CT Evaluation of Acute Enteritis and Colitis: - PowerPoint Presentation

Slide1

CT Evaluation of Acute Enteritis and Colitis:Is It Infectious, Inflammatory, or Ischemic?

Brandon C. Childers, MD

1

Sarah Wallace Cater, MD

1

Karen M. Horton, MD

1

Elliot K. Fishman, MD

1

Pamela T. Johnson, MD

1

*

1

The Russell H. Morgan Department of Radiology and Radiological Science

The Johns Hopkins Hospital, Baltimore, Maryland

*

Corresponding author: Pamela T. Johnson, MD

601 North Caroline Street, Room 4223

Baltimore, MD 21287

Email: pjohnso5@jhmi.edu

Office: (410) 955-6785 Fax: (410) 955-6786

RSNA 2014, Educational Exhibit ERE121 14001401

Slide2

Financial Disclosures

The authors of this electronic publication have nothing to disclose.

Slide3

Overview

Enteritis and colitis are among the more common causes of abdominal pain. The causes are variable, as are the appropriate clinical management strategies.

Although computed tomography (CT) is generally not indicated for first-line diagnosis of infectious or even inflammatory

enterocolitis

, many of these patients undergo CT evaluation during an acute abdomen workup.

This exhibit reviews the CT findings of enteritis and colitis on the basis of cause.

Infection

—bacterial, viral, fungal, parasitic

Inflammation

—Crohn disease, ulcerative colitis

Ischemia

—arterial occlusion, venous occlusion, decreased flow

Although there are many overlapping features of

enterocolitis

at CT, specific findings and patterns can offer important diagnostic clues to facilitate distinction.

Although definitive diagnosis often relies on endoscopic biopsy result, stool culture result, or other clinical features, the radiologist can help guide the diagnosis.

Emphasis is placed on geographic distribution, morphology of the wall and

extraintestinal

findings—often the key for distinguishing causes.

Slide4

Key Concepts

1. Characteristic intestinal and

extraintestinal

CT findings are associated with each cause.

2. An optimized CT protocol is key to identify these features.

3. Infectious

enterocolitis

typically follows a geographic distribution depending on the organism responsible.

4. Ulcerative colitis and

Crohn

disease differ in distribution and in radiographic manifestations.

5. Ischemic enteritis and colitis have a highly variable appearance depending on the cause and chronicity of the bowel ischemia.

Slide5

Learning Objectives

1. Be able to distinguish the various causes of

enterocolitis

by using key CT features.

2. Explain the importance of the general anatomic distribution of infectious

enterocolitis

.

3. Identify the key imaging features to differentiate ulcerative colitis from Crohn disease.

4. Recognize the range of appearances for ischemic

enterocolitis

and critical ancillary findings.

Slide6

CT TechniqueIf enteritis or colitis is suspected, the optimal technique is administration of neutral or negative enteric contrast material and intravenous contrast material. The intravenous contrast reveals mucosal hyperemia and submucosal

edema in the bowel, which are better appreciated against neutral or negative contrast in the gastrointestinal lumen.

Mucosal hyperemia (red arrow) and

submucosal

edema (yellow arrow) are well delineated when water by mouth (neutral) and intravenous contrast material are administered, as demonstrated in these coronal

multiplanar

reconstructions.

Slide7

CT TechniqueMultiplanar reconstructions (MPRs) and three-dimensional renderings are helpful for characterization of bowel wall thickening and displaying mesenteric findings.

Asymmetric wall thickening (red arrows) and mesenteric vascular enlargement (yellow arrows) are better appreciated by using coronal two-dimensional MPR

(A)

and maximum intensity projection renderings

(B)

.

A

B

Slide8

CT Technique

Celiac and superior mesenteric artery (SMA) pathologic findings are more conspicuous on sagittal and coronal

multiplanar

reconstructions.

On axial sections

(A-C),

the distal SMA emboli are very subtle (circles), but multiple SMA emboli (arrows) are well seen on

coronal MPR

(D)

.

C

B

A

D

Slide9

Distinguishing Features- Infectious

Enterocolitis

Epidemiology

Children—viruses (

ie

, rotavirus),

Escherichia coli

,

Salmonella

,

Shigella

,

Campylobacter

Risk factors

Immunocompromised (human

immunodeficiency virus [HIV])—cytomegalovirus (CMV), cryptosporidiosis

Immunocompromised (neutropenic)—

typhlitisAntibiotic use—Clostridium difficile

Symptoms

Diarrhea, often profuse

Bloody diarrhea (dysentery)—

Shigella

,

Campylobacter

,

E. coli

,

Salmonella

Distribution

Proximal small bowel—

Giardia

,

Strongyloides

,

Mycobacterium

avium-intracellulare

(MAI)

