Imaging in Abdominal

Tuberculosis

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% )

Extrapulmonary TB

• Genitourinary TB (MC)• Bone and joint TB• Miliary TB• Meningeal TB• Gastrointestinal ( abdominal ) TB : 3-4%

Abdominal Tuberculosis

• 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 !!!!

Clinical spectrum

• 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 ,

Pancreas, Spleen

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

Omentum

• 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

USG

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)

USG

• Discrete or conglomerate masses

• Mixed heterogeneous echotexture with central hypoechoic area

• FIG : enlarged hypoechoic nodes (arrows) in a thickened hyperechoic mesentery

USG

• D/D : Lymphoma : homogeneous hypoechoic nodes

• Caseation and calcification : highly suggestive of TB , uncommon in lymphoma

Rarely

• 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

Esophageal TB

• Usually secondary to advanced pulmonary or mediastinal disease

• MC involves the tracheal bifurcation• C/F : dysphagia , odynophagia, chest pain or

cough

(A and B) Esophagograms showing a longStricture in the middle third of the esophagus with multiple diverticula

Mild esophageal wall thickening with mediastinal lymphadenopathy

Gastric tuberculosis

• 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

Duodenal tuberculosis

• 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

Tubercular enteritis

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

Stage 2

• Ulcerations

• Fig : marked spiculations in the asc colon,caecum and terminal ileum

Stage 3

• Hour glass stenosis of bowel• Multiple strictures with segmental dilatation• Fixity/ matting of loops

Ileocaecal tuberculosis

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.

Barium studies

• MOC for evaluating mucosal changes in ileocecal TB.

• 70-100 % sensitivity.• Earliest finding: accelerated transit time due

to spasm and hypermotility of the bowel.

Fleischner sign

• 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

String sign

• 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

USG

• 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

CT

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)

CT Enteroclysis

• Greater senstivity and specificity than NCCT in detecting low grade small bowel obstruction

• Allows detection of luminal and extraluminal pathology

MRI

• 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

Differential Diagnosis

MASS• Appendicular mass• Actinomycosis • Crohns disease• Caecal carcinoma• Lymphoma

EJR 2005:55:173-80.

The ulceration in TB is circumferential while that in Crohn’s disease is along the mesentric border !!!!

Colonic tuberculosis

• 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

Anorectal TB

• Fistula, stricture, chronic ischiorectal abscess• Anal canal : ulcer fissures, fistulae, abscess,

warty growths

Pakistan Armed Forces Medical Journal:2012

4. Visceral tuberculosis

• Hepatic Tb• Spleenic Tb• Pancreatic Tb

Hepatospleenic Tuberculosis

• 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

enhancement.

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.

D/D

• Tuberculous microabscesses : metastases, fungal infections (histoplasmosis), sarcoidosis and lymphoma.

• Macronodular form : metastases, abscess and primary malignancy.

Pancreatic tuberculosis

• 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

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