Radiology: Only PA view needed for tuberculosis screening
A single posteroanterior (PA) view is sufficient for tuberculosis screening of individuals with positive purified protein derivative (PPD) skin test results, according to a study in the September issue of Radiology.

According to Ronald L. Eisenberg, MD, and colleagues from the department of radiology at Beth Israel Deaconess Medical Center in Boston, the Centers for Disease Control and Prevention and the American Thoracic Society recommend that individuals with PPD skin test results undergo screening chest radiography to allow physicians to confirm or exclude a diagnosis of pulmonary tuberculosis (TB). The organizations also suggested that the screening consist of a PA radiograph and that additional radiographs should be performed with the physician's discretion. Despite those recommendations, both PA and lateral radiographs continue to commonly obtained during TB screening.

Because of the value in reducing radiation dose, costs and workflow, the authors decided to investigate whether or not lateral radiographs provide any additional relevant diagnostic infomation when screeing for TB.

For purposes of the retrospective study, the authors studied 875 adults who, with positive PPD skin test results during pre-employment examinations, underwent PA and lateral view during chest radiography between Jan. 1, 2007 and Dec. 31, 2007.

All PA and lateral chest radiographs were available for reading at a PACS workstation (Centricity, version 2.1; GE Healthcare). Two attending chest radiologists interpreted the radiographs.

At first, only PA radiographs were analyzed. Thereafter, PA and lateral radiographs were analyzed together, with a specific note made as to whether any observed finding was identifiable only on the lateral radiograph or if it was present on both images. In all cases, a determination was made as to whether the findings on the lateral radiograph changed the decision made on the basis of findings on the PA radiograph.

The PA radiograph revealed abnormalities in all 91 (10.4 percent) of the subjects with positive findings at radiography. The lateral radiograph revealed no abnormality in 75 subjects (83.4 percent).

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.

The authors concluded that in a pre-employment settting one PA radiograph is sufficient for TB screening of individuals with abnormal PPD skin test results. They further concluded that lateal radiographs provide no additional diagnostic value and that by eliminating them physicians can decrease radiation exposure without compromising patient care.