Distal small

bowel—

Yersinia

,

Salmonella

,

Campylobacter

,

Shigella

,

Anisakis

Terminal

ileum and cecum—

typhlitis

, tuberculosis,

amebiasis

Right colon—

Yersinia

,

Salmonella

,

Entamoeba

histolytica

Left colon—

Shigella

,

schistosomiasis

Sigmoid—herpes simplex virus, gonorrhea, chlamydia

Pancolitis

—

C

.

difficile

, CMV,

E. coli

CT findings

Thumbprinting

, accordion sign—

C. difficile

Target sign—

Salmonella

,

Shigella

Stranding

often absent in infectious colitis

Absence

of luminal contents (empty colon sign)

Slide10

Infectious Enteritis: Location

Proximal:

Giardia

Strongyloides

Mycobacterium

avium-intracellulare

Terminal ileum and cecum:

Typhlitis

Tuberculosis

Amebiasis

Distal small bowel:

Yersinia

Salmonella

Campylobacter

Shigella

Anisakis

Slide11

Giardiasis

HIV and positive finding from giardia stool antigen test in 16-year-old male patient. Axial contrast-enhanced

multidetector

CT images demonstrate fold thickening (arrows) of the proximal small bowel (jejunum).

Slide12

Mycobacterium Avium-Intracellulare

MAI infection in 40-year-old man. Axial

(A)

and coronal

(B)

reformation from oral and intravenous contrast-enhanced

multidetector

CT show diffuse small bowel wall thickening and mesenteric adenopathy (arrows). Small bowel wall thickening, soft-tissue attenuation adenopathy, and hepatosplenomegaly are findings reported in abdominal MAI.

B

A

Slide13

Infectious Colitis: Location

Terminal ileum and cecum:

Typhlitis

Tuberculosis

Amebiasis

Right colon:

Yersinia

Salmonella

Entamoeba

histolytica

Left colon:

Shigella

Schistosomiasis

Sigmoid:

Herpes virus

Gonorrhea

Chlamydia trachomatis

Pancolitis

:

C.

difficile

CMV

E. coli

Slide14

Pseudomembranous Colitis

C.

difficile

overgrowth

Often secondary to antibiotic use

Most commonly involves entire colon (

pancolitis

)

May be limited to right colon in up to 40% of cases

CT findings:

Substantial wall thickening (can be >3 cm), thicker than all other causes except Crohn disease

Irregular or eccentric wall thickening

Mural

hypoattenuation

(edema) or

hyperattenuation

(acute inflammation)

Thumbprinting

—thickened

haustra

due to edema

Accordian

sign—oral contrast between thickened

haustra

Slide15

Pseudomembranous Colitis

Pseudomembranous colitis secondary to

C. difficile

overgrowth in 36-year-old woman. Axial

(A, B)

and coronal

(C)

MPR from intravenous contrast-enhanced

multidetector

CT depict mural and

haustral

thickening which accounts for

thumbprinting

(arrows). No substantial

pericolic

stranding is noted, as the infection is often limited to the mucosa and submucosa (a distinguishing feature).

A

B

C

Slide16

Pseudomembranous Colitis

A

B

Pseudomembranous colitis secondary to

C. difficile

overgrowth in 60-year-old patient. Axial

(A)

and coronal

(B)

reformation from oral and intravenous contrast-enhanced

multidetector

CT images demonstrate enteral contrast between the thickened

haustra

, which accounts for the accordion sign (arrows).

Slide17

Typhlitis

Inflammation of predominantly the cecum and often terminal ileum in

immunocompromised

patients (most commonly neutropenia)

Often with associated infection—typically gram-positive gut flora (including

C.

difficile

)

Medical emergency, with mortality rate as high as 50%, owing to high rates of necrosis, rupture, and peritonitis

Slide18

Typhlitis

Acute myeloid leukemia and

neutropenic

fever in 60-year-old man. Axial

(A,B)

and coronal

(C)

non-contrast–enhanced CT images reveal wall thickening of the distal ileum and cecum (red arrows), severe mesenteric inflammation, and mesenteric vascular hyperemia (yellow arrows). Blood cultures grew

vancomycin

-resistant enterococci.

A

B

C

Slide19

Viral Colitis

Viral

pancolitis

in 40-year-old man. Axial

(A)

and coronal

(B)

reformation from oral and intravenous contrast-enhanced

multidetector

CT images reveal wall thickening of ascending, transverse, and descending colon (arrows).

