Image Processing Reference
2, , 6) are the portal-vein points with TDR larger than 0; P 1 and P 4 are selected as cut-
points on branches B 1 and B 2 , respectively.
Step 2 : For each branch, the downstream part of the cut-point is computed by region growing
( Figure 4(b) ). For all the portal-vein points of these downstream parts, the perfused regions
Step 3 : The ideal resected region is given by a union of all the perfused regions of all the
points on downstream parts as shown in Figure 4(d) .
Let us compare the proposed method with the manual approach on the conventional 3D
simulation software program (Synapse VINCENT ver.2). Figure 5 shows the sample date used
for evaluation. The samples 1 and 2 are the cases where the small tumor exists near the liv-
er surface; the sample 3 is the case where the large tumor exists near the main stem of the
portal vein. The liver, vessels, and a tumor are extracted in advance by the other software pro-
grams. Tables 1 - 3 summarize the results for samples 1-3, respectively. From Tables 1 and 2 ,
the proposed optimization method is very useful compared to the manual approach, that is,
the volume of the estimated resected region by the proposed method is much smaller than
that of the manual approach. This is because the degree of freedom of cut-point selection is
high and the effect of optimization is large for the case where the small tumor exists near the
liver surface. On the other hand, from Table 3 , the optimization is not very effective when the
tumor exists near the main stem of the portal vein since the degree of freedom of cut-point
selection is low.
FIGURE 5 Samples for evaluation.
Comparison Results for Sample 1
Manual Approach by a Surgeon Proposed
Resected volume (cc)
The number of cut-points 1