By Dr. Hytham Nafady By Dr. Hytham Nafady

Segmental anatomy of the lungSegmental anatomy of the lung

Truncus anterior

Interlobar artery

Basal trunk

In the central portions of the lungs, the In the central portions of the lungs, the upper lobe arteries are generally central to upper lobe arteries are generally central to their associated bronchi; and the middle and their associated bronchi; and the middle and lower lobe and lingular arteries are generally lower lobe and lingular arteries are generally peripheral to their associated bronchi (12). peripheral to their associated bronchi (12). The pulmonary veins are generally anterior The pulmonary veins are generally anterior to the arteries except in the right upper lobe.to the arteries except in the right upper lobe.

Pathology Pathology

Non thrombtic pulmonary Non thrombtic pulmonary embolismembolism

Fat embolism.Fat embolism. Air embolism.Air embolism. Amniotic fluid embolism.Amniotic fluid embolism. Tumor embolism (Tumor embolism (HCCHCC & & RCCRCC).).

Thrombotic pulmonary Thrombotic pulmonary embolismembolism

Risk factors:Risk factors: PPrimary hypercoagulable statesrimary hypercoagulable states

– protein C deficiencyprotein C deficiency– lupus anticoagulantlupus anticoagulant

PPostoperativeostoperative PPregnancyregnancy PProlonged bed rest / immobilityrolonged bed rest / immobility PParaneoplastic syndromearaneoplastic syndrome PPills (Oral contraceptives)ills (Oral contraceptives)

LocationLocation

Multiple 65%Multiple 65% Lower lobe 50% Lower lobe 50% Bilateral 42%Bilateral 42%

C.P of Acute pulmonary C.P of Acute pulmonary embolismembolism

Acute pulmonary embolism has a wide spectrum of Acute pulmonary embolism has a wide spectrum of clinical manifestations ranging from absence of clinical manifestations ranging from absence of symptoms to sudden death.symptoms to sudden death.

1.1. Most patients are asymptomatic.Most patients are asymptomatic.

2.2. Dyspnea, tachypnea & pleuritic chest pain.Dyspnea, tachypnea & pleuritic chest pain.

3.3. Syncope.Syncope.

4.4. ECG evidence of right ventricular overload.ECG evidence of right ventricular overload.

DVTDVT Non-compressible venous segmentNon-compressible venous segment Increased venous diameter : acute thrombusIncreased venous diameter : acute thrombus Decreased venous diameter : chronic thrombusDecreased venous diameter : chronic thrombus Loss of phasic flow on Valsalva maneuverLoss of phasic flow on Valsalva maneuver Absent colour flow : if completely occlusiveAbsent colour flow : if completely occlusive Increased flow in superficial veinsIncreased flow in superficial veins Lack of flow augmentation of calf squeezeLack of flow augmentation of calf squeeze

Absent color flowAbsent color flow

Serlogical testsSerlogical testsD dimer (ELISA)D dimer (ELISA)

Sensitivity & -ve predictive value: (100%).Sensitivity & -ve predictive value: (100%). Specificity: (50%)Specificity: (50%) False positives: False positives:

inflammatory conditions, inflammatory conditions, pregnancy, pregnancy, anemia, and anemia, and leukocytosis.leukocytosis.

Imaging modalities for acute Imaging modalities for acute pulmonary embolismpulmonary embolism..

Chest x-ray.Chest x-ray. Ventilation perfusion lung scan:Ventilation perfusion lung scan:Using Technetium-99m labeled macro aggregated Using Technetium-99m labeled macro aggregated

albumin (MAA) for perfusion scans & Xenon-133 albumin (MAA) for perfusion scans & Xenon-133 for ventilation scans.for ventilation scans.

Helical CT angiography and indirect CT Helical CT angiography and indirect CT venography.venography.

MRAMRA Pulmonary angiographyPulmonary angiography

Chest x-rayChest x-ray

Advantages:Advantages:

The main role of chest x-ray is to exclude other The main role of chest x-ray is to exclude other diseases such as pneumonia or pneumothorax diseases such as pneumonia or pneumothorax that may mimic pulmonary embolism clinically.that may mimic pulmonary embolism clinically.

Also chest x-ray helps in the interpretation of Also chest x-ray helps in the interpretation of ventilation perfusion lung scans (PIOPED criteria).ventilation perfusion lung scans (PIOPED criteria).

Disadvantages:Disadvantages:

Chest x-ray has a low sensitivity & specificity in Chest x-ray has a low sensitivity & specificity in diagnosis of acute pulmonary embolism.diagnosis of acute pulmonary embolism.

Radiographic signs of acute Radiographic signs of acute pulmonary embolismpulmonary embolism

Signs with relative high specificity but low sensitivity for Signs with relative high specificity but low sensitivity for acute pulmonary embolism:acute pulmonary embolism:

Decreased vascularity in the peripheral lung (Decreased vascularity in the peripheral lung (WestermarkWestermark signsign).).

Enlargement of the central pulmonary artery (Enlargement of the central pulmonary artery (Fleischner Fleischner signsign).).

Pleural based areas of increased opacity (Pleural based areas of increased opacity (Hampton humpHampton hump).). Hemidiaphragm elevation.Hemidiaphragm elevation.Non specific signs associated with acute pulmonary Non specific signs associated with acute pulmonary

embolism that may be associated with other diseases:embolism that may be associated with other diseases: Focal area of increased opacity.Focal area of increased opacity. Linear atelectasis.Linear atelectasis. Pleural effusion.Pleural effusion.

