IMAGING IN INFLAMMATORY BOWEL
DISEASE
DR.KHYATI VADERA REFERENCES: RADIOGRAPHICS RESIDENT DOCTOR RUMACK M.D RADIODIAGNOSIS RADIOLOGY ASSISTANT MEDICAL COLLEGE BARODA SSG HOSPITAL
• INTRODUCTION• DEFINATIONS• IMAGING MODALITIES• DIFFERENCE BETWEEN CHRON’S AND UC• DIFFERENTIAL DIAGNOSIS• CONCLUSION
PROTOCOLS
Group of chronic disorders that cause inflammation and ulceration in small and large bowel.
Mainly two most common diseases are –chron’s disease and ulcerative colitis
INTRODUCTION
Idiopathic, chronic, transmural inflammatory process of bowel - affect whole GI system starting from mouth to anus.
Most commonly involved- terminal ileum, ileocaecal valve and caecum with regional enteritis.
SKIP LESIONS ARE PATHOGNOMIC Diagnosed typically between 15-25 years of age
group. No gender predilection, runs in families. Smokers - more affected.
CHRON’S DISEASE
• Chron’s disease can be –Stricturing,Penetrating,Inflammatory
• Etiology – idiopathic, genetic(DR5 DQ1 alleles), immunologic, microbial, psychosocial
• Clinical presentation- diarrhoea, abdominal pain, weight loss
• Intermittent attacks of active disease followed by periods of remission.
• Disease re-activation by triggers like stress, dietary factors, smoking.
• Risk of colonic adenocarcinoma is increased in long standing cases.
• on X-ray- plain radiograph of abdomen is usually helpful in cases of obstruction secondary to chron’s or extraintestinal manifestations
MUCOSAL ULCERS APHTHOUS ULCERS initially deeper transmural ulcers typically either longitudinal or
circumferential in orientation
when severe leads to COBBLESTONE APPEARANCE may lead to sinus tracts and fistulae
thickened folds due to oedema
pseudodiverticula formation: due to contraction at the site of ulcer with ballooning of the opposite site
STRING SIGN: tubular narrowing due to spasm or stricture depending on chronicity partial obstruction
Barium small bowel follow-through
APTHOUS ULCERSFirst sign of chron’s disease on barium
Cobblestone appearance: due to deep fissuring ulcers around inflammed mucosa
Fissuring ulceration in Crohn's disease - graphically called
`raspberry thorn' ulcers.
String sign: spasm/fibrosis of bowel wall
ILEOILEAL FISTULA: long standing chron’s
ULTRASOUND
limited role, it has been evaluated as an initial screening tool
Typically examination is limited to the small bowel and wall thickness assessed:
Bowel wall thickness should be <3 mm, normally
thickness < 3 mm helps exclude the disease in a low risk patient. thickness > 4 mm helps establish the diagnosis in a high risk
patient.
Ultrasound in the assessment of extraintestinal manifestations.
US image - stricture in a patient with active Crohn's disease
FAT HALO SIGN COMB SIGN Bowel wall enhancement Bowel wall thickening (1-2 cm) -terminal
ileum strictures and fistulae mesenteric/intra-abdominal abscess or
phlegmon formation
CT FINDINGS
Fat halo sign in chron’s diseaseTransverse CT scan shows the central fatty submucosal layer of low attenuation (*) surrounded by higher-attenuation inner (long arrow) and outer(short arrow) layers grossly corresponding to the mucosa and muscularis propria and serosa of the descending colon, respectively.
COMB SIGN:Hypervascular appearance of the mesentery in active Crohn's disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel, which give the appearance of the teeth of a comb.
CECT image, coronal section, venous phase - enterocecal fistula with secondary traction of the cecum and right psoas muscle abscess
CT AND MR ENTEROGRAPHY
Useful for both mural and extramural spread of disease.
Inflammed bowel loops show thickening and contrast enhancement.
Extramural spread: fibrofatty proliferation-thickening of extramural fat
:vascular engorgement(comb sign) Stenosis and strictures
MRI enteroclysis - placement of a nasojejunal catheter through which 1.5-2 L of contrast solution (e.g. water with polyethylene glycol and electrolytes) are injected.
