Detection of Internal Mammary Adenopathy in Patients With Breast Cancer by PET/CT and MRI

Abstract

OBJECTIVE The purpose of this study was to assess the prevalence of internal mammary node (IMN) adenopathy in patients with breast cancer and compare breast MRI and PET/CT for detection of IMN adenopathy. MATERIALS AND METHODS This retrospective study included 90 women who underwent MRI and PET/CT before neoadjuvant chemotherapy for clinical stage IIA through IIIA disease. MRI and PET/CT examinations were read independently by two readers trained in breast imaging and nuclear medicine. All patients underwent follow-up MRI at the end of chemotherapy, and 10 with hypermetabolic IMNs underwent follow-up PET/CT. Histology was not obtained. Women were considered to have IMN adenopathy when nodes seen on MRI or having standardized uptake value (SUV) greater than mediastinal blood pool decreased in either size or SUV (or both) after treatment. Features including lymphovascular invasion, tumor quadrant(s), and axillary adenopathy were compared between presence and absence of IMN adenopathy using Fisher’s exact test. Prevalence was determined on the basis of the percentage of patients with IMN adenopathy by either modality. The McNemar test compared the prevalence of IMN adenopathy on MRI to its prevalence on PET/CT. RESULTS Prevalence of IMN adenopathy was 16% (14/90) by MRI and 14% (13/90) by PET/CT (p = 0.317). After chemotherapy, IMN adenopathy resolved in 12 of 14 patients (86%). In two patients with poor responses in primary tumors, IMN adenopathy persisted, and both patients developed metastatic disease within 6 months. At 3 years, survival was significantly worse in patients with IMN adenopathy than in those without (85.7% vs 53.3%, respectively; p = 0.009). CONCLUSION In women with advanced breast cancer receiving neoadjuvant chemotherapy, prevalence of IMN adenopathy was 16%, equally detected by breast MRI and PET/CT. Identification of IMN adenopathy may affect treatment and provides prognostic information.

Optimal radiotherapy for patients with internal mammary lymph node metastasis from breast cancer

“…The EQD2 > 63. 5 Gy was associated with improved DFS in patients with IMN size ≥1.0 cm. However, the association between IMN radiation dose and DFS was not significant in patients with IMN size < 1.0 cm.…”

“…Previous surgical studies found that the frequency of pathologic IMN involvement was between 28 and 52% in patients with axillary lymph node (ALN) metastasis, while it was between 5 and 17% for patients without ALN metastasis [2,3]. According to recent studies in which contemporary imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography-computed tomography (PET-CT) were performed, the incidence of cIMN+ ranged between 11 and 16% in breast cancer patients with advanced nodal disease (cN2-N3) [4,5]. Even though cIMN+ is frequently observed in patients with breast cancer, the optimal treatment method and prognosis have not been well identified.…”

Does the TNM classification of solitary internal mammary lymph node metastases in breast cancer still apply?

“…Possible explanations for improved overall survival can be the introduction of other systemic regimen, such as trastuzumab, or detecting smaller IMLNMs with SLNB. Nowadays, the size of internal mammary lymph nodes detected using state-of-the-art imaging techniques such as PET/CT and MRI approaches the size of internal mammary nodes visualized during SLNB [15–17]. This suggests comparable prognosis of SLNB-detected IMLNMs and imaging-detected IMLNMs.…”

“…As a consequence, there was no distinction in our cohort of pN2b patients detected by for instance physical examination, ultrasound, MRI, or PET-CT. Yet, a previous study of Jochelson et al demonstrated a difference in the prevalence between several imaging techniques for detecting internal mammary adenopathy [17]. …”

Breast PET/MR Imaging

“…38,42,43 PET and MR imaging have demonstrated similar performance for the detection of internal mammary adenopathy. 44 MR imaging and PET/MR imaging have been shown to be more likely than PET/CT to determine the correct maximum diameter of the tumor (T stage), which may be useful in surgical and oncologic planning. 38 Hybrid PET/MR imaging may be of particular use in this extent-of-disease setting, where the increased sensitivity of MR imaging for multifocal disease and the increased sensitivity of PET for axillary nodal disease could come together in a single examination.…”