Reassessment of the clinical usefulness of 67Ga-citrate scanning in lung cancer using a log-likelihood-ratio method

To reassess prospectively clinical usefulness of Ga-67 imaging in abnormal shadow on chest roentgenogram, 78 patients were scintigraphed after intravenous injection of 111MBq (3 mCi) of Ga-67 citrate. Before and after Ga-67 scanning, the same physician completed two questionnaires indicating his differential diagnosis, diagnostic confidence (expressed as a percentage) and therapeutic plan, referring chest roentgenograms (dorsoventral and lateral views) and chest roentgen tomograms (frontal projection only). The impact of the imaging of the physician's diagnostic confidence was expressed as a log-likelihood-ratio (LLR). The mean log-likelihood-ratio (LLR) for this series was 0.191+-0.308 (n=78), with 47 out of 78 (60.3%) patients demonstrating a LLR, 0.00. In only two out of 78 (2.6%) patients, a LLR greater than 1.0 was achieved. These results reflect the little impact of Ga-67 scanning on the decision-making process for lung cancer. However, Ga-67 scanning may be useful for detecting N2 (mediastinal lymphnode) and determing of the staging in patients with lung cancer, indicating a sensitivity of 60.0% and a specificity of 88.2%. (author)