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CTA   of   Pulmonary Embolism:  Diagnostic Criteria and Causes of Misdiagnosis Presented by  EKKASIT SRITHAMMASIT, MD.
REVIEW Wittram C et al .  Radiographics .  2004  Sep - Oct;24 ( 5 ): 1219-38 .  PubMed PMID :  15371604 .  From the Depart...
Introduction <ul><li>M ost common acute cardiovascular disease   </li></ul><ul><li>M yocardial infarction  </li></ul><ul><...
Introduction <ul><li>Diagnostic tests for thromboembolic disease   </li></ul>5.  Pulmonary angiography  : standard for con...
Figure 1.  Graph illustrates that the number of  pulmonary angiographic  studies performed per inpatient with suspected th...
Figure 2.  Graph illustrates that the number of  ventilation-perfusion scans  performed per inpatient with suspected throm...
Figure 3.  Graph illustrates that the number of  CT studies  performed for pulmonary embolism per inpatient increased sign...
Introduction <ul><li>LEARNING OBJECTIVES </li></ul><ul><li>CT Technique </li></ul><ul><li>List the diagnostic criteria for...
CT Technique
CT  Technique <ul><li>16-section CT scanners: </li></ul><ul><li>IV access: 18- 20 G into antecubital vein. </li></ul><ul><...
 
CT  Technique <ul><li>Images displayed for interpretation  </li></ul>100 700 Pulmonary thromboembolism-specific window 40 ...
<ul><li>Multiplanar reformatted images </li></ul><ul><li>Maximum intensity projection images  </li></ul>
Diagnostic Criteria   for   PE
Diagnostic Criteria for PE <ul><li>Examined: Pulmonary artery. </li></ul><ul><ul><li>Main arteries. </li></ul></ul><ul><ul...
Diagnostic Criteria for PE <ul><li>Examined: Pulmonary artery. </li></ul><ul><ul><li>Normal </li></ul></ul><ul><ul><li>Con...
Acute Pulmonary Embolism <ul><li>Complete occlusion  :  </li></ul><ul><ul><li>Failure to enhance the entire lumen  due to ...
Acute Pulmonary Embolism <ul><li>Partial occlusion  :  </li></ul><ul><ul><li>“ Polo mint” sign </li></ul></ul><ul><ul><li>...
Acute Pulmonary Embolism <ul><li>Partial occlusion  :  </li></ul><ul><ul><li>“ Polo mint” sign </li></ul></ul><ul><ul><li>...
Acute Pulmonary Embolism <ul><li>Partial occlusion  :  </li></ul><ul><ul><li>“ Polo mint” sign </li></ul></ul><ul><ul><li>...
Acute Pulmonary Embolism <ul><li>Infarct </li></ul><ul><ul><li>Peripheral wedge-shaped areas of hyperattenuation </li></ul...
Acute Pulmonary Embolism <ul><li>Rt - sided heart failure   </li></ul><ul><ul><li>RV dilatation with or without contrast r...
Acute Pulmonary Embolism <ul><li>Unenhanced CT </li></ul><ul><ul><li>hyperattenuating filling defect  </li></ul></ul><ul><...
Acute Pulmonary Embolism
<ul><li>CTPA :help identify diseases that have symptoms similar to those of acute PE </li></ul><ul><ul><li>Pericarditis. <...
<ul><li>If findings in the pulmonary arteries are indeterminate and the lungs are clear </li></ul><ul><ul><li>ventilation-...
Chronic Pulmonary Embolism
Chronic Pulmonary Embolism <ul><li>C omplete  o cclusion  of a vessel that is  smaller than adjacent vessels . </li></ul>
Chronic Pulmonary Embolism <ul><li>A peripheral, crescent-shaped intraluminal defect that forms obtuse angles with the ves...
Chronic Pulmonary Embolism <ul><li>C ontrast material flowing through thickened, often smaller arteries due to recanalizat...
Chronic Pulmonary Embolism <ul><li>A  web or flap within a contrast material–filled artery </li></ul>
Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels ...
Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels ...
Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels ...
Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels ...
Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels ...
Chronic Pulmonary Embolism <ul><li>Pulmonary arterial hypertension </li></ul><ul><ul><li>A pulmonary artery diameter great...
Chronic Pulmonary Embolism
Causes of Misdiagnosis of Pulmonary Embolism
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Respiratory Motion Artifact <ul><li>Most common cause of misdiagnosis of PE . </li></ul><ul><li>Best seen with lung window...
Respiratory Motion Artifact
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Image Noise <ul><li>L arge patients have more quantum mottle . </li></ul><ul><li>Therefore, for patients weighing more tha...
Image Noise
 
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Pulmonary Artery Catheter <ul><li>Itself mimic pulmonary embolism.  </li></ul><ul><li>Beam-hardening artifacts. </li></ul>...
Pulmonary Artery Catheter
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Flow-related Artifact <ul><li>Poor mixture of blood and contrast material. </li></ul><ul><li>A flow-related artifact can b...
Flow-related Artifact Flow-related artifact in a 60-year-old woman with pleuritic chest pain. Coronal reformatted image of...
Flow-related Artifact
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Window Settings <ul><li>Very bright vessel contrast can obscure small pulmonary emboli.  </li></ul><ul><li>Pulmonary embol...
Window Settings WW  400  552  700 WL   40  267   100 Brink et al PE specific window
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Streak Artifact <ul><li>Beam-hardening Streak artifacts from dense contrast material within the SVC are commonly seen. </l...
Streak Artifact
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Lung Algorithm Artifact <ul><li>The lung algorithm  </li></ul><ul><ul><li>A high-spatial-frequency reconstruction convolut...
Lung Algorithm Artifact lung algorithm standard algorithm
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Partial Volume Artifact <ul><li>Result of axial imaging of an axially oriented vessel.  </li></ul><ul><li>Contiguous image...
Partial Volume Artifact ( a ) inferior to  ( a) supe rior to  ( a) anterior segment of the left upper lobe
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Stair Step Artifact <ul><li>Traversing low-attenuation lines on coronal and sagittal images. </li></ul><ul><li>Accentuated...
Stair Step Artifact
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Partial Volume Averaging Effect in Lymph Nodes <ul><li>Hilar lymph nodes : upper lobe, interlobe, middle lobe (lingular), ...
Partial Volume Averaging Effect in Lymph Nodes
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Vascular Bifurcation <ul><li>On axial images, vascular bifurcations may simulate linear filling defects .  </li></ul><ul><...
Vascular Bifurcation
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Misidentification of Veins <ul><li>False filling defects may be demonstrated within the pulmonary veins.  </li></ul><ul><l...
Misidentification of Veins CT scan shows unenhanced pulmonary veins (arrows), which can mimic complete occlusive pulmonary...
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Mucus Plug <ul><li>A mucus plug within a bronchus, which may also demonstrate peripheral wall enhancement related to infla...
Mucus Plug
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Perivascular Edema <ul><li>Peribrochovascular interstitial thickening from heart failure can mimics PE.  </li></ul><ul><li...
Perivascular Edema
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Localized Increase in Vascular Resistance <ul><li>A focal increase in vascular resistance from  consolidation or atelectas...
Localized Increase in Vascular Resistance
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Pulmonary Artery Stump In Situ Thrombosis <ul><li>Intravascular thrombosis can identified in a pulmonary artery stump. </l...
Pulmonary Artery Stump In Situ Thrombosis Pulmonary artery stump in situ thrombosis in a 69-year-old man who had undergone...
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Primary Pulmonary Artery Sarcoma <ul><li>Primary pulmonary artery sarcoma </li></ul><ul><ul><li>An uncommon cause of an in...
Primary Pulmonary Artery Sarcoma Pulmonary artery sarcoma in a 65-year old woman with dyspnea. Contrast-enhanced CT scan s...
Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul...
Tumor Emboli <ul><li>In a review of microscopic pulmonary tumor emboli associated with dyspnea,  Kane et al   found that  ...
