Contains radiology imaging of pulmonary embolism

1. By- Harshvardhan Singh

2.  Pulmonary embolism (PE) is a blockage of the main
artery of the lung, or one of its branches by a
substance that has travelled from elsewhere in the
body through the bloodstream (embolism).
 Most commonly results from DVT that breaks off and
migrates to the lung, a process termed venous
thromboembolism.
 A small proportion of cases are caused by the
embolization of air, fat, or talc in drugs of
intravenous drug abusers.

3. • The obstruction of the blood flow through the
lungs and the resultant pressure on the right
ventricle of the heart leads to the symptoms and
signs of PE. The risk of PE is increased in various
situations, such as cancer or prolonged bed rest.
• This is an extremely common and highly lethal
condition that is a leading cause of death in all
age groups.
• One of the most prevalent disease processes
responsible for in-patient mortality (30%)
• Overlooked diagnosis

4. • 3rd most common cause of death.
• 2nd most commoncause of unexpected
death in most age groups.
• 60% of patients dying in the hospital have
had a PE.
• Diagnosis has been missed in about 70%
of the cases.

5. MOST COMMON SYMPTOMS
 Dyspnea (73%)
 Pleuritic chest pain (66%)
 Coughing
 Hemoptysis

6. RISK FACTORS
• Condition of stoppage or reduced blood flow
through the veins.
• Prolonged immobilization - fracture, paralysis,
bedridden due to illness or being elderly.
• Trauma and surgery
• Oral Contraception - combined with cigarette
smoking is well documented as a cause of
sudden death in healthy women.
• Pregnancy - cause is contributed to a
decrease in fibrinolytic function.
• Congenital( Hereditary antithrombin def, Leidin
V mutation)

7. ECG FINDINGS
• Sinus tachycardia: M/C abnormality
• Right heart strain pattern: seen as a RBBB
pattern or right axis deviation
• SIQIIITIII pattern: Deep S wave in lead I, Q
wave and T wave inversion in lead III;
This sign is seen as classical of PE

11. CHEST X-RAY FINDINGS
14% Normal
68% Atelectasis or parenchymal density
48% Pleural Effusion
35% Pleural based opacity
24% Elevated diaphragm
15% Prominent central pulmonary artery
7% Westermark’s sign
7% Cardiomegaly
5% Pulmonary edema

12. Initial CxR always NORMAL.

13.  May show – Collapse, consolidation, small pleural
effusion, elevated diaphragm.
 Pleural based opacities with convex medial margins are
also known as a Hampton's Hump

15. • Westermark sign – Dilatation of pulmonary
vessels proximal to embolism along with
collapse of distal vessels, often with a sharp
cut off.

16. Focal area of oligemia in the right middle zone and cutoff of the pulmonary artery
in the upper lobe of the right lung.
CTpulmonary angiography confirmed the presence of a thrombus in the right
pulmonary artery, with an occlusive thrombus in the pulmonary arteries of the
right upper and middle lobes

17. PALLA’S SIGN- enlarged right
descending pulmonary artery.

18. 1.Diagnostic Criteriafor acute PE
 Complete arterial occlusion
 The artery may be enlarged compared with
adjacent patent vessels

20. ACUTE PE WITHIN THE POSTEROBASAL SEGMENTOF RLL.

21. 2.Diagnostic Criteriafor acute PE
 A partial filling defect surrounded by
contrast material
 “polo mint” sign
 “railway track” sign

23. AcutePartial filling defect surrounded by contrast material (railway track sign) .

24. 3.Diagnostic Criteriafor acute PE
 A peripheral intraluminal filling defect
 Acute angles with the arterial wall

25. AcuEccentrically positioned partial filling defect,which is surroundedby contrast material and forms
acute angleswith the arterial wall.

26. 4.Diagnostic Criteriafor acute PE
 Peripheral wedge-shaped areas
of hyperattenuation
 Linear bands
Not specific for pulmonary embolism.

27. SPeripheral wedge-shaped area of hyperattenuation in the lung (arrow), a finding thatmay represent an
infarct,as well as a linear band (arrowhead).

28. 5.Diagnostic Criteriafor acute PE
If Pulmonary arteries are indeterminate.
Lungs are clear.
To evaluate for pulmonary embolism do-
 Ventilation-perfusion scintigraphy
 Repeat CT pulmonary angiography

29. CHRONIC PE

30. 1.Diagnostic Criteriafor chronic PE
 Complete occlusion
 smaller than adjacent patent vessels

31. Complete occlusion of vessels (arrowheads)that are smallerthan adjacentpatent vessels. Note the
collateral blood supply from a branch of the right hemidiaphragmatic artery (arrow).

