Threshold of detection of diffuse lung disease

A scintigraphic model of the lungs was used to study the threshold of detec tion of diffuse disease of the lungs. Methods: Randomly distributed cold le sions of 4, 8, 12 and 16 mm(3) block sizes were created, occupying 0%-50% o f lung tissue in steps of 1%. These were submitted for reporting to five ob servers each with a normal study for comparison. Results: No observer detec ted lesions of 4-mm(3) block size even when up to 50% of the lung was invol ved. All observers detected lesions of 8-mm(3) block size when a mean of 27 % or lung tissue was involved with lesions. As lesion size increased to 12 and 16 mm(3), observers detected lesions when a mean of 10% and 6% of lung tissue was involved, respectively. Comparison between views for each observ er showed that the lateral and anterior oblique views were used more often than the anterior, posterior oblique and posterior views. Conclusion: This model suggests that pulmonary scintigraphy has the potential to detect a di ffuse disease such as emphysema at an early stage of lung involvement. In g eneral, small anatomic lesions appear to have more profound scintigraphic c onsequences. However, even scintigraphic lesions of the order of sire of th e pulmonary acinus are easily detected.