MULTIDETECOR CT AND EMBOLIC MESENTERIC ISCHEMIA:

TAKE A LOOK AT THE HEART!

I BEN YAACOUB, F SNENE, R KHARRAT, R BENNACEUR, H RAJHI, N MNIFRadiology department, Charles Nicolle hospital

Introduction

Mesenteric ischemia (MI) is a frequent clinical condition characterized by its clinical polymorphism.

It has an increasing prevalence because of eldering of the population.

1% of emergency admission for acute abdomen . It is associated with a high mortality rate due to

diagnosis delay.

Introduction

MI is considered as a diagnosis and therapeutic emergengy.

The prognosis is closely related to the delay between the symptoms onset and the preoperative correct diagnosis.

Rapid diagnosis the original cause and mechanism of MI is of great concern for the therapeutic issues.

Material & Methods

10 patients Mean age: 50 ans, sex ratio: 3/7. History:

• Cardiac rythm abnormalities (n=4)• Coagulopathy (n=3)• Atherosclerosis (n=6)

Clinical features: • Abdominal pain (n=10) with rapid (n=7) or progressive onset

(n=3).• No relevant abnormalities on abdominal examination or

blood tests (n=10).

Abdominal CT was performed in all patients( MDCT GE 16) with:

• Unenhanced CT

• Enhanced CT (2ml/kg of iodinate contrast media, 350mgI/ml, rate: 4ml/sec)

Arterial phase: performed with bolus detection technique (smart prep)

Portal phase: 70 – 80 sec 3D and Multiplanar reformations (MPR) were performed

Material & Methods

Results

Ostial filling defect of the superior mesenteric

artery (SMA) (n=2).

Filling defect of the main branch of the SMA

(n=2).

No vascular filling defect (n=6)

VASCULAR SIGNS

Analyzing the filling of mesenteric vessels on transversal images demonstrated abrupt defect of

SMA while superior vein is well enhanced

MPR allow better spatial assessment of vascular abnormalities.Thrombosis of the SMA without underlying vascular lesions (no evidence of atherosclerosis) is very suggestive of embolic MI.

Subocclusion of SMA

3D vascular reformation showed clearly the atherothrombosis of the SMA with

heavy calcifications distally

On upper CT images involving the lower thoracic region, we saw an apical thrombus of the left ventricle. This finding was diagnostic for embolic MI

Cardiac MRI performed in this 25-year-old women showed a transmural infarction in the LAD territory.

CARDIAC EMBOLISM

SMA thrombosis associated with renal infarct

The upper thoracic images showed bilateral pulmonary embolism

PARADOXICAL EMBOLISM

Results

Bowel infarct (n=10)

Unehancement of bowel wall (n=8)

Thickening of bowel wall (n=2)

Pneumatosis (n=3)

Aeroportie (n=0)

DIGESTIVE SIGNS

Bowel wall thickeningDefect of enhancement of bowel wall

Aeroportie

Pneumatosis Aeromesenterie: air within arterial branchs of SMA

Discussion Small bowel has terminal arterial

vascularisation configuration Obstruction of a branch or the main SMA

resulats in arterial MI Extension of bowel infarct is correlated to

situation of arterial occlusion:• Occlusion of the main SMA results in

extensive MI with poor prognosis• Occlusion of a distal branch results in

segmental MI that can be managed surgically.

Discussion

Mortality and morbidity of arterial MI are very high although progress in diagnostic and therapeutic issues.

Early diagnosis of arterial MI is critical and remain the unique chance to improve the prognosis

MDCT is now recognized to be an important tool for the diagnosis and must be performed with adapted technique for every MI clinical suspicion.

MDCT reliabilty has grown in the last few year reaching 95% in 2009 ( 75% in 1996)

Discussion

Surgical management consist of resection of infarcted bowel that should be performed as soon as possible in order to reduce necrosis extension.

Etiologic investigation of arterial MI is of great concern because it may change management of patients

Discussion

Mecanisms of arterial MI:

Arterial thrombosis:

Arterial embolism:

• ATHEROSCLEROSIS +++• Aged patients• Cardiovascular risk factors• (Hypertension, Diabetes, obesity…)• Evidence of multivascular involvment• (carotid, renal artery, coronaropathy,…)

• EXTRA INTESTINAL THROMBOSIS MIGRATION• Younger patients• Cardiovascular risk factors =0• Cardiac rythm disorders • Atrial fibrillation +++• Evidence of multivascular involvment• (carotid, renal artery, coronaropathy,…)

Discussion

Besides the MI diagnosis MDCT may offer precious arguments for the etiologic investigation especially in differenciating embolic versus thrombotic mechanism.

DiscussionEmbolic MI Thrombotic MI

Multiple embolism sites

Normal underlying arterial wall

Abrupt filling defect of the arterial lumina

Extra mesenteric cardiovascular thrombosis:- Cardiac thrombosis- Aortic thrombosis or dissection

Isolated MI

Diseased arterial wall:- Atherosclerotic infiltration- Heavy arterial calcification- Arterial stenosis

Progressive arterial occlusion due to underlying stenosis

Extra mesenteric atherosclerotic vascular involvment

DiscussionOrigin of arterial MI embolism:

• Cardiac thrombus

• Paradoxical embolism

• Aortic thombus: due to- Aortic athrothrombosis

- Chronic/acute aortic dissection

Discussion

• Cardiac source of embolism

- Myocardial infarction (left ventricle+++)

- Atrial fibrillation (left atrium+++)

- Valvular disease (Aortic stenosis)

- Endocarditis (septic embolism)

- Cardiac tumors (myxoma +++)

Discussion

• Paradoxical embolism:- Definition: systemic arterial embolism requiring the

passage of a venous thrombus into the arterial circulatory system through a right-to-left shunt.

- Cause: intra cardiac communication: Inter auricular communication Aneurysm of the interauricular septum Patent foramen ovale (PFO) +++

Discussion

• Paradoxical embolism: can be presumed in the following criteria:

- Deep venous thrombosis with or without pulmonary embolism.

- Abnormal communication between right (venous) and left (systemic) circulation.

- Clinical, angiographic, or pathologic evidence for systemic embolism.

- Presence of a favourable pressure gradient, promoting right-to-left shunting.

Discussion

• Aortic source of embolism: Are at higher risk of embolism:

- Atherosclerotic aortic plaques > 4 mm

- ulcerated plaques

- plaques with mobile intra aortic components

- hypodense and noncalcified plaques

Discussion

• In our series, the cardiac source of MI embolism was detected thanks to MDCT while analyzing the upper images of the abdominal acquisition.

• One of these two patient was a young women with no cardiovascular history. Further investigation were diagnostic for myocardial infarction due to coronary malformation

Conclusion

• Determination of MI mechanism is of great concern for therapeutic issues and patients outcome.

• MDCT is the key imaging technique for the diagnosis and prognosis of MI

• Moreover, MDCT may help considering the mechanism of MI (embolism vs thrombosis)

• Systematic analysis of a technically reliable MDCT may even be diagnostic for the origin of embolic MI.

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