Purpose: To test the hypothesis that lateral radiography adds no clinically relevant information to that acquired with posteroanterior (PA) radiography in individuals with positive purified protein derivative (PPD) skin test results.
Materials and methods: As part of routine practice, all 875 adults with positive PPD skin test results at pre-employment examinations performed at a medical center during 2007 underwent PA and lateral chest radiography. In this institutional review board-approved HIPAA-compliant study, the patient informed consent requirement was waived. Two radiologists retrospectively and independently interpreted each radiograph for evidence of abnormalities that were indicative of acute or chronic tuberculosis (TB) infection. First, only the PA radiograph was analyzed. Thereafter, both the PA radiograph and the lateral radiograph were analyzed together to determine if any observed finding was identified on only the lateral radiograph. If a finding was seen on both images, a determination was made as to whether the finding on the lateral radiograph changed the radiologist's decision based on the PA radiograph alone.
Results: The PA radiograph revealed abnormalities in all 91 (10.4%) subjects with positive findings at radiography. The lateral radiograph revealed no abnormality in 75 subjects (83.4%). All abnormalities seen on lateral radiographs were also seen on PA radiographs. When abnormalities were seen on both images, the information on the lateral image never caused the radiologist to change the decision he or she made on the basis of the PA image alone.
Conclusion: In a pre-employment setting, one PA radiograph is sufficient for TB screening of individuals with positive PPD skin test results. Elimination of the acquisition of lateral radiographs would substantially reduce radiation exposure.