Semiautomated versus Manual Evaluation of Liver Metastases Treated by Radiofrequency Ablation

PURPOSE: To determine the accuracy of semiautomated volume and density measurements of liver metastases from colorectal and breast cancer before and after radiofrequency (RF) ablation compared with manual evaluation. MATERIALS AND METHODS: Twenty-five patients (mean age, 63.2 years +/- 10.7) with 50 known liver metastases from underlying primary breast (n = 15) or colorectal cancer (n = 35) underwent triphasic contrast-enhanced multidetector computed tomography (CT) to evaluate hepatic tumor load and localization before RF ablation and for postinterventional follow-up. Each lesion was quantified in terms of volume and CT value (in HU) with a semiautomated software tool and manually by an experienced radiologist before and 4 months after RF ablation. RESULTS: Before RF ablation, all 50 liver metastases, and after ablation, 49 of 50 ablation zones (98%), were correctly evaluated by the software. Mean lesion volumes before and after the intervention were 5.5 cm(3) and 22.4 cm(3), respectively. Corresponding concordance correlation coefficients between measurement techniques were 0.98 and 0.99, respectively, for volume; and 0.90 and 0.76, respectively, for CT value. CONCLUSIONS: Compared with manual measurements, semiautomated volumetric assessment of liver metastases before and after RF ablation demonstrated a high degree of correlation. Agreement of attenuation was slightly worse, particularly when assessing the postinterventional multidetector CT examination, probably because of the different regions of interest used for manual and semiautomated assessment of CT values.