Combined Use of Contrast-Enhanced Intraoperative Ultrasonography and a Fluorescence Navigation System for Identifying Hepatic Metastases

Background The purpose of this study was to assess the concomitant use of contrast-enhanced intraoperative ultrasound (CE-IOUS) using the new microbubble agent Sonazoid, and to assess the fluorescence navigation system (Photo Dynamic Eye, or PDE) using indocyanine green (ICG) as a novel tool for identifying colorectal metastatic lesions compared with preoperative contrast-enhanced multiple row-detected computed tomography (MDCT) and gadoxetic acid-enhanced MRI. Methods Thirty-two patients who underwent a liver resection for colorectal metastatic carcinoma from 2008 to 2009 were included in the present study. ICG was intravenously injected within 2 weeks of the operation. The liver was inspected with CE-IOUS using Sonazoid and PDE for visualizing small metastatic lesions. A lesion analysis was performed with the postoperative histopathological examination of the resected tissues. The clinical values of CE-IOUS and PDE to confirm the malignant lesion diagnoses were statistically evaluated. Results A total of 56 lesions were identified based on the histopathological findings of the biopsies and resected tissues; of these, 52 were confirmed to be metastases, whereas 4 were benign tumors. The numbers of identified metastases by MDCT/MRI and CE-IOUS/PDE were 46 and 51, respectively. The use of CE-IOUS and PDE improved the diagnostic sensitivity compared with the use of MDCT and EOB-MRI (98.1 vs. 88.5%, respectively; P = 0.050). Conclusions The present results suggested that the concomitant use of CE-IOUS with the Sonazoid and PDE system may be a useful and safe method, in addition to CT or MRI.