8 Image Interpretation: Invasive Cancer





Abstract


In this chapter, we review the imaging characteristics of invasive breast cancer, focusing primarily on their various morphologic and kinetic findings on MRI. Additionally, we discuss the heterogeneous nature not only of the imaging findings, but also the clinical, histologic and molecular characteristics of invasive breast cancer as they apply to patient outcome. Microarray-based, high-throughput gene expression profiling methods have been applied to the investigation of breast cancer. These efforts are aimed towards improved understanding of the molecular basis of tumor biological features such as histologic grade, metastatic propensity, and identification of tumor genetic signatures that are associated with prognosis and therapeutic response. We show the imaging characteristics of invasive breast cancer and characterize their findings on MRI according to the BI-RADS Atlas- MRI. The most common histologic type of invasive breast cancer is now classified as Invasive Breast Carcinoma of No Special Type (IBC-NST), a change from the prior edition of the WHO Classification of Tumors of the Breast where it was designated Invasive Ductal Carcinoma Not Otherwise Specified (IDC-NOS). We review the MR imaging findings for invasive cancers grouped by both histology and their molecular signatures. These findings are shown in the 86 case examples that accompany this chapter.


As future research unfolds, it is possible that the imaging phenotype of invasive breast cancer, particularly as applied to DCE-MRI with associated advanced computer analysis, may well provide even more independent prognostic and predictive markers, complementing existing biomarkers, and thus improving patient care.




8 Image Interpretation: Invasive Cancer



8.1 Introduction


In this chapter, we will review the magnetic resonance imaging (MRI) characteristics of the various subtypes of invasive cancer and correlate the MR lesion phenotype and kinetic characteristics with histology and established biomarkers.



8.2 Background


Invasive breast cancer is a heterogeneous disease often harboring various histologic subtypes within a main tumor mass (intratumoral heterogeneity) or within separate tumor satellite lesions (intertumoral heterogeneity). Histologic heterogeneity may be found even within the morphologic types of invasive cancer, such as ductal, lobular, and other less common subtypes. 1 For many decades, breast cancer treatment has been primarily guided by the histologic classification of cancers using tumor grade, morphology, and the tumor–node–metastasis (TNM) staging method, based on cancer size, nodal status, and the presence or absence of distant metastases. The TNM classification predates the era of modern imaging and identifies the size of the largest invasive tumor focus as the main descriptive factor, discounting tumor multifocality in the overall assessment. 2 Tumors vary in both grade and histopathology. Grade is based on cellular differentiation: the higher the grade, the more “poorly differentiated” the cancer cells. It is well known that imaging phenotypes based on morphologic analysis of invasive cancers seen on mammography, ultrasound, and MRI can provide prognostic information.


In recent years, molecular subtyping of breast cancer has complemented the standard histologic classification to encompass treatment stratification based on prognostic indicators. 2 , 3 Microarray-based, high-throughput gene expression profiling methods have been applied to the investigation of breast cancer. These efforts are aimed toward improved understanding of the molecular basis of tumor biological features such as histologic grade, metastatic propensity, and identification of tumor genetic signatures that are associated with prognosis and therapeutic response. Although molecular subtyping for every patient with breast cancer could potentially enable clinicians to guide therapy more effectively, the costs of genetic analysis are high because of the need for technical expertise, and specialized equipment for individual sample processing. Molecular subtype analysis is not currently feasible for all patients and other markers have been established. Immunohistochemical (IHC) analyses are used to substitute for genetic profiling and are widely used in clinical practice. IHC markers of breast cancer include estrogen (ER) and progesterone (PR) receptors, and HER-2/neu overexpression. They have the advantage of rapid testing at a lower cost than formal genetic analysis; however, their results have been less robustly predictive of patient outcomes. A report by the IMPAKT 2012 Working Group on molecular subclasses of breast cancer showed that concordance for molecular subtype classification, between IHC and formal genetic analysis, ranges from 41 to 100% within varying subtypes. 4 Despite increased costs, tumor stratification based on tumor biology and gene expression profiles derived from DNA microarrays can now be made available to patients and are slowly being integrated into clinical practice.


The original influential studies published by Perou et al 5 , 6 defined a molecular subtype classification of breast cancer into four main categories: luminal A, luminal B, HER-2/neu positive, and basal-like. These groups are distinguished by distinct patterns of genomic additions and deletions, providing prognostic information and influencing systemic treatment decisions. The main distinction between these molecular subtypes is at the ER level and secondarily on the level of HER-2/neu. Of these molecular subtypes, two are ER positive, the luminal A (human epidermal growth factor receptor 2 negative [HER2–]) and luminal B (HER2+) groups, and two are ER negative, the basal (HER2–) and ERBB2 (HER2+) groups. These transcriptome-based subtypes


Transcriptome is the set of all messenger RNA molecules in one cell or a population of cells.

correlate well with other histological and clinical features; luminal A and B lesions generally are of a lower grade with a more favorable prognosis when compared to basal and ERBB2 subtypes, which are often higher grade with a worse prognosis. Additionally, rapidly growing tumors overexpress genes such as Ki-67, a marker of cellular proliferation known to correlate with increased mitotic indices at histopathology. Prognostic information, obtained from the tumor of each individual patient using tumor genetic signatures, or IHC markers, can guide therapy and provide selected treatment for each individual patient. Why are imaging biomarkers important? Imaging is quantitative, can sample the entire cancer, measure intratumoral heterogeneity, and complement other predictive and prognostic indicators. Serial imaging is noninvasive and can monitor tumor response during therapy.



8.3 MRI of Invasive Cancer


The vast majority of invasive cancers present as masses, noting that only a small subset of invasive cancers exhibit non–mass enhancement as the primary imaging finding. The most common histologic type of invasive breast cancer is now classified as invasive breast carcinoma of no special type (IBC-NST), changed in the fourth edition of the World Health Organization (WHO) Classification of tumors of the breast from invasive ductal carcinoma not otherwise specified (IDC-NOS). 1 The term “ductal” is no longer included in the new definition, the rationale being that the term “ductal” conveys unproven histogenetic assumptions, and that IDC-NOS does not comprise a uniform group of cancers. The IBC-NST lesions constitute about 75 to 80% of all breast cancers; invasive lobular carcinomas (ILCs) contribute another 10 to 15%; and special subtypes, tubular, medullary, papillary, and mucinous constitute the majority of the remaining malignant lesions. Invasive tumors may be further defined by their distribution and extent and are categorized as unifocal (Fig. 8‑1; Fig. 8‑2), multifocal/multicentric (Fig. 8‑3; Fig. 8‑4; Fig. 8‑5; Fig. 8‑6), and diffuse (Fig. 8‑7).