Tumor Emboli <ul><li>Manifestations of tumor emboli at CT include   </li></ul><ul><ul><li>Large  emboli in the main, lobar...
Tumor Emboli <ul><li>Common : small tumor emboli leading to progressive dyspnea and subacute pulmonary HT. </li></ul><ul><...
Tumor Emboli Tumor embolus in a 78-year-old woman with dyspnea and  endometrial stromal sarcoma  that invaded the inferior...
Tumor Emboli Tumor emboli in a 60-year-old man with dyspnea and primary renal cell carcinoma. vascular dilatation and bead...
The end….
Signs of pulmonary hypertension  <ul><li>Main pulmonary artery diameter  more than 29 mm . </li></ul><ul><li>Diameter of M...
Main pulmonary artery diameter more than 29 mm
Chronic pulmonary thromboembolism and pulmonary hypertension in a 42-year-old man. Axial contrast-enhanced CT scan.
<ul><li>Chronic pulmonary thromboembolism in an 80-year-old woman with a history of acute pulmonary thromboembolism. </li>...
Signs of pulmonary hypertension  <ul><li>RV myocardial thickness  greater than 4 mm . </li></ul><ul><li>RV dilatation : a ...
<ul><li>Right heart abnormalities secondary to chronic thromboembolic pulmonary hypertension in a 47-year-old man. </li></...
<ul><li>Right heart abnormalities secondary to chronic thromboembolic pulmonary hypertension in a 47-year-old man. </li></...
Pulmonary embolism severity index (PESI) <ul><li>Points are assigned as follows: </li></ul><ul><ul><li>1 for each year of ...
PESI score <ul><li>Class I <65 </li></ul><ul><li>Class II 66-85 </li></ul><ul><li>Class III 86-105 </li></ul><ul><li>Class...
Image Noise
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CTA OF PULMONARY EMBOLISM

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CTA OF PULMONARY EMBOLISM

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CTA OF PULMONARY EMBOLISM

  1. 1. CTA of Pulmonary Embolism: Diagnostic Criteria and Causes of Misdiagnosis Presented by EKKASIT SRITHAMMASIT, MD.
  2. 2. REVIEW Wittram C et al . Radiographics . 2004 Sep - Oct;24 ( 5 ): 1219-38 . PubMed PMID : 15371604 . From the Department of Radiology, Massachusetts General Hospital and Harvard Medical School
  3. 3. Introduction <ul><li>M ost common acute cardiovascular disease </li></ul><ul><li>M yocardial infarction </li></ul><ul><li>S troke </li></ul><ul><li>Pulmonary embolism </li></ul>PE : results in thousands of deaths each year because it often goes undetected
  4. 4. Introduction <ul><li>Diagnostic tests for thromboembolic disease </li></ul>5. Pulmonary angiography : standard for confirm Spec. 83%–100% Sen. 53%–100% 4. CTA high specificity low sensitivity 3. Lower limb US poor specificity high sensitivity 2. VP scintigraphy poor specificity high sensitivity 1. D - dimer assay
  5. 5. Figure 1.  Graph illustrates that the number of pulmonary 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. 6. Figure 2.  Graph illustrates that the number of ventilation-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. 7. Figure 3.  Graph illustrates that the number of CT 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. 8. Introduction <ul><li>LEARNING OBJECTIVES </li></ul><ul><li>CT Technique </li></ul><ul><li>List the diagnostic criteria for acute and chronic PE at CTPA. </li></ul><ul><li>Describe the causes of misdiagnosis and indeterminate of PE at CTPA. </li></ul>
  9. 9. CT Technique
  10. 10. CT Technique <ul><li>16-section CT scanners: </li></ul><ul><li>IV access: 18- 20 G into antecubital vein. </li></ul><ul><li>Field : </li></ul><ul><ul><li>widest rib - to - rib </li></ul></ul><ul><ul><li>during breath hold after inspiration </li></ul></ul><ul><li>CT Protocol </li></ul>
  11. 12. CT Technique <ul><li>Images displayed for interpretation </li></ul>100 700 Pulmonary thromboembolism-specific window 40 350 Mediastinum window 600 1500 Lung window window level window width
  12. 13. <ul><li>Multiplanar reformatted images </li></ul><ul><li>Maximum intensity projection images </li></ul>
  13. 14. Diagnostic Criteria for PE
  14. 15. Diagnostic Criteria for PE <ul><li>Examined: Pulmonary artery. </li></ul><ul><ul><li>Main arteries. </li></ul></ul><ul><ul><li>Lobar arteries. </li></ul></ul><ul><ul><li>Segmental arteries. </li></ul></ul><ul><ul><li>Subsegmental arteries. </li></ul></ul><ul><li>PE: sharp intraluminal filling defects. </li></ul>
  15. 16. Diagnostic Criteria for PE <ul><li>Examined: Pulmonary artery. </li></ul><ul><ul><li>Normal </li></ul></ul><ul><ul><li>Containing acute pulmonary embolism </li></ul></ul><ul><ul><li>Containing chronic pulmonary embolism </li></ul></ul><ul><ul><li>Indeterminate with reason </li></ul></ul>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.
