CTA OF PULMONARY EMBOLISM

CTA OF PULMONARY EMBOLISM

1. CTACTA ofof

Pulmonary

Pulmonary
:
Embolism
:
Embolism

DiagnosticCriteriaand

DiagnosticCriteriaand

CausesofMisdiagnosis

CausesofMisdiagnosis
Presented by Presented by
EKKASIT SRITHAMMASIT, MD.EKKASIT SRITHAMMASIT, MD.

2. REVIEW
Wittram C et al.
Radiographics. 2004
Sep-Oct;24(5):1219-38.
PubMed PMID: 15371604.
From the Department of
Radiology, Massachusetts G
eneral Hospital and Harvard
Medical School

3. IntroductionIntroduction
MMost common acute cardiovascular ost common acute cardiovascular
diseasedisease
•Myocardial infarction
•Stroke
•Pulmonary embolism
PE : results in thousands of deaths each year
because it often goes undetected

4. IntroductionIntroduction
Diagnostic tests for thromboembolic diseaseDiagnostic tests for thromboembolic disease
5. Pulmonary angiographyPulmonary angiography : standard for confirm
Spec. 83%–100%Spec. 83%–100% Sen. 53%–100%Sen. 53%–100%4. CTA 4. CTA
high specificitylow sensitivity3. Lower limbLower limb USUS
poor specificityhigh sensitivity2. VP scintigraphyVP scintigraphy
poor specificityhigh sensitivity1. DD--dimer assaydimer assay

5. Figure 1. Graph illustrates that the number of pulmonary angiographicpulmonary angiographic studies performed
per inpatient with suspected thromboembolic disease decreased significantly between 1992
and 2001 (P = .02)
Wittram C et al. Radiographics 2004;24:1219-1238
©2004 by Radiological Society of North America

6. Figure 2. Graph illustrates that the number of ventilation-perfusion scansventilation-perfusion scans performed per
inpatient with suspected thromboembolic disease decreased significantly between 1992 and
2001 (P = .0003)
Wittram C et al. Radiographics 2004;24:1219-1238
©2004 by Radiological Society of North America

7. Figure 3. Graph illustrates that the number of CT studiesCT studies performed for pulmonary embolism
per inpatient increased significantly between 1992 and 2001 (P = .006)
Wittram C et al. Radiographics 2004;24:1219-1238
©2004 by Radiological Society of North America

8. IntroductionIntroduction
LEARNING OBJECTIVES
•CT Technique
•List the diagnostic criteria for acute and
chronic PE at CTPA.
•Describe the causes of misdiagnosis
and indeterminate of PE at CTPA.

9. CTTechnique

CTTechnique

10. CTTechnique

CTTechnique
•16-section CT scanners:
•IV access: 18- 20 G into antecubital vein.
•Field :
–widest rib-to-rib
–during breath hold after inspiration
•CT Protocol

12. CTTechnique

CTTechnique
•Images displayed for interpretation
100700Pulmonary thromboembolism-
specific window
40350Mediastinum window
6001500Lung window
window
level
window
width

13. •Multiplanar
reformatted
images
•Maximum
intensity
projection
images

14. Diagnostic

Diagnostic
CriteriaCriteria
forfor
PEPE

15. DiagnosticCriteriaforPE

DiagnosticCriteriaforPE
•Examined: Pulmonary artery.
–Main arteries.
–Lobar arteries.
–Segmental arteries.
–Subsegmental arteries.
•PE: sharp intraluminal filling defects.

16. DiagnosticCriteriaforPE

DiagnosticCriteriaforPE
Examined: Pulmonary artery.
–Normal
–Containing acute pulmonary embolism
–Containing chronic pulmonary embolism
–Indeterminate with reasonreason
Vessels may appear normal to the level of the
segmental arteries; however, the presence of PE in
subsegmental arteries may remain indeterminate
depending on the quality of the study.

17. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
Complete occlusionComplete occlusion :
–Failure to enhance the
entire lumen due to a
large filling defect.
–The artery may be
enlarged compared
with adjacent patent
vessels

18. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
Partial occlusionPartial occlusion :
–“Polo mint” sign
–“railway track” sign
– Acute angles
peripheral intraluminal
filling defect

19. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
Partial occlusionPartial occlusion :
–“Polo mint” sign
–“railway track” sign
– Acute angles
peripheral intraluminal
filling defect

20. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
Partial occlusionPartial occlusion :
–“Polo mint” sign
–“railway track” sign
– Acute angles
peripheral intraluminal
filling defect

21. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
•InfarctInfarct
–Peripheral wedge-
shaped areas of
hyperattenuation
–Linear bands
Not specific

22. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
•RtRt--sided heart failuresided heart failure
–RV dilatation with or
without contrast reflux
into the hepatic veins
–Deviation of the
interventricular septum
toward the LV
 Right ventricular strain or failure is optimally monitored with echocardiography.

23. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism
•Unenhanced CTUnenhanced CT
–hyperattenuating filling defect
 PE have been identified on 1.5% of CECT scans obtained for reasons other
than evaluation for PE .

24. AcutePulmonaryEmbolism

AcutePulmonaryEmbolism

25. CTPA :help identify diseases that CTPA :help identify diseases that
have symptoms similar to those of have symptoms similar to those of
acute PEacute PE
–Pericarditis.Pericarditis.
–Acute myocardial infarction.Acute myocardial infarction.
–Aortic dissection.Aortic dissection.
–Esophagitis, esophageal rupture.Esophagitis, esophageal rupture.
–Pneumonia, lung cancerPneumonia, lung cancer
–Pneumothorax and pleuritisPneumothorax and pleuritis. .
–Chest wall : rib fractures and Chest wall : rib fractures and
metastatic.metastatic.

26. If findings in the pulmonary If findings in the pulmonary
arteries are indeterminate arteries are indeterminate
and the lungs are clearand the lungs are clear
–ventilation-perfusion ventilation-perfusion
scintigraphyscintigraphy
–repeat CT pulmonary repeat CT pulmonary
angiographyangiography
–conventional pulmonary conventional pulmonary
angiographyangiography

27. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism

28. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Complete occlusion of a vessel that is
smaller than adjacent vessels.

29. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•A peripheral, crescent-shaped intraluminal
defect that forms obtuse angles with the vessel
wall

30. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Contrast material flowing through thickened,
often smaller arteries due to recanalization

31. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•A web or flap within a contrast material–
filled artery

32. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Secondary signs
–Bronchial or other
systemic collateral
vessels
–Mosaic perfusion
pattern
–Calcification within
eccentric vessel thicke
ning
Rt hemidiaphragmatic artery

33. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Secondary signs
–Bronchial or other
systemic collateral
vessels
–Mosaic perfusion
pattern
–Calcification within
eccentric vessel thicke
ning
Bronchial artery

34. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Secondary signs
–Bronchial or other
systemic collateral
vessels
–Mosaic perfusion
pattern
–Calcification within
eccentric vessel thicke
ning

35. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Secondary signs
–Bronchial or other
systemic collateral
vessels
–Mosaic perfusion
pattern
–Calcification within
eccentric vessel thicke
ning

36. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Secondary signs
–Bronchial or other
systemic collateral
vessels
–Mosaic perfusion
pattern
–Calcification within
eccentric vessel thicke
ning

37. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism
•Pulmonary arterial hypertensionPulmonary arterial hypertension
–A pulmonary artery diameter greater than 33 mm.
–Pericardial fluid.

38. ChronicPulmonaryEmbolism

ChronicPulmonaryEmbolism

39. Causesof

Causesof

Misdiagnosisof

Misdiagnosisof

PulmonaryEmbolism

PulmonaryEmbolism

40. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

41. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

42. RespiratoryMotionArtifact

RespiratoryMotionArtifact
•Most common cause of misdiagnosis of
PE.
•Best seen with lung window: “Seagull
sign”
•Diminish as higher-order multisection CT,
which requires a shorter breath hold,
becomes more widely used.