Fig. 8.1 Unifocal IDC. MRI screen-detected 4-mm unifocal, round, enhancing mass is visible on MIP image (a, arrow) as a low signal mass on T2w image (b) and on precontrast T1w image (c). Postcontrast source and subtracted images (d,e) show margin irregularity and angiomap (f) shows washout enhancement within the mass. Histology: IDC grade 3, with apocrine features. ER/PR (+), HER-2/neu (–).
Fig. 8.2 Unifocal IDC. MLO, CC views (a,b, arrows) and spot ML and CC views (c, d, arrows) demonstrate a 9-mm, round, indistinct mass with an ultrasound correlate (e). MIP image (f) demonstrates a unifocal round mass, visible on precontrast series, hypointense on T2w (g, arrow) and isointense on T1w (h, arrow). Postcontrast source and subtracted images (i, j) show the mass to exhibit rim enhancement and an adjacent postbiopsy marker clip is present (arrows). Angiomap with washout kinetics (k) and sagittal and coronal reconstructed images (l, m) are also shown. Histology: IDC grade 2. ER/PR (+), HER-2/neu (–).
Fig. 8.3 Multicentric ID. A 43-year-old patient presented with a 4-cm palpable mass in the inferomedial right breast, visible on MLO and CC views (a, b) as an irregular, spiculated mass with fine pleomorphic internal calcifications. Ultrasound correlate (c, d) shows an irregular shadowing mass with internal vascularity. MIP image (e) demonstrates confluent abnormal enhancement throughout the right medial breast with increased vascularity and marked bilateral BPE. T2w image exhibits anterior skin thickening and fluid is seen posterior to the mass extending to the pectoral muscle indicating an aggressive lesion (f, arrow ). Precontrast image (g) shows anterior skin thickening. Postcontrast source and subtracted images (h, i) show diffuse skin thickening without skin enhancement and an irregular mass with heterogeneous internal enhancement, and linear enhancement extending to the nipple. MPR slab images (j, k, l) show the extent of malignant involvement. Histology: IDC (tubulo-lobular) grade 2, focally associated with DCIS, low and intermediate nuclear grade, cribriform, micropapillary and solid type, ER/PR (+), HER-2/neu (–), blood vessel and lymphatic invasion. 20/29 axillary lymph nodes were confirmed positive for malignancy.
Fig. 8.4 Multifocal IDC. A partly obscured right breast mass with internal pleomorphic calcifications is seen on a cropped MLO MG view (a). Correlative ultrasound shows an irregular hypoechoic mass with rim vessels (b, c). An irregular enhancing mass is found on MIP image (d) with associated increased breast vascularity and an enlarged axillary lymph node (arrow). The mass is hypointense on T2 (e, arrow) and isointense on T1 precontrast (f, arrow), and exhibits heterogeneous internal enhancement and increased size, on postcontrast source and subtracted images (g, h). Angiomap (i) exhibits heterogeneous enhancement with washout and slab MPR images (j, k, l) are shown. Histology: IDC grade 2 with lymphovascular invasion and DCIS, high nuclear grade, comedo type and solid type. ER/PR (+), HER-2/neu (–). Six axillary lymph nodes were positive for malignancy (6/21).
Fig. 8.5 Multicentric IDC. A 44-year-old woman presents with a palpable mass in the inferior, posterior, and medial left breast, identified with a skin marker, but obscured on MLO and CC views (a,b) and visible on a spot MG view (c). Correlative ultrasound demonstrates an irregular spiculated mass (d). MIP image (e) shows multiple irregular masses in the mid and posterior left breast. The largest palpable mass exhibits hypointensity on T2w (f), isointensity on T1 precontrast (g), and multiple homogeneous enhancing masses of various sizes on postcontrast series (h, i). Slab MPR images (j, k, l) demonstrate to advantage the overall lesion sizes and location. Histology: IDC grade 2, ER (+), PR (–), HER-2/neu (+).
Fig. 8.6 Multicentric IDC. Screen-detected asymmetry is seen at 9:00 on LT MG- MLO/CC views (a,b, arrows) just inferior and anterior to an incidental calcified fibroadenoma. Correlative ultrasound reveals an irregular heterogeneous mass with internal vascularity (c,d). MIP image (e) shows extensive confluent enhancement in the medial left breast. T2w image (f) demonstrates a correlative area of hypointensity and posterior fluid extending to the pectoral muscle (arrow), a sign of tumor aggressiveness. The primary mass is isointense on precontrast T1w image (g) and enhances robustly on the source image (h). Adjacent slice (i) shows the extent of tumor involvement with multiple additional masses of various sizes demonstrated. Confluent enhancement, with internal focal areas of necrosis, is seen on source image (j) with heterogeneous kinetics, including washout, seen on angiomap (k). Reformatted T2w and T1w images, in the sagittal and coronal planes are shown (l, m, n, o). Histology: IDC grade 3, ER (+), PR (–), HER-2/neu (+), Ki-67: 20%.
Fig. 8.7 Diffuse IDC. A large palpable right breast mass with skin marker and lymphadenopathy is seen on MG image (a) and MIP image (b). The mass is hypointense on T2w (c) and medial fluid is present (arrows). Precontrast image (d) identifies the isointense mass (arrow) which enhances robustly and heterogeneously, with spiculation noted on postcontrast source and subtracted images (e, f). Diffuse skin thickening, but no skin enhancement, is present. Sagittal and coronal slab images (g, h) show extent of disease. Enhancement of the pectoral muscle on axial, angiomap, and sagittal images (i, j, k, arrows) denote pectoral muscle invasion. Histology: inflammatory carcinoma, IDC grade 2, with malignant involvement of dermal lymphatics. ER/PR (+), HER-2/neu (–), LVN. Sixteen axillary lymph nodes were positive for malignancy (16/25).


Multifocal cancer is usually defined as disease confined to one quadrant, whereas multicentric disease may involve more than one quadrant. This distinction may be difficult to apply in clinical practice, whereas confluent tumor involvement of most of the breast tissue is easily defined as diffuse disease. Inflammatory carcinoma is distinguished by its clinical presentation rather than by a distinct histologic subtype.



8.3.1 BI-RADS Atlas—MRI


The BI-RADS Atlas 7 defines a mass as a three-dimensional space-occupying structure, with a convex-outward contour and is further categorized by shape, margin, and internal enhancement characteristics. High spatial resolution techniques allow optimal morphologic analysis with superior definition of both shape and margins. A mass may or may not displace or otherwise affect the surrounding normal breast tissue, and may be associated with other enhancing or nonenhancing findings (Table 8‑1; Table 8‑2).
































