The document discusses diagnostic criteria for acute and chronic pulmonary embolism (PE) based on CT imaging findings. For acute PE, findings include complete arterial occlusion seen as an enlarged artery, partial filling defects known as the "polo mint" or "railway track" signs, and peripheral intraluminal defects. Chronic PE criteria consist of complete occlusions that are smaller than adjacent vessels, peripheral crescent-shaped defects, recanalized smaller arteries, webs or flaps, and bronchial collaterals. The document also reviews methods of assessing PE severity including pulmonary artery clot load scores and signs of right heart strain. Common causes of misdiagnosing PE include mimic pathologies and technical imaging factors.

1. CHEST CONFERENCE
03.03.2015
THORSANG CHAYOVAN R1
CHAIYAPONGSE TANGSITTITUM R1

2. Outline
 Image findings in acute and chronic PE
 PE severity index by imaging
 Causes of misdiagnosis

3. Pulmonary embolism
 The third most common acute CVS disease after
myocardial infarction and stroke
 Diagnostic tests for thromboembolic disease include
 D-dimer assay
○ high sensitivity but poor specificity
 ventilation-perfusion scintigraphy,
○ high sensitivity but very poor specificity
 lower limb ultrasonography
○ high specificity but low sensitivity
 CTA
○ sensitivities of 53%–100% and specificities of 83%–
100%

4. Pulmonary embolism
 Diagnostic criteria for
 Acute PE
 Chronic PE

5. Acute PE

6. Diagnostic Criteria for acute PE
 Complete arterial occlusion
 The artery may be enlarged compared with
adjacent patent vessels

7. Acute occlusive PE in a 32-year-old womanwith chestpain.CT scan shows a PE within the posterobasal
segmentof RLL.

8. Diagnostic Criteria for acute PE
 A partial filling defect surrounded by
contrast material
 “polo mint” sign
 “railway track” sign

9. Same pt: CT scan shows a pulmonary embolus thataffects the segmentalartery of the laterobasalsegmentof the
RLL.This partialfilling defectsurrounded by contrastmaterialproducesthe polo mint sign

10. Acute pulmonary embolism in a 66-year-old man .
CT scan shows an acute PE that causes a partialfilling defectsurroundedby contrastmaterial(railway tracksign)

11. Diagnostic Criteria for acute PE
 A peripheral intraluminal filling defect
 Acute angles with the arterial wall

12. Acute PE in a 58-year-old woman.CT scan demonstrates a PE thatresults in an eccentrically positioned partial
filling defect,which is surroundedby contrastmaterialand forms acute angleswith the arterial wall (arrows).

13. Diagnostic Criteria for acute PE
 Ancillary findings: infarcts
 Peripheral wedge-shaped areas of
hyperattenuation
 Linear bands
Not specific for pulmonary embolism.

14. Same ptwith acute PE. CT scan shows ancillary findings of a peripheralwedge-shaped area of hyperattenuation in
the lung (arrow), a finding thatmay representan infarct,as well as a linear band (arrowhead).

15. Diagnostic Criteria for acute PE
Pulmonary arteries are indeterminate.
Lungs are clear.
To evaluate for pulmonary embolism
 Ventilation-perfusion scintigraphy
 Repeat CT pulmonary angiography

16. Chronic PE

17. Diagnostic Criteria for chronic PE
 Complete occlusion
 smaller than adjacent patent vessels

18. Figure 11. Chronic pulmonaryembolismin a 27-year-old man with dyspnea.CT scan showscomplete occlusion
of vessels in the left lung (arrowheads)thatare smallerthan adjacentpatentvessels.Note the collateralblood
supply from a branch of the right hemidiaphragmatic artery (arrow).

19. Diagnostic Criteria for chronic PE
 Peripheral, crescent-shaped, obtuse
angles with vessel wall

20. Chronic PE in a 62-year-old man with dyspnea.CT scan showsan eccentrically located thrombus thatforms
obtuse angles with the vesselwall (arrows).Silated collateralbronchialartery (arrowhead).

21. Diagnostic Criteria for chronic PE
 Smaller arteries(recanalization)

22. Same patient. CT scan reveals a small, recanalized pulmonary artery with contrastmaterialin the centrallumen

23. Diagnostic Criteria for chronic PE
 A web or flap within a contrast material–
filled artery

24. Chronic PE in a 56-year-old man with dyspnea.CT scan showsa flap (arrow) within a small right interlobar
pulmonary artery.Collateralbronchialartery dilatation is also noted (arrowhead)

25. Diagnostic Criteria for chronic PE
 Bronchial or other systemic collateral
vessels

26. Same patientas in Figure 12. CT scan shows a large chronic PE in the main and left main pulmonary arteries
(arrowhead).Arrows indicate collateralbronchialarteries.

