Lymph Node Imaging in Patients with Primary Breast Cancer: Concurrent Diagnostic Tools

Abstract

The detection of lymph node metastasis affects the management of patients with primary breast cancer significantly in terms of staging, treatment, and prognosis. The main goal for the radiologist is to determine and detect the presence of metastatic disease in nonpalpable axillary lymph nodes with a positive predictive value that is high enough to initially select patients for upfront axillary lymph node dissection. Features that are suggestive of axillary adenopathy may be seen with different imaging modalities, but ultrasound is the method of choice for evaluating axillary lymph nodes and for performing image-guided lymph node interventions. This review aims to provide a comprehensive overview of the available imaging modalities for lymph node assessment in patients diagnosed with primary breast cancer. IMPLICATIONS FOR PRACTICE: The detection of lymph node metastasis affects the management of patients with primary breast cancer. The main goal for the radiologist is to detect lymph node metastasis in patients to allow for the selection of patients who should undergo upfront axillary lymph node dissection. Features that are suggestive of axillary adenopathy may be seen with mammography, computed tomography, and magnetic resonance imaging, but ultrasonography is the imaging modality of choice for evaluating axillary lymph nodes. A normal axillary lymph node is characterized by a reniform shape, a maximal cortical thickness of 3 mm without focal bulging, smooth margins, and, depending on size, a discernable central fatty hilum.

Keywords: Axilla; Lymph nodes; Magnetic resonance imaging; Positron emission tomography; Ultrasonography.

Figure 1

Female patient aged 40 years with an invasive ductal carcinoma in the left breast. (A): Left digital mammography, mediolateral‐oblique projection, demonstrates a high‐density lymph node in axilla and an irregular mass, spiculated, in the upper quadrants. (B): Ultrasonography confirmed the suspicious nature of the mass (Breast Imaging – Reporting and Data System [BI‐RADS] score 5) and a single enlarged lymph node in the axilla suspicious for metastatic involvement.

Figure 2

Sonographic morphologic characteristics that are predictors of malignancy. These include cortical thickness greater than 2.5–3.0 mm (A, C, D), focal cortical lobulation (B), loss of the fatty hilum (C, D), a round shape (C, D), and abnormal blood flow (A, B).

Figure 3

MRI and sonographic characteristics of benign nodes. T1 fat‐saturated magnetic resonance imaging 2 minutes after administration of contrast media (A) in a woman aged 68 years with a suspicious mass in the median‐inner quadrant of the left breast (B, red arrow) showing bilateral enlarged nodes with central fatty hilum. (C): The targeted ultrasound demonstrated normal appearance of one of the nodes. A fine‐needle aspiration was performed with a cytologic diagnosis: polymorphous lymphoid population, negative for malignant cells.

Figure 4

Partial SI decrease in metastatic lymph node in a woman aged 45 years with primary stage pT2N1 tumor. Sagittal nonenhanced (A) and ultra‐small superparamagnetic iron oxide (USPIO)–enhanced (B) T2‐weighted fast spin echo magnetic resonance (MR) images (7,600/120) as well as nonenhanced (C) and USPIO‐enhanced (D) T2*‐weighted fast field echo MR images (683/14) of left axilla show a 1.4 × 0.9 cm metastatic lymph node (large arrow) with partial signal intensity (SI) decrease after USPIO administration. Adjacent nonmetastatic node (small arrow) shows homogeneous SI decrease after USPIO administration. Primary tumor is seen. Reproduced, with permission, from Memarsadeghi et al., Axillary lymph node metastases in patients with breast carcinomas: Assessment with nonenhanced versus USPIO‐enhanced MR imaging. Radiology 2006;241:367–377 46. © 2006 RSNA.

Figure 5

A woman aged 45 years with invasive ductal cancer of the right breast. Computed tomography (CT) of the whole body. Axial (A) and coronal (D) views show enlarged node in the right axilla (A, arrow; C) associated with an irregular mass within the right breast (A, circle). Whole body positron emission tomography (PET) examination. Axial (B) and coronal (E) views demonstrate high fluorodeoxyglucose uptake for both the mass and the enlarged node in the axilla that is also confirmed by hybrid imaging PET/CT (C, F).

Figure 6

Single‐photon emission computed tomography (SPECT) of the breast. A patient aged 50 years after left lumpectomy with left axillary nodal dissection with recurrent left breast cancer undergoing left breast lymphoscintigraphy. Lymphoscintigraphy shows extensive heterogeneous tracer accumulation throughout the skin of the left breast, including multiple serpiginous trails of activity as well as irregular accumulations (A). Additionally, isolated foci are seen in the right axillary region and lower left neck. SPECT and computed tomography localize these two foci to the right axilla (B) and left supraclavicular region (C). Additionally, a left internal mammary node was visualized (D).

Figure 7

Radiomics workflow. Reprinted by permission from Springer Nature, from Han et al., Radiomic nomogram for prediction of axillary lymph node metastasis in breast cancer. European Radiology 2019;7:3820–3829 76. © 2019 European Society of Radiology. Abbreviations: LN, lymph node; ROI, region of interest.