Table 8.1 Mass descriptors

Shape


Margin


Internal enhancement characteristics


Oval


Circumscribed


Homogeneous


Round


Not circumscribed


Heterogeneous


Irregular


– Irregular


Rim enhancement



– Spiculated


Dark internal septations


Source: ACR BI-RADS Atlas MRI: Second edition.






















Table 8.2 Nonenhancing findings

Ductal high-contrast signal on T1w


Posttherapy skin thickening and trabecular thickening


Cyst


Architectural distortion


Postoperative collections (seroma, hematoma)


Signal void from foreign bodies, clips, etc.


Nonenhancing mass



Source: ACR BI-RADS Atlas MRI: Second edition.




Shape Descriptors

An oval mass is elliptical or egg-shaped and includes lobulation, with two or three undulations (Fig. 8‑8; Fig. 8‑9; Fig. 8‑10). A round mass is spherical, ball-shaped, circular, or globular in shape (Fig. 8‑11) and an irregular lesion’s shape is neither round nor oval and usually implies a suspicious finding (Fig. 8‑12).

Fig. 8.8 Oval mass. Tubular adenoma. (a) T2w: hypointense oval mass in the anterior and lateral left breast with circumscribed margins (arrow). (b) T1w precontrast: isointense oval mass (arrow). (c) T1w postcontrast 120s: heterogeneously enhancing oval mass with circumscribed margins. (d) Subtraction image. (e, f, g, h) Source and subtraction reformatted sagittal and coronal images.
Fig. 8.9 Oval mass: IDC grade 2. (a) T2w: hypointense oval mass with spiculation. (b) T1w precontrast: hyperintense irregular mass. (c) T1w postcontrast: heterogeneous enhancement and spiculated margins. (d) Subtraction image. (e) Angiomap shows washout enhancement. (f, g) Multiplanar slab images.
Fig. 8.10 Lobulated mass: IDC grade 2. (a) MIP: oval enhancing mass. (b) T2w: hypointense lobulated mass (arrow). (c) T1w precontrast: isointense mass (arrow). (d) T1w postcontrast: lobulated mass with heterogeneous internal enhancement. (e) Subtraction image. (f) Angiomap: predominantly persistent enhancement with some washout. (g, h) Sagittal and coronal reformatted images.
Fig. 8.11 Round mass: IDC triple negative. (a) T2w: hyperintense round mass with irregular margins. Note: linear fluid posterior to the cancer, sign of an aggressive tumor (arrows). (b) T1w precontrast: hyperintense round mass. (c) T1w postcontrast: heterogeneous internal enhancement, irregular margins. (d) Subtraction image. (e) Angiomap: washout kinetics. (f, g) Reformatted sagittal and coronal images.
Fig. 8.12 Irregular mass: IDC. (a) T2w: hypointense irregular mass with irregular margins (arrow). (b) T1w precontrast: isointense irregular mass (arrow). (c) T1w postcontrast: homogeneous internal enhancement, with spiculation. (d) Subtraction image. (e) Angiomap: heterogeneous uptake with washout kinetics. (f-h) MPR slab images.



Margin Descriptors

The margin is the edge or border of a lesion. The descriptors of margin, in addition to the descriptors of shape, are important predictors of benignity or malignancy. A circumscribed margin (changed from smooth in the prior lexicon) is sharply demarcated with an abrupt transition between the lesion and surrounding tissue (Fig. 8‑13). The entire margin must be well defined in its entirety to be qualified as “circumscribed.” A not circumscribed margin may be categorized as irregular, edges that are either uneven or jagged (Fig. 8‑14), or spiculated, lines radiating from a mass implying a suspicious finding (Fig. 8‑15; Fig. 8‑16; Fig. 8‑17; Fig. 8‑18). When reporting a mass with both irregular shape and margin, the MRI report should indicate that there is “a mass of irregular shape and margin.” In general, circumscribed masses are indicative of benign lesions in all imaging methods in contradistinction to noncircumscribed masses, which are suspicious for carcinoma. Margin analysis is highly dependent on optimal spatial and temporal resolution for accurate diagnosis at MRI.

Fig. 8.13 Circumscribed margin: fibroadenoma. (a) T2w: hyperintense circumscribed round mass (arrow). (b) T1w precontrast: no findings. (c) T1w postcontrast: homogeneously enhancing mass with circumscribed margins. (d) Subtraction image. (e) Angiomap: plateau kinetics. (f, g) MPR slab images.
Fig. 8.14 Irregular margin: IDC grade 2, HER-2/neu +, (a) T2w: hypointense irregular mass and margin (arrow). (b) T1w precontrast: hyperintense irregular mass and margin (arrow). (c) T1w postcontrast: heterogeneously enhancing mass with irregular margins. (d) Subtraction image. (e) Angiomap: heterogeneous washout kinetics. (f, g) MPR slab images: sagittal and coronal images.
Fig. 8.15 Spiculated margin: IDC grade2. (a) Subtraction MIP: spiculated mass left breast with increased vascularity. (b) T2w: hypointense irregular mass with spiculated margins. Note subcutaneous edema and diffuse skin thickening. (c) T1w precontrast: isointense irregular mass with spiculated margins. Note diffuse skin thickening. (d) T1w postcontrast: heterogeneously enhancing mass with spiculated margins. (e) Subtraction image. (f) Angiomap: heterogeneous enhancement with washout kinetics. (g, h, i) MPR images.
Fig. 8.16 Spiculated margin: IDC grade 2. (a, b) ML and CC MG views: spiculated mass at 12:00. (c) MIP: correlative mass (arrow). (d) T2w: hypointense irregular mass with spiculated margins. (e) T2w: sagittal view shows a superficial spiculated mass. (f) T1w precontrast: isointense small spiculated mass. (g) T1w postcontrast: homogeneously enhancing mass with spiculation. (h) Subtraction image. (i) Angiomap: heterogeneous washout enhancement. (j, k) MPR images.
Fig. 8.17 Spiculated margin: ILC grade 2. (a) T2w: spiculated mass (arrow). (b) T1w precontrast: hyperintense small spiculated mass (arrow). (c) T1w postcontrast: heterogeneously enhancing mass with spiculated margins (arrow). (d) Subtraction image shows a small enhancing spiculated mass (arrow). (e) Angiomap: heterogeneous enhancement with persistent kinetics (arrow). (f, g) Axial/sagittal reformatted image (arrows).
Fig. 8.18 Spiculated margin: IDC grade 2. (a) MIP image. (b) T2w: hypointense spiculated mass. (c) T1w precontrast: isointense spiculated mass. (d) T1w postcontrast: homogeneously enhancing mass with spiculated margins. (e) Subtraction image: note the focal medial skin enhancement from an incidental focal skin infection (arrows). (f) Angiomap: homogeneous enhancement with washout kinetics and medial skin enhancement (arrows). (g, h) Reformatted sagittal and coronal images.



