Utility of real-time image fusion technology in ultrasonography-guided fiducial marker implantation for stereotactic body radiation therapy for liver tumors

Background Ultrasonography (US) is useful when implanting fiducial markers in the liver. However, the implant position is sometimes lost. Recently, real-time image fusion technology (Volume Navigation [V-navi]; GE Healthcare, Milwaukee, WI, USA) has been introduced as a technique for using images from different modalities, and its utility for fiducial marker implantation has been hypothesized. Purpose To evaluate the utility of US-guided fiducial marker implantation in the liver using V-navi compared to conventional US. Material and Methods We retrospectively reviewed 35 patients who underwent fiducial marker implantation for stereotactic body radiation therapy of liver tumors in 2013–2018. To avoid artifacts obscuring the tumor, the target point of implantation was set 10 mm cranial or caudal to the tumor. Marker implantation was then performed using US alone (US group, n = 24) or V-navi with computed tomography (CT) or magnetic resonance imaging (V-navi group, n = 11). Postprocedural CT was evaluated to determine technical success, distances between marker and either tumor surface or target point, and whether marker-induced artifacts obscured the tumor. Complications were also evaluated. Results were compared between groups. Results Technical success was obtained in 33 patients. Distance between the tumor and marker showed no significant difference between groups. Distance between target point and marker was shorter in the V-navi group ( P = 0.0093). Tumor-obscuring artifacts were seen in 12 patients (V-navi group, n = 1; US group, n = 11; P = 0.055). The only complication was minor bleeding in the US group (n = 1). Conclusion V-navi appears useful for US-guided fiducial marker implantation in the liver compared with conventional US.