Dr ahmed esawy 5 bowel imaging acute bowel ischemia abi

An Article By

Dr. Ahmed Abdullah

Esawy

Acute Mesenteric

Ischemia

ABI ACUTE BOWEL ISCHEMIA

Mesenteric ischemia is a medical condition in which inflammation and injury of the small intestine

occlusive Causes

Arterial occlusion

venous occlusion

Thromboembolism

Vasculitis

Bowel Obstruction

Decreased cardiac output (from

any cause, ncluding primary cardiac disease,

infarction, arrhythmia, and hypovolemia)

Neoplasms

Abdominal Inflammatory Conditions

Trauma

Blood disease

Drugs (Chemotherapy)

Radiation

Corrosive

Unfortunately, common CT findings in bowel ischemia are not specific

specific findings are rather uncommon.

Therefore, it often is a combination of nonspecific clinical, laboratory, and radiologic findings—especially detailed knowledge about the pathogenesis of acute bowel ischemia in different conditions—that helps most in correct interpretation of CT findings.

Role of

Plain x- ray

In ABI/AMI

PLAIN ABDOMINAL FILMS

Normal

Air distribution (intramural gas

Extraluminal air)

focally thickened bowel

adynamic ileus

small bowel obstruction

abscess

Air in L. bowel

NO

Distended loops

Localized ileus

few

Generalized ileus

multiple

Air in S. bowel

LBO SBO

Decompressed LBO

Air in the rectum

Yes

SUPINE VIEW UPRIGHT VIEW

SUPINE VIEW UPRIGHT VIEW

LBO decompressed into SB

Extra-luminal air

a.Crescent sign :air beneath the diaphragm

b.Falciform ligament sign: air delineating the falciform ligament

c. Football sign: A large air collection beneath that does not conform to any bowel loop

d.Rigler's sign: If both the serosal and the related mucosal walls of the bowel are delineated it means free air is at that serosal surface

Falciform

Ligament

Sign

Football sign

Free intra-peritoneal air

Air on both sides of bowel wall –

Rigler’s Sign

1. Differentiation between mechanical

obstruction and paralytic ileus.

2- . Differentiation between small and

large bowel obstruction

3-Diagnosis of perforated viscus

ROLE OF

BARIUM ENEMA

In ABI/AMI

SUPINE VIEW BARIUM ENEMA

C T Computerized tomography

In ABI/AMI

low attenuation (thrombosis) in the SMV,

thickening of the small bowel wall

presence of peritoneal fluid

thrombosis of mesenteric arteries or veins circumferential or nodular thickening dilatation of the bowel lumen pneumatosis intestinalis poor enhancement of the bowel wall along its

mesenteric border, which is evidence of ischemia;

ascites, which is commonly present . mesenteric fat stranding, mesenteric fluid, and/or ascites adynamic ileus pleural effusion mesenteric/portal venous gas peritonitis

-intussception

-small bowel obstruction causes

-hernia

The most common manifestation of accompanying bowel ischemia is bowel wall thickening

more specific signs of ischemic bowel disease

bowel dilatation

intestinal pneumatosis

mesenteric or portal venous gas

Free intraperitoneal air

a filling defect within the proximal SMA (arrow) as well as a wedge-shaped infarct in the right kidney, compatible with prior embolic disease.

thickening of small bowel loops (short arrow) and mesenteric edema (long arrow) from venous occlusion.

White attenuation

thickened bowel wall that is equal to or

greater than that of venous

opacification in the same scan

The white pattern

The lower attenuation layer of the water halo sign is believed to represent edema

Water halo sign

water halo sign

equivalent of pneumatosis

Black attenuation

Black attenuation

SMV thrombus with infarction.

extraluminal free air •pneumatosis of the cecum (short arrow), with linear gas extending into the mesenteric veins (long arrow).

Splenic and portal vein thrombosis

•thrombus extends into

the right portal vein

(arrow). The cluster of

vessels seen anterior to

the portal vein thrombus

represents cavernous

transformation.

Chronic portal vein occlusion with cavernous transformation.

a tangle of collateral veins in seen

in the porta hepatis (arrow).

Small and large bowel ischemia on CT. Note the dilated and thick-walled loops of small bowel (S) and large bowel (L) with associated low-density submucosal edema, creating the "target sign." A large amount of pelvic free fluid (F) is also present.

several infarcted small-bowel loops (arrows), which manifest with dilatation and air-fluid levels

large cholesterol embolus (arrows) in the superior mesenteric artery, confirmed at surgery, which caused acute mesenteric infarction.

Stent can be seen in an infrarenal aortic aneurysm (arrows). The stent caused occlusion of the inferior mesenteric artery and subsequent ischemia of the sigmoid colon.

No c

Note moderate wall thickening of sigmoid colon (arrows), which has undergone transmural infarction.

pneumatosis (arrowheads) along the left-sided colon, due to transmural colonic infarction.

No c

•The patient had low cardiac output, but the wrong position of the intraaortic balloon (arrow), occluded the IMA

mesenteric venous infarction with massive small-bowel wall thickening (arrows)total absence of bowel wall enhancement, pronounced edema of mesenteric fat (arrowheads), ascites

c

patient with polycythemia vera who developed multiple thromboses of distal and intramural mesenteric veins.

pronounced homogeneous cecal wall thickening (arrows), representing transmural necrosis with superinfection in a patient with isolated cecal infarction.

