Margin, Border, and Boundary Zone of Breast Tumor Ultrasonography
Hidemitsu Yasuda, Ei Ueno, Tokiko Endo, Mitsuhiro Kubota, Yutaka Konishi, Hiroshi Sakuma, Kazuhiro Shimamoto, Hiroko Tsunoda-Shimizu, Isamu Morishima, and
Takanori Watanabe
62
Key words.
Margin, Border, Boundary zone, Periphery, Halo
Introduction
In November 1999, the first meeting of the Subcommittee of Diagnostic Criteria for Breast Diseases under the Japan Association of Breast and Thyroid Sonology was held.
The diagnostic criteria and the lexicon used for breast diseases were discussed. About 40 conferences were held over 5 years. More than 200 cases of breast disease were dis- cussed, and experiments were done to define the consistency of diagnostic criteria.
Methods
Two hundred photographs of breast diseases were gathered from ten institutions, and 20 standard cases were selected. The precise features of the breast lesion were recorded on a diagnosis sheet. The items for diagnostic criteria were the shape and boundary, the existence of boundary high echo, and the intensity and homogeneity of the inter- nal echo. The results were estimated, and appropriate technical terms were chosen.
Results
In the subcommittee of the Japan Association of Breast and Thyroid Sonology, margin is defined as the peripheral part of the tumor adjacent to the border (Fig. 1).
The border is a plane located between the tumor and the tissue around the tumor.
Many other expressions are possible, such as boundary, borderline, margin, and limit line [1–3]. The periphery is the area surrounding the tumor.
The boundary zone means the area including margin, border, and periphery [4].
The border may not always be able to be defined clearly. Sometimes it may be diffi-
Subcommittee of Diagnostic Criteria for Breast Diseases under the Japan Association of Breast and Thyroid Sonology, International Medical Center of Japan, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan
cult to define margin or periphery clearly; therefore, we propose to use “boundary zone” to include margin, border, and adjacent zone.
The properties of the border are classified into four categories:
1. Well defined and smooth.
2. Well defined and rough.
3. Not clear, ill-defined, unclear. In this category, we classify two subgroups accord- ing to whether a halo (boundary high echo) appears at the boundary zone or not:
a. Appears at the boundary zone b. Does not appear at the boundary zone 4. Difficult to evaluate.
“Difficult to evaluate” means a condition where is difficult to evaluate the posterior or lateral boundary of a tumor due to attenuation or deficiency of ultrasound.
Diagnosis must be made at the most suitable plane that represents the property of the lesion. The properties of one lesion may have plural findings. If the border is well defined, it means that the margin and periphery can be divided by a single line.
“Boundary high echo,”“marginal hyperechoic zone,” echogenic halo “or” halo,“hyper- echoic boundary echo,” “echogenic rim”—all these phrases could mean the hypere- choic area appearing at the boundary zone (Fig. 2). Although we have not reached a conclusion, “halo” may be the most simple and plain word as well as that most com- monly used in Japan.
At the hyperechoic boundary zone, it is difficult to define the precise point of the boundary (Fig. 3); therefore, it is better to define the property of the boundary as not clear.
Conclusions
To make a standard diagnosis, it is important to have a standard lexicon. Although many kinds of expression are possible for the same feature of a breast tumor, a tech- nical term must be a word that is seldom confused with another different concept.
Especially, a halo or boundary high echo must be a word that is used to express a malignant sign.
Definitions of Margin, Border, and Boundary Zone 63
Fig. 1. The border (solid line) is a plane located between the tumor and the tissue around the tumor, the periphery is the area surrounding the tumor, and the boundary zone means the area including margin, border, and periphery
64 H. Yasuda et al.
Fig. 2. Two cases (A, B) show halos on both sides, the typical boundary high echo observed in malignant tumors. Images C–E present findings that look similar to halos at a glance, but these are not true halos. The case in C is a tumor associated with mastopathy. The beltlike zone seen around the hypoechoic area corresponds to the site where a group of gland cavities are located.
This echo level of the beltlike lesion is intermediate between the adjacent mammary gland and the hypoechoic area. True malignant halos are higher than the adjacent tissue. The case in D is a cyst and the case in E is a fibroadenoma. Both cases are surrounded by a thin rim of normal mammary gland; these also are not true halos
Fig. 3. At a hyperechoic boundary zone, it is difficult to define the precise point of the bound- ary; therefore, it is better to define the property of the boundary as not clear
A B
C D E
References
1. Sawaki A, Shimamoto K, Satake H, et al (1999) Breast ultrasonography: diagnostic efficacy of a computer-aided diagnostic system using fuzzy inference. Radiat Med 17(1):41–45
2. Jackson VP, Rothschild PA, Kreipke DL, et al (1986) The spectrum of sonographic findings of fibroadenoma of the breast. Invest Radiol 21(1):34–40
3. Chen CM, Chou YH, Han KC, et al (2003) Breast lesions on sonograms: computer-aided diagnosis with nearly setting-independent features and artificial neural networks.
Radiology 226(2):504–514
4. Kim KG, Kim JH, Min BG (2002) Classification of malignant and benign tumors using boundary characteristics in breast ultrasonograms. J Digit Imaging 15(suppl 1):224–227 Definitions of Margin, Border, and Boundary Zone 65
