Evaluation of virtual CT sonography for enhanced detection of small hepatic nodules: a prospective pilot study

Virtual CT sonography is a system for synchronizing multiplanar reconstructed CT scans with corresponding conventional ultrasound images in real time. The aim of this study was to prospectively evaluate the feasibility of virtual CT sonography for detection of nodules difficult to detect with conventional sonography alone.

Fifty-nine patients with 140 nodules were included in the study. All patients underwent CT angiography then conventional sonography and finally virtual CT sonography. The number, location, and echogenicity of nodules and parenchyma were assessed.

Among 140 nodules detected with CT angiography, 71 were detected with conventional sonography and another 46 were detected with virtual CT sonography, increasing the overall sensitivity from 50.7% to 83.57%. The average diameter of nodules detected only with virtual CT sonography (9.7 +/- 3.3 mm) was significantly smaller than that of nodules detected with conventional sonography (16.6 +/- 6.2 mm). The results of multivariate analysis suggested that nodule size (p < 0.001), echo pattern (p = 0.004), and location (p = 0.028) are associated with the difference in detection. Interestingly, 87% of the nodules 10 mm in diameter or smaller were already dysplastic or malignant.

Nodules 10 mm in diameter or smaller have significant malignant potential and therefore are clinically important. Even though we do not consider virtual CT sonography a screening tool, we conclude it superior to conventional sonography for detection of small hepatic nodules, allowing bedside percutaneous ultrasound-guided biopsy and treatment that would not be possible with conventional sonography alone.