Fig. 3.1
Calcified grade 2 DCIS: craniocaudal spot magnification mammogram (a) and gray-scale reversed image (b) show a cluster of fine pleomorphic calcifications
Fig. 3.2
Calcified grade 2 DCIS: craniocaudal spot magnification mammogram (a) and gray-scale reversed image (b) show a cluster of fine linear and pleomorphic calcifications
Fig. 3.3
Calcified grade 2 DCIS: craniocaudal spot magnification mammogram (a) and gray-scale reversed image (b) show fine linear calcifications with segmental distribution
Fig. 3.4
Calcified grade 3 DCIS: craniocaudal spot magnification mammogram (a) and gray-scale reversed image (b) show a cluster of fine pleomorphic calcifications
Fig. 3.5
Calcified grade 3 comedo-type DCIS: craniocaudal (a) and mediolateral oblique (b) spot magnification mammograms show a cluster of fine linear and fine linear-branching calcifications
Fig. 3.6
Calcified grade 1 DCIS: craniocaudal spot magnification mammogram (a) and gray-scale reversed image (b) show a cluster of fine pleomorphic and amorphous calcifications. US image (c) shows echogenic foci consistent with calcifications
Fig. 3.7
Multifocal DCIS with necrosis and calcifications (grade 2): craniocaudal mammogram (a) and spot magnification mammograms (b, c) of the left breast show an area of architectural distortion and a contiguous focus of fine pleomorphic calcifications
Less commonly, DCIS may also manifest as a mass at mammography in 10% of cases and as architectural distortion in 7–13% (Fig. 3.8) [3, 19].
Fig. 3.8
Noncalcified grade 2 DCIS: mediolateral oblique mammogram (a) shows architectural distortion asymmetry in the lower part of the left breast, which corresponds on axial contrast-enhanced (b) and maximal intensity projection (c) MR images to a region of clumped nonmass-like enhancement. The kinetic curve of this lesion (d) demonstrates early enhancement with plateau (type 2 kinetics)
A mass-like appearance of DCIS may be related to two different conditions: it may be a direct manifestation of an existing soft tissue mass or it may be a result of periductal fibrosis or elastosis producing an irregular or spiculated margin around a nonmass-like lesion.
Architectural distortion was noted in 7% of patients with sclerosing adenosis, which may have been the cause of this manifestation [20, 21]. Other pathologic conditions that may lead to architectural distortion include radial scarring and sclerosis in the interstitium around the DCIS and carcinomatous invasion of the Cooper’s ligament [4].
Correlation studies between mammographic and histopathologic findings or grades of DCIS have shown that fine pleomorphic or fine linear and fine linear-branching calcifications seen in a grouped or segmental distribution are usually associated with higher-grade DCIS according to the World Health Organization (WHO) classification system (Figs. 3.4 and 3.5), whereas amorphous calcifications are associated with low-grade DCIS (Fig. 3.6) [18, 19, 22].
There is also a significant correlation between findings of fine pleomorphic or fine linear-branching calcifications and the presence of necrosis [23].
In addition, it was observed that low-grade DCIS lesions are more likely than lesions of higher grades to manifest as noncalcified abnormalities at imaging such as masses or asymmetries [19].
Despite these patterns, there is considerable overlap in the mammographic appearances of the different histologic subtypes of DCIS, and it has been shown that fine pleomorphic calcifications are the most common appearance for both high-grade and non-high-grade lesions [18, 22]. Thus, the histologic grade cannot be determined prospectively with any accuracy on the basis of the mammographic appearance of microcalcifications.
Although mammography, as the primary screening examination, is the main tool for detecting DCIS, it has some limitations. Because not all DCIS calcifies, the reported sensitivity of mammography ranges between 87 and 95% [18]. Disease extent is also frequently underestimated at mammography due to incomplete lesion calcification, which can result in additional operations such as surgical bed reexcision or completion mastectomy being performed to obtain negative margins.
3.3 MR Imaging Appearances of DCIS
MR imaging is the most sensitive modality available for identifying DCIS and is more accurate than mammography in evaluating the extent of disease [24–26]. It does allow the visualization of mammographically occult DCIS lesions, likely because of its ability to demonstrate tumor vascularity, vessel density, and permeability.
The sensitivity of MR imaging for detection of DCIS has been shown to be higher for high-grade and intermediate-grade DCIS as compared with low-grade DCIS (98%, 91%, and 80%, respectively). Overall, MR imaging is more sensitive than mammography in the detection of all grades of DCIS (92% vs. 56%, respectively) [13].
Most studies have shown that MR imaging provides either an accurate assessment or overestimation of DCIS disease extent compared with the pathologic evaluation. Although DCIS may be underestimated at MR imaging, underestimation occurs less frequently than it does at mammography [27]. The sensitivity of MR imaging in the accurate assessment of the extent of DCIS reaches almost 89%, compared with 55% at mammography and 47% at US [26, 28]. Thus, the results of the MR imaging evaluation can alter the course of treatment of DCIS by allowing correct identification of the extent of disease.
MR imaging can allow improved presurgical planning of the known cancer as well as depict additional foci of multifocal or multicentric DCIS and contralateral disease. It can be used to better delineate the margins of the disease before surgery, which theoretically may decrease the frequency with which positive margins occur. Nevertheless, the COMICE (comparative effectiveness of MR imaging in breast cancer) trial has not shown any reduction in the reexcision rate with the use of preoperative MR imaging; thus, its use in this setting remains controversial [29].
3.3.1 Morphologic Features of DCIS
DCIS may have variable morphologic features on MR images, with “nonmass enhancement” (NME) morphology being the most common manifestation (60–81% of cases) [24, 30–32]. Less commonly, DCIS may also manifest as a mass (14–41% of cases) on dynamic contrast material-enhanced MR images, in which case it is most likely to be irregular, or as a focus (1–12%) (Table 3.1).
Nuclear grade | Focus (%) | Mass (%) | NME (%) |
|---|---|---|---|
High | 0–62.5 | 54.5–56 | 25–72.2 |
Intermediate | 18.8–66.6 | 31.3–33.3 | 0–50 |
Low | 0 | 11.1–50 | 0–50 |
Different morphologic features have been seen in DCIS lesions of different nuclear grades. However, no statistically significant difference has been seen between the morphologic features and nuclear grades of DCIS. Thus, there is no morphologic feature predictive of the nuclear grade of pure DCIS [30, 32].
DCIS is usually not visible on non-contrast material-enhanced T1-weighted images or on nonfat-saturated or fat-saturated T2-weighted images because it is masked by the normal breast parenchyma. DCIS may sometimes appear bright on T2-weighted images because of either ductal secretions or necrosis.
NME DCIS can manifest with various internal enhancement patterns, the most common of which is a clumped pattern (41–64% of cases) (Figs. 3.8 and 3.9), followed by a heterogeneous pattern (16–29%) [24, 30–32]. Less frequently, DCIS can manifest as reticular/dendritic enhancement (0–9% of cases), as well as clustered ring enhancement (Table 3.2).
Fig. 3.9
Noncalcified DCIS: axial contrast-enhanced MR image (a) shows a segmental area of clumped NME in the outer part of the left breast. The lesion demonstrated persistent (type 1) kinetics (b)
Internal enhancement pattern | BI-RADS definition | Portion of time seen in NME DCIS (%) |
|---|---|---|
Clumped | Cobblestone-like enhancement, with occasional confluent areas | 41–64 |
Heterogeneous | Nonuniform enhancement in a random pattern | 16–29 |
Homogeneous | Confluent uniform enhancement | 0–16 |
Reticular, dendritica | Enhancement with fingerlike projections extending toward the nipple | 0–9 |
Stippled, punctate | Punctate, similar-appearing, enhancing foci, sandlike or dotlike | 0–8 |
Clustered ring enhancement | Cluster of small ring enhancement | …b |
Clustered ring enhancement, a term in the new MR imaging BI-RADS (Breast Imaging Reporting and Data System) lexicon, represents periductal enhancement and is the result of contrast material pooling in the periductal stroma or ductal wall of DCIS. This pattern was seen in 63% of malignant lesions, compared with only 4% of benign lesions [33].