27. Diagnostic Criteria for chronic PE
 Calcification within eccentric vessel
thickening

28. Chronic pulmonaryembolism in a 62-year-old man with dyspnea.CT scan shows pulmonary arterialwallcalcificatio
(arrows),a secondary sign of chronic pulmonary embolism.

29. Diagnostic Criteria for chronic PE
 PA diameter > 30 mm, pericardial fluid

30. Same pt: Pulmonary arterialHTN secondaryto chronic PE--PA41 mm in diameter

31. Diagnostic Criteria for chronic PE
 Pericardial fluid

32. Chronic pulmonary embolismin the same patientas in Figure 12. CT scan demonstratespericardialfluid
(arrows)associatedwith pulmonary arterialhypertensionsecondaryto chronic pulmonaryembolism.

33. Common findings
in both acute and chronic PE

34. Other findings of both acute and
chronic PE
 Mosaic perfusion pattern

35. Chronic PEin a 60-year-old woman.CT scan demonstrates a mosaic perfusionpattern.The darkregions of
underperfused lung are seen to contain vessels (arrows)thatare smaller than the adjacentpatentvessels in the

36. Right ventricular strain or failure
 Optimally monitored with echocardiography
 CT pulmonary angiography
 RV dilatation
○ wider RV cavity than in the short axis
○ ± contrast material reflux into the hepatic veins
 Deviation of the interventricular septum toward
the LV

37. Acute PE in a 42-year-old man.CT scan reveals thatthe short axis of the right ventricle (dashed line)is wider than
thatof the left ventricle (solid line)

38. PE severity index

39. PE severity index by imaging
 PA clot load scores
 Right heart strain
 Leftward bowing of the interventricular
septum
 IVC contrast reflux

40. PA Clot Load Scores
 The presence, location, and degree of
obstruction of arterial clots
 Four different scoring systems by
 Miller et al
 Walsh et al
 Qanadli et al
 Mastora et al
Angiography
CTA
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Walsh PN, Greenspan RH, Simon M, et al. An angiographic severity index for pulmonary embolism. Circulation 1973;47-
48(suppl):101–108.
Qanadli SD, El Hajjam M, Vieillard-Baron A, et al. New CT index to quantify arterial obstruction in pulmonary embolism: comparison
with angiographic index and echocardiography.AJR Am J Roentgenol 2001;176:1415–1420.
Mastora I, Remy-Jardin M, Masson P, et al. Severity of acute pulmonary embolism: evaluation of a new spiral CT angiographic score
in correlation with echocardiographic data. Eur Radiol 2003;13: 29 –35.

41. Qanadli Score
 Each lung has 10 segmental PAs
 3 to the upper lobes
 2 to the middle lobe or lingula
 5 to the lower lobes
 An embolus in a segmental PA = 1 point, and
 Emboli at the most proximal arterial level = No. of
segmental PAs arising distally.
 Perfusion distal to the embolus weighting factor
 0 no defect
 1 partial occlusion
 2 complete occlusion
 An isolated subsegmental embolus is considered a
partially occluded segmental PA and is assigned a value of
1.
 The maximum CT obstruction index is 40

42. Mastora Score
 5 mediastinal PAs
 PA trunk
 Right and left Pas
 Right and left interlobar Pas
 6 lobar PAs
 20 segmental PAs
 Three in the upper lobes
 Two in the middle lobe or lingula
 Five in the lower lobes
 based on the percentage of obstructed surface of each
central and peripheral PA section and uses a 5-point scale
 1 25%, 2 25%– 49%, 3 50%–74%, 4 75%–99%, 5 100%
 The maximum CT obstruction score is 155
Central
Peripheral

43. PA Clot Load Scores
 Wu et al
 PA clot load score > 60% tended to succumb
 Wu et al and Van der Meer et al
 Qanadli score is a significant predictor of
death
Wu AS, Pezzullo JA, Cronan JJ, Hou DD, MayoSmith WW. CT pulmonary angiography: quantifi-
cation of pulmonary embolus as a predictor of patient outcome—initial experience. Radiology
2004;230:831– 835.
Van der Meer RW, Pattynama PM, van Strijen MJ, et al. Right ventricular dysfunction and
pulmonary obstruction index at helical CT: prediction of clinical outcome during 3-month follow-up in
patients with acute pulmonary embolism. Radiology 2005;235:798 – 803

44. PA Clot Load Scores
 Indicator of the severity of the current
episode of PE or treatment
effectiveness, it seems that they cannot
be used as a predictor of RV failure and
death of the patient.
Collomb D, Paramelle PJ, Calaque O, et al. Severity assessment of acute pulmonary embolism:
evaluation using helical CT. Eur Radiol 2003;13: 1508 –1514.
Ghaye B, Ghuysen A, Willems V, et al. Pulmonary embolism CT severity scores and CT
cardiovascular parameters as predictor of mortality in patients with severe pulmonary embolism.
Radiology.
Araoz PA, Gotway MB, Trowbridge RL, et al. Helical CT pulmonary angiography predictors of in-
hospital morbidity and mortality in patients with acute pulmonary embolism. J Thorac Imaging
2003;18:207–216.

45. PA Diameter Measurement
 A PA diameter > 30 mm indicates a PA
pressure > 20 mm Hg.
 Qanadli et al reported a poor correlation
between the PA clot load scores and the
mean PA pressure.
Kuriyama K, Gamsu G, Stern RG, Cann CE, Herfkens RJ, Brundage BH. CT-determined pulmonary
artery diameters in predicting pulmonary hypertension. Invest Radiol 1984;19:16 –22.
Qanadli SD, El Hajjam M, Vieillard-Baron A, et al. New CT index to quantify arterial obstruction in
pulmonary embolism: comparison with angiographic index and echocardiography.AJR Am J
Roentgenol 2001;176:1415–1420.

46. Leftward bowing of the
interventricular septum
 Related to severe PA obstruction.
 However, this sign does not seem to be
an indicator of outcome.
Oliver TB, Reid JH, Murchison JT. Interventricular septal shift due to massive pulmonary embo lism
shown by CT pulmonary angiography: an old sign revisited. Thorax 1998;53:1092–1094.
Collomb D, Paramelle PJ, Calaque O, et al. Severity assessment of acute pulmonary embolism:
evaluation using helical CT. Eur Radiol 2003;13: 1508 –1514.

47. Reflux of Contrast Medium into
IVC
 No significant difference between
patients with severe PE and patients
with nonsevere PE in regard to this sign.
Collomb D, Paramelle PJ, Calaque O, et al. Severity assessment of acute pulmonary
embolism: evaluation using helical CT. Eur Radiol 2003;13: 1508 –1514.

48. Causes of Misdiagnosis of
Pulmonary Embolism

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

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

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

52. Causes of Misdiagnosis of PE:
Pathologic Factors
 Pulmonary Artery Stump In Situ Thrombosis

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

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

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

56. Causes of Misdiagnosis of PE:
Pathologic Factors
 Takayasu Arteritis

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

60. Other causes of Misdiagnosis of
PE
 Anatomic Factors
 Partial Volume Averaging Effect in Lymph
Nodes
 Vascular Bifurcation
 Misidentification of Veins
 Technical Factors
 Window Settings
 Streak Artifact
 Lung Algorithm Artifact
 Partial Volume Artifact

61. Other causes of Misdiagnosis of
PE
 Patient-related Factors
 Respiratory Motion Artifact
 Image Noise
 Pulmonary Artery Catheter
 Flow-related Artifact

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

65. PE severity index by imaging
 PA clot load scores
 > 60%
 Unreliable
 Right heart strain
 Relate with PHTN
 Leftward bowing of the interventricular
septum
 IVC contrast reflux

66. Causes of Misdiagnosis of PE
 Technique-related
 Patient-related
 Anatomic-related
 Another pathology of the lung or vessels

67. References
 Wittram, C., M. M. Maher, A. J. Yoo, M. K.
Kalra, J.-A. O. Shepard, and T. C. Mcloud. "CT
Angiography of Pulmonary Embolism:
Diagnostic Criteria and Causes of
misdiagnosis." Radiographics 24.5 (2004):
1219-238.
 Ghaye, B., A. Ghuysen, P.-J. Bruyere, V.
D'orio, and R. F. Dondelinger. "Can CT
Pulmonary Angiography Allow Assessment of
Severity and Prognosis in Patients Presenting
with Pulmonary Embolism? What the
Radiologist Needs to
Know." Radiographics 26.1 (2006): 23-39

68. References
 Pena, E., Dennie, C., Veinot, J., & Muniz, S.
(2012). Pulmonary Hypertension: How the
Radiologist Can Help. Radiographics, 9-32
 Grosse, C., & Grosse, A. (2010). CT Findings
in Diseases Associated with Pulmonary
Hypertension: A Current
Review. Radiographics, 1753-1777.
 Wijesuriya, S., Chandratreya, L., & Medford, A.
(2013). Chronic Pulmonary Emboli and
Radiologic Mimics on CT Pulmonary
Angiography. Chest Journal, 1460-1471.