A

B

Slide20

Distinguishing

Features

- Inflammatory Bowel

Disease

Epidemiology

Teen

and young adults; second peak in adulthood

Risk factors

Family history

Symptoms

Tenesmus

, diarrhea (may be bloody),

weight loss,

Extraintestinal

features—large joint arthritis, erythema

nodosum

,

pyoderma

gangrenosum

Distribution

Crohn—Distal ileum,

right colon

Ulcerative colitis

always

involves the rectum but pattern otherwise

variable

Segmental

with skip lesions—Crohn

Continuous—

Ulcerative colitis

Transmural

involvement—Crohn

CT findings

Bowel halo sign

Mesenteric comb sign, creeping

fat sign—

Crohn

Perirectal

fibrofatty

proliferation—Ulcerative colitis

Eccentric, very thick wall

—

Crohn

Circumferential, mildly thick wall—Ulcerative colitis

Fistulous

tracts,

phlegmon

, abscess—Crohn

Adenopathy

may be present

Slide21

CT of Inflammatory Bowel Disease: Crohn versus Ulcerative Colitis

Crohn

Disease

Mural thickening

~11-13 mm

Eccentric (mesenteric)

Segmental

Terminal ileum/right colon (although can involve anywhere in the gastrointestinal tract)

Mesenteric comb sign (hyperemic vasa recta) and creeping fat sign

Halo sign, perirectal fat proliferation

Fistulae, abscesses (

transmural

inflammation)

Ulcerative Colitis

Mural thickening

~8 mm

Symmetric

Continuous

Rectum/left colon (involves rectum as a rule)

Halo sign, perirectal fat proliferation

No fistulae (not

transmural

)

Slide22

Crohn versus Ulcerative Colitis: Mural Thickening

A

B

(A)

Coronal MPR from intravenous contrast-enhanced

multidetector

CT image in a female patient with Crohn disease. Note the marked thickening of the sigmoid colon (arrows), measuring up to 12 mm and slightly more prominent on the mesenteric side.

(B)

Axial intravenous contrast-enhanced

multidetector

CT image in a male patient with ulcerative colitis. Smooth circumferential thickening of the sigmoid colon less than 7 mm (arrows) is less prominent than in image

A

.

Slide23

Crohn Disease:Mesenteric Comb Sign

Crohn disease in 16-year-old female patient. Coronal MPR from intravenous contrast-enhanced CT shows mural thickening and enhancement of the terminal ileum (red arrows).

The

mesenteric comb sign (black arrows) is also noted

owing to increased blood flow on the mesenteric side of the involved small bowel and perivascular inflammation.

Slide24

Crohn Disease:Sinus Tract and

Phlegmon

B

Coronal reformation

(A)

and axial

(B)

contrast-enhanced

multidetector

CT images in a patient with Crohn disease.

Marked, somewhat irregular thickening of the terminal ileum (measuring up to 13 mm) is seen with narrowing and

stricturing

(yellow arrows).

Phlegmonous

changes (red circle) are noted along the mesenteric border, likely extending from a small sinus tract.

A

Slide25

Crohn Disease: Contained

Cecal

Perforation

Coronal reformation from oral contrast-enhanced

multidetector

CT image in a patient with Crohn disease who presented to the emergency department with acute abdominal pain.

Phlegmon

(circle) is identified medial to the

ileocecal

region with few foci of

extraluminal

air. Perforation is a feature of Crohn disease given

transmural

inflammation (compared with ulcerative colitis).

Slide26

Ulcerative Colitis: Diffuse Colonic Involvement

A

B

(A, B)

Coronal reformations from intravenous contrast-enhanced

multidetector

CT images in a patient with ulcerative colitis. Right, left, and

rectosigmoid

colon are mildly thickened (arrows). In contrast,

Crohn

disease often demonstrates more pronounced, irregular wall thickening. It is also rare for Crohn disease to affect the entire colon and rectum.

Slide27

Ulcerative Colitis:Halo Sign and Fat Proliferation

Axial oral and intravenous contrast-enhanced

multidetector

CT image in a young patient with ulcerative colitis.

Submucosal

hypoattenuation

between the enhancing layers of the

muscularis

and mucosa

results in the characteristic halo sign (red arrow).

Fibrofatty

proliferation and increased perirectal fat (yellow arrows) are noted surrounding

the rectum, a finding often seen in chronic, long-standing ulcerative colitis. It is thought to be a mechanism to insulate and contain the inflammation.

Slide28

Distinguishing Features—Ischemic Bowel

Epidemiology

Advanced

age

Risk factors

Ischemia—hypotension, digitalis (

nonocclusive

)

Embolism or thrombus—atrial fibrillation

(atrial thrombus),

hypercoagulability

Bowel distention—

dilatation

proximal to an

obstruction

Symptoms

Pain out of proportion to physical examination

Gastrointestinal

bleeding, bloody diarrhea

Distribution

Follows vascular distribution

SMA, superior mesenteric vein (SMV)—small bowel, ascending and proximal two-thirds of transverse colon

Inferior mesenteric artery (IMA), inferior mesenteric vein (IMV)—descending and sigmoid colon

Low flow

–

water shed zones (splenic flexure,

rectosigmoid

junction)