Internal Enhancement Characteristics

Internal enhancement describes the enhancement pattern within an abnormally enhancing structure, and is an important reflection of lesion biology. 8 Enhancement patterns are characterized as homogeneous, a confluent uniform enhancement of a mass, and heterogeneous, a nonuniform enhancement of a mass with variable signal intensity. Homogeneous enhancement is suggestive of a benign process; however, some small cancers can exhibit homogeneous enhancement, and careful margin assessment with high spatial and temporal resolution is essential for an accurate diagnosis of benignity (Fig. 8‑19). Heterogeneous enhancement is generally more characteristic of malignant lesions (Fig. 8‑20). 8 Rim enhancement is more pronounced at the periphery of a mass, and is commonly seen in high-grade malignancies. Cysts can become inflamed and enhance peripherally, but are usually bright on T2-weighted (T2w) sequences confirming internal fluid, unless they are very small or contain proteinaceous material (Fig. 8‑21). Fat necrosis (oil cysts) and normal postoperative seromata may exhibit smooth peripheral enhancement. Rim enhancement of a solid mass is a suspicious finding (Fig. 8‑22; Fig. 8‑23). The MRI features with the highest predictive value for malignancy are lesion mass types with irregular shape, irregular or spiculated margins, and marked enhancement. 9 Dark internal septations are seen as nonenhancing lines within an enhancing mass. These dark septations are seen more frequently at higher spatial resolution (3.0 Tesla) on either T2w precontrast or T1-weighted (T1w) postcontrast series and are suggestive of a fibroadenoma if other morphologic and kinetic characteristics support benignity (Fig. 8‑24; Fig. 8‑25). Myxoid fibroadenomata are highly cellular with moderate internal mucoid material exhibiting hyperintense signal on T2 in some cases. These circumscribed masses usually show dark internal septations and heterogeneous enhancement on T1w series (Fig. 8‑26, Fig. 8‑27). Fibroadenomata are frequently seen on breast MR studies, often occult at mammography, and must be confidently recognized as benign lesions whenever possible. Nonenhancing masses with benign morphology are benign.

Fig. 8.19 Homogeneous enhancement. IDC grade 3: triple negative. (a) MIP image: homogeneously enhancing posteromedial mass. (b) T2w: hypointense irregular mass. (c) T1w precontrast: isointense mass. (d) T1w postcontrast source: homogeneously enhancing mass. (e) T1w postcontrast subtraction: thin rim and central homogeneous enhancement. (f) Angiomap: homogeneous internal enhancement with washout kinetics. (g, h) Reformatted sagittal and coronal images.
Fig. 8.20 Heterogeneous enhancement. IDC grade 3: HER2 enriched. (a) MIP image: heterogeneously enhancing mass with central enhancing nidus. (b) T2w: hypointense, round, circumscribed mass. (c) T1w precontrast: isointense mass with anterior ductal fluid (arrow). (d) T1w postcontrast source: heterogeneously enhancing mass with anterior ductal fluid (arrow). (e) T1w postcontrast subtraction: heterogeneously enhancing mass with central enhancing nidus (note: benign ductal fluid subtracted out). (f) Angiomap: heterogeneous internal enhancement with washout kinetics. (g, h) Reformatted sagittal and coronal images. Note focal failed fat suppression medially on source T1w images.
Fig. 8.21 Rim enhancement: tiny enhancing inflammatory cyst. (a) T2w: no high fluid signal. (b) T1w precontrast: no findings. (c) T1w postcontrast: 5-mm smooth rim-enhancing mass (arrow). (d) Subtraction image: 5-mm smooth rim-enhancing mass (arrow). (e) Angiomap: persistent rim enhancement (arrow). (f) sagittal subtraction image (arrow).
Fig. 8.22 Rim enhancement: IDC grade 2. (a) T2w: isointense mass (arrow). (b) T1w precontrast: no findings. (c) T1w postcontrast: irregular rim-enhancing mass. (d) Subtraction image. (e) Angiomap: predominantly persistent kinetics. (f) Sagittal image: rim enhancement with spiculation noted. (g) Coronal image: rim enhancement with spiculation noted.
Fig. 8.23 Rim enhancement: IDC grade 2. (a) T2w: partially visible hyperintense mass (arrow). (b) T1w precontrast: partially visible isointense mass (arrow). (c) T1w postcontrast: irregular rim-enhancing mass with spiculation (incidental rim-enhancing cyst, arrow). (d) Subtraction image. (e) Angiomap: rim enhancement, predominantly plateau with some washout. (f, g) MPR images.
Fig. 8.24 Unenhancing internal septations: small fibroadenoma. (a) T2w: hyperintense mass (arrow). (b) T1w precontrast: oval mass, circumscribed margins (arrow). (c) T1w postcontrast: enhancing mass with unenhancing internal septations. (d) Subtraction image. (e) Angiomap: homogeneous persistent enhancement. (f) Sagittal image.
Fig. 8.25 Unenhancing internal septations: tiny fibroadenoma. (a) T2w: no findings. (b) T1w precontrast: no findings. (c) T1w postcontrast: enhancing mass with a transverse unenhancing internal septation (short arrow). Note: Focal BPE lateral to the lesion (long arrow). (d) Subtraction image: enhancing mass with a transverse unenhancing internal septation (arrow). (e) Angiomap: predominant persistent enhancement. (f, g) MPR images: mass with transverse septation (arrows).
Fig. 8.26 Unenhancing internal septations: myxoid fibroadenoma. MIP Image (a) reveals a lobulated subareolar enhancing mass, seen as isointense on T2w (b) (arrow) and isointense on T1w precontrast image (c). Post contrast source and subtraction images (d, e) reveal robust enhancement with unenhancing internal septations and heterogeneous washout kinetics on angiomap (f). (g, h) MPR images.
Fig. 8.27 Unenhancing internal septations: myxoid fibroadenoma. (a) T2w: mixed hyper- and isointense circumscribed mass (arrow). (b) T1w precontrast: isointense circumscribed mass (arrow). (c) T1w postcontrast: heterogeneously enhancing mass with unenhancing internal septations. (d) Subtraction image. (e) Angiomap: uniform persistent enhancement. (f, g) MPR images.



