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SPECIAL FEATURE Imaging findings of triple-negative breast cancer
MR imaging of triple-negative breast cancer
Takayoshi Uematsu
Received: 30 August 2010 / Accepted: 23 September 2010 / Published online: 23 December 2010
� The Japanese Breast Cancer Society 2010
Abstract Little is known about the MR imaging features
of triple-negative breast cancer (TNBC), but TNBC has a
worse prognosis because it has no effective therapeutic
targets, such as estrogen receptor for endocrine therapy and
human epidermal growth factor receptor 2 (HER2) for anti-
HER2 therapy. MR findings of a unifocal lesion, mass
lesion type, smooth mass margin, rim heterogeneous
enhancement, persistent enhancement pattern, and very
high signal intensity on T2-weighted images are typical
features of breast MR imaging associated with TNBC.
Although TNBC can mimic a benign morphology, the early
MR imaging recognition of TNBC could assist in both the
pretreatment planning and the prognosis, as well as adding
to our understanding of the biological behavior of TNBC.
Keywords Triple-negative breast cancer � Breast MRI
Introduction
Triple-negative breast cancer (TNBC) is defined by a
lack of expression of estrogen receptor (ER), progester-
one receptor (PR), and human epidermal growth factor
receptor 2 (HER2). It is characterized by distinct
molecular, histological, and clinical features including a
particularly unfavorable prognosis despite increased
sensitivity to standard cytotoxic chemotherapy regimens
[1]. TNBC is used as a surrogate marker for basal-like
breast cancer defined by gene expression profiling [2].
The basal-like subtype characterized by negativity for
ER, PR, and HER2, is associated with an aggressive
histology, poor prognosis, and unresponsiveness to the
usual endocrine therapies, a shorter survival, and
BRCA1-related breast cancer [2, 3].
Contrast-enhanced breast MR imaging is known for
high sensitivities of 89–100%; however, the specificity is
low or intermediate [4]. Breast MR imaging can provide
important information not only on the morphology of the
lesions but also on the pathology reflected by signal
intensity characteristics on T1- and T2-weighted images
and on the functional aspects reflected by the temporal and
spatial uptake of contrast medium. Therefore, a recent
study reported no rationale to criticize the low specificity of
breast MR imaging [5]. In addition, a previous study
showed that breast cancers with circumscribed mass could
be differentiated from benign masses by using internal
enhancement and the kinetic pattern of contrast-enhanced
breast MR imaging [6]. Few reports exist on the MR
imaging characteristics of TNBC [7, 8]; however, several
breast MR imaging features can also be used for detecting
TNBC. Breast MR imaging can be the most accurate
imaging modality for diagnosis of TNBC by showing
malignant MR imaging features that may not be identified
by using mammography or ultrasonography.
Breast MR imaging technique
The technical requirements for breast MR imaging are
challenging. High temporal and spatial resolutions are
necessary although acquisition speed and spatial resolu-
tion are diverging demands. Detailed descriptions of the
T. Uematsu (&)
Breast Imaging and Breast Intervention Section,
Department of Clinical Physiology,
Shizuoka Cancer Center Hospital, Naga-izumi,
Shizuoka 411-8777, Japan
e-mail: [email protected]
123
Breast Cancer (2011) 18:161–164
DOI 10.1007/s12282-010-0236-3
technical requirements for breast MR imaging have been
published elsewhere [4, 9–11]. As an example, we present
the clinical breast MR imaging protocol used during the
study period [7]. The breast MR examinations were per-
formed with the patients in the prone position. The
instrument used was a 1.5-T commercially available sys-
tem (Gyroscan Intera; Philips Medical Systems, Best,
Netherlands) with double breast-surface coils. The imag-
ing protocol included a localizing sequence followed by
sagittal fast spin-echo T2-weighted imaging (repetition
time/echo time (TR/TE), 5056/90; echo train length
(ETL), 15; matrix, 158 9 320) with fat suppression
(spectral presaturation inversion recovery, SPIR) of the
affected breast. Other parameters were field-of-view
18 cm, section thickness 4 mm, interslice gaps 0.8 mm.
This examination was followed by a dynamic study of the
affected breast, consisting of serial imaging of a three-
dimensional (3D) sagittal turbo field-echo T1-weighted
sequence (TR/TE 11/5.4, flip angle 20, matrix 143 9 256)
with fat suppression (principle of selective excitation
technique, ProSet). The parameters were field-of-view
18 cm, section thickness 2 mm, slices were interpolated to
1 mm. Gadopentetate dimeglumine (Magnevist; Bayer
Schering Pharma AG, Berlin, Germany) was administered
as a bolus intravenous injection (2 mL/s) at a dose of
0.1 mmol/kg body weight. This was followed by a 20-mL
saline solution flush. For dynamic studies, 1 pre- and 3
post-enhancement scans were acquired. The scan time was
2 min per scan.
