Researchers in Seoul, Korea, found early-phase contrast-enhanced CT useful for differentiating pulmonary metastases from hepatocellular carcinoma and primary lung cancer. They specifically measured the attenuations of pulmonary nodules on the CT scans.
For this retrospective study, 13 patients with pulmonary metastases from hepatocellular carcinoma and 25 patients with primary lung cancer were evaluated. Attenuation values and the size of the pulmonary nodules were measured on contrast-enhanced CT scans.
CT and clinical features were analyzed with regard to age, gender, body surface area of the patients, the attenuation values and size of the nodules, and CT machines using univariate analysis. Multiple linear regression analysis was used to eliminate confounding factors (Acta Radiol online, August 27, 2009).
According to the results, the mean attenuation value of metastatic pulmonary nodules from hepatocellular carcinoma (75.7 ± 24.9 HU) was higher than that of primary lung cancer nodules (45.8 ± 14.4 HU; P < 0.01). Other variables (age, gender, body surface area, etc) were not significant on multiple regression analysis.
When a cut-off value of 75 HU was applied, the positive predictive value for diagnosing metastatic nodules from hepatocellular carcinoma was 100%.
The authors , led by Joon-Il Choi, MD, acknowledged that a larger prospective analysis is required to confirm these positive results.