CT of the Chest

1. CT of the Chest Dorith Shaham, M.D. Department of Radiology Hadassah Medical Center

2. Indications for Chest CT • To evaluate abnormalities shown on CXR • To demonstrate or exclude a suspected CXR abnormality • To demonstrate an abnormality in a patient with a normal CXR

3. Types of Chest CT • Standard chest CT • Without IV contrast • With IV contrast • CT-angiography • PCTA (r/o PE) • Coronary CTA • HRCT • CT-guided intervention • Biopsy • Pleural drainage • Low-dose CT

4. IV contrast • Not used for pulmonary parenchimal abnormalities • Inherent high contrast • Always used for CT-angiography • May be used for evaluation of • Mediastinum • Hilum • Pleura

5. Metastatic Lung Ca (Adenocarcinoma)Rt. Hilar mass and small pleural effusion Without IV contrast

6. Anterior Mediastinal Mass : Germ cell tumor Without IV contrast With IV contrast

7. Chest CT with IV contrast Venous collaterals Thrombus SVC syndrome

8. CT-Angiography

9. Pulmonary Embolism:Imaging Modalities • Chest X-ray • V/Q scan • Computed tomography • Helical (spiral) CT • MRI • Pulmonary angiography: the “gold standard”

10. 69- year old female with shortness of breath

13. Ventilation-perfusion (V/Q) scan • Perfusion scan: distribution of blood flow • Macroaggregated human serum albumin (10-100 micron) labeled with Tc-99m • Ventilation scan: distribution of alveolar ventilation • Radioactive inert gas: X-133 • V/Q mismatch: abnormal perfusion and normal ventilation

14. Interpretation of V/Q scanning • Probability stratification approach (based on the assumption that the only reason for performing a V/Q scan is to diagnose PE): • High probability • Intermediate probability/ indeterminate • Low probability • Normal

16. Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) • Multi-institutional study conducted in the mid-80’s, • Purpose: to determine the sensitivity and specificity of V/Q scan compared with pulmonary angiogram • 933 patients with suspected PE • 931 had V/Q scan • 755 had pulmonary angiography • Study patients were followed clinically for 1 Y

17. PIOPED STUDY • High sensitivity of V/Q scan: 98% of patients with PE had abnormal scans (low, intermediate or high probability) • Low specificity: 10% • Non-diagnostic V/Q scans: 72%

18. CTPA • Direct visualization of clot • Imaging of associated findings • Pulmonary infarction • Pleural effusion • Imaging of alternative diagnosis

19. Pulmonary Embolism

20. Pulmonary Embolism with Infarction Atelectasis Infarction

21. Pulmonary Embolism

22. Combined PCTA/CTV • No additional contrast injection • Rapid examination • Imaging of portions of the deep venous system that are inadequately imaged by Duplex (pelvic veins, adductor canal)

23. HL: Massive PE

24. HL: Bilateral DVT

25. PIOPED II • To determine the sensitivity, specificity, positive/negative predictive value of spiral CT for the diagnosis of PE. • Reference for PE: various combinations of • V/P scan • Venous U/S • Pulmonary angiography • Contrast venography

26. PIOPED II • 824 patients with suspected PE • CTPA alone: • Sensitivity: 83% • Specificity: 96% • PPV: 96% (concordant high/low clinical probability), 92% (intermediate clinical probability)

27. PIOPED II • Combined CTPA + CTV: • Sensitivity: 90% • Specificity: 95% • Additional testing is necessary when clinical probability is inconsistent with imaging results N Engl J Med 2006;354:2317-27

28. 15-year old male with chest pain

30. Intramural hematoma Pericardial effusion Small right pleural effusion

31. Collateral blood flow

32. Coarctation of the aorta with enlarged internal mammary arteries

33. CT Coronary Angiography

34. High Resolution CT (HRCT)

35. HRCT: Technique • Narrow slice width • “Bone” reconstruction algorithm • Small field of view

36. HRCT: Ground glass opacity Chest CT HRCT

37. HRCT: scanning protocols • 1-mm slices every 10-mm/ Contiguous 1-mm slices • Supine/ Prone • Full inspiration/ Expiration

38. HRCT: patterns of lung disease • Reticular and short linear • Nodular • Increased lung opacity (“ground glass”) • Decreased lung density • Cysts • Emphysema • Bronchiectasis

39. CT vs. HRCT Sarcoidosis Multiple tiny perilymphatic nodules

40. HRCT: Bronchiectasis

41. CT-guided Needle Biopsy

42. Indications • Evaluation of • Solitary pulmonary nodule • Multiple pulmonary nodules • Mediastinal/hilar masses/lymphadenopathy • Chest wall masses • Retrieval of organisms from infectious lung lesions • Staging of tumors (lung cancer, extrathoracic)

43. Contraindications • An uncooperative patient • Bleeding diathesis • INR>1.3 • Platelet count<50,000 mm3 • Severe underlying lung disease • emphysema • Intractable cough

44. Image Guidance • CT • Fluoroscopy • visualization in 2 projections • Ultrasound • chest wall • pleura • anterior mediastinum • lung periphery

45. Advantages of CT-guided Biopsy • Needle path that avoids • aerated lung • fissures • large vessels • bullae • vital cardiovascular structures • Differentiation of necrotic vs. viable portions of tumor • I.V. contrast

46. Biopsy Needles:Westcott and Turner

47. Biopsy Needles:Cutting Spring-Acivated

48. Lung Biopsy: SPN(Squamous cell ca.)

49. Lung Biopsy: Multiple nodules(Alveolar soft part sarcoma)

50. Rib Biopsy: Multiple myeloma