When disease is transmural, with cobblestone appearance, the abnormalities are evident as high T2 signal linear regions.
CT AND MR ENTEROCLYSIS
Introduction of the 12 to 14-F enteroclysis tube (under fluoroscopy or through duodenoscope).
Contrast is administered either on the fluoroscopy table or after transferring the the patient to the CT unit for commencement of the CT scan (usually 1.5-2L of oral contrast).
In the CT unit, the position of the enteroclysis tube is checked in the topogram.
In case negative oral contrast will be used, intravenous contrast injection will be given (approximately 100-150ml).
CT ENTEROCLYSIS
placement of a nasoduodenal tube under fluoroscopic guidance
the small-bowel is distended with 1-3L of methylcellulose (0.5%) and water solution or isosmotic water solution through an electric infusion pump infusion rate: 80-200 mL/min.
multislice HASTE(half-Fourier acquisition single-shot turbo spin-echo) images with fat saturation and unenhanced and enhanced (0.1 mmol/kg gadolinium) T1 coronal and axial fast low-angle shot (FLASH) 2D images with fat saturation are obtained 60 seconds after contrast injection
MR ENTEROCLYSIS
Perirectal phlegmon on axial T2 Single Shot TSE (left) and T1 contrast enhanced (right) sequences. Rectal wall thickening with avid contrast uptake due to active disease. Perirectal phlegmon surrounded by a hyperenhancing perirectal fascia, displaces the rectum anteriorly.
For extraintestinal disease: Perianal fistula/abscess Hepatobiliary manifestations Sacroiliac joints
ROUTINE MRI
Causes superficial ulceration of colon and rectum.
It starts from rectum and retrogradely involves whole colon continuously.
In total colitis- back wash ileitis.
More common in DR2 related genes.
More female predilection, age group 30-40 yrs.
Clinical symtoms- diarrhoea, tenesmus, bleeding per rectum, passage of mucus, crampy abdominal pain.
ULCERATIVE COLITIS
MILD DISEASE: fine granularity
MODERATE: marked erythema, coarse granularity, contact bleeding and no ulceration.
SEVERE: spontaneous bleeding,edematous and ulcerated Long standing cases epithelial regeneration- pseudopolyps, pre
cancerous condition Eventually shortening and narrowing of colon
FULMINANT DISEASE: toxic colitis/megacolon
PATHOGENESIS
Acute UC – descending colon has irregular outline. No fecal residue in colon S/O total colitis
Mucosal inflammation-granular appearance to the surface of the bowel.
Mucosal ulcers are undermined -button-shaped ulcers
Islands of mucosa remain giving it a pseudo-polyp appearance
In chronic cases the bowel becomes featureless with loss of normal haustral markings, luminal narrowing and bowel shortening- lead pipe sign
BARIUM ENEMA
FINE MUCOSAL GRANULARITY- FIRST SIGNNARROWING OF LUMEN
COLLAR BUTTON ULCERS
LEAD PIPE COLON
Back wash ileitis : patulous IC valve and dilated granular terminal ileum
CT FINDINGS
Inflammatory pseudopolyps
Inflamed and thickened bowel - target appearance, due concentric rings of varying attenuation- mural stratification
In chronic cases, submucosal fat deposition is seen particularly in the rectum fat halo sign
Extramural deposition of fat, leads to thickening of the perirectal fat, widening of the presacral space
Marked muscularis mucosa hypertrophy-lead pipe sign.
INFLAMMATORY PSEUDOPOLYPS
Wall Thickening- median wall thickeness of colon ranges from 4.7 to 9.8 mm, more severe the disease more thicken the wall
Increased Enhancement- enhancement of the mucosa with no or less enhancement of the submucosa
Loss of haustral markings
MRI
Mri image reveals thickening of colon with loss of haustral markings
DIFFERENCE
CHRON’S DISEASE 70-80%Small bowel
involvement Skip lesions Fat halo sign seen in 8% Apthous ulcers are seen Bowel wall more thicker Irregular serosal surface Perianal fistula/sinus/abscess
more common Creeping fat and abscess are
very common in chronic cases
ULCERATIVE COLITIS 95% cases rectal involvement Continuous spread from rectum
upwards Fat halo sign is commonly seen Collar button ulcers are seen.