CT findings

Thin or thick wall depending on cause and time interval

between onset and imaging

Thin wall

(arterial occlusion, intermediate phase)

Thick wall, halo sign (venous occlusion, intermediate phase)

Abnormal wall enhancement (absent, increased,

or decreased)

Mesenteric edema,

inflammation

Pneumatosis

,

portomesenteric

venous gas (late phase)

Mesenteric arterial or venous thrombus

may be the cause

(intravenous contrast

enhancement critical in these patients)

Slide29

Colonic Ischemia—Right Colon

Images in 67-year-old woman who presented with lower gastrointestinal bleeding due to ischemic colitis. Axial

(A)

, coronal

(B),

and sagittal

(C)

images from oral and intravenous contrast-enhanced CT show severe

submucosal

edema, decreased enhancement and wall thickening of the cecum and proximal ascending colon (yellow arrows), as well as moderate mesenteric inflammation (red arrows).

A

B

C

Slide30

Colonic Ischemia– Left Colon

Descending colon ischemic colitis due to pathologically proven mesenteric

venoocclusive

disease in 53-year-old man. Axial

(A)

and coronal

(B)

images from oral and intravenous contrast-enhanced CT show severe descending and sigmoid colon

submucosal

edema, decreased enhancement and wall thickening (yellow arrows), as well as marked mesenteric inflammation (red arrows).

A

B

A

Slide31

Ischemic Enteritis: Time Course

Arterial insufficiency

Early—reflex spastic ileus (bowel contracted, gasless)

Intermediate—reflex hypotonic ileus (paper thin wall, dilated gas-filled bowel)

Late—paralytic ileus (no enhancement, still dilated and gas/fluid filled,

pneumatosis

)

Reperfusion—

submucosal

edema, mural thickening, heterogeneous enhancement, hemorrhage

Venous insufficiency

Homogeneous mural thickening (<1.5 cm) due to

submucosal

edema and mucosal hemorrhage

Slide32

Ischemic Enteritis—Late Phase

A

B

(A)

Axial intravenous contrast-enhanced

multidetector

CT image in an elderly patient who presented to the emergency department with acute abdominal pain and elevated lactate level. Portal venous air (red arrow) is seen extending to the periphery of the liver.

(B)

Axial

nonenhanced

multidetector

CT in another patient with abdominal pain and elevated lactate. Note the paper thin wall of the bowel, a feature that is not typically seen in infectious or inflammatory enteritis. Fluid- and air-distended bowel loops are present with circumferential

pneumatosis

(red arrows) and mesenteric venous gas (yellow arrow).

Slide33

Ischemic Bowel: Extraintestinal Findings

Arterial compromise

Emboli or thrombi in SMA, IMA, or branches

Venous insufficiency

Thrombus in SMV, IMV, or branches

Engorgement of mesenteric veins with collateral vessels

Nonocclusive

Small caliber SMA and branches

Reperfusion injury

Mesenteric fat stranding—often pronounced and localized

Late phase

Portomesenteric

venous gas

Slide34

Ischemic Enteritis—SMA OcclusionIschemic small bowel in 62-year-old man. Axial

(A)

and coronal

(B)

images from intravenous contrast-enhanced

multidetector

CT show small bowel wall thickening (arrows) reflecting bowel ischemia.

A

B

Slide35

Ischemic Enteritis—SMA Occlusion

C

SMA embolism secondary to left atrial appendage thrombus in 62-year-old man. Sagittal

(C)

and axial

(D)

images from intravenous contrast-enhanced

multidetector

CT demonstrate large SMA thrombus (yellow arrow in

C

). Discovery of SMA thrombus should prompt inspection of the cardiac chambers for a source of embolism, which was a left atrial appendage thrombus (red arrow in

D

) in this case.

D

Slide36

(A)

Axial CT image with oral but no intravenous contrast material shows

cecal

pneumatosis

(yellow arrows) and high attenuation intraluminal hemorrhage (97 HU) layering in the

cecal

lumen.

Ischemic Colitis—SMV Thrombus

Coronal

(B)

and sagittal

(C)

MPRs depict acute superior mesenteric vein thrombus (red arrow), which is

hyperattenuated

(65 HU) at unenhanced CT.

A

B

C

Slide37

Conclusions

Enteritis and colitis are extremely common causes of abdominal pain.

Enterocolitis

is usually due to one of three causes: infection, inflammatory bowel disease, or ischemia.

CT technique with intravenous contrast material and neutral or negative oral contrast material is essential to evaluate the bowel, mesentery, and vasculature in these patients and demonstrate characteristic findings.

By focusing on distribution patterns and gastrointestinal and

extraintestinal

manifestations, the radiologist can determine the cause in many cases, facilitating proper and timely treatment.

Slide38

AcknowledgmentWe thank Hannah Ahn for creating the graphic art in slides 10 and 13.

Slide39

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