  16. 17. Acute Pulmonary Embolism <ul><li>Complete occlusion : </li></ul><ul><ul><li>Failure to enhance the entire lumen due to a large filling defect. </li></ul></ul><ul><ul><li>The artery may be enlarged compared with adjacent patent vessels </li></ul></ul>
  17. 18. Acute Pulmonary Embolism <ul><li>Partial occlusion : </li></ul><ul><ul><li>“ Polo mint” sign </li></ul></ul><ul><ul><li>“ railway track” sign </li></ul></ul><ul><ul><li>Acute angles peripheral intraluminal filling defect </li></ul></ul>
  18. 19. Acute Pulmonary Embolism <ul><li>Partial occlusion : </li></ul><ul><ul><li>“ Polo mint” sign </li></ul></ul><ul><ul><li>“ railway track” sign </li></ul></ul><ul><ul><li>Acute angles peripheral intraluminal filling defect </li></ul></ul>
  19. 20. Acute Pulmonary Embolism <ul><li>Partial occlusion : </li></ul><ul><ul><li>“ Polo mint” sign </li></ul></ul><ul><ul><li>“ railway track” sign </li></ul></ul><ul><ul><li>Acute angles peripheral intraluminal filling defect </li></ul></ul>
  20. 21. Acute Pulmonary Embolism <ul><li>Infarct </li></ul><ul><ul><li>Peripheral wedge-shaped areas of hyperattenuation </li></ul></ul><ul><ul><li>L inear bands </li></ul></ul><ul><ul><li>N ot specific </li></ul></ul>
  21. 22. Acute Pulmonary Embolism <ul><li>Rt - sided heart failure </li></ul><ul><ul><li>RV dilatation with or without contrast reflux into the hepatic veins </li></ul></ul><ul><ul><li>Deviation of the interventricular septum toward the LV </li></ul></ul><ul><ul><li>Right ventricular strain or failure is optimally monitored with echocardiography. </li></ul></ul>
  22. 23. Acute Pulmonary Embolism <ul><li>Unenhanced CT </li></ul><ul><ul><li>hyperattenuating filling defect </li></ul></ul><ul><ul><li>PE have been identified on 1.5% of CECT scans obtained for reasons other than evaluation for PE . </li></ul></ul>
  23. 24. Acute Pulmonary Embolism
  24. 25. <ul><li>CTPA :help identify diseases that have symptoms similar to those of acute PE </li></ul><ul><ul><li>Pericarditis. </li></ul></ul><ul><ul><li>Acute myocardial infarction. </li></ul></ul><ul><ul><li>Aortic dissection. </li></ul></ul><ul><ul><li>Esophagitis, esophageal rupture. </li></ul></ul><ul><ul><li>Pneumonia, lung cancer </li></ul></ul><ul><ul><li>Pneumothorax and pleuritis . </li></ul></ul><ul><ul><li>Chest wall : rib fractures and metastatic. </li></ul></ul>
  25. 26. <ul><li>If findings in the pulmonary arteries are indeterminate and the lungs are clear </li></ul><ul><ul><li>ventilation-perfusion scintigraphy </li></ul></ul><ul><ul><li>repeat CT pulmonary angiography </li></ul></ul><ul><ul><li>conventional pulmonary angiography </li></ul></ul>
  26. 27. Chronic Pulmonary Embolism
  27. 28. Chronic Pulmonary Embolism <ul><li>C omplete o cclusion of a vessel that is smaller than adjacent vessels . </li></ul>
  28. 29. Chronic Pulmonary Embolism <ul><li>A peripheral, crescent-shaped intraluminal defect that forms obtuse angles with the vessel wall </li></ul>
  29. 30. Chronic Pulmonary Embolism <ul><li>C ontrast material flowing through thickened, often smaller arteries due to recanalization </li></ul>
  30. 31. Chronic Pulmonary Embolism <ul><li>A web or flap within a contrast material–filled artery </li></ul>
