubercular adenitis, probably relating to the different stages of the pathological process !!!!
Role of MRI in TB Lymphadenopathy
Differentiate enlarged nodes that are
abutting the pancreas from a cystic neoplasm of the pancreas !!!
3. Gastrointestinal tuberculosis
• Can involve any segment of bowel• However, it almost always involves the
ileocecal region (90% of cases), usually both the terminal ileum and the cecum
• Usually secondary to advanced pulmonary or mediastinal disease
• MC involves the tracheal bifurcation• C/F : dysphagia , odynophagia, chest pain or
(A and B) Esophagograms showing a longStricture in the middle third of the esophagus with multiple diverticula
Mild esophageal wall thickening with mediastinal lymphadenopathy
• Rare ( 0.36-2.3% of patients with pulmonary TB)
• Occurs due to spread from adjacent lymph nodes or hematogeneous spread
• Usually affects antrum and distal body
Marked narrowing of the body of stomach due to TB
• 2 % of intestinal tb cases• Lymph nodes causing extrinsic compression
on C loop of duodenum• Ulcer /stricture • Hyperplastic growth• Incompetence of sphincter of oddi• Perforation / fistula
Widening of the C loop of duodenum
Long stricture of duodenum due to TB
Stage 1• Accelerated intestinal transit• Disturbances in tone and peristaltic
contractions : hypersegmentation of barium column (chicken intestine )
• Flocculation / dilution of barium• Irregular , crenated intestinal contours• Softened , thickened folds
• Fig : marked spiculations in the asc colon,caecum and terminal ileum
• Hour glass stenosis of bowel• Multiple strictures with segmental dilatation• Fixity/ matting of loops
MC affected in small bowel TB because of• Physiological statis• Abundant lymphoid tissue• Increased rate of absorption in the region and
closer contact of bacilli with the mucosa of the region
Ileocecal involvement is seen in 80%–90% of patients with abdominal tuberculosis.
• MOC for evaluating mucosal changes in ileocecal TB.
• 70-100 % sensitivity.• Earliest finding: accelerated transit time due
to spasm and hypermotility of the bowel.
• Thickening of the ileocaecal valve lips and/or wide gaping of the valve, with narrowing of the terminal ileum
• Inverted umbrella sign
Pulled up caecum
• Caecum becomes conical, shrunken, retracted out of the illiac fossa due to contraction of the mesocolon
Goose neck deformity
• Loss of normal ileocaecal angle and dilated terminal ileum appears as suspended and hanging from a retracted , shortened caecum
Stierlin’s sign• Conical and shrunken
cecum, widely open ileocecal valves, narrowing terminal ileum, rapid emptying of diseased segment
• Represents acute inflammation superimposed on a chronically involved segment of the ileum, caecum or ascending colon
• Persistent narrow stream of barium in the distal ileum
Both stierlin’s sign and string sign are noted in Crohns disease and should not be considered specific for tuberculosis !!!
Group1: Highly s/o intestinal TB if one or more of the following features are present
a. Deformed ileocaecal valve with dilatation of terminal ileum
b. Contracted caecum with an abnormal ileocaecal valve and/or terminal ileum
c. Stricture of the ascending colon with shortening of and involvement of ileocaecal region
Group 2 : suggestive if any of the following features are present
a. Contracted caecumb. Ulceration or narrowing of the terminal ileumc. Stricture of the ascending colond. Multiple areas of dilatation, narrowing and
matting of small bowel loops
• Group 3 : non specific includes features of matting,dilatation or mucosal thicekening of small bowel loops
• Group 4 : normal study
• Often reveals a mass made up of matted loops of small bowel with thickened walls, diseased omentum, mesentery and loculated ascites
• Regional lymph nodal enlargement
USG shows thlckened, echogenicmesentery containing multiple enlarged
hypoechoic, discrete, andconglomerate lymph nodes. Smallamount of ascites is seen (arrows).
Dilated, fluid-filled, thick-walled bowel loops at periphery.
Pseudo kidney sign
• Ileocaecal region is pulled upto subhepatic region
Preferential thickening of the medial caecal wall with an exophytic mass engulfing the terminal ileum associated with massive lymphadenopathy is characteristic of tuberculosis !!!
Regular and concentric thickening of the ascending colon (arrow in a) and cecum (arrow in b)
• Greater senstivity and specificity than NCCT in detecting low grade small bowel obstruction
• Allows detection of luminal and extraluminal pathology
• No added advantage• Mucosal abnormalities are less well
demonstrated on MRI as compared to barium
Masserli G et al.Abdominal imaging 2006;29:326-34
MASS• Appendicular mass• Actinomycosis • Crohns disease• Caecal carcinoma• Lymphoma
The ulceration in TB is circumferential while that in Crohn’s disease is along the mesentric border !!!!
• Involved in 9% of cases without small bowel involvement
• Long or short segment involvement with spiculation, rigidity, ulceration, inflammatory polyps, perforation, fistulae, pericolic abscess
• D/D : UC, Crohns disease, amoebic colitis, mailgnancy
• Fistula, stricture, chronic ischiorectal abscess• Anal canal : ulcer fissures, fistulae, abscess,
Pakistan Armed Forces Medical Journal:2012
4. Visceral tuberculosis
• Hepatic Tb• Spleenic Tb• Pancreatic Tb
• Common in patients with disseminated disease and is either micronodular- miliary or macronodular
• Miliary hepatic involvement is seen in patients with miliary pulmonary tuberculosis
• Macronodular hepatic tuberculosis is uncommon and occurs due to spread via portal vein or hepatic artery from the para aortic or portal nodes.
In a patient with PUO, marked elevation of serum alkaline phosphatase(3 to 6 times) with mild elevation of S.transaminases, normal PT, S.albumin and a slight increase in bilirubin hepatic tuberculosis should be suspected !!!
Lesions are hypoattenuating at CT with irregular ill-defined margins and minimal central but definite peripheral contrast enhancement
Multiple hepatic and splenic abscesses (arrows) appearing ashypoenhancing, nodular, well defined lesions. They have a slightly rim
Spleenic involvement is common in HIV positive patients with TB,with macronodular involvement seen in 15% of HIV positive patients.
Schunk K.Topics in MRI 2002 ;13(6): 409-25
• At MR imaging, these lesions are hypointense with T1WI and hyperintense with T2WI.
Hepatic tuberculomas eventually tend to calcify, and the presence of calcified granulomas at CT in patients with known risk factors and in the absence of a
known primary tumor should raise suspicion for tuberculosis.
• CT shows multiple calcified granulomas within the liver, spleen, periportal and peripancreatic lymph nodes.
• Tuberculous microabscesses : metastases, fungal infections (histoplasmosis), sarcoidosis and lymphoma.
• Macronodular form : metastases, abscess and primary malignancy.
• Often associated with miliary tuberculosis and occurs more often in immunocompromised
• May present as acute or chronic pancreatitis• May mimic malignancy• FNAC and biopsy are helpful
CECT : focal attenuated mass with peripheral enhancement
USG : hypoechoic lesionMRCP : pancreatic head mass compressing on CBD
Role of PET-CT IN TB