Fat-Containing Lesions

These masses are generally benign and include lesions such as lipomata, fibroadenolipomata (hamartoma) (Fig. 8‑28, Fig. 8‑29), and lymph nodes (Fig. 8‑30; Fig. 8‑31). The key to accurate diagnosis is identification of fat signal within the lesion on a non–fat-suppressed high-resolution T2w or T1w series. Fat necrosis may present as a rim-enhancing mass exhibiting varying enhancement (Fig. 8‑32). History of prior trauma or surgery may explain the enhancing finding, and verified central fat content on non–fat-suppressed images may confirm the diagnosis (Table 8‑3).

Fig. 8.28 Fat-containing lesion: fibroadenolipoma. (a) T2w: oval, fat-containing, circumscribed subareolar mass (arrow). (b) T2w: sagittal view (arrow). (c) T1w precontrast: thin capsule with breast tissue and internal fat signal (arrow). (d) T1w postcontrast: selective enhancement of breast tissue within the thin capsule. (e) Subtraction image: no findings.
Fig. 8.29 Fat-containing lesion: fibroadenolipoma. (a) T2w: oval, fat-containing mass with thin capsule (arrow). (b) T2w sagittal view: (arrow). (c) T1w precontrast: oval mass with internal fat signal (arrow). Note skin thickening resulting from BCS 5 years previously. (d) T1w subtraction: selective enhancement of breast tissue within the thin capsule (arrow). (e) Angiomap: persistent parenchymal enhancement within the lesion (arrow).
Fig. 8.30 Fat-containing lesion: intramammary lymph nodes (IMLN). (a) T2w: several oval and round masses with internal fat signal (arrows). (b) T2w: sagittal image (arrows). (c) T2w: coronal image (arrows). (d) T1w precontrast: circumscribed masses (arrows). (e) Angiomap: washout kinetics (arrows).
Fig. 8.31 Fat-containing lesion: intramammary lymph node (IMLN). IMLN no. 1: (a) T2w: oval circumscribed mass with fatty hilum (arrow). (b) T1w precontrast: oval circumscribed mass with fatty hilum (arrow). (c) T1w postcontrast: oval circumscribed mass with fatty hilum (arrow). (d) Subtraction image: (arrow). (e) Angiomap: washout kinetics, typically present in IML nodes. Identification of a fatty hilum is helpful for a confident benign diagnosis. IMLN no. 2: (f) T2w: round circumscribed mass with fatty hilum (arrow). (g) T1w subtraction: round circumscribed mass with fatty hilum (arrow). (h) Angiomap: washout kinetics, (i, j) reformatted: T2w sagittal and coronal images (arrows). (k, l) reformatted: T1w subtraction sagittal and coronal images (arrows).
Fig. 8.32 Fat-containing lesion: fat necrosis 6 months post-BCS. (a) T2w: irregular mass with internal fat signal (arrow). (b) T1w postcontrast: irregular rim-enhancing mass with internal fat signal (short arrow). Note: adjacent nonmass enhancement with tiny foci of internal fat signal represents an additional region of fat necrosis (long arrows). (c) Subtraction image: (arrows). (d) Angiomap: washout enhancement is noted in the main mass (short arrow). Persistent enhancement is noted in the additional region of fat necrosis (long arrows).
















Table 8.3 Fat-containing lesions

Lymph nodes: normal or abnormal


Hamartoma/Fibroadenolipoma


Fat necrosis


Postoperative seroma/hematoma with fat


Source: ACR BI-RADS Atlas MRI: Second edition.




T2w Precontrast Mass Findings

High-resolution T2w sequences provide important information and, when evaluating breast masses, can improve specificity of diagnosis. Comparing the morphology and signal intensity on T2w and T1w images can be helpful. High T2w signal may signify extensive necrosis seen most frequently in high-grade lesions, or in mucinous/loose myxoid stroma seen in mucinous carcinoma. Cystic or microcystic tumor components are rare and can be found most frequently in papillary cancers. Intratumoral fat-containing tissue usually indicates a benign diagnosis. The presence of peritumoral, stromal, subcutaneous, or prepectoral edema augurs an aggressive malignancy type.



8.4 Kinetic Curve Assessment


Kinetic analysis of suspect lesions should be assessed after complete evaluation of the MRI findings. The first postcontrast series is generally selected for kinetic analysis because abnormal tissue is usually most intense and distinct from normal background parenchymal enhancement at this time point. Kinetic information is typically expressed as a time intensity curve (TIC), plotting the signal intensity of the most suspicious enhancement finding on a pixel-by-pixel basis, depicting the enhancement rate over time. The TIC can be manually calculated by placing a region of interest (ROI) of at least three pixels within a lesion or can be automatically created by CAD systems (dedicated software generating lesion color maps and TIC graphs). The TIC depicts the initial phase of enhancement within the first 2 minutes following injection or until peak enhancement is reached, and the delayed phase of enhancement depicts the TIC after 2 minutes or after the peak enhancement is reached and is used to describe the curve shape. Malignancies generally enhance rapidly in the initial phase of contrast enhancement with contrast washout in the delayed phase. Evaluation of both morphologic and kinetic data is essential for diagnosis.



8.4.1 Initial Phase


Initial enhancement is determined by comparing signal intensity in the precontrast image to the first postcontrast image acquired. An intensity increase of less than 50% is classified as “slow,” 50 to 100% is classified as “medium,” and greater than 100% enhancement is classified as “fast.”



8.4.2 Delayed Phase


Delayed enhancement is divided into three main categories:




  • Persistent curves (type 1) are defined as showing ≥10% of the initial enhancement with continuously increasing enhancement throughout the delayed phase.



  • Plateau curves (type 2) are equal to the initial enhancement and remain constant in their signal intensity once peak enhancement is reached, usually after 2 to 3 minutes.



  • Washout curves (type 3) are defined as showing ≤10% of the initial enhancement with continuous decreasing signal intensity after peak enhancement is reached (Fig. 8‑33).

Fig. 8.33 Kinetic analysis graph.


Kinetic Curve Assessment

In general, benign lesions exhibit persistent curves, and malignant lesions exhibit washout curves, although there is considerable overlap between the kinetic curves that depict malignant and benign lesions. Diagnosis should only be made after consideration of both the morphologic and kinetic features of an enhancing lesion. Kinetic features reflect underlying lesion biology and the efficacy of advanced computerized analytic methods, using both morphologic and kinetic data, will be discussed in Chapters 12 and 13.



8.5 Histologic Subtypes of Invasive Cancer


As previously noted, the most common type of invasive breast carcinoma (75–80%) is classified as IBC-NST. This category incorporates all breast adenocarcinomas that fail to exhibit specific histologic characteristics that would warrant classification as one of the special types. The WHO classification recognizes the existence of at least 17 distinct histological special types. 1 Invasive malignancies exhibit distinctive morphologic, kinetic, and molecular characteristics that are reflected on mammography, ultrasound, and MRI. The imaging characteristics of the most common special types of invasive cancer will be reviewed.