  31. 32. Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels </li></ul></ul><ul><ul><li>M osaic perfusion pattern </li></ul></ul><ul><ul><li>C alcification within eccentric vessel thickening </li></ul></ul>Rt hemidiaphragmatic artery
  32. 33. Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels </li></ul></ul><ul><ul><li>M osaic perfusion pattern </li></ul></ul><ul><ul><li>C alcification within eccentric vessel thickening </li></ul></ul>Bronchial artery
  33. 34. Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels </li></ul></ul><ul><ul><li>M osaic perfusion pattern </li></ul></ul><ul><ul><li>C alcification within eccentric vessel thickening </li></ul></ul>
  34. 35. Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels </li></ul></ul><ul><ul><li>M osaic perfusion pattern </li></ul></ul><ul><ul><li>C alcification within eccentric vessel thickening </li></ul></ul>
  35. 36. Chronic Pulmonary Embolism <ul><li>S econdary signs </li></ul><ul><ul><li>B ronchial or other systemic collateral vessels </li></ul></ul><ul><ul><li>M osaic perfusion pattern </li></ul></ul><ul><ul><li>C alcification within eccentric vessel thickening </li></ul></ul>
  36. 37. Chronic Pulmonary Embolism <ul><li>Pulmonary arterial hypertension </li></ul><ul><ul><li>A pulmonary artery diameter greater than 33 mm. </li></ul></ul><ul><ul><li>Pericardial fluid. </li></ul></ul>
  37. 38. Chronic Pulmonary Embolism
  38. 39. Causes of Misdiagnosis of Pulmonary Embolism
  39. 40. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  40. 41. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  41. 42. Respiratory Motion Artifact <ul><li>Most common cause of misdiagnosis of PE . </li></ul><ul><li>Best seen with lung window: “Seagull sign” </li></ul><ul><li>Diminish as higher - order multisection CT , which requires a shorter breath hold , becomes more widely used . </li></ul>
  42. 43. Respiratory Motion Artifact
  43. 44. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  44. 45. Image Noise <ul><li>L arge patients have more quantum mottle . </li></ul><ul><li>Therefore, for patients weighing more than 250 pounds (113.4 kg) , we modify our protocol by increasing detector width to 2.5 mm </li></ul><ul><li>However, this increased detector width also decreases sensitivity for detection of pulmonary embolism. </li></ul>
  45. 46. Image Noise
  46. 48. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  47. 49. Pulmonary Artery Catheter <ul><li>Itself mimic pulmonary embolism. </li></ul><ul><li>Beam-hardening artifacts. </li></ul><ul><li>Identification of the catheter will demonstrate the true nature of this pitfall. </li></ul>
  48. 50. Pulmonary Artery Catheter
  49. 51. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  50. 52. Flow-related Artifact <ul><li>Poor mixture of blood and contrast material. </li></ul><ul><li>A flow-related artifact can be confidently diagnosed by </li></ul><ul><ul><li>Ill-defined margins </li></ul></ul><ul><ul><li>Demonstrating an attenuation level above 78 HU. </li></ul></ul><ul><li>However, further imaging may be necessary to exclude thrombus hidden in poorly enhanced vessels. </li></ul>
  51. 53. Flow-related Artifact 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).
