Infections

1. Infections

2. Pneumonia • 6th leading cause of death in the US • 1st leading cause of death by infection • Early diagnosis by the clinician is key to decreasing morbidity and mortality and expenses for treating pneumonia

3. Role of Imaging in Pneumonia • Diagnosis of infection • Recognition of complications • Not necessarily pathogen diagnosis • Organisms may cause more than one radiographic pattern • Most useful when read in setting of clinical diagnosis.

4. Radiographic patterns • Lobar- Most common associations S. pneumo and K. Pneumo • Lobular (broncho pneumonia)-Mycoplasma most commonly associated • Interstitial-viruses • Lobar and bronchopneumonia are alveolar filling pneumonias- consolidation • Interstitial pneumonia will look like too many lines

5. Associated findings • air bronchograms • the silhouette sign • parapneumonic effusions

6. Lobar pneumonia S. pneumoinae K. pneumoniae Also seen with Legionella, Mycoplasma, H. Influenza Bronchopneumonia Gram-’s, anaerobes Legionella Actinomycosis Nocardia Mycoplasma Typical, atypical Tb Parasites Etiologic agents

7. Radiographic patterns • Lobar pna tends to be homogeneous • Prominent air bronchograms • Preserved volume- vs atelectasis

8. Bronchopneumonia Tends to be heterogeneous, patchy, coarse and irregular Can be difficult to differentiate from interstitial pna Radiographic patterns

9. Radiographic patterns • Interstitial pna • Usually viral pnas • Influenza A,B,C • Parainfluenza • RSV • Adneoviruses • Herpes viruses • SARS • “Too many lines”

10. Complications of Pneumonias • Pleural infection- • Empyema- purulent exudate,WBC > 25,000 and positive organisms

11. Complications of Pneumonias • Cavitation • Cavitary pneumoina • Lung abscess • Pneumatocele • Gangrene

12. Complications of Pneumonias • Pneumatocele- Ball-valve mechanism • Most common with S. aureus

13. Complications of Pneumonias • Bronchiectasis-dilatation of bronchi usually due to chronically impacted bronchi with mucus increasing pressure • Common with atypical Tb and aspergillus

14. Caution! • Beware of nonresolving consolidation • There are noninfectious causes of chronic consolidation- especially in elderly people • Ex include • Bronchoalveolar Carcinoma • Eosinophilic pna • Cryptogenic organizing pna • Consider consult or biopsy!

15. Tuberculosis • Primary tuberculosis- can present without sx and normal chest x-ray, • Can appear with lobar consolidation in any lobe with preference for upper lobes, adenopathy, atelectasis and pleural effusion • Adenopathy is usually unilateral, usually on the right or paratracheal- more common in children • Pleural effusion more common in adults • Cavitation is RARE! • Usually heals with calcification-granulomas and calcified Lymph nodes

16. Primary Tb

17. Tuberculosis • Post primary Tb • Reactivation Tb-Usually in adults is a reactivation of a focus acquired in childhood • Limited to apical and posterior segments of upper lobes and superior segments of lower lobes • Healing occurs with contraction and fibrosis • Patterns- • Cavitation is common with thin walled cavity • Transbronchial spread – ex from one upper lobe to contralateral lower lobe • Bronchostenosis-narrowed airways • Pleural effusion- direct extension to pleural cavity • Direct extension to ribs

18. Reactivation Tb

19. Miliary Tb • Hematogenous spread of bacilli during primary Tb infection • Fever, chills, night sweats • 1mm nodules initially

20. Aspergillus • Ubiquitous fungus • May result in disease when inhaled in susceptible hosts • Infection usually occurs in immunocompromised hosts • Degree of immunocompromise determines pattern of infection

21. Aspergillus • Main patterns of infection • Decreased immunity • Invasive aspergillosis – angioinvasive, airway invasive • Chronic necrotizing • Normal Immunity • Aspergilloma • Hyperimmunity • Allergic bronchopulmonary aspergillosis (ABPA) • Hypersensitivity pneumonitis

22. Angioinvasive • Severe immunocompromise- BMT, AIDS, high dose steroids, hematogenous malignancy • Maximal Risk: WBC < 500 cells/mm3 • Patchy consolidation and nodules that have ground glass halo, which then cavitate when neutropenia improves ( “ air cresecent sign”

23. Angioinvasive

24. Aspergilloma • Occur in pre-existing cavity in upper lobes- COPD, Bronchiectasis, Sarcoid • Cavity with internal opacity- opacity is mobile and demonstrates air crescent sign

25. ABPA • Occurs with systemic hypersensitivity • Occurs usually in asthmatics • Eosinophilia documented • Components • Bronchiectasis- mid and upper lungs, centrally • Mucoid impaction- transient and recurrent- “gloved finger”

26. ABPA

27. Mediastinum • The key to the mediastinum is knowing the anatomy and what resides in each compartment • Pathology includes a range of tumors as well as infections, congenital abnormalities, vascular malformations, cardiac pathology and esophageal pathology

28. Mediastinal Compartments • Anteriorsuperior (retrosternal space)- includes the thymus, the extrapericardial aorta and its branches, the great veins, and lymphatic tissue • Middle-includes the heart, intrapericardial great vessels, pericardium, and trachea • Posterior- includes the esophagus, vagus nerves, thoracic duct, sympathetic chain, and azygous venous system,and extends to the posterior aspect of the vertebral bodies and posterior ribs.