8.5.1 Invasive Lobular Carcinoma


Invasive lobular carcinoma accounts for 10 to 15% of all invasive cancers, is known to be difficult to diagnose both on clinical examination and on mammography, and is usually larger at initial presentation, more frequently exhibiting multifocal/multicentricity than IDC. Palpable thickening and skin or nipple retraction may be the most common clinical findings rather than detection of a discrete breast mass. The growth pattern of uniform, small, round tumor cells, typically infiltrating in a single file without mass formation, may limit conspicuity at mammography. The reported sensitivity of mammography ranges from 34 to 92% 10 ; however, even when detected, size underestimation is common. Lack of desmoplastic reaction and absence of associated ductal carcinoma in situ (DCIS) with visible microcalcification also contribute to difficulties in lesion perception. ILC is diagnosed, in part, by absence of e-cadherin expression, a gene involved in cell–cell cohesion, thought to account for the singular growth pattern.


The most common presentation on mammography is that of a spiculated or ill-defined mass; however, findings of asymmetry and architectural distortion are more commonly found in ILC lesions than in IDC lesions. In some cases, a sheet-like infiltrating pattern of the tumor may result in decreased natural breast elasticity in the affected breast, limiting breast compression at mammography so that the breast appears to be smaller than the contralateral breast. This finding is known as the “shrinking breast” sign. The affected breast may appear to be of normal size, however, on clinical examination “thickening” of the breast may be evident. 10 , 11 , 12 Ultrasound has a higher sensitivity for ILC than mammography (68–98%) and findings usually present as an irregular, hypoechoic mass with indistinct or spiculated margins and acoustic shadowing. 13



Histology

The heterogeneous nature of ILC is well established, and histologic subtypes of ILC lesions have been described. In 1982, Dixon and colleagues categorized 103 ILC lesions as classical, solid variant, alveolar variant, or mixed histologic subtypes, the classic and mixed types being the most common. 14 The classic type of ILC is described as a single filing growth pattern, with “peri-parenchymal” distribution and diffuse multifocal invasion. The solid variant consists of a “sheet-like” pattern or irregular-shape nests of cells, whereas the alveolar type is described as globular aggregates of 20 or more cells. These three subgroups exhibit small noncohesive regular cells with round or oval nuclei, whereas the fourth mixed type demonstrates cohesive cells with nuclear pleomorphism. Recently, subclassification has been reported using histological features and IHC 15 ; however, no clear differences in long-term patient outcome between the different histologic subtypes was found in either study. 14 , 15


Two studies have reported on the mammographic imaging appearance of ILC subtypes and histopathology. 16 , 17 In 2014, Tabar and colleagues 16 reported on 428 consecutive cases of ILC, diagnosed in the screening era, from 1996 through 2010, and compared patient outcome of these cases with a cohort of ILC cases diagnosed and treated in the prescreening era 25 to 30 years earlier. 7 A classification of the mammographic features of ILC lesions was made with an approximate correlation to the earlier histologic classification of Dixon and colleagues 14 (Table 8‑4). ILC subtypes vary in their imaging characteristics and lesion size at diagnosis. The alveolar subtype is often extremely difficult to detect at mammography even though it is often palpable and multifocal, because it consists of many individual, tiny, scattered 2- to 3-mm cancer foci, often involving an entire quadrant but without a discrete tumor mass. Tumor sizes differed significantly in this study according to their mammographic subtypes (p < 0.001). Large tumor sizes (≥30 mm) were overwhelmingly more likely to be found in architectural distortion cases (76%) than in spiculated masses (21%), round masses (25%), and equivocal asymmetric densities (34%). Patient outcome was shown to be related to mammographic appearance when long-term survival of women with ILC lesions was compared in the two groups (1960–1970 vs. 1996–2010). Outcome for women with spiculated and circular/oval-shape lesions diagnosed during the screening era was dramatically improved; however, no change in survival was found in women with the classical architectural distortion subtype, despite the advent of screening mammography in the latter group and the introduction of new therapeutic regimens.






















Table 8.4 Mammographic features of ILC subtypes

Classical


Architectural distortion


Solid variant pattern


Round- or oval-shape mass


Alveolar


Equivocal asymmetries


Mixed pattern


Solitary or multifocal spiculated mass


Abbreviation: ILC, invasive lobular carcinoma.




Magnetic Resonance Imaging

The MRI findings of ILC reflect the morphologic findings seen on mammography and ultrasound; however, determination of disease extent is more accurate at MRI, and ILC lesions, found to be occult on mammography and ultrasound, are almost always visible on MRI. An irregular or spiculated-shape mass, with heterogenous internal enhancement, is a common presentation of ILC, although focal and “sheet-like” regional nonmass enhancement may also be found. 12 , 18 , 19 , 20 ILC rarely presents as a round mass, an important distinction compared to IDC lesions, which may often present as round masses with not circumscribed margins, and are generally grade 2 lesions. Mann and colleagues reported that a round-shape mass was identified in only 1 of 143 ILC lesions. 18 ILC has been described as a “stranding” pattern of tumor enhancement, associated with multiple, small, enhancing foci, by some investigators, possibly reflecting the single-file pattern of tumor growth. 14 , 21 Reports on the kinetic features of ILC generally conclude that in the initial phase of enhancement, ILC enhances more slowly than IDC, although peak enhancement measures may be similar. In the delayed phase of enhancement, ILC exhibits washout curves less frequently and a larger proportion of the tumor shows persistent delayed-phase curves than are seen in IDC. 22


Multimodal images of the four main presentations of ILC are shown.




