title: Evaluation of the image quality of temporal subtraction images produced automatically in a PACS environment.
abstract: The aim of the study is to evaluate the reliable production of temporal subtraction images in a picture archiving and communication system environment and to establish objective criteria for the evaluation of image quality. A total of 117 temporal subtraction chest images (55 in the upright position, 62 in the supine position) were obtained in five consecutive days. In all of these, we confirmed that there were no interval changes on the original images, and cases with diffuse lung disease were excluded. The temporal subtraction images were classified by three chest radiologists into five levels: 5, excellent; 4, good; 3, acceptable; 2, poor; and 1, very poor. The following were examined: (1) the yield of adequate quality of the temporal subtraction images; (2) whether the temporal subtraction images were obtained in the warping or nonwarping mode; and (3) the correlation of the overall subjective image quality with the relative shift angles, relative shift distances, and the standard deviation of gray levels in the temporal subtraction images. The percentages of acceptable temporal subtraction images were 100% and 66% in the upright and supine positions, respectively. Sixteen (26%) of the 62 supine-position images were made in nonwarping mode, whereas all upright images were made in warping mode. Significant correlations were obtained in the relative shift angle (P < 0.05), relative horizontal shift distance (P < 0.05), and standard deviation of gray levels (P < 0.0001). Temporal subtraction images with acceptable image quality were obtained in the upright position. The objective criteria may be useful for the evaluation of image quality.
authors.affiliation: Department of Health Sciences, School of Medicine, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. sakai@shs.kyushu-u.ac.jp
authors.forename: Shuji
authors.initials: S
authors.lastname: Sakai
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Soeda
authors.forename: Akio
authors.initials: A
authors.lastname: Furuya
authors.forename: Hidetake
authors.initials: H
authors.lastname: Yabuuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Okafuji
authors.forename: Keiji
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
authors.forename: Kunio
authors.initials: K
authors.lastname: Doi
mesh_terms: D006801:Humans; D015588:Observer Variation; D011857:Radiographic Image Interpretation, Computer-Assisted; D013902:Radiography, Thoracic; D011873:Radiology Information Systems; D015203:Reproducibility of Results; D013382:Subtraction Technique