Special Contribution

Yonago Acta medica 2009;52:115–120

Recent Advances in Ultrasound Imaging of Breast Lesions
Yasuaki Hirooka, Noriko Aika, Takuya Ishisugi, Masayoshi Ohguri, Chiharu
Nagashima, Shota Morishita, Yosuke Kato and Chisako Fukuda
Department of Pathobiological Science and Technology, School of Health Science, Tottori University
Faculty of Medicine, Yonago 683-8503, Japan

Ultrasonography works as an essential tool in diagnosing breast cancer. For mass screening of breast cancer, mammography is used worldwide as a main tool. However, in thescreening of women with dense breasts and in detecting small cancer of the breast, ultrasonography is known to be more useful than mammography. Most Japanese women contract breast cancer in their 40s. Women in their 40s have more dense breasts than thosein their 50s. It is expected that mass screening for breast cancer in the future will be done
by a combined use of mammography and sonography. A randomized control trial of thecombined use is being carried out at present in Japan. In recent years, the degree and distribution of tissue strain induced by tissue compression with an ultrasound device has enabled evaluation with color. The method, real-time tissue elastography, is used as an auxiliary tool in diagnosing diseases of various organs. Breast elastography images, classified
into patterns and scores, have also begun to be widely used. Compared with conventional
B-mode sonography, elastography is superior in specificity. Based on this fact, we haveconsidered omitting available histological examinations for some breast lesions in the nearfuture. Furthermore, elastography was useful in preoperative assessment of the margin ofbreast cancer. Further development of ultrasound elastography in the future is expected.
Key words: breast cancer; elastography; mass screening; ultrasonographymura et al., 1999). Because the usefulness of mammography had been established (Kerlikowsker etal., 1995; Ohuchi et al., 1995; Jonsson et al., 2003),
breast screening with mammography was started
in 2004. Actually, the number of breast cancer
patients detected at mammography screening hasincreased. It is known, however, that mammography has a problem when used for mass screening.
In Japan, breast cancer is most common among
women in their 40s who tend to have dense breasts(Wakai et al., 1995). The problem with mammography screening is that its sensitivity is often decreased in dense breast tissue (Osako et al., 2007;
Tohno et al., 2009). In a study on mammography
screening, its sensitivity was observed to be lower
in women in their 40s than in their 50s (Hasegawaet al., 2003).

Role of ultrasound imaging
in breast screening
In mass screening for breast cancer, women arecommonly examined by inspection and palpation of the breasts (Ota et al., 1989; Kanemura etal., 1999), mammography (Kerlikowsker et al.,
1995; Ohuchi et al., 1995; Jonsson et al., 2003) andsonography (Leconte et al., 2003; Yanagida et al.,
2003; Osako et al., 2007; Tohno et al., 2009). InJapan, breast screening had been conducted since1987 by interview and inspection and palpation of
the breasts, but the screening produced no significant decrease in mortality (Ota et al., 1989; KaneAbbreviations: MR, magnetic resonance; MRI, MR imaging

