Novel Technique for Liver Segmentation by Fluorescence Intensity Gradient Using Two Different Doses of Indocyanine Green

Background: Techniques involving dye injection or regional ischemia are commonly used for the precise identification of liver regions during hepatectomy.^1,2 The visualization of regions with indocyanine green (ICG) has been widely used for liver segmentation.³ ICG is typically administered only once during each hepatectomy. We developed a threshold-adjustable Medical Imaging Projection System (MIPS) that projects ICG fluorescent images directly onto a patient's organ, which shows potential for real-time navigation.^4,5 We report a case in which a fluorescence intensity gradient using two different doses of ICG was effective during anatomical right anterior sectionectomy.

Methods: A 73-year-old man underwent one radiation treatment and three radiofrequency ablations for hepatocellular carcinoma over the past 4 years. A follow-up computed tomography scan revealed a low-density lesion in segment 8 with a portal vein tumor thrombus (PVTT), and we planned a right anterior sectionectomy. A direct approach to the pedicle with the PVTT was not recommended as portal patency in the anterior section was unknown; therefore, we identified the three liver regions using a fluorescence intensity gradient.

Results: The ICG fluorescence intensity gradient was established using two doses of ICG, which effectively identified the right posterior and anterior sections and the left lobe. MIPS clearly projected each section boundary onto the liver surface. Right anterior sectionectomy was successfully performed with no postoperative complications. Pathological examination revealed a negative surgical margin.

Conclusions: Utilizing multiple ICG dosages for boundary identification of liver regions has potential use for anatomic hepatectomy.