Liver-lung scan in the diagnosis of right subphrenic abscess

To assess the value of liver-lung scanning in the diagnosis of right subphrenic abscess, 148 scans were reviewed against corresponding charts. Of 91 scans with adequate clinical data, overall scanning error was 19.3% with 14 false positive and 3 false negative scans. Among 49 scans (of the initial group of 91 studies) with presence or absence of actual pathology proved by surgery and/or autopsy, there were 3 true positive, 12 false positive, 29 true negative, and 3 false negative scans. Analysis of data indicated (1) lower accuracy of scan interpretations than generally reported, (2) low specificity for positive scans and high specificity for negative scans, (3) correlations of false interpretations with atypical degrees of liver-lung separation and with scanning defects in liver and lung, and (4) failure of rereading significantly to improve accuracy of interpretation.