No c

widely dilated colon with mildly thickened colonic wall, mesenteric gas, and mixed bubblelike (arrowheads) and bandlike (arrows) pneumatosis.

c occlusive transmural colonic infarction

massive circumferential and bandlike pneumatosis (arrows) of multiple necrotic loops and pronounced edema of mesenteric fat.

No c embolic transmural

small-bowel infarction

mesenteric venous gas with an air-contrast material level in the superior mesenteric vein (arrow). The infarcted small bowel shows minimal pneumatosis (arrowhead) but no wall thickening.

c embolic transmural small-bowel infarction

pronounced intrahepatic portal venous gas (branching hypoattenuating areas) extending into the periphery of both liver lobes.

c acute transmural mesenteric infarction

herniation of stool-filled, thin-walled colon (arrow) through a narrow abdominal wall defect. The patient was asymptomatic but presented with acute abdomen 1 month later.

c

Incarcerated

hernia

•multiple ventral hernias (arrowheads). The sac of the hernia shown in a now contains extraluminal fluid and fluid-filled, mildly thickened colon and causes colonic obstruction. Incarceration with colonic obstruction was confirmed at surgery.

strangulated umbilical hernia (arrows) causing small bowel obstruction (arrowheads). A herniated bowel loop with a C-shaped configuration, discrete mesenteric engorgement, and ascitic fluid within the hernia sac are also seen.

amplitude of the umbilical defect (thin arrows), air-fluid

levels in herniated bowel loops, and dilatation of

intraabdominal bowel loops secondary to small bowel

obstruction (arrowhead).

Note the ascitic fluid within the scrotum (thick arrow), a

finding that is characteristic of inguinoscrotal hernia.

Spiral CT and rapid bolus injection of CM

Multidetector row CT provides more detailed information. 3D volume rendering and MIP imaging.

CTA rendering of an SMA aneurysm in patient with Leriche's syndrome.

Celiac artery aneurysms. Reformatted MRA images demonstrate aneurysms of the proximal celiac artery in three different patients (white arrows in A–C).

SMA dissection. Localized dissection of the SMA on CPR and VR images. A: Coronal CPR of SMA demonstrating intimal flap from dissection (short arrow) and aneurysmal dilatation of false lumen (long arrow). B: Lateral CPR revealing entry point into false lumen (arrow). VR image (C) demonstrates dilated false lumen (arrow).

Portomesenteric venous thrombosis

Portomesenteric venous thrombosis

enlarged portal vein

enlarged splenic vein

SMV

portovenous confluence (black

arrow)

with evidence of small-vessel

collateralization (white arrow).

Portomesenteric venous thrombosis

absence of flow in the splenic vein (black arrow) and

within the portovenous confluence (white arrow).

filling defects in the portal vein (arrow) with

cavernous transformation at the porta hepatis

thrombus in the SMV (white arrow). Prominence

of the pancreatic head (black arrows) and several

peripancreatic lymph nodes (arrowheads)

haziness of the

adjacent fat (arrow).

Portomesenteric venous thrombosis

obliteration of the SMV

(arrowhead) and proximal

portal vein near the

confluence. Diffuse tumor

infiltration along the aorta is

also present.

Bowel dilatation in a 54-year-old woman with mesenteric venous thrombosis. CT image shows multiple loops of distended, fluid-filled small intestine (B) secondary to SMV thrombosis (arrowhead). There is no pneumatosis or free intraperitoneal air. Trace ascites is also present (arrow).

Intestinal pneumatosis air along the course of the SMV (arrowhead), and pneumatosis is

present (arrow) within the wall of the distal ileum, ascending colon, and transverse colon. Extensive portal venous gas was also noted. At laparotomy, no large vascular (arterial or venous) clot was identified; therefore, thromboembolic disease at a microvascular level was suspected to be the likely cause.

MRI

pancreatic cancer encasing SMA

demonstrates both soft tissue encasement of the SMA (arrow) and the bland thrombus (arrowhead) within the SMV.

Time of Flight MRA

PC MRA

2D ECG gated cine PC MRA

Systolic-gated 3D PC MRA

3D Gd-enhanced MRA

Portomesenteric venous thrombosis

nonocclusive

thrombus at the

splenoportal venous

confluence (arrow).

nonocclusive thrombus

in the SMV (arrow).

the SMV thrombus (arrow).

Portomesenteric venous thrombosis

large heterogeneous mass (M) in

the lower pole of the right kidney,

consistent with renal cell carcinoma.

A filling defect is seen in the SMV

(arrow

long thrombus in the SMV

(arrows) that extends into the

portal vein

proximal extent of

the clot in the portal

vein (arrows).

thrombus that involves

the inferior vena cava

(arrow

long thrombus in the

SMV (arrows) that

extends into the

portal vein (PV).

superior extent of the

filling defect (solid arrow)

in the portal vein (PV).

The filling defect in the

SMV is not visualized due

to absence of flow, but the

inferior mesenteric vein is

seen (open arrows). The

hepatic vein (HV) and

splenic vein (SV) are well

visualized

The thrombus in

the proximal

portal vein (PV) is

seen (arrow).

ANGIOGRAPHY

Angiogram of the celiac trunk, showing absence of the common hepatic artery. The gastroduodenal artery arises directly from the bifurcation of the celiac trunk. The proper hepatic artery divides into the right and left hepatic arteries