MR imaging characteristics of TNBC
Enhancement lesion type
The BI-RADS lexicon [12] describes three types of
enhancing lesions seen on contrast-enhanced breast MR
imaging: first, ‘‘focus/foci’’ defined as a tiny spot
enhancement, less than 5 mm that is too small to allow
further morphologic characterization; second, ‘‘mass’’
defined as a 3D space-occupying lesion that is one process,
usually round, oval, or irregular in shape; and third, ‘‘non-
mass-like enhancement’’ that is not a mass enhancement
and is characterized by distribution and internal enhance-
ment patterns. Previous studies [7, 8] have shown that
TNBC most often presents as mass (Fig. 1) enhancement
and less commonly non-mass-like enhancement.
Mass shape
Triple-negative breast cancer did not tend to have an
irregular mass shape, but this difference was not statisti-
cally significant in contrast to ER?/PR?/HER2- breast
cancer [7]. TNBC tended to have a round, oval, or lobu-
lated mass shape [7, 8]. For mass shape, TNBC tends to
have a benign mass shape (Fig. 1) although mass shape is
not very important to differentiate malignancy from
benignancy.
Mass margin
Uematsu et al. [7] reported that the majority of these
tumors were a mass lesion type on MR images (95%), and
of the 56 mass lesions studied 39% had smooth mass
margins. Dogan et al. [8] also reported that of the 34 mass
lesions studied 38% had smooth mass margins. A smooth
mass margin (Fig. 1) tended to be associated with TNBC.
This is important because a smooth border of a mass is
frequently used as being indicative of a benign lesion.
Schrading and Kuhl [13] reported that familial breast
cancer tended to exhibit smooth mass margins. High-
grade tumors, such as triple-negative and familial breast
cancer, are likely to manifest as benign morphologic
features.
Mass enhancement
Uematsu et al. [7] reported that 80% of TNBC had rim
enhancement, and rim enhancement was associated with
smooth margins of the mass. Dogan et al. [8] reported that
76.5% of TNBC had rim enhancement. Teifke et al. [14]
reported that visible rim enhancement was the most accu-
rate prognostic enhancement criterion for estrogen receptor
status. The results of these studies show that rim
enhancement may be the most useful MR finding for
identifying TNBC.
Kinetic pattern
Uematsu et al. [7] reported that a persistent enhancement
pattern was significantly associated with TNBC. Initially
rapid enhancement and a washout pattern are generally
regarded to be a malignant pattern on breast MR imaging;
however, this may not apply to TNBC. This different
enhancement pattern of TNBC may come from the hetero-
geneity of the TNBC because TNBC showed no homoge-
neous internal enhancement in our study [7]. Schrading and
Kuhl [13] reported a high percentage (33%; 25/76) of
familial breast cancer to exhibit benign kinetic features. The
results of our study and Schrading’s study show that high-
grade breast cancer is therefore likely to manifest as benign
kinetic features. However, Dogan et al. [8] reported that
time–intensity analysis revealed type 3 in 91% of the 44
TNBC studied. This difference may come from the different
populations of these studies and the inter- and intraobserver
variabilities in breast MR imaging interpretation.
162 Breast Cancer (2011) 18:161–164
123
Nevertheless, further study is needed to evaluate the time–
intensity curve pattern of TNBC.
Intratumoral very high signal on T2-weighted images
Uematsu et al. [7] reported that intratumoral very high
signal on T2-weighted images was significantly associated
with TNBC. Intratumoral very high signal on T2-weighted
images (Fig. 1) corresponds to necrosis, and necrosis is a
prognostic factor in invasive breast cancer. An area of in-
tratumoral very high signal on T2-weighted images is a
common finding identified in 34–48% of TBNC [7, 8].
Contrast-enhanced breast MR imaging without T2-weighted
images can not reveal the presence of intratumoral necrosis.
Dynamic contrast-enhanced breast MR imaging with
T2-weighted images can increase the specificity of breast
MR imaging.
Unifocal lesion
The frequency depends on the population studied, the
methods used, and the cutoff point separating multifocal/
multicentric lesions from unifocal lesions. Uematsu et al.
[7] showed unifocal lesions to be significantly associated
with TNBC. Unifocal type may be a characteristic of
TNBC.
Conclusion
Unifocal lesion, mass lesion type, smooth mass margin, rim
enhancement, persistent enhancement pattern, and very
high signal intensity on T2-weighted images are typical
features of breast MR imaging associated with TNBC.
Contrast-enhanced breast MR imaging can be the most
Fig. 1 Triple-negative breast
cancer of right breast in
60-year-old woman. a Sagittal
fat-suppressed T2-weighted MR
image shows a mass with a
relatively smooth border with an
area of intratumoral very high
intensity. b Sagittal turbo
field-echo T1-weighted
contrast-enhanced MR image
with fat suppression shows a
rim enhancing mass with a
relatively smooth border.
c Kinetic analysis shows a fast
and persistent enhancement
pattern in the thick rim
enhancement area (L10 and
L12). A necrosis selected as a
region of interest (ROI) (L11)
shows no enhancement
Breast Cancer (2011) 18:161–164 163
123
accurate imaging modality for diagnosis of TNBC by
showing malignant MR imaging features that may not be
identified by using mammography or ultrasonography.
Breast MR imaging can be an effective noninvasive
imaging technique for detecting TNBC. The MR findings
could assist in both the pretreatment planning and the
prognosis, as well as adding to our understanding of the
biological behavior of TNBC.
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