RESUMO
Purpose: The purpose of this study was to evaluate the role of vacuum-assisted biopsy (VAB) in resecting breast cancers. Methods: Retrospective database analysis of 116 cancers [both invasive breast cancers (IC) and ductal carcinoma in situ (DCIS)] diagnosed by VAB submitted to standard surgical treatment with complete histological data from VAB and surgery. Excision following VAB was defined as complete resection (CR) if there was no residual tumor in the surgical specimen, minimal residual disease (MRD) if residual tumor ≤ 3 mm, gross residual disease (GRD) if residual tumor > 3 mm, and upgrade from DCIS on VAB to IC. CR and MRD were combined as potentially resected percutaneously (PRP). GRD and those with upgrade to IC were determined not eligible for percutaneous resection (NPR). Factors predictive of PRP were evaluated. Results: Mean age was 55.6 years (20-91; SD: 12,27). CR was seen in 29 of 116 cases (25%), MRD in 18 of 116 cases (15.5%), GRD in 64 of 116 cases (55.2%), and five of 116 cases (4.3%) were upgraded from DCIS to IC, and those groups combined represented 47 cases of PRP (40.5%) and 69 (59,5%) of NPR. For 77 tumors ≤ 10 mm, 45 (58.5%) were PRP. Multivariate analysis reveals significance for enlarged VAB (EVAB) (p = 0.008, OR: 4.4, 95% CI), low/intermediate nuclear grade (p < 0.001, OR: 12.5, 95% CI) and final tumor size (T) ≤ 10 mm (p = 0.001, OR: 50.1, 95% CI) for PRP. Conclusions: This study showed that lesions completely excised with VAB that were cancer could have been treated with VAB rather than surgery but tumor selection in terms of subtype and size is important.
RESUMO
In this work we investigate the pair interaction of magnetic particles in a dilute polydisperse sedimenting suspension. The suspension is composed of magnetic spherical forms of different radii and densities immersed in a Newtonian fluid, settling due to the gravity. When in close contact, the particles may exert on each other a magnetic force due to a permanent magnetization. We restrict our attention to dispersions of micromagnetