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 StudyUnder-reading % of positives Over-reading % of negatives 5 experts25- General271.7 Mass radiography321.7 Danish mass radiography321.6 Reader panel (15,000)391.2 10 best radiologists210.5 10 best physicians260.3 Average322 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
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 CXRs Estimate the probability of TB