Smooth serosal surface Perianal disease rare Mesenteric creeping fat and
abscess are uncommon. Carcinoma is more common in long
standing cases.
Ileocaecal tuberculosis Acute appendicitis Mesenteric adenitis Malignancy Acute diverticulitis Acute epiploic appendagitis Ischaemic colitis Pseudomembranous colitis
DIFFERENTIAL DIAGNOSIS
On BMFT: Mucosal irregularity and rapid emptying Stiffened and thickened folds. Luminal stenosis(hour glass stenosis) Dilated loops and strictures. Aderent fixed and matted loops
Ileocaecal tuberculosis
BMFT:partially contracted caecum with coarse nodular mucosal thickening and a stricture of terminal ileum
TB: narrowing & irregularity of the terminal ileum and rt side of colon.
Increased ileocaecal angle: obtuseGoose neck deformity: fibrosed and retracted caecum
Thickening of ileocaecal junction with surrounding necrotic lymph nodes
Peritoneal thickening in intestinal tuberculosis
• Lymph nodes with peripheral rim enhancement giving multilocular appearance
• Bowel wall thickening
TB CROHN’S
Involvement of terminal ileum
shorter longer
Features Narrowed, thickened, rigid terminal ileum with pulled up ceacum
Asymmetry and cobblestoning
Longitudinal Ulceration
absent present
TUBERCULOSIS VS CHRON’S
Acute appendicitis
Mesenteric adenitis
3 or more nodes with a short-axis diameter of at least 5 mm clustered in the right lower quadrant
Lymphoma
bowel wall thickening: 1-7cm and aneurysmal dilatation:
Lymphoma on ultrasound: hypoechoic vascular mass with multiple pre para aortic lymph nodes
COLORECTAL CARCINOMA
Acute diverticulitis
Pericolic stranding- disproportionate to the amount of bowel wall thickening
segmental thickening of the bowel wall enhancement of the colonic wall diverticular perforation - air and fluid into the pelvis
and peritoneal cavity abscess formation (seen in up to 30% of cases)
may contain fluid, gas or both fistula formation-gas in the bladder/direct
visualisation of fistulous tract
Diverticulum of colon
In acute diverticulitis: barium studies are contraindicated
Ischemic colitis
On CT: segmental region of abnormality submucosal oedema may produce low-density ring
bordering lumen (target sign) intramural or portal venous gas mesenteric oedema WITH NON ENHANCING BOWEL
WALL superior mesenteric artery or vein
thrombus/occlusion may be demonstrated
Ischemic colitis(thumb printing ): edematous thickened bowel wall will cause indentations into the air-filled colonic lumen
Pseudomembranous colitis
Pseudomembranous colitis-caused by the bacterium Clostridium difficile due to bacterial overgrowth of the colon in patients who are treated with broad-spectrum antibiotics.
ascites and hyper enhancement of the bowel wall with submucosal edema and edema in the mesocolon.
Ct findings:• Circumferential and
diffuse mural thickening with submucosal edema.
• Prominent haustrae.
• Eccentric polypoid wall thickening.
• Shaggy luminal contour.
Accordion sign
The sign is described as alternating edematous haustral folds separated by mucosal ridges filled with oral contrast material
CONCLUSION
Inflammatory bowel diseases are chronic group of disorders which have a long course of disease with intermittent periods of active disease and remission.
They can be easily diagnosed by multimodality approach combining clinical symptoms , colonoscopy, and radiology.
Conventional radiological investigations like barium studies are still necessary for diagnosis of characteristic intramural changes.
However the CT and MRI investigations are nowadays frequent and less invasive, useful for detection of extraintestinal manifestations of IBD.
Colonoscopy at regular intervals is also must to look for progression of disease and malignancy in long standing cases
THANKS