1. Dr/ ABD ALLAH NAZEER. MD.
Radiological imaging of pulmonary embolism.

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). PE most commonly results
from deep vein thrombosis (a blood clot in the deep
veins of the legs or pelvis) that breaks off and migrates
to the lung, a process termed venous thromboembolism
(VTE). A small proportion of cases are caused by the
embolization of air, fat, or talc in drugs of intravenous
drug abusers or amniotic fluid. The obstruction of the
blood flow through the lungs and the resultant pressure
on the right ventricle of the heart lead to the symptoms
and signs of PE. The risk of PE is increased in various
situations, such as cancer or prolonged bed rest.

3. Most Common Symptoms of PE (PIOPED Study) Dyspnea (73%)
Pleuritic chest pain (66%)
Coughing (37%)
Hemoptysis (13%)
Atypical Presentations of PE Abdominal/pelvic pain
Decreasing level of consciousness
Fever
Productive cough
Seizures
Syncope
Wheezing

4. Common Risk Factors for DVT and PE
AIDS
Antithrombin III deficiency
Bechet disease
Blood type A
Burns
Indwelling venous catheters, Pacemaker
Chemotherapy
CHF, myocardial infarct
History of prior DVT
Oral contraceptives, Estrogen replacement
Fractures, Surgery
Malignancy
Obesity
Prolong bed rest
Pregnancy
Protein C deficiency, resistance to active protein C
Systemic lupus erythematosus (SLE)
Trauma
Varicose veins, venous stasis, venography

5. The Most Common Risk Factors for DVT and PE Venous stasis - a condition of
stoppage or reduced blood flow through the veins.
Prolonged immobilization - this situation occurs when one is put in a cast to
heal a fracture, or suffers paralysis of a limb, or is bedridden due to illness or
being elderly.
Trauma and surgery - these conditions carry an increased risk of developing
VTE and PE. When there are major multisystem injuries, such as a high impact
motor vehicle accident, the incidence rate for DVT is approximately 58%.
Oral Contraception - has been known for many years to be a contributor to PE.
Oral contraceptive use combined with cigarette smoking is well documented
as a cause of sudden death in healthy women.
Pregnancy - In some women venous stasis can be a complication of
pregnancy. The cause is contributed to a decrease in fibrinolytic function.
Congenital - In a small fraction of the general population there are those who
suffer chronic hypercoagulable blood condition. Often this is a congenitally
caused hypercoagulation because of mutated Factor V. Mutated Factor V is
the most common cause of congenital hypercoagulation and is seen in some
form in about 5% of the population. Acquired deficiencies are seen in protein
C, protein S and Antithrombin III. Acquired deficiencies occur in nearly 10% of
young people who are diagnosed with PE.

6. Evaluation Scheme Based on Clinical Probability.

11. Radiological Imaging:
Chest X-ray
This noninvasive test shows images of your heart and lungs on film. Although X-
rays can't diagnose pulmonary embolism and may even appear normal when
pulmonary embolism exists, they can rule out conditions that mimic the disease.
Ultrasound
A noninvasive "sonar" test known as duplex ultrasonography (sometimes called
duplex scan or compression ultrasonography) uses high-frequency sound waves to
check for blood clots in your thigh veins. In this test, your doctor uses a wand-
shaped device called a transducer to direct the sound waves to the veins being
tested. These waves are then reflected back to the transducer and translated into
a moving image by a computer. The absence of the presence of clots reduces the
likelihood of DVT. If clots are present, treatment likely will be started immediately.
CT scan
Regular CT scans take X-rays from many different angles and then combine them
to form images showing 2-D "slices" of your internal structures. In a spiral (helical)
CT scan, the scanner rotates around your body in a spiral — like the stripe on a
candy cane — to create 3-D images. This type of CT can detect abnormalities in
the arteries in your lungs with much greater precision, and it's also much faster
than are conventional CT scans. In some cases, contrast material is given
intravenously during the CT scan to outline the pulmonary arteries.

12. V/Q lung scan
This test uses small amounts of radioactive material to study airflow (ventilation) and
blood flow (perfusion) in your lungs. For the first part of the test, you inhale a small
amount of radioactive material while a camera that's able to detect radioactive substances
takes pictures of the movement of air in your lungs. Then a small amount of radioactive
material is injected into a vein in your arm, and pictures are taken as the blood flows into
the blood vessels of your lungs. Comparing the results of the two studies helps provide a
diagnosis.
Pulmonary angiogram
This test provides a clear picture of the blood flow in the arteries of your lungs. It's the
most accurate way to diagnose pulmonary embolism, but because it requires a high degree
of skill to administer and carries potentially serious risks, it's usually performed when other
tests fail to provide a definitive diagnosis.
In a pulmonary angiogram, a flexible tube (catheter) is inserted into a large vein — usually
in your groin — and threaded through your heart into the pulmonary arteries. A special
dye is then injected into the catheter, and X-rays are taken as the dye travels along the
arteries in your lungs.
A risk of this procedure is a temporary change in your heart rhythm. In addition, the dye
may cause kidney damage in people with decreased kidney function.
MRI
MRI scans use radio waves and a powerful magnetic field to produce detailed images of
internal structures. Because MRI is expensive, it's usually reserved for pregnant women
and people whose kidneys may be harmed by dyes used in other tests

13. CTA Anatomy.

14. CTA Anatomy.

15. CTA Anatomy.

16. CTA Anatomy.

17. Types of pulmonary
embolism.
Thrombotic
pulmonary
embolism.
Acute
pulmonary
embolism.
Chronic
pulmonary
embolism.
Non-thrombotic
pulmonary
embolism.
Pathology.

18. Hi Sensitivity D-Dimer.
• High negative predictive value for PE (based
on pulmonary angiography)
• 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%
• PPV and NPV are affected by prevalence.
• Test is also useful for DVT rule out
(<500ng/mL): NPV 92%
• If pretest probability is intermediate (27.8)
you are supposed to image, but if you order
a D-Dimer what do the results mean?

19. D-Dimer
• False Positive D-Dimer
–Pregnancy
–Trauma
–Postoperative Recovery
–Inflammation
–Cancer
–Rheumatoid Factor
–Older Age
• False Negative D-Dimer
–Heparin

20. D-Dimer

25. CTA Diagnostic criteria for Pulmonary Embolism.

27. Acute Pulmonary Embolism.

28. Acute pulmonary embolism.

29. Acute pulmonary embolism.

30. Massive filling defects over bilateral pulmonary
arteries and almost total obliteration of right
pulmonary arterial flow (arrows).
Bilateral severe emboli can be
shown in coronal MIP as well.

31. These two CT images show a large pulmonary embolus in the left
main branch of the pulmonary artery. On the left is a lateral view of
the artery and on the right is the anterior view of the same artery.

32. Coronal CT images show large occluding pulmonary emboli in branches of
the left pulmonary artery and distal peripheral branches (orange arrows).

33. Two coronal CT images are of the same patient who presented with dyspnea,
chest pain, and mild core pulmonale. The chest CT angiogram reveals multiple PE
(arrows) as was suspected by clinical observations. Pulmonary emboli were found
in several secondary, tertiary, and distal branches of the pulmonary arteries.

34. The axial CT image (left) shows large pulmonary emboli bilaterally. The pulmonary arteries
from this image are magnified on the right to show these emboli better (yellow arrows)

35. These two axial CT images show profound pulmonary emboli. On the left the embolus almost
completely blocks the right pulmonary artery (yellow arrow). Right image show an extensive
saddle embolus forming in both pulmonary arteries and becoming extensive. Both of these types
of pulmonary emboli are life threatening and require immediate medical attention.

36. This coronal image shows a large pulmonary embolus in a branch of the left
pulmonary artery and scattered emboli in both lung fields. A magnified view of
the chest is seen on the right with arrows pointing to several pulmonary emboli.

37. Sagittal images are not routinely made for the chest CTA; however, it is shown here (right)
to show the extensive distribution of the pulmonary embolus seen on the coronal image (left).

38. Sagittal CT image shows small subsegmental branches of the pulmonary artery.
Radiocontrast outlines pulmonary emboli in some of these small branches (yellow arrows).

39. Acute pulmonary embolism.

40. Acute pulmonary embolism.

41. Acute Pulmonary Embolism

42. Acute
bilateral
Pulmonary
Embolism.

43. Multiple filling defects both at the bifurcation ("saddle"
pulmonary embolism) and in the pulmonary arteries.

44. Bilateral pulmonary embolism.

46. (a) CT angiography shows thromboembolic material in both lower lobe pulmonary arteries
(arrows). (b) High spatial resolution MR angiography demonstrates the same findings (arrows).

48. Chronic Pulmonary Embolism.

49. Chronic Pulmonary Embolism.

50. Chronic Pulmonary Embolism.

51. Chronic Pulmonary Embolism.

52. Chronic Pulmonary Embolism.

53. Chronic Pulmonary Embolism.

54. Chronic Pulmonary Embolism.

55. Chronic Pulmonary Embolism.

56. Chronic Pulmonary Embolism.

57. Chronic Pulmonary Embolism.

58. Chronic Pulmonary embolism and Pulmonary Hypertension. Eccentric wall-adherent
thrombus in principal pulmonary arteries, and bending of the interventricular septum

59. Chronic Pulmonary Embolism.

60. • High probability scans identify only ~50% of patients with PE overall
• Abnormal (high + intermediate + low prob) scans detect 98% of PE's, but
low specificity
• About 60% of V/Q scans will be in determinant (intermediate + low
probability)
• Of intermediate probability scans, ~33% occur with angiographically
proven PE
• Test results not affected by presence of pre-existing cardiac or pulmonary
disease
• Conclude: normal test rules out PE in ~98% of cases
• Note that low probability test still has ~15-25% chance of PE
• However, there were no deaths due to PE within 6 months in a study of
536 patients with low probability scans
• Further evaluation is clearly required for intermediate probability scans
• For low probability scan with normal D-dimer level, no additional workup
needed
• Consider helical CT in patients with non-diagnostic V/Q scan.
• NPV of helical CT with non-diagnostic V/Q is 96%.
Ventilation-Perfusion (V/Q) Scans.

61. Normal ventilation. Left upper lobe PE.

62. Ventilation-Perfusion (V/Q) Scans.

63. V/Q with Large Defect.

64. V/Q with Multiple Defects

65. V/Q with Subsegmental Defects

69. Lower Extremity Doppler US.
• 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 (or non-diagnostic) V/Q
scans and positive D-Dimers.
• These US should be carried out on days 1, 3, 7, and
14.
• A positive US on any of these days with abnormal
V/Q rules IN a PE.
• Negative serial US scans reduce likelihood of PE to
<2%.

70. Normal US and Color Doppler
DVT
Location of
Vein Marked

71. A subtotal occlusive thrombus in
the right popliteal vein is shown
in this colour Doppler image.
Right lower extremity (A) transverse and (B)
sagittal images from color Doppler
ultrasound demonstrates blood flow in the
femoral artery but not in the common
femoral vein (arrows). This is an indirect
finding that suggests common femoral DVT.

72. Echocardiography.
• Transthoracic echocardiography is not sensitive as screening test to rule
out PE.
• However, echocardiography is a very sensitive indicator of massive or
unstable PE
• Echocardiography should be done on any patient with suspected massive
or unstable PE
• Also critical for selecting patients for thrombolysis or other aggressive
therapy.
• Right ventricular (RV) function is most predictive of outcomes
• About 40% of patients with PE and normal blood pressure (BP) have
abnormalities of the RV
• Unstable patients include those with RV hypokinesis, dilation, abnormal
septal motion, patent foramen ovale, free floating right-heart thrombus
• Large PEs predicted by >30% loss of blood flow to either lung (on V/Q
Scanning)
• Pulmonary artery pressures can be estimated (physical exam has poor
sensitivity).
• May be used for chronic monitoring of P-HTN as well.

73. Echocardiography.

74. RV greater than LV with septal shift.

75. Echocardiography.
Clot in RA. Clot in RV.

76. Echocardiography

77. Contrast Pulmonary Angiography.
• This has been the gold standard for diagnosis but it is highly
invasive
• The pulmonary catheter may also be used therapeutically
(angioplasty)
• Angiography can be avoided in most patients by using other
tests above
• Positive result is a filling defect or sharp cutoff in a pulmonary
artery branch
• A negative angiogram with magnification excludes clinically
significant PE
• Increased sensitivity is obtained with sub-selective dye
injection
• May be morbid with worsening shortness of breath, artery
perforation, others
• Spiral CT scanning can be used to detect proximal PEs instead
of angiography.
• CT pulmonary angiography is safer than standard invasive
angiography and can be used to effectively rule out PE.

78. Contrast Pulmonary Angiography

79. Contrast Pulmonary Angiography.

80. Selective Angiography with Clot.

81. Magnetic Resonance Angiography (MRA).
• Techniques for use of 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

82. Large pulmonary embolus (arrows) at the bifurcation of the right pulmonary
artery in a 67 year old female. (A) CTPA, (B) bolus-triggered 3D MRPA, axial
reformations, (C) recirculation phase 3D GRE and (D) free-induction steady state
precession with ECG gating and respiratory triggering (TFISP-T).

83. MRA After resolution with PE.

84. Pulmonary embolism. transverse real-time MR image show large embolus in left pulmonary artery. Arrowheads
indicate embolic material. SPECT show the same finding and MRV show lower and upper leg DVT.

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

86. CT angiography clearly shows the central embolic material (arrow). (b) Coronal
real-time MR, performed the same day, with similar information (arrow). (c)
Transversal real-time image showing the saddle thrombus (arrows).

87. Pulmonary embolism within the right interlobar branch of pulmonary artery.

88. Axial and coronal SSFP localizer raised the suspicion of a
saddle embolus (white arrow) at the RPA/LPA bifurcation

89. Conclusions
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 for both PE
and VTE can reduce the risk of recurring disease to
below 2%, which is medically acceptable.

90. Thank You.