Clinical Technology Jpn J Radiol Technol 2000 ;
Clinical Utility of Temporal Subtraction for Detection
of LungAbnormalities on Digital Chest Radiographs

KATSUMI NAKAMURA, TOSHIMI UOZUMI, HIROYUKI TAKAHASHI,
HIROKO OKAZAKI, SHINGO KAKEDA, KOJI KAMADA, NOBUHIRO ODA,1) SEIICHI MURAKAMI,1) KEIJI FUJIMOTO,1) HAJIME NAKATA,
SHIGEHIKO KATSURAGAWA,2) and KUNIO DOI3)
Department of Radiology, University of Occupational and Environmental Health, School of Medicine
1) Department of Radiology, University of Occupational and Environmental Health, School of Medicine
2) Department of Radiology, Iwate Medical University
3) Department of Radiology, University of Chicago
Received Nov. 19, 1999; Revision accepted Jan. 22, 2000; Code No. 253
Summary
Temporal subtraction is a technique by which a previous chest radiograph is automatically registered with and subtracted from a current radiograph for the enhancement of interval changes. In this study, we evaluated the clinical utility of temporal subtraction in various lung abnormalities. Detection of lung nodules, particularly those overlapping normal anatomical structures such as ribs, heart, and pulmonary hilum was improved. For follow-up examinations of diffuse infiltrative lung diseases, new abnormalities, such as acute exacerbation or associated lung cancer, become more apparent on subtraction images because pre-existing fibrotic changes are clearly subtracted. Diffuse ground-glass opacities, which may be difficult to evaluate by chest radiography, are demonstrated as characteristic mild diffuse inhomogeneous opacities by temporal subtraction. Our results indicate that temporal subtraction can provide improved accuracy in the interpretation of chest radiographs.
Key words: Chest rediography, Digital radiography, Temporal subtraction