Dec 15, 2015
Chest radiographs and TB
Graham Bothamley
Jean-Paul Zellweger
Plan of session
1. The typical chest x-ray of TB
2. Atypical chest x-rays
3. Extrapulmonary TB on the chest x-ray
4. Inactive tuberculosis
5. The normal chest x-ray with C+PTB
6. Differential diagnoses
What are the typical features of tuberculosis on a chest x-ray?
Chest x-rays
Study Under-reading% of positives
Over-reading% of negatives
5 experts 25 -
General 27 1.7
Mass radiography 32 1.7
Danish mass radiography 32 1.6
Reader panel (15,000) 39 1.2
10 best radiologists 21 0.5
10 best physicians 26 0.3
Average 32 2
Improvement only if >20,000 films read annually. Nakamura et al. Kekkaku 1970; 45:121
Conclusions from mass x-ray surveys
• Sudden, symptomatic onset as common as insidious onset
• Disease extent unrelated to duration (extensive S+PTB within first 3-6 m)
• Cavitation is not a late occurrence – its frequency is nearly the same at all temporal stages of the disease
Toman. Case finding and chemotherapy. WHO, Geneva, 1979
Atypical TB
• Lower zone
• No cavitation
• (miliary)
Atypical TB
• Female
• Diabetes
• HIV
• Elderly
Extrapulmonary TB
• Mediastinal lymph nodes
• Pleural effusions
• Paraspinal abscess
• Spinal disease
Pleural effusion
Pericardial TB
TB of the spine
Inactive or self-healed tuberculosis
• Primary focus/calcified granuloma
• Coin lesion
• Fibrosis
The normal chest radiograph with a positive M.tb culture
• Single isolate or repeated?
• Lab contamination – strain typing
• CT scan
• Treat?
Differential diagnosis
• Non-tuberculous mycobacterial disease
• Sarcoidosis
• Fungal disease
M. xenopi
NTMD
• Background of COPD
• Thicker pleural reaction
M. fortuitum
BronchiectasisTree in bud
Nodules
Mycobacterium spp. Runyon group III
The Quiz
Estimate the probability of the diagnosis of tuberculosis and indicate whether you think the person will be sputum smear-positive
• Read the histories and estimate a prior probability of TB
• Look at the CXRs again – in a different order this time and again estimate the probability of TB and whether the sputum smear will be positive
Exercise: 20 CXRsEstimate the probability of TB
1
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20