Revised Diagnostic Criteria for the Breast (Draft): Internal Echoes

Mitsuhiro Kubota

, Yutaka Konishi

, Kazuhiro Shimamoto

, Kumiko Tanaka

, Hiroko Tsunoda-Shimizu

,

Hideyuki Hashimoto

, Norikazu Masuda

, Mitsuhiro Mizutani

, Isamu Morishima

, Hidemitsu Yasuda

, Takanori Watanabe

, Ei Ueno

, and Tokiko Endo

66

Introduction

In discussion, the committee has consumed more than 4 years for revision of the lexicon and diagnostic criteria of breast lesions. Internal echoes of mass image- forming lesions were also one of the themes. These have been summarized as follows.

The criteria are not yet final and are presented with discussion.

Definition and Lexicon of Internal Echoes

Internal echoes means echoes from the inside of the mass. They do not concern echoes from a marginal area. Homogeneity and echo level of internal echoes from some area are assessed. If there are two or more regions with a different nature of internal echoes, they should be recorded together. If it is a mass with mixed pattern, that is, having both cystic and solid parts, only internal echoes of solid parts are assessed.

1. Homogeneity

Regularity of internal echoes (texture) is assessed.

a. Homogeneous b. Heterogeneous 2. Echo level

Echo level means intensity of internal echoes. It is classified into five levels, as follows, comparing with the subcutaneous fatty layer, not with mammary tissue.

a. Free b. Very low c. Low d. Equal e. High

3. Additional findings

Findings as follows are recorded if present:

1

Yamachika Memorial Hospital, 3-19-14 Koyawata, Odawara, Kanagawa 256-0815, Japan

2

JABTS Committee of Lexicon and Diagnostic Criteria, Japan

a. High echo spots b. Cyst

c. Fluid–fluid level (FFL)

High echo spots are classified into three types as follows:

Fine Small Coarse

Examples

Several ultrasound (US) images of breast tumors are shown, particularly concerning internal echoes. These images are part of samples delivered from institutes or hospi- tals of members of the committee (Figs. 1–8).

Discussion

Internal echoes have been one of the important items in diagnostic criteria of breast tumors since the beginning of modern breast ultrasonography. In the diagnostic cri- teria of breast tumor proposed by the Japan Society of Ultrasonics in Medicine (JSUM) in 1987, internal echoes were one of the seven items. There were three categories, that is, echo-free, fine homogeneous, and coarse heterogeneous, combined with the likeliness of benignancy to malignancy.

The most conspicuous difference between the previous diagnostic criteria of JSUM and the revised criteria of the Japan Association of Breast and Thyroid Sonology (JABTS) is that the echo level of internal echoes has been discussed in the latter.

Echoes from the inside of a tumor present its tissue characteristics. In ultrasonogra- phy, the tissue characteristics of a tumor are defined through the nature of both its internal and posterior echoes. Internal echoes mean the summation of intratumoral attenuation and reflections and backscattering.

Fig. 1. Papillotubular carci-

noma. Internal echoes are

low and homogeneous

low rather than very low and homogeneous rather than heterogeneous

Fig. 3. Solid tubular carci- noma. Internal echoes are low or very low, and heteroge- neous rather than homoge- neous. Fine high echo spots are present

Fig. 4. Scirrhous carcinoma.

Internal echoes are low rather

than very low. They are

heterogeneous rather than

homogeneous. High echo

spots are fine

Fig. 5. Internal echoes are low rather than very low. They are homogeneous rather than heterogeneous. High echo spots are fine.This tumor was revealed to be a cyst

Fig. 6. Internal echoes are equal or hyperechoic, and heterogeneous. Fine high echo spots are present

Fig. 7. Fibroadenoma. Inter-

nal echoes are low, and het-

erogeneous. High echo spots

are coarse

As to internal echo level, it was discussed why the subcutaneous fatty layer, not the surrounding mammary gland, should be referred to as the standard. The most impor- tant point is that the echo level of the mammary gland is too variable, according to many factors including age, reproductive stage, and obesity, to be a stable standard of echo level. Furthermore, if ordinarily a hyperechoic mammary gland is referred to as the standard, a mass in the gland is always assessed to be hypoechoic. The subcuta- neous fatty layer is relatively invariable and is better as the standard of echo level than the mammary gland, although it is not always directly beside the tumor and, rarely, is almost absent, particularly when the patient is young and very thin.

In general, benign tumors such as fibroadenoma have a tendency to be high and malignant tumors low in internal echo level. In other words, this may mean that tumors with various tissue components have a tendency to be high and tumors his- tologically more monotonous low in internal echo level, according to their level of reflection and backscattering. Tumors with a high internal echo level include fat- containing benign tumors such as lipoma and hamartoma. They also include malig- nant tumors such as mucinous carcinoma in which multilayered many fine mucinous lakes cause high reflection or backscattering, thus a high echo level. It is also insisted that ductal or lobular carcinoma with extremely high invasiveness occasionally presents as a mass with a high internal echo level. An isoechoic mass with echo level equal to subcutaneous fatty tissue is recognized with some difficulty if it is located superficially; this happens occasionally in fibroadenoma and rarely in carcinoma.

Another discussion as to echo level is whether it is necessary to divide low from

very low. It may be important if this division contributes to a suggestion of two dif-

ferent natures of the tumor. In highly cellular tumors such as malignant lymphoma

or medullary carcinoma, the internal echo level is very low because of high penetra-

tion of ultrasound without much reflection or backscattering associated with poste-

rior echo accentuation. In contrast, in highly fibrous tumors such as scirrhous

carcinoma, the internal echo level is also very low because of high attenuation of ultra-

sound in the tumor associated with a posterior echo attenuation or defect. Other types

echo spots are fine rather than

coarse

of carcinoma or benign tumors usually show their echo level to be simply low, but this is not yet conclusive. Further study is needed.

Assessment of homogeneity of internal echoes is frequently complicated. Should high echo spots be included? This is also still in debate. Homogeneity can be said of different categories, such as distribution of echoes, size, or brightness of each echoes and so on. These are not a concern at this time. Instead, here regularity of internal texture was considered important.

As to high echo spots, one of the discussions was their classification by size. The tentative proposition is that fine high echo spots are less than 1 mm, small are 1 mm or more, and coarse high echo spots correspond with spots of 3 mm or more in size.

These should be documented further through studies in many institutes.

Fluid–fluid level (FFL) usually means hemorrhage in the cystic lesion. With this phenomenon, the possibility of malignancy of the lesion is increased. Other causes of FFL are oil cyst and the concentrated type of cyst (complicated cyst). In a cystic lesion with internal hemorrhage, the lower part below the FFL is more hyperechoic. In an oil cyst, the oily component is lighter than the watery one and is located above the FFL. In concentrated cysts, a thick concentrated fluid component occasionally gathers in the upper part, forming FFL, and is hyperechoic.

Conclusions

Many aspects of internal echoes of mass image-forming breast lesions have been dis-

cussed. These points, as well as other themes, should be documented or corrected

through further investigation in wide clinical practice.