29. Mediastinum

30. Anterior mediastinum • Masses- differential diagnosis • The 4 “T”’s- not all inclusive- but includes majority • Thymus tumors- Thymoma, thymolipoma • Teratoma- and other Germ Cell tumors (e.g. seminoma) • Thyroid goiter • Terrible Lymphoma

31. Anterior mediastinum • Radiology: • Terrible Lymphoma: big bulky LAD, absence of calcification is a discriminating feature • Thymomas- Age over 40, 20-25% contain calcium, solid and well defined, unilateral, can be cystic . Associated with Myasthenia Gravis • Teratomas (Germ Cell tumors)predominately cystic, age < 40.  Often calcification or fat  • Thyroid goiter/CA is continuous with thyroid in neck, high attenuation (iodine) – usually superior mediastinum

32. Where is the mass?

33. Anterior mediastinal mass • Anterior- crosses midline- germ cell tumor or lymphoma

34. Substernal Goiter

35. Thymoma- > age 40, typically solid, can have peripheral thin calcifications, can be cystic, usually to one side of midline

36. Morgagni Hernia

37. Middle medisatinum • Tumors of the middle mediastinum include pericardial cysts, bronchogenic cysts and lymphomas. A middle mediastinal mass may also represent lymphadenopathy as a result of infectious, malignant (metastatic), and idiopathic (eg sarcoidosis) etiologies. • Mediastinitis from prior granulomatous disease

38. Middle mediastinal masses • Pericardial cyst Bronchogenic cyst

39. Fibrosing mediastinitis • Notice soft tissue thickening surrounding trachea and narrowing it after histoplasmosis infection. Esophagus may be obliterated.

40. Posterior mediastinal mass

41. Posterior Mediastinum • Neurogenic tumor:  Schwannoma, neurofibroma, ganglioneuroma, neuroblastoma • Enteric/neurenteric cyst • Lateral thoracic meningocele • Osteocartilaginous tumor • Pulmonary mass or consolidation abutting mediastinum • Extramedullary hematopoesis • Paraspinal abscess, hematoma

42. Posterior mediastinal mass • Paraspinal ganglioneuroma- notice intimacy with spinal canal and mass effect on trachea

43. Aortic Aneurysm • Anuerysm can occur in any part of the mediastinum depending on where the aneurysm occurs, so consider it in all your differentials

44. Nodules and Masses

45. Definitions • Nodule: any pulmonary lesion represented in a radiograph by a sharply defined, discrete, nearly circular opacity ranging from 2-30 mm • Mass= nodule > 3 cm • Not all masses or nodules are malignant, but frequency of malignancy is higher in masses

46. Solitary Pulmonary Nodule • What should you do next?

47. Diagnostic Dilemma • Solitary Pulmonary Nodule- What do you do with it? • Options- compare with old films, get follow up films, CT scan, PET scan, biopsy or lung resection • Multiple guidelines have been issued and are confusing • Clinicians must consider age of the patient and risk factors such as smoking for possibility of cancer • Certain radiologic characteristics can help suggest that a nodule or mass is benign or malignant • Calcification pattern- central, popcorn or lamellated are benign • Fat within lesion- suggests hamartoma, benign • Spiculated margins and distortion of vessels suggests malignancy • Cavitation can occur in either- but malignant tumors have thicker walled cavities • Stability in size for 2 years • Double in volume equals increase in diameter by 25%- suggests malignant

48. Diagnostic Considerations • Neoplasm - Primary malignancy- Small Cell, Squamous Large Cell, Adenocarcinoma - Metastasis - Benign – hamartoma Infection: fungus, prasites, abscess Congenital: sequestration, CCAM Non- infectious inflammatory- Wegener’s Granulomatosis Non- parenchymal lesions

49. Solitary Pulmonary Nodule • Nodule has central fat suggesting hamartoma. • No more work up necessary. • Also can see popcorn calcifications which is also characteristic

50. Malignant Primary neoplasms of lungs • Adenocarcinoma- (50%) most common, usually peripheral, low association with smoking, slow growth and early metastasis • Large Cell- (5%)Peripheral mass, nonspecific appearance, least • Squamous Cell (25%)–Central, endobronchial, Pancoast Tumor, most likely to cavitate, high association with smoking • Small Cell (20%)- Central, perihilar, SVC syndrome, Paraneoplastic sydromes, Fast growing and early mets