Westermark’s signWestermark’s sign

Westermark sign, with hilar enlargement

Hampton’s humpHampton’s hump

Hampton’s humpHampton’s hump

Dome shaped pleural based opacity due to Dome shaped pleural based opacity due to lung infarction.lung infarction.

Pulmonary infarct is dome shaped instead of Pulmonary infarct is dome shaped instead of being wedge shaped because of double being wedge shaped because of double blood supply with preserved bronchial blood supply with preserved bronchial arteries resulting in sparing of the expected arteries resulting in sparing of the expected apex of the wedge.apex of the wedge.

Scintigraphy Scintigraphy (ventilation perfusion lung scan)(ventilation perfusion lung scan)

Advantages:Advantages:

Very high sensitivity 98% (it was the imaging Very high sensitivity 98% (it was the imaging modality of choice in diagnosis of pulmonary modality of choice in diagnosis of pulmonary embolism).embolism).

Disadvantages:Disadvantages:

The main one was high percentage of non The main one was high percentage of non diagnostic intermediate probability scans.diagnostic intermediate probability scans.

Very low specificity 10%.Very low specificity 10%.

Scintigraphic findings for acute Scintigraphic findings for acute pulmonary embolismpulmonary embolism

Ventillation perfusion mismatch.Ventillation perfusion mismatch.

NormalVentilation

LUL PE

Perfusion scanVentillation scan

Modified PIOPED criteria for Modified PIOPED criteria for diagnosis of pulmonary embolismdiagnosis of pulmonary embolism.. High probability.High probability. Intermediate probability.Intermediate probability. Low probability.Low probability. Normal.Normal.

Helical CT angiography Helical CT angiography & &

indirect CT venographyindirect CT venographyAdvantages:Advantages: More accurate than scintigraphy.More accurate than scintigraphy. Rapid.Rapid. Non invasive.Non invasive. Readily available.Readily available. Also in patients without pulmonary embolism Also in patients without pulmonary embolism

helical CT provides an alternative diagnosis.helical CT provides an alternative diagnosis.Disadvantages:Disadvantages:Various pitfalls.Various pitfalls.

CT findings of acute pulmonary CT findings of acute pulmonary embolismembolism

Vascular abnormalities:Vascular abnormalities: Intraluminal filling defects that forms an acute Intraluminal filling defects that forms an acute

angle with the vessel wall & may be surrounded angle with the vessel wall & may be surrounded by contrast material (polo mint sign or railway by contrast material (polo mint sign or railway sign).sign).

Total cutoff of vascular enhancement.Total cutoff of vascular enhancement. Enlargement of the occluded vessel.Enlargement of the occluded vessel.Ancillary findings:Ancillary findings: Pleural based wedge shaped areas of increased Pleural based wedge shaped areas of increased

attenuation with no contrast enhancement.attenuation with no contrast enhancement. Linear atelectasis.Linear atelectasis.

Partial eccentric filling defect with Partial eccentric filling defect with acute angle with the vessel wallacute angle with the vessel wall

Intraluminal filling defectIntraluminal filling defect((polo mint signpolo mint sign))

Intraluminal filling defectIntraluminal filling defect(railway track sign)(railway track sign)

Enlargment of the occluded Enlargment of the occluded vesselvessel

Ancillary findings of acute pulmonary Ancillary findings of acute pulmonary embolismembolism

(atelectatic band)(atelectatic band)

MRAMRAAdvantages:Advantages:

Disadvantages (Pitfalls and artifacts):Disadvantages (Pitfalls and artifacts):

Patient related: Patient related:

respiratory motion.respiratory motion.

MR reconstruction related:MR reconstruction related:

Gibbs artifactGibbs artifact

Wrap around.Wrap around.

Amplifier over ranging.Amplifier over ranging.

Contrast injection related:Contrast injection related:

Transient interruption of bolus.Transient interruption of bolus.

MRA findingsMRA findings

Visualization of the intravascular filling Visualization of the intravascular filling defect.defect.

Provide physiologic information including the Provide physiologic information including the regional distribution of ventilation & regional distribution of ventilation & perfusion.perfusion.

Pulmonary MRAPulmonary MRA

Pulmonary hypertension with dilated central Pulmonary hypertension with dilated central pulmonary arteries and pruning of peripheral pulmonary arteries and pruning of peripheral pulmonary arteriespulmonary arteries

Pulmonary angiographyPulmonary angiography

Advantages:Advantages:The most definitive technique for diagnosis of acute The most definitive technique for diagnosis of acute

pulmonary embolism.pulmonary embolism.Disadvantages:Disadvantages:Invasive technique with the following possible Invasive technique with the following possible

complications,complications,Bleeding in the groin.Bleeding in the groin.Recurrent ventricular arrhythmias.Recurrent ventricular arrhythmias.Respiratory arrest requiring ventilatory support.Respiratory arrest requiring ventilatory support.

Pulmonary angiographic findingsPulmonary angiographic findings

Primary signs:Primary signs:

The only primary sign of acute pulmonary The only primary sign of acute pulmonary embolism is filling defect.embolism is filling defect.

Secondary signs:Secondary signs:

Abrupt occlusion of pulmonary artery.Abrupt occlusion of pulmonary artery.

Areas of oligemia with pruning of the Areas of oligemia with pruning of the branching vessels.branching vessels.

Chronic thromboembolic pulmonary Chronic thromboembolic pulmonary embolismembolism

Patients with chronic thromboembolic Patients with chronic thromboembolic pulmonary embolism are evaluated for the pulmonary embolism are evaluated for the possible thmboendarterectomy:possible thmboendarterectomy: