Ring Enhancement in Non-Neoplastic Breast Tissue on MRI During Neoadjuvant Chemotherapy for Breast Cancer: Incidence and Clinical Implications.

RATIONALE AND OBJECTIVES: This study aimed to describe new lesions called ring enhancement in non-neoplastic breast tissue on breast magnetic resonance imaging (MRI) after neoadjuvant chemotherapy (NAC) in breast cancer patients, and to investigate the factors influencing their occurrence. MATERIALS AND METHODS: We retrospectively reviewed 811 consecutive patients (mean age; 50.0 [range, 24-81] years) with breast cancer who had undergone NAC between January 2020 and December 2021, identifying cases with new ring enhancement on post-NAC MRI. We analyzed the MRI findings and identified factors that were potentially associated with ring enhancement through statistical analyses using the chi-square test, univariate and multivariate logistic regression analysis. RESULTS: Forty-seven (5.8%) patients developed new ring enhancement on post-NAC MRI. The variables associated with ring enhancement were premenopausal status (p = 0.0007), younger age (p = 0.0011), high mammographic density (p = 0.0076), and high background parenchymal enhancement (BPE) on baseline MRI (p = 0.0001). Among these, high BPE was independently associated with the occurrence of ring enhancement (p = 0.0294, OR = 2.08; CI: 1.08-4.03). In a subset of high BPE patients, an association between HER2-positive cancers and ring enhancement was observed (odds ratio = 5.51 vs. 2.54). New lesion development exhibited no association with any specific NAC drug (p = 0.1676-0.7583 per drug). CONCLUSION: Ring enhancement often occurs on post-NAC MRI and mostly disappears on subsequent MRI scans. High BPE on MRI was associated with this finding and HER2-positive cancers potentiated it. Knowledge of this finding can prevent unnecessary biopsies.

The combined influence of substrate elasticity and ligand density on the viability and biophysical properties of hematopoietic stem and progenitor cells.

Hematopoietic stem cells (HSCs) are adult stem cells with the capacity to give rise to all blood and immune cells in the body. HSCs are housed in a specialized microenvironment known as the stem cell niche, which provides intrinsic and extrinsic signals to regulate HSC fate: quiescence, self-renewal, differentiation, mobilization, homing, and apoptosis. These niches provide a complex, three dimensional (3D) microenvironment consisting of cells, the extracellular matrix (ECM), and ECM-bound or soluble biomolecules that provides cellular, structural, and molecular signals that regulate HSC fate decisions. In this study, we examined the decoupled effects of substrate elasticity, construct dimensionality, and ligand concentration on the biophysical properties of primary hematopoietic stem and progenitor cells (HSPCs) using homologous series of two and three dimensional microenvironments. Microenvironments were chosen to span the range of biophysical environments presented physiologically within the bone marrow, ranging from soft marrow and adipose tissue (<1 kPa), to surrounding cell membranes (1-3 kPa), to developing osteoid (>30 kPa). We additionally investigated the influence of collagen ligand density on HSPC biophysical parameters and compared these behaviors to those observed in HSPCs grown in culture on stiff glass substrates. This work suggests the potential for substrate stiffness and ligand density to directly affect the biophysical properties of primary hematopoietic stem and progenitor cells at the single cell level and that these parameters may be critical design criteria for the development of artificial HSC niches.