Diagnostic Evaluation Medical Evaluation & CXR Interpretation University of Michigan TB Consultant Washtenaw County Medical history Physical examination Testing for TB exposure (previously covered) Radiologic examination (X-Ray or CT scan of chest) Bacteriologic examination (covered this afternoon) Medical History Symptoms and duration History of TB exposure, infection, or disease Previous treatment for TB (completion status) Demographic risk factors for TB (age, country of origin, etc.) Medical risk factors for TB (HIV infection, diabetes, etc.) Symptoms of Pulmonary TB Cough: productive, prolonged Chest pain Hemoptysis Systemic symptoms: Fever, chills, night sweats, loss of appetite, weight loss Specific symptoms of extrapulmonary TB depend on site of disease Clinical Features of Pulmonary TB 188 adults with pulmonary TB, Los Angeles, prospective evaluation Clinical features % Cough 78 Weight loss 74 Fatigue 68 Fever 60 Night sweats 55 Chills 51 Anorexia 46 Chest pain 40 SOB 37 Hemoptysis 28 Barnes PF, et al. Chest 1988:94:316-320 When to Suspect TB Disease Cough illness >2-3 weeks + o Fever, night sweats, weight loss, and/or hemoptysis High risk for TB, unexplained illness, including respiratory symptoms of > 2-3 weeks duration o Recent exposure, known (+) TST, HIV, drug use, immigrant <5 years from high-risk region, high-risk congregate setting, homeless, immunosuppressed, advanced CKD, silicosis, others HIV (+), unexplained cough, fever High risk and unresponsive CAP after 7 days High risk and worrisome CXR MMWR 54:1 (2005) 1
Diagnosis of TB Disease Consideration of these factors leads to high, medium, or low index of suspicion Epidemiologic information Clinical, pathological, chest x-ray findings Know global and local TB epidemiology Demographics of cases Locations where potential transmission has occurred Endogenous and exogenous risk factors Illustrative case 33 yo woman presenting to the ER Two week h/o cold Cough-minimally productive Possible low grade fevers Malaise No chills or night sweats. Weight stable Recently arrived from China No h/o previous TB, or exposure. PPD status unknown No HIV risk factors Which of the following is the next best step? A. Send blood for a IGRA or place a PPD B. Start treatment for MTB with 4 drugs C. Order a CXR D. Discharge to home. F/U with primary care physician in one week Pathogenesis of Tuberculosis Droplet nuclei (1 to 5 µm) containing 2 or 3 organisms reach the alveoli Alveolar macrophages ingest M. tuberculosis organisms If the organism survives the initial defenses, it multiplies intracellularly After 2-12 weeks organisms grow to 10 3 to 10 4 in number, sufficient to elicit a cellular immune response Pathogenesis of Tuberculosis Before cellular immunity develops, organisms spread via lymphatics to hilar nodes and the blood stream Organisms deposited in the upper lung zones, kidneys, bones, and brain find environments that favor growth Activated T cells and macrophages from immune individuals form granulomas that limit spread Pathogenesis of Tuberculosis The majority of pulmonary M. tuberculosis infections are clinically and radiographically inapparent Most commonly, a positive tuberculin skin test or IGRA is the only indication infection with M. tuberculosis has occurred Patients with latent M. tuberculosis infection (LTBI) are not infectious and cannot transmit the organism 2
Transmission of Tuberculosis A CXR is a critical part of evaluating someone with suspected TB Do they have tuberculosis? Are they infectious? Small and Fujiwara NEJM 345:189-200, 2001 X-Rays When x-rays are produced and directed toward the patient, they may act in three basic ways: They may be unabsorbed completely absorbed scattered Which means they pass through the patient unchanged and strike the x-ray film the energy of the x-ray is totally deposited within the patient they are deflected within the patient but may still strike the x-ray film Tissue Density Whitest/Most Dense Metal Contrast material (i.e., x-ray dye) Bone Calcium Soft tissue Fat Air or gas Blackest/Least Dense Normal Frontal (PA) Chest Radiograph Normal Lateral Chest Radiograph 3
Lobes and Fissures Right Lung major (oblique) and minor (horizontal) fissures upper, middle, and lower lobes Left lung major (oblique) fissure lower and upper lobes (the lingula is part of the upper lobe) Basic Patterns of Disease Consolidation Interstitial Solitary nodule Mass Lymphadenopathy Cyst/cavity Pleural abnormalities Consolidation Also known as air space disease (ASD), alveolar filling disease, or acinar disease Normal Consolidation Appearance and Findings increased opacity ill defined, hazy, patchy, fluffy, or cloud-like silhouette sign air bronchograms butterfly or bat-wing pattern lobar or segmental distribution 4
Consolidation Pneumonia - RML & RLL Interstitial Lung Disease (ILD) Appearance and Findings reticular pattern, increased linear opacities interlobular septal thickening (Kerley B lines) peribronchial thickening (cuffing or tram tracking) honeycombing discrete miliary nodules reticulonodular pattern Normal Interstitial disease Linear Opacities Miliary Pattern 5
Lymphadenopathy Cavity Pleural Effusion See anything? Lordotic view Primary TB 6
TB in a 10 year old Post-Primary (Reactivation) Tuberculosis Tuberculoma TB: Paratracheal Adenopathy in HIV Anti-TNF therapy Baseline 3 months later 7
Could this be TB? Importance of screening contacts The effect of treatment Case 1 Baseline 2 months later Case 1: 6 months later Case 2 8
Case 2 CT scan Summary: TB radiographs Tuberculosis has a myriad of radiographic appearances Chest x-rays are snapshots and can t determine if the disease is active or infectious Tuberculosis may present atypically when patients are immune compromised Direct comparison to old films is critically important to follow disease progression Acknowledgements Daley, C.L., Gotway, M.B., Jasmer, R.M. (2006). Radiographic Manifestations of Tuberculosis (2 nd ed.). Francis J. Curry National TB Center (www.nationaltbcenter.edu) Goodman, L.R. (1999) Felson s principles of chest roentgenology: a programmed text (2 nd ed.). Philadelphia: Saunders. 9