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On the other hand, ultrasonography has some advantages such as easeof use and no emission of radiation,
so it is widely used for individual examinations for breast cancer at many
medical institutions. In particular, ultrasound is superior in detecting small
breast tumors 1 cm or less in diameter(Yanagida et al., 2003), and useful inmass screening of women with densebreasts (Leconte et al., 2003). In
2008, the 2nd edition of “Guidelinefor Breast Ultrasound: Managementand Diagnosis” was published by theJapan Association of Breast and Thyroid Sonography, which contributes tobetter understanding of the standardFig.1. Mammograms obtained from a 74-year-old woman at mass screenized criteria for mass screening and ing. A: Massive image in the right breast, Area C. B: Mass image in therequisites for minute examination. left breast, Area B.
We examined a 74-year-old woman
with mammography at breast screening. Figure 1 shows a massive image in Area C of to be mastopathy. Furthermore, as seen in Fig. 2,
the right breast (Fig. 1A) and a mass image in Area
another very small mass, 5 mm in diameter, was
B of the left breast (Fig. 1B). Both were assessed newly discovered in the left breast area, where C
as Category 3. However, the ultrasound following bordered D. The little mass had an interruption
mammography showed the massive in the rightof the mammary gland. According to the formubreast to be a cyst, and the mass in the left breast lated criteria for breast ultrasound screening (JapanAssociation of Breast and Thyroid
Sonography, 2008), we assessed it as
Category 4 and suspected malignancy.
Examined with aspiration cytology,
the patient showed positive for scirrhous carcinoma, and was treatedwith breast conserving surgery. As
described, ultrasound seems very useful in detecting breast cancer, but its
usefulness as a screening method has
not clearly established. No country
adopts ultrasound for breast screening
at present. However, recently, performance of screening in women athigh risk for breast cancer was compared between ultrasound with mammography and mammography alone
Fig. 2. Ultrasound image of the left breast of the same woman in Fig. 1(Berg et al., 2008). Adding this single
taken with conventional B-mode sonography. A mass of about 5 mm indiameter is visible in Area C, which shows an interruption into the anterior
technique to mammography yielded aborder of the mammary gland. This lesion was assessed as Category 4.
higher detection rate of breast cancer.

AB116

Ultrasound images for breast lesions

Score 1

Score 2

Score 3Fig. 3. Clinical images
obtained from our subjective
cases are classified according
to the Tsukuba Elastography
Score. Score 4 or over isdetermined to be malignant.

Score 4

Score 5

plied clinically in diagnosing breast disease (Itoh etal., 2006). This is a tissue elasticity imaging technic that visualizes the degree and distribution ofstrain induced by light compression in a real-timemanner when artificial light compression is applied
to breast tissue. Results are noted when soft tissue
receives greater strain, while stiff tissue receives
less (Shiina et al., 2002). Itoh and workers classified breast elastography images into 5 patterns (Fig.
3) (Itoh et al., 2006), and reported the results using
the Tsukuba Elastography Score (Itoh et al., 2006;Itoh, 2007). Scores from 1 to 3 showing green images of strain with and without tense blue images
are judged to be benign: (1) strain in the entire
hypoechoic area; (2) strain not seen in part of theBecause of these observations, a Japanesestudy group with Dr. Noriaki Ohuchi of Tohoku
University as leader has started a randomized control trial to investigate the efficacy of ultrasoundwith mammography for breast cancer screening.
We expect that results of the trial will prove thecombination to be useful within a few years.
Real-time tissue elastography
for breast disease
Recently, real-time tissue elastography was developed to evaluate tissue elasticity with ultrasound(Shiina et al., 2002), which has been gradually ap117

Y. Hirooka et al.

AFig. 4. Ultrasound images obtained withconventional B-mode sonography andelastography.
A: Fibroadenoma of the right breast assessed as Category 3 with conventional
B-mode sonography (right) and Score
1 with Tsukuba Elastography Scorepatterns (left).
B: Papillotubular carcinoma of the left
breast assessed as Category 4 withconventional B-mode sonography(right) and Score 4 with Tsukuba Elastography Score patterns (left).

B
hypoechoic area; (3) strain only in the peripheral
areas and not at the center of the hypoechoic area.
Scores 4 and 5 showing blue images are diagnosed
as malignant: (4) no strain in the entire hypoechoicarea; and (5) no strain either in the hypoechoic orsurrounding areas. Figure 4 shows ultrasound images of fibroadenoma (Fig. 4A) and papillotubularcarcinoma (Fig. 4B) obtained by elastography andconventional B-mode sonography. Elastographyshows a green fibroadenoma mass in the region ofinterest (Fig. 4A left), which means that the mass ismade of soft tissue. We therefore judged the scoreof the lesion to be 1, based on Tsukuba Elastography Score patterns. On the other hand, the whole
papillotubular carcinoma in the region of interest(Fig. 4B left) is blue, that is, the mass is more solid
than the surrounding tissue. We assessed this lesion as Score 4. Differentiation from benign tomalignant can be made even with conventional Bmode sonography in many cases of breast disease.
However, elastography has enabled examiners tojudge in a more reliable manner, visually by color.
Elastography seems very useful as a subsidiary diagnostic tool for all workers from little-experienced
medical technologists to skilful breast-disease
specialists or medical sonographers. Table 1 shows
the ratio of sensitivity, specificity and accuracy ofconventional B-mode sonography and real-timetissue elastography performed in 101 patients withbreast disease (61 benign and 40 malignant lesions)
we have experienced. Elastography showed lower
Table 1. Comparison of ultrasound imaging
techniques for breast lesions