  1. The classical subgroup of ILC: architectural distortion (Fig. 8‑34).



  2. The solid variant pattern subgroup of ILC: round/oval mass (Fig. 8‑35; Fig. 8‑36).



  3. The alveolar subtype of ILC: asymmetric density/NME (Fig. 8‑37, Fig. 8‑38; Fig. 8‑39; Fig. 8‑40; Fig. 8‑41).



  4. The mixed pattern of ILC: spiculated mass(s): (Fig. 8‑42; Fig. 8‑43; Fig. 8‑44).

Fig. 8.34 ILC: classic subtype. A triangular sebaceous marker indicates the site a palpable architectural distortion in the superolateral left breast on MLO and CC mammographic views (a,b, arrows). MIP image (c) shows increased vascularity and multiple enhancing masses of variable sizes, the aggregate extending beyond the mammographic extent. T2w image (d) reveals a low signal lesion on T2w image with fluid posterior to the lesion, indicating aggressive histology (arrow). T1w, pre- and postcontrast, and subtraction images (e, f, g,) reveals multiple enhancing masses. Angiomap shows robust, mostly plateau, enhancement (h). Reformatted sagittal and coronal images (i, j) are shown. Histology: ILC classic-type grade 2 with LCIS. ER/PR (+), HER-2/neu (–), Ki-67: 15%.
Fig. 8.35 (a-l) ILC: solid variant pattern. A mass with obscured margins is seen on MLO and CC mammographic views (a,b, arrows; note the palpable skin markers). Multilobulated mass is identified on ultrasound (c). MIP image (d) shows a round enhancing mass with irregular margins with low signal on T2w image (e). T1w, pre- and postcontrast, and subtraction images (f,g,h) show a unifocal mass with heterogeneous internal enhancement. Washout enhancement is seen within a predominantly persistently enhancing mass (i). MPR images (j,k,l). Histology: ILC grade 2, ER/PR (+), HER-2/neu (+).
Fig. 8.36 ILC: solid variant pattern (1.5 T). A partially obscured mass, identified by a palpable skin marker, is visible in the right breast MLO and spot CC views (a, b, short arrows) and a suspicious lymph node is seen in the axilla (a, long arrow). A round isoechoic mass is seen on ultrasound (c) presenting as a unifocal, homogeneously enhancing mass on MIP image (d). The mass is isointense and partly outlined on T2w image (e) but not visible on precontrast image (f, g). T1w postcontrast source, subtracted and sagittal images demonstrate homogeneous enhancement. Histology: ILC grade 2, ER/PR (+), HER-2/neu (–). One axillary lymph node was positive for malignancy (1/10).
Fig. 8.37 ILC: classic subtype. A distortion is seen in the posterior right breast at 9:00 on MLO and CC mammographic views (a, b) and a second area of distortion with intervening asymmetry is noted in the subareolar region (arrows). An irregular shadowing mass is seen at 9:00 on ultrasound (c). MIP image (d); T2w (e); and T1w, pre-, postcontrast and subtraction images (f, g, h) demonstrate two irregular masses with some distortion, spiculation, and intervening NME. Angiomap exhibits some washout within an area of predominantly persistent enhancement (i) and MPR slab images (j, k, l) show disease extent to advantage. Histology: ILC classic-type grade 2, 6.5 cm, with focal pleomorphic features, ER/PR (+), HER-2/neu (–), Ki67: 10%. One axillary node was positive for malignancy (1/14).
Fig. 8.38 (a–m) ILC. Alveolar subtype “shrinking” left breast. The left breast appears smaller than the right, and a diffuse asymmetry is noted in the posterior left breast at the fibroglandular/fat junction on bilateral mammographic views (a,b,c,d, arrows). Regional NME is seen in the posterior left breast on MIP image (e) and posterior fluid indicating an aggressive lesion is seen on T2w image (f). T1w precontrast image (g) shows no findings; however, postcontrast source and subtracted images (h, i) and adjacent slice (j) show NME predominantly in the medial posterior breast, correlating in location with the mammographic findings. Histology: ILC grade 2, alveolar subtype: ER/PR (+), HER-2/neu (–). 27/30 axillary lymph nodes were positive for malignancy.
Fig. 8.39 ILC. Alveolar subtype. A developing asymmetry is noted in the left breast at 12.00 on mammographic views (a, b, arrows). A correlative focal NME is seen on MIP image (c, arrow). T2w and T1w precontrast images (d, e) show no abnormal findings; however, a small round mass (arrows) indicate a transverse section of a blood vessel, confirmed when adjacent slices are viewed. Postcontrast source and subtracted images (f, g) exhibit NME, correlating in location and size with the mammographic findings. Persistent enhancement is noted within the lesion on angiomap (h). MPR views (i, j) are shown. Histology: ILC grade 1, alveolar subtype, with ALH. ER/PR (+), HER-2/neu (–). The sentinel node was negative for malignancy (0/1).
Fig. 8.40 ILC. Alveolar subtype. Example of a challenging diagnosis: a developing posterior asymmetry and periareolar skin thickening is noted in the right breast on mammographic views (a, b, arrows). Ultrasound image (c) demonstrates an irregular mass, and MIP shows minimal NME in the right breast (d, arrows). T2w images (e, f, arrows) and T1w precontrast images (g, arrow) show nipple retraction and associated skin thickening. Postcontrast source and subtracted images (h, i) show regional NME, larger in extent than the mammographic findings. Subthreshold enhancement in the lesion is noted by absence of color on angiomap (j). Reformatted sagittal and coronal images are shown (k, l). Histology: ILC grade 2, with LCIS. ER/PR (+), HER-2/neu (–), Ki-67: 5%. Sentinel nodes were negative for malignancy (0/2).
Fig. 8.41 ILC. Alveolar subtype. Bilateral MLO and CC views (a, b, c, d) are shown. The right breast is less compressible and thus appears smaller than the left, due to presence of a diffuse infiltrative malignancy. A palpable right inferomedial architectural distortion (long arrows) and an enlarged right intramammary lymph node (short arrows) are identified. Ultrasound image (e) demonstrates two irregular masses with increased vascularity (f). 70s postcontrast MIP image (g) shows diffuse NME, increasing in degree and extent as shown on 210s MIP image (h). T2w images of both breasts show decrease in right breast size with distorted breast tissue (i). T1w precontrast image (j) shows skin thickening, postcontrast source, and subtracted images (k, l) show regional NME with persistent kinetics on angiomap (m). MPR slab views are shown (n, o, p). Histology: ILC grade 2 with blood vessel and lymphatic invasion present at mastectomy. ER/PR (+), HER-2/neu (–). Twelve axillary lymph nodes were positive for malignancy (12/13).
Fig. 8.42 ILC. Mixed pattern subtype. Spiculation and distortion is noted in the left breast at 9:00 on mammographic views (a, b, arrows) and spot magnification views (c, d, arrows). Ultrasound image (e) demonstrates an irregular mass with spiculation, and MIP image shows enhancement correlating with the location of the MG and ultrasound findings (f, arrow). T2w image (g) and T1w precontrast images (h) show no abnormal findings. Postcontrast source and subtracted images (i, j) show enhancement of the spiculated mass and surrounding foci with persistent kinetics on angiomap (k). MPR slab views are shown (l, m, n). Histology: ILC grade 1, total lesion size 4.3 cm. ER/PR (+), HER-2/neu (–). Sentinel nodes were negative for malignancy (0/3).
Fig. 8.43 ILC. Mixed pattern subtype. MIP image (a) shows an irregular, spiculated mass in the lateral left breast (short arrow) and a focal area of NME anterior to the mass (long arrow). The previously biopsied index mass is visible on precontrast T2w and T1w images (b,c). Postcontrast source (d), subtraction (e), and angiomap images (f) show internal enhancement with a postbiopsy marker clip and heterogeneous kinetics including washout. Axial subtraction image (h) shows NME located anterior to the mass, representing additional malignancy (long arrow). Sagittal image (h) shows both the mass (short arrow) and anterior NME (long arrow). A coronal image of the index mass (i) is also shown. Histology: extensive ILC grade 2 representing the index lesion and the focal anterior NME, both associated with LCIS classic type. ER/PR (+), HER-2/neu (–), Ki-67: 5%. One axillary node was positive for malignancy.
Fig. 8.44 ILC. Mixed pattern subtype. Screening MLO and CC MG views (a,b) show a partly obscured mass in the anterior right breast (arrows) and correlative ultrasound (c,d) demonstrating an irregular spiculated mass with hypoechogenicity, which is also seen on MIP image (e). The index spiculated mass is seen well on precontrast image T2w (f, arrow) and a marker clip from prior biopsy is seen within the mass on T1w image (g, arrow). Postcontrast images, source (h), subtraction (i), and angiomap (j) show relatively homogeneous internal mass enhancement with predominantly persistent kinetics. A focal area of minimal NME was also found on an additional slice, in the posteromedial breast on image (k, arrow), suggesting additional malignant involvement and confirmed with MR BX. Sagittal and coronal images (l,m) are shown. Histology: ILC grade 2, > 6 cm, with associated LCIS classic type: ER (+), PR (–), HER-2/neu (–), Ki-67: 5%. 28/28 axillary lymph nodes were positive for malignancy with extranodal extension.