43. RespiratoryMotionArtifact

RespiratoryMotionArtifact

44. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

45. ImageNoise

ImageNoise
•Large patients have more quantum mottle.
•Therefore, for patients weighing more than 250 pounds
(113.4 kg), we modify our protocol by increasing
detector width to 2.5 mm
•However, this increased detector width also decreases
sensitivity for detection of pulmonary embolism.

46. ImageNoise

ImageNoise

48. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

49. PulmonaryArteryCatheter

PulmonaryArteryCatheter
•Itself mimic pulmonary embolism.
•Beam-hardening artifacts.
•Identification of the catheter will demonstrate the true
nature of this pitfall.

50. PulmonaryArteryCatheter

PulmonaryArteryCatheter

51. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

52. -
FlowrelatedArtifact
-
FlowrelatedArtifact
•Poor mixture of blood and contrast material.
•A flow-related artifact can be confidently
diagnosed by
–Ill-defined margins
–Demonstrating an attenuation level above 78 HU.
•However, further imaging may be necessary to
exclude thrombus hidden in poorly enhanced
vessels.

53. -
FlowrelatedArtifact
-
FlowrelatedArtifact
Flow-related artifact in a 60-year-old woman with pleuritic chest pain. Coronal
reformatted image of the right interlobar artery and the posterobasal segment of
the pulmonary artery demonstrates dense contrast material superior and inferior
to a region of poorly enhanced blood (arrow).

54. -
FlowrelatedArtifact
-
FlowrelatedArtifact

55. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

56. WindowSettings

WindowSettings
•Very bright vessel contrast can obscure small
pulmonary emboli.
•Pulmonary embolism–specific window: window width
and level of 700 and 100 HU.

57. WindowSettings

WindowSettings
WW 400 552 700
WL 40 267 100
Brink et alPE specific window

58. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

59. StreakArtifact

StreakArtifact
•Beam-hardening Streak artifacts from dense contrast
material within the SVC are commonly seen.
•This artifact can be distinguished from pulmonary
embolism by
–Nonanatomic
–Poorly defined
–Radiating nature
•Reduced by flushing the SVC with saline solution using
dual chamber injectors.

60. StreakArtifact

StreakArtifact

61. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

62. LungAlgorithmArtifact

LungAlgorithmArtifact
•The lung algorithm
–A high-spatial-frequency reconstruction convolution kernel
–Used to improve the quality of images of the pulmonary
vessels, bronchi, and interstitium.
•This algorithm can create image artifacts that appear
similar to pulmonary emboli.
•However, these artifacts can be removed with a
standard algorithm.

63. LungAlgorithmArtifact

LungAlgorithmArtifact
lung algorithm standard algorithm

64. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

65. PartialVolumeArtifact

PartialVolumeArtifact
•Result of axial imaging of an axially oriented vessel.
•Contiguous images will not demonstrate more apparent
filling defects.
•The margins are often not sharp.
•Partial volume artifact will become less of an issue with
routine use of narrow detector widths.

66. PartialVolumeArtifact

PartialVolumeArtifact
(a) inferior to (a) superior to (a)
anterior segment of the left upper lobe

67. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

68. StairStepArtifact

StairStepArtifact
•Traversing low-attenuation lines on coronal and sagittal
images.
•Accentuated by cardiac and respiratory motion.
•Reduced by reconstructing the raw data with a 50%
overlap prior to three-dimensional image reconstruction.
•For example, when acquiring images with a 1.25-mm
detector width, a set of images with an overlap of 0.625
mm should be retrospectively generated.

69. StairStepArtifact

StairStepArtifact

70. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

71. PartialVolumeAveragingEffect

PartialVolumeAveragingEffect

inLymphNodes

inLymphNodes
•Hilar lymph nodes : upper lobe, interlobe, middle lobe
(lingular), and lower lobe groups.
•The location of lymph nodes are varies among patients.
•With a 1.25-mm detector width, lymphatic tissue can be
more easily distinguished from PE than 5 mm detector
width.
•Lymphatic tissue is extramural lesion.
•The review of sagittal and coronal reformatted images
can help in difficult cases.

72. PartialVolumeAveragingEffect

PartialVolumeAveragingEffect

inLymphNodes

inLymphNodes

73. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

74. VascularBifurcation

VascularBifurcation
•On axial images, vascular bifurcations may
simulate linear filling defects .
•Sagittal and coronal reformatted images can
help identify these normal anatomic structures.

75. VascularBifurcation

VascularBifurcation

76. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

77. MisidentificationofVeins

MisidentificationofVeins
•False filling defects may be demonstrated
within the pulmonary veins.
•Generally, arteries course adjacent to the
corresponding bronchi, with the exception of
the apical-posterior segment of the left upper
lobe and the lingular arteries.

78. MisidentificationofVeins

MisidentificationofVeins
CT scan shows unenhanced pulmonary veins (arrows), which can mimic complete
occlusive pulmonary embolism. However, this pitfall can be recognized by observing
veins on contiguous images to the level of the right atrium.

79. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

80. MucusPlug

MucusPlug
•A mucus plug within a bronchus, which may
also demonstrate peripheral wall enhancement
related to inflammation, can mimic acute
pulmonary embolism.
•In addition, viewing the bronchus on contiguous
images will demonstrate the true nature of the
artifact.

81. MucusPlug

MucusPlug

82. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

83. PerivascularEdema

PerivascularEdema
•Peribrochovascular interstitial thickening from
heart failure can mimics PE.
•Accompanying CT findings in heart
failure
–Diffuse ground-glass attenuation
–Interlobular septal thickening
–Diffuse peribronchovascular interstitial
thickening
–Bilateral pleural effusions.

84. PerivascularEdema

PerivascularEdema

85. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

86. LocalizedIncreaseinVascular

LocalizedIncreaseinVascular
ResistanceResistance
•A focal increase in vascular resistance from
consolidation or atelectasis.
•The unenhanced vessel may be normal
•The poor contrast enhancement may obscure
thrombus.
•A region of-interest measurement may be helpful if the
attenuation is greater than 78 HU.
•Further imaging may be necessary, consisting of either
repeat CT pulmonary angiography with an increased
delay or pulmonary angiography.

87. LocalizedIncreaseinVascular

LocalizedIncreaseinVascular
ResistanceResistance

88. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

89. PulmonaryArteryStumpInSitu

PulmonaryArteryStumpInSitu
ThrombosisThrombosis
•Intravascular thrombosis can identified in
a pulmonary artery stump.
•The criteria for in situ thrombus include
– Thrombus at the surgical site only.
– Absence of other pulmonary artery thrombi
remote from the stump site.

90. PulmonaryArteryStumpInSitu

PulmonaryArteryStumpInSitu
ThrombosisThrombosis
Pulmonary artery stump in situ thrombosis in a 69-year-old man who had undergone right
pneumonectomy for lung cancer. CT scan demonstrates pulmonary artery stump in situ
thrombosis that affects the right pulmonary artery (arrow).

91. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

92. PrimaryPulmonaryArtery

PrimaryPulmonaryArtery
SarcomaSarcoma
•Primary pulmonary artery sarcoma
–An uncommon cause of an intraluminal
arterial filling defect.
–Unilateral, lobulated, heterogeneously
enhancing masses at CT.
–May demonstrate vascular distention and
local extravascular spread.
–Acute angle and enhancement.

93. PrimaryPulmonaryArtery

PrimaryPulmonaryArtery
SarcomaSarcoma
Pulmonary artery sarcoma in a 65-year old woman with dyspnea. Contrast-enhanced
CT scan shows a heterogeneously enhancing, lobulated mass within the main
pulmonary artery (arrow). A metastatic deposit is noted within the right pulmonary artery
(arrowhead).