Sonography*
Elastogrpahy†

Sensitivity(%)

Specificity(%)

Accuracy
(%)

90
77.5

91.8
100

91.1
91.1

* Conventional B-mode sonography: category 4 and over,diagnosed as malignant.
† Real-time tissue elastogrpahy: score 4 and over, diagnosed as malignant.

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Ultrasound images for breast lesions

AFig. 5. Ultrasound images and pathology of a breast mass.
A: Ultrasound images of breast cancer with conventional
B-mode sonography (right) and elastography (left).
Elastography clearly visualizes a blue infiltration (whitearrow) which is not clear with conventional B-mode
sonography.
B: Hitstopathological apperance of the resected mass. The
infiltration to the surrounding tissue (black arrow) isclear (hematoxylin and eosin stain). Bar = 3.75 mm.

Bsensitivity than B-mode sonography, but 100% inspecificity. Furthermore, we confirmed no malignant disease for lesions determined as Score 1. It
was highly expected that in the future, we can omit
histological examinations such as aspiration cytology or needle biopsy for lesions judged to be Score
1 (Itoh et al., 2006; Itoh, 2007).
As described, we have great expectations in
the future development of elastography. But forbreasts with big lesions of wide diameter, we must
learn how to give proper pressure to the breast with
an ultrasound device (Sato et al., 2008) which canbe achieved through complete training.

intraductal component. If the resected mass hasa negative margin, the disease-free survival ratio
also improves (Fortin et al., 1999). As a tool for
preoperative assessment of the extent of cancer
in the breast, 3-dimensional MR mammography
which utilizes MRI is superior to mammography
or ultrasound in providing more accurate anatomic
information (Esserman et al., 1999; Nakamura etal., 2002). On the other hand, to achieve negative
margins in the operating room, the usefulness ofultrasound with its easy portability and improvements in technology is well known (Henry-Tillmanet al., 2001). However, ultrasound is superior in
specificity but inferior to MRI in sensitivity (Tamakiet al., 2002). Considering the above facts, we applied ultrasound elastography to the assessment of
the extent of breast cancer before surgery. As seenin Fig. 5, elastography clearly visualized some blue
infiltration (Fig. 5A, white arrow) which was notclear with conventional B-mode sonography. Histopathological examination of the resected massconfirmed the blue depicted to be an infiltration

Preoperative ultrasoundto achieve negative margins
Breast conserving surgery for breast cancer has become popular in these 10 and a few years. One important point of note is to avoid the risk of leaving
carcinomatous lesions. For this, we must precisely
grasp the degree of cancer invasion into the breast
tissue and the presence and degree of the extensive119

Y. Hirooka et al.

to the surrounding tissue (Fig. 5B, black arrow).
As described above, we think that elastography isfully applicable not only to differential diagnosis
between benign and malignant tumors, but also topreoperative assessment of infiltrating margins.
In conclusion, ultrasound is an essential tool
in diagnosing breast cancer, and its significance atmass screening seems to increase. Elastography isa newly developed ultrasound-based function, anda very useful auxiliary tool in diagnosing breastcancer. Further development of ultrasound elastography in the future is highly expected.
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Received and accepted November 12, 2009
Corresponding author: Yasuaki Hirooka, MD