32. 2.Diagnostic Criteriafor chronic PE
 Peripheral, crescent-shaped, obtuse
angles with vessel wall

33. Chronic pulmonary embolism

34. 3.Diagnostic Criteriafor chronic PE
 Smaller rencanalized arteries

36. 4.Diagnostic Criteriafor chronic PE
 A web or flap within a contrast material–
filled artery

38. 5.Diagnostic Criteriafor chronic PE
 Bronchial or other systemic collateral
vessels

39. Large chronic PE in the main and left main pulmonary arteries (arrowhead).

40. 6.Diagnostic Criteriafor chronic PE
 Calcification within eccentric vessel

41. Pulmonary arterial wall calcificatio n (arrows), a secondary sign of chronic pulmonary
embolism.

42. 7.Diagnostic Criteriafor chronic PE
 PA diameter > 30 mm

43. Pulmonary arterial HTN secondaryto chronic PE--PA41 mm in diameter

44. 8.Diagnostic Criteriafor chronic PE
 Pericardial fluid

45. Acute Short axis of the right ventricle (dashed line)is wider than thatof the left ventricle (solid line)

46. Conclusion
Acute Chronic
Impacted artery large small
Angle acute obtuse
Others Polomint/railway track Recanalisation
Web/flap
Collateral arteries
Calcification
Mosaic
PHTN
Mosaic
right heart strain right heart strain

47. D-DIMER.
• For D-dimer <500ng/mL, negative predictive
value (NPV) 91-99%
• For D-dimer >500ng/mL, sens=93%, spec=25%,
and positive predictive value (PPV) = 30%
• Test is also useful for DVT rule out

48. VENTILATION-PERFUSION (V/Q) SCANS
• Identifies only ~50% of patients with PE.
• Abnormal (high + intermediate + low prob)
scans detect 98% of PE's but has low specificity
• About 60% of V/Q scans will be indeterminant
• Of intermediate probability scans, ~33% occur
with angiographically proven PE

51. LOWER EXTREMITY DOPPLER
USG.
• First-line if radiographic imaging
contraindicated or not readily available.
•Not likely required in patient with negative CT-PA
• Helpful to rule out DVT in patient with non-
diagnostic V/Q scan

52. • To evaluate for DVT as possible cause of PE or
to help rule in PE
• Up to 40% of patients with DVT without PE
symptoms will HAVE a PE by angiography.
• Serial US should be probably be performed in
patients with abnormal V/Q scans and positive
D-Dimers.
• These USG should be carried out on days 1, 3,
7, and 14.

53. PULMONARY ANGIOGRAPHY.
 GOLD STANDARD.
 Positive angiogram provides 100% certainty
that an obstruction exists in the pulmonary
artery.
 Negative angiogram provides > 90% certainty
in the exclusion of PE.

54.  Catherterisation of the subclavian vein
 Subclavian vein – Superior vena cava – right
atrium – right ventricle – main pulmonary artery
 Contrast
 DSA

55. Contrast Pulmonary Angiography

56. MAGNETIC RESONANCE
ANGIOGRAPHY (MRA)
• MRA for diagnosing PE are evolving rapidly
• Estimated sensitivity ~80% (~100% for larger
emboli), specificity 95%
• Non-invasive with little morbidity
• Dynamic gadolinium enhancement is used,
allowing high quality images
• Strongly consider prior to standard invasive
pulmonary angiography.

57. Thromboembolic material in both pulmonary arteries
(dotted arrows.

58. CT angiography clearly shows central embolic material (arrow).
(b) Coronal MR, showed similar information
(c) Axial image showing the thrombus

59. • Advantages
 Lack of ionizing
radiation
 Limitations
 Respiratory and cardiac motion artifact
 Suboptimal resolution for peripheral
pulmonary arteries
 Complicated blood flow patterns

60. CAUSESOF MISDIAGNOSIS OF
PULMONARY EMBOLISM

61. Causes of Misdiagnosis of PE:
Pathologic Factors
 Mucus Plug

62. Causes of Misdiagnosis of PE:
Pathologic Factors
 Perivascular Edema

63. Causes of Misdiagnosis of PE:
Pathologic Factors
 Localized Increase in Vascular Resistance

64. Causes of Misdiagnosis of PE:
Pathologic Factors
 Primary Pulmonary Artery Sarcoma(rare)

65. Causes of Misdiagnosis of PE:
Pathologic Factors
 Tumor Emboli

66. Causes of Misdiagnosis of PE:
Pathologic Factors
 Idiopathic Pulmonary Hypertension

67. Causes of Misdiagnosis of PE:
Pathologic Factors
 Proximal Interruption of the Pulmonary Artery

68. • Pulmonary embolus is a major health problem that is
highly treatable when diagnosed, but carries high risk for
morbidity and mortality is undiagnosed.
• Radiography is a major diagnostic tool in finding
pulmonary embolus.
• There are several diagnostic studies like CT, nuclear V/Q
scan and angiographic procedures that diagnose
pulmonary embolus. The main cause of PE is venous
thromboembolus that is diagnosed with ultrasound.
• Treatment can reduce the risk of recurring disease to
below 2%, which is medically acceptable.