There are several different NME distribution patterns. Segmental or linear/ductal enhancement patterns are a hallmark of DCIS on MR images. Segmental distribution is the most common pattern, seen in 14–77% of cases [24, 30–32]. Regional asymmetric enhancement is another frequent appearance of DCIS (Table 3.3).
NME distribution | BI-RADS definition | Portion of time seen in NME DCIS (%) |
|---|---|---|
Segmental | Triangular region of enhancement, apex pointing to the nipple, suggesting a duct or its branches | 14–77 |
Linear | Enhancement in a line that may not conform to a duct | 6–24 |
Ductala | Enhancement in a line that may have branching, conforming to a duct | 0–22 |
Focal | Enhancement in a confined area, less than 25% of a quadrant | 16–33 |
Regional | Enhancement in a large volume of tissue not conforming to a ductal distribution geographic | 6–28 |
Diffuse | Enhancement distributed uniformly throughout the breast | 1–9 |
DCIS manifests as a mass on MR images in 14–41% of cases [13, 24, 30, 31]. A mass is defined as a three-dimensional space-occupying lesion. Masses are further characterized by their shape, margin, and internal enhancement pattern.
DCIS manifests most frequently as an irregular mass, seen in 14–83% of cases [24, 30, 32]. Oval, round, and lobular masses are less commonly noted, with 1–25%, 0–25%, and 0–25% frequency, respectively, as described in the literature. Various types of mass margins have been described, including irregular (14–92% of cases) and spiculated (0–92%). Smooth mass margins are uncommon, observed in 4–8% of cases. DCIS that manifests as a mass can have various internal enhancement patterns, including heterogeneous, homogenous, and rim enhancement. A heterogeneous enhancement pattern is the most common (9–67% of cases), followed by homogenous (9–25%) and rim (0–8%) enhancement (Table 3.4).
Internal enhancement pattern | BI-RADS definition | Portion of time seen in mass DCIS (%) |
|---|---|---|
Heterogeneous | Nonspecific mixed enhancement | 9–67 |
Homogeneous | Confluent uniform enhancement | 9–25 |
Rim enhancement | Enhancement more pronounced at the periphery of the mass | 0–8 |
A focus is defined as a region of enhancement that is small (<5 mm) and may not allow confident further characterization. DCIS is least likely to manifest as a focus, although this finding may represent selection bias, because the vast majority of cases in which foci of enhancement are observed do not proceed to biopsy. According to the literature, pure DCIS manifests as a focus up to 12–20% of cases, while a focal enhancing area was observed in only 3.0% of cases of pure invasive carcinoma. Most of these foci were high-grade or intermediate-grade lesions rather than low-grade lesions [24, 31].
3.3.2 Kinetic Characteristics of DCIS
Various kinetic patterns have been seen in DCIS lesions detected on MR images [24]. BI-RADS lexicon defines the initial phase as the curve that develops within 2 min or when the shape of the kinetic curve begins to change, and the delayed phase is defined as the curve that develops after 2 min or after the kinetic curve changes. The initial phase is described as fast, medium, or slow, and the delayed phase is described as persistent, plateau, or washout. The curves may also be classified into type 1 (persistent), type 2 (plateau), and type 3 (washout). Quantitative kinetic parameters can also be derived from the curves, including initial enhancement percentage (E1), peak enhancement percentage (Epeak), and time-to-peak enhancement (Tpeak); these quantitative parameters may aid in lesion characterization.
In DCIS, the most common initial phase is fast uptake, which is seen in 49–68% of cases [24, 30, 34]. The delayed phase is more variable, with a plateau curve being the most common pattern (Fig. 3.8), seen in 20–52% of cases, followed by washout (28–44%) and persistent enhancement (20–30%) (Fig. 3.9).
In DCIS cases in which there is a high density of ducts, an abundance of blood vessels, and a high degree of inflammatory cell infiltration, there is a rapid washout pattern; this pattern is most often seen in cases of high-grade DCIS. Low-grade DCIS more often shows a benign blood flow pattern [18, 35]. Nevertheless, no individual kinetic parameter neither qualitative nor quantitative has been demonstrated to predict DCIS grade [18, 30].
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