94. CausesofMisdiagnosisofPE

CausesofMisdiagnosisofPE
Patient-related Factors.Patient-related Factors.
•Respiratory Motion Artifact.
•Image Noise.
•Pulmonary Artery Catheter.
•Flow-related Artifact.
Technical Factors.Technical Factors.
•Window Settings.
•Streak Artifact.
•Lung Algorithm Artifact.
•Partial Volume Artifact.
•Stair Step Artifact.
Anatomic Factors.Anatomic Factors.
•Partial Volume Averaging Effect
in Lymph Nodes.
•Vascular Bifurcation.
•Misidentification of Veins.
Pathologic Factors.Pathologic Factors.
•Mucus Plug.
•Perivascular Edema.
•Localized Increase in Vascular
Resistance.
•Pulmonary Artery Stump In Situ
Thrombosis.
•Primary Pulmonary Artery
Sarcoma.
•Tumor Emboli.

95. TumorEmboli

TumorEmboli
•In a review of microscopic pulmonary
tumor emboli associated with dyspnea,
Kane et al found that
–Most common causes: CA prostate and CA
breast.
–Followed by hepatoma, CA stomach and
pancreas.

96. TumorEmboli

TumorEmboli
•Manifestations of tumor emboli at CT include
–Large emboli in the main, lobar, and segmental
pulmonary arteries, mimic PE.
–Small tumor emboli that affect subsegmental arteries
and produce vascular dilatation and beading that
increases in size over time
–Small tumor emboli that affect secondary pulmonary
lobule arterioles and have a tree-in-bud appearance.

97. TumorEmboli

TumorEmboli
•Common : small tumor emboli leading to
progressive dyspnea and subacute
pulmonary HT.
•Rare : larged tumor emboli.

98. TumorEmboli

TumorEmboli
Tumor embolus in a 78-year-old woman with dyspnea and endometrial stromal
sarcoma that invaded the inferior vena cava. CT scan shows a large tumor embolus
within the right lower lobe pulmonary artery (arrow).

99. TumorEmboli

TumorEmboli
Tumor emboli in a 60-year-old man with dyspnea and primary renal cell carcinoma.
vascular dilatation and beading of
subsegmental arteries
tree-in-bud appearance

100. The end….The end….

101. Signs of pulmonary hypertension Signs of pulmonary hypertension
•Main pulmonary artery diameter more than 29 mm.
•Diameter of MPA : Aorta > 1:1 = strong correlation
with elevated pulmonary artery pressure, especially in
patients younger than 50 years.
•Central pulmonary arteries in patients with chronic
thromboembolic pulmonary hypertension often are
asymmetric in size.
•Atherosclerotic calcification of arterial wall.
•Tortuous pulmonary vessels.

102. Main pulmonary artery diameter more than 29 mm

103. Chronic pulmonary thromboembolism and pulmonary hypertension in a 42-year-old man.
Axial contrast-enhanced CT scan.

104. Chronic pulmonary thromboembolism in an 80-year-old woman with a history of
acute pulmonary thromboembolism.
Oblique coronal 10-mmthick maximum intensity projection CT image

105. Signs of pulmonary hypertension Signs of pulmonary hypertension
•RV myocardial thickness greater than 4 mm.
•RV dilatation : a ratio of more than 1:1 between the
RV:LV diameters. (At widest points)
•Mild pericardial thickening or a small pericardial
effusion.
•May have enlarged lymph nodes.

106. Right heart abnormalities secondary to chronic thromboembolic pulmonary
hypertension in a 47-year-old man.
Axial contrast-enhanced CT scan.

107. Right heart abnormalities secondary to chronic thromboembolic pulmonary
hypertension in a 47-year-old man.
Axial contrast-enhanced CT scan.

108. Pulmonary embolism severity index
(PESI)
Points are assigned as follows:
1 for each year of age
10 for male sex
20 for HR>110 beats/min
10 for heart failure
30 for malignancy
10 for chronic lung disease
30 for SBP<100
20 for RR>30
20 for temp <36 degrees Celcius
60 for AMS
20 for PaO2<90%

109. PESI score
Class I <65
Class II 66-85
Class III 86-105
Class IV 106-125
Class V >125
30 day mortality increases with each class
Class V has a 25 fold higher risk of postdischarge
death than Class I
The PESI score can help you determine LOS at a
hospital

110. ImageNoise

ImageNoise