Detection and Clinical Significance of Sternal Lesions on Breast MRI

Abstract

The purpose of this study is to characterize sternal lesions detected on breast magnetic resonance imaging (MRI), compare MRI detection of sternal lesions with other imaging modalities (bone scan, positron emission tomography/computed tomography (PET/CT) and chest CT), and ascertain how often patient management is altered by discovery of sternal lesions. Retrospective review of 1143 breast MRIs between 2007 and 2012 identified 17 patients with sternal lesions including 15 patients with newly diagnosed breast cancer and two patients with remote history of breast cancer. Tumor size, histopathology, receptor status, nodal and distant metastasis, and images of breast MRI, and other modalities were reviewed. Sternal lesions in 9 of the 17 patients were determined to be malignant (metastasis) either by biopsy or presence of widespread metastases. Sternal lesions in 8 of the 17 were benign, confirmed by biopsy or presumed benign as not detected by other modalities. The malignant group had statistically significant larger breast cancer size (malignant: 6.4 cm; benign: 2.3 cm), a higher percentage of diffuse sternal lesions (malignant: 56%; benign: 0%), and more frequently showed rapid initial enhancing (malignant: 100%; benign: 63%) and delayed washout curves (malignant: 67%; benign: 13%). Although not statistically significant, the malignant group had a higher frequency of invasive lobular carcinoma (malignant: 44%; benign: 13%) and more lymph node involvement (malignant: 78%; benign: 50%). Breast MRI detected more sternal lesions than did bone scan, PET/CT and chest CT. Four of the 17 (24%) patients were upgraded to stage 4 due to unsuspected metastatic sternal lesions on breast MRI. In conclusion, breast MRI is more sensitive than other modalities in detecting sternal lesions. Sternal metastases occur more frequently in aggressive breast cancer and exhibit malignant-type dynamics on breast MRI. Detection of unsuspected sternal metastasis alters staging and improves patient management with more appropriate treatment.

Frequency and Clinical Significance of Extramammary Findings on Breast Magnetic Resonance Imaging

“…In this series, malignant sternal lesions occurred more frequently in association with aggressive breast cancer and had malignant type dynamics on breast MRI scans. 27 Overall, we had a relatively low rate of EMFs in our study, with a very low rate of malignant EMFs. The greatest portion of EMFs came from women who underwent MRI for evaluation of known breast cancer, although we did have a single patient who underwent an MRI for high risk status and was found to have metastatic disease based on an EMF found on the screening MRI.…”

The sternum: An important review area when reporting pre‐surgical staging breast MRI studies

“…Schaefer et al reported on 17 patients with a breast cancer diagnosis and MRI‐detected sternal lesions of which 9 proved to be malignant, with MRI making the prospective diagnosis of Stage IV disease in 4 (the remainder with bone metastases already identified by other imaging). They also noted that some metastatic lesions identified by MRI were not evident on either 99mTc‐MDP bone scan or PET/CT 3 …”

“…They also noted that some metastatic lesions identified by MRI were not evident on either 99mTc-MDP bone scan or PET/CT. 3 In a more recent study, patients with metastatic lesions detected on either PET/CT or bone scan had their prior breast MRI scans reviewed. Of 14 sternal metastases, Lee et al 4 found that 12 (86%) were retrospectively identifiable on breast MRI, but only 8 (57%) had been prospectively reported.…”

“…2). 3,4 In the setting of either current or previous breast cancer, any enhancing sternal lesion should always be carefully evaluated and should prompt a PET/CT scan (Figs 2 and 3). Metastases will usually but not invariably exhibit low marrow signal on T1 and T2 spin-echo images due to replacement by tumour (Figs 4 and 5).…”