  52. 54. Flow-related Artifact
  53. 55. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  54. 56. Window Settings <ul><li>Very bright vessel contrast can obscure small pulmonary emboli. </li></ul><ul><li>Pulmonary embolism–specific window: window width and level of 700 and 100 HU. </li></ul>
  55. 57. Window Settings WW 400 552 700 WL 40 267 100 Brink et al PE specific window
  56. 58. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  57. 59. Streak Artifact <ul><li>Beam-hardening Streak artifacts from dense contrast material within the SVC are commonly seen. </li></ul><ul><li>This artifact can be distinguished from pulmonary embolism by </li></ul><ul><ul><li>Nonanatomic </li></ul></ul><ul><ul><li>Poorly defined </li></ul></ul><ul><ul><li>Radiating nature </li></ul></ul><ul><li>Reduced by flushing the SVC with saline solution using dual chamber injectors. </li></ul>
  58. 60. Streak Artifact
  59. 61. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  60. 62. Lung Algorithm Artifact <ul><li>The lung algorithm </li></ul><ul><ul><li>A high-spatial-frequency reconstruction convolution kernel </li></ul></ul><ul><ul><li>Used to improve the quality of images of the pulmonary vessels, bronchi, and interstitium. </li></ul></ul><ul><li>This algorithm can create image artifacts that appear similar to pulmonary emboli. </li></ul><ul><li>However, these artifacts can be removed with a standard algorithm. </li></ul>
  61. 63. Lung Algorithm Artifact lung algorithm standard algorithm
  62. 64. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  63. 65. Partial Volume Artifact <ul><li>Result of axial imaging of an axially oriented vessel. </li></ul><ul><li>Contiguous images will not demonstrate more apparent filling defects. </li></ul><ul><li>The margins are often not sharp. </li></ul><ul><li>Partial volume artifact will become less of an issue with routine use of narrow detector widths. </li></ul>
  64. 66. Partial Volume Artifact ( a ) inferior to ( a) supe rior to ( a) anterior segment of the left upper lobe
  65. 67. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  66. 68. Stair Step Artifact <ul><li>Traversing low-attenuation lines on coronal and sagittal images. </li></ul><ul><li>Accentuated by cardiac and respiratory motion. </li></ul><ul><li>Reduced by reconstructing the raw data with a 50% overlap prior to three-dimensional image reconstruction. </li></ul><ul><li>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. </li></ul>
  67. 69. Stair Step Artifact
  68. 70. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  69. 71. Partial Volume Averaging Effect in Lymph Nodes <ul><li>Hilar lymph nodes : upper lobe, interlobe, middle lobe (lingular), and lower lobe groups. </li></ul><ul><li>The location of lymph nodes are varies among patients. </li></ul><ul><li>With a 1.25-mm detector width, lymphatic tissue can be more easily distinguished from PE than 5 mm detector width. </li></ul><ul><li>Lymphatic tissue is extramural lesion. </li></ul><ul><li>The review of sagittal and coronal reformatted images can help in difficult cases. </li></ul>
  70. 72. Partial Volume Averaging Effect in Lymph Nodes
  71. 73. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  72. 74. Vascular Bifurcation <ul><li>On axial images, vascular bifurcations may simulate linear filling defects . </li></ul><ul><li>Sagittal and coronal reformatted images can help identify these normal anatomic structures. </li></ul>
  73. 75. Vascular Bifurcation
  74. 76. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  75. 77. Misidentification of Veins <ul><li>False filling defects may be demonstrated within the pulmonary veins. </li></ul><ul><li>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 . </li></ul>
  76. 78. Misidentification of Veins 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.
