Comparison of Takasakis Segmentation with Other Classifications

The General Rules for the Clinical and Pathological Study of Primary Liver Cancer, edited by the Liver Cancer Study Group of Japan, adopted the classification of five segments according to Healey: the posterior and anterior segments of the right lobe, the lateral and medial segments of the left lobe, and the caudate area.

These five segments are further subdivided into two areas: superior and inferior areas.

When compared with our classification of three segments, the posterior segment corresponds to the right segment, the anterior segment to the medial segment, and the left lobe to the left segment (Table 1). In the General Rules, the left lobe is divided into two segments. Regarding the distribution of the

Fig. 2.8. Our segment classification
Table 1. Comparison of classification systems

Healey's

Couinaud's

Takasaki's

Right lobe

Posterior segment

Post inferior area Post superior area

SVI SVII

Right segment

Anterior segment

Anterior inferior area Anterior superior area

SV SVIII

Middle segment

Left lobe

Medial segment Lateral segment

Medial superior area Medial lateral area

SIV SIII SII

Left segment

Caudate lobe

Caudate process

SI

Caudate area

Caudate left portion Caudate right portion

Caudate left portion Caudate right portion portal tree, there is one secondary branch giving rise to several tertiary branches. This pattern is similar to that of the right and medial segments. The term "left lobe" is not used in the General Rules as opposed to the term "right lobe". Rather, the term "left lobe" is used to correspond to the left segment, as one of three segments: left, right, and middle.

In recent years, Couinaud's segmentation has been utilized for convenience. However, this segmentation does not always correspond to the distribution of the Glissonean pedicle. Each Couinaud's segment does not necessarily contain only one single tertiary branch. In many individuals, it is difficult to evaluate which Glissonean pedicle branch (or how many branches) supplies one Couinaud's segment. The idea of Couinaud's segmentation still has utilitarian value because of its simplicity. One Couinaud's segment consists of several cone units (see Fig. 4.1). Compared with my segmentation, Couinaud's S2, S3, and S4 correspond to the left segment, S5 and S8 to the middle segment, and S6 and S7 to the right segment.

3 Ramification of the Tertiary Branches from the Secondary Branches of the Glissonean Pedicle

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