Liver functional volumetry for portal vein embolization using a newly developed 99mTc-galactosyl human serum albumin scintigraphy SPECT-computed tomography fusion system

We developed a new combined Tc-99m-galactosyl human serum albumin (GSA) scintigraphy single-photon emission computed tomography (SPECT)/CT system to evaluate the changes in functional liver volume with portal vein embolization (PVE). We performed a prospective analysis of 25 patients treated with right PVE, and evaluated their functional liver volume perioperatively with a Tc-99m-GSA scintigraphy SPECT-CT fusion system. The percentage of the non-tumorous remnant liver volume (%LV) and the percentage of functional remnant liver volume (%FLV) were estimated by using the following calculations: (future remnant volume - tumor volume)/(total liver volume - tumor volume) and functional future remnant liver volume/functional total liver volume, respectively. Before PVE, the correlation was strongly significant between %LV and %FLV of the non-embolized liver, and the data were nearly equal (the regression coefficient was 1.005, P < 0.0001). In contrast, after PVE, there was a significant correlation between %LV and %FLV (P < 0.0001), but the regression coefficient was 1.192. The % LV increased significantly, from 38.1 to 52.0%, and the increment was 13.9% (P < 0.0005). The %FLV was also increased significantly, from 36.6 to 58.0%, and the increment was 21.4% (P < 0.0001). The increment was 7.5% greater for the %FLV compared to that of the %LV (P < 0.001). The Tc-99m-GSA scintigraphy SPECT-CT fusion system can estimate the correct functional liver volume and is useful in comparison with conventional CT volumetry.