  77. 79. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  78. 80. Mucus Plug <ul><li>A mucus plug within a bronchus, which may also demonstrate peripheral wall enhancement related to inflammation, can mimic acute pulmonary embolism. </li></ul><ul><li>In addition, viewing the bronchus on contiguous images will demonstrate the true nature of the artifact. </li></ul>
  79. 81. Mucus Plug
  80. 82. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  81. 83. Perivascular Edema <ul><li>Peribrochovascular interstitial thickening from heart failure can mimics PE. </li></ul><ul><li>Accompanying CT findings in heart failure </li></ul><ul><ul><li>Diffuse ground-glass attenuation </li></ul></ul><ul><ul><li>Interlobular septal thickening </li></ul></ul><ul><ul><li>Diffuse peribronchovascular interstitial thickening </li></ul></ul><ul><ul><li>Bilateral pleural effusions. </li></ul></ul>
  82. 84. Perivascular Edema
  83. 85. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  84. 86. Localized Increase in Vascular Resistance <ul><li>A focal increase in vascular resistance from consolidation or atelectasis . </li></ul><ul><li>The unenhanced vessel may be normal </li></ul><ul><li>The poor contrast enhancement may obscure thrombus. </li></ul><ul><li>A region of-interest measurement may be helpful if the attenuation is greater than 78 HU. </li></ul><ul><li>Further imaging may be necessary, consisting of either repeat CT pulmonary angiography with an increased delay or pulmonary angiography. </li></ul>
  85. 87. Localized Increase in Vascular Resistance
  86. 88. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  87. 89. Pulmonary Artery Stump In Situ Thrombosis <ul><li>Intravascular thrombosis can identified in a pulmonary artery stump. </li></ul><ul><li>The criteria for in situ thrombus include </li></ul><ul><ul><li>Thrombus at the surgical site only. </li></ul></ul><ul><ul><li>Absence of other pulmonary artery thrombi remote from the stump site. </li></ul></ul>
  88. 90. Pulmonary Artery Stump In Situ Thrombosis 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).
  89. 91. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  90. 92. Primary Pulmonary Artery Sarcoma <ul><li>Primary pulmonary artery sarcoma </li></ul><ul><ul><li>An uncommon cause of an intraluminal arterial filling defect. </li></ul></ul><ul><ul><li>Unilateral, lobulated, heterogeneously enhancing masses at CT. </li></ul></ul><ul><ul><li>May demonstrate vascular distention and local extravascular spread. </li></ul></ul><ul><ul><li>Acute angle and enhancement. </li></ul></ul>
  91. 93. Primary Pulmonary Artery Sarcoma 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).
  92. 94. Causes of Misdiagnosis of PE <ul><li>Patient-related Factors. </li></ul><ul><li>Respiratory Motion Artifact. </li></ul><ul><li>Image Noise. </li></ul><ul><li>Pulmonary Artery Catheter. </li></ul><ul><li>Flow-related Artifact. </li></ul><ul><li>Technical Factors. </li></ul><ul><li>Window Settings. </li></ul><ul><li>Streak Artifact. </li></ul><ul><li>Lung Algorithm Artifact. </li></ul><ul><li>Partial Volume Artifact. </li></ul><ul><li>Stair Step Artifact. </li></ul><ul><li>Anatomic Factors. </li></ul><ul><li>Partial Volume Averaging Effect in Lymph Nodes. </li></ul><ul><li>Vascular Bifurcation. </li></ul><ul><li>Misidentification of Veins. </li></ul><ul><li>Pathologic Factors. </li></ul><ul><li>Mucus Plug. </li></ul><ul><li>Perivascular Edema. </li></ul><ul><li>Localized Increase in Vascular Resistance. </li></ul><ul><li>Pulmonary Artery Stump In Situ Thrombosis. </li></ul><ul><li>Primary Pulmonary Artery Sarcoma. </li></ul><ul><li>Tumor Emboli. </li></ul>
  93. 95. Tumor Emboli <ul><li>In a review of microscopic pulmonary tumor emboli associated with dyspnea, Kane et al found that </li></ul><ul><ul><li>Most common causes: CA prostate and CA breast. </li></ul></ul><ul><ul><li>Followed by hepatoma, CA stomach and pancreas. </li></ul></ul>
  94. 96. Tumor Emboli <ul><li>Manifestations of tumor emboli at CT include </li></ul><ul><ul><li>Large emboli in the main, lobar, and segmental pulmonary arteries, mimic PE . </li></ul></ul><ul><ul><li>Small tumor emboli that affect subsegmental arteries and produce vascular dilatation and beading that increases in size over time </li></ul></ul><ul><ul><li>Small tumor emboli that affect secondary pulmonary lobule arterioles and have a tree-in-bud appearance . </li></ul></ul>
  95. 97. Tumor Emboli <ul><li>Common : small tumor emboli leading to progressive dyspnea and subacute pulmonary HT. </li></ul><ul><li>Rare : larged tumor emboli. </li></ul>
  96. 98. Tumor Emboli 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).