Additional ipsilateral malignant lesions detected only on MRI were found in 32% of patients, in a study of preoperative assessment of ILC extent, resulting in changed management in 28% of cases. 18 Another study of preoperative assessment of ILC showed management change in 49% women, 40% needing more extensive surgery and 9% needing less extensive surgery (Fig. 8‑43, Fig. 8‑44). 23 Patients with an ILC diagnosis are more likely to have positive surgical margins after lumpectomy than patients with IDC lesions. Reduction in reexcision rates of ILC lesions by use of preoperative MRI has been shown in a study of 267 patients undergoing breast conserving surgery (BCS). Investigators reported a 9% reexcision rate in the MRI group compared to a 27% reexcision rate in the group without preoperative MRI. 24 MRI has been shown to be an essential imaging method in the preoperative assessment of women with a new diagnosis of ILC.



8.5.2 Invasive Duct Carcinoma



Tubular Subtype

Tubular carcinoma is an uncommon, low-grade subtype of invasive carcinoma accounting for fewer than 2% of all invasive breast cancers, its incidence increasing with the use of screening mammography. These cancers are generally small and node negative with a favorable prognosis, the overall 10-year disease-free survival rate for tubular cancer being greater than 90%. Tubular carcinoma contains a central fibroelastotic core that entraps glandular proliferating elements, exhibiting round, ovoid, or angulated tubules formed by a single layer of small, regular cells with little nuclear pleomorphism. A tubular component greater than 90% is a requirement for a histologic diagnosis of tubular carcinoma. 25 , 26



Imaging Findings

The hallmark finding, on all modalities, is that of spiculation, which corresponds to reactive stroma surrounding the tumoral mass, seen on ultrasound as an echogenic “halo.” Small tubular cancers usually present on MRI as spiculated or irregular masses, with heterogeneous enhancement and persistent kinetics (Fig. 8‑45; Fig. 8‑46, Fig. 8‑47). Minimal enhancement or initial enhancement rates less than 100% are commonly found. This enhancement pattern can be explained by the slow progression of the contrast material within the dense fibrous and elastotic stromal components. The morphologic features of radial scar (complex sclerosing lesion) often mimic those of tubular carcinoma and their kinetic behavior is often variable. Although visible on MRI, the distinction between these two lesions is usually not possible if lesion enhancement is present, and pathologic examination of the surgically excised tumor is generally needed.

Fig. 8.45 IDC. Tubular subtype. Screening MG views of the right breast (a, b) show a 4-mm irregular mass, centrally located at 12:00 and a lateral, normal IMLN incidentally noted (long arrows). MIP image (c) shows a correlative irregular enhancing mass, also seen well on precontrast T2w image (d) (short arrow) and a fat-containing IMLN (long arrow). Marker clip from prior biopsy is seen on precontrast T1w image (e) (short arrow), and the IMLN (long arrow). Postcontrast images, source (f), subtraction (g), and angiomap (h) show homogeneous persistent enhancement in the index mass. Sagittal and coronal images (i, j) are shown. Histology: IDC grade 1 with tubular features. ER/PR (+), HER-2/neu (–), Ki-67: 6%. Sentinel nodes negative for malignancy (0/4).
Fig. 8.46 IDC. Tubular subtype. Screening MG views of the right breast (a, b) show an 11-mm, partly obscured, irregular mass at 10:00 MIP image with correlative ultrasound images (c, d) and increased blood flow shown on image (d). MIP image (e) shows a lobulated, irregular, enhancing mass, also seen well on precontrast T2w image (f). Marker clip from prior biopsy is seen in the mass on precontrast T1w image (g) (arrow). Postcontrast images, source (h), subtraction (i), and angiomap (j) exhibit robust mass enhancement with heterogeneous washout kinetics. Sagittal and coronal images (k, l) are shown. Histology: IDC grade 1 with tubular features and low grade, solid DCIS. ER/PR (+), HER-2/neu (–). Sentinel nodes were negative for malignancy (0/3).
Fig. 8.47 IDC. Tubular subtype. Screening MG views of the left breast (a,b, arrows ) and spot compression views (c,d) demonstrate a 7-mm irregular indistinct mass at 10:00, with correlative ultrasound images (e,f) showing an irregular mass, with a surrounding echogenic halo representing dense surrounding fibrous tissue (arrows). MIP image (g) shows robust enhancement in the mass, which is visible on precontrast T2w and T1w images (h,i, short arrows ). A biopsy-placed marker clip artifact is also seen (long arrows). Postcontrast images, source (j) shows the enhancing mass with spiculation and postbiopsy focal skin enhancement (arrow). Subtraction image (k) and angiomap (l) exhibit enhancement with heterogeneous washout kinetics. Sagittal and coronal images (m, n) are shown. Histology: IDC grade 2 with tubular features and low grade, solid DCIS. ER/PR (+), HER-2/neu (–). The sentinel node was negative for malignancy (0/1).

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Feb 15, 2021 | Posted by in BREAST IMAGING | Comments Off on 8 Image Interpretation: Invasive Cancer

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