  97. 99. Tumor Emboli 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
  98. 100. The end….
  99. 101. Signs of pulmonary hypertension <ul><li>Main pulmonary artery diameter more than 29 mm . </li></ul><ul><li>Diameter of MPA : Aorta > 1:1 = strong correlation with elevated pulmonary artery pressure, especially in patients younger than 50 years. </li></ul><ul><li>Central pulmonary arteries in patients with chronic thromboembolic pulmonary hypertension often are asymmetric in size. </li></ul><ul><li>Atherosclerotic calcification of arterial wall. </li></ul><ul><li>Tortuous pulmonary vessels. </li></ul>
  100. 102. Main pulmonary artery diameter more than 29 mm
  101. 103. Chronic pulmonary thromboembolism and pulmonary hypertension in a 42-year-old man. Axial contrast-enhanced CT scan.
  102. 104. <ul><li>Chronic pulmonary thromboembolism in an 80-year-old woman with a history of acute pulmonary thromboembolism. </li></ul><ul><li>Oblique coronal 10-mmthick maximum intensity projection CT image </li></ul>
  103. 105. Signs of pulmonary hypertension <ul><li>RV myocardial thickness greater than 4 mm . </li></ul><ul><li>RV dilatation : a ratio of more than 1:1 between the RV:LV diameters. (At widest points) </li></ul><ul><li>Mild pericardial thickening or a small pericardial effusion. </li></ul><ul><li>May have enlarged lymph nodes. </li></ul>
  104. 106. <ul><li>Right heart abnormalities secondary to chronic thromboembolic pulmonary hypertension in a 47-year-old man. </li></ul><ul><li>Axial contrast-enhanced CT scan. </li></ul>
  105. 107. <ul><li>Right heart abnormalities secondary to chronic thromboembolic pulmonary hypertension in a 47-year-old man. </li></ul><ul><li>Axial contrast-enhanced CT scan. </li></ul>
  106. 108. Pulmonary embolism severity index (PESI) <ul><li>Points are assigned as follows: </li></ul><ul><ul><li>1 for each year of age </li></ul></ul><ul><ul><li>10 for male sex </li></ul></ul><ul><ul><li>20 for HR>110 beats/min </li></ul></ul><ul><ul><li>10 for heart failure </li></ul></ul><ul><ul><li>30 for malignancy </li></ul></ul><ul><ul><li>10 for chronic lung disease </li></ul></ul><ul><ul><li>30 for SBP<100 </li></ul></ul><ul><ul><li>20 for RR>30 </li></ul></ul><ul><ul><li>20 for temp <36 degrees Celcius </li></ul></ul><ul><ul><li>60 for AMS </li></ul></ul><ul><ul><li>20 for PaO2<90% </li></ul></ul>
  107. 109. PESI score <ul><li>Class I <65 </li></ul><ul><li>Class II 66-85 </li></ul><ul><li>Class III 86-105 </li></ul><ul><li>Class IV 106-125 </li></ul><ul><li>Class V >125 </li></ul><ul><li>30 day mortality increases with each class </li></ul><ul><li>Class V has a 25 fold higher risk of postdischarge death than Class I </li></ul><ul><li>The PESI score can help you determine LOS at a hospital </li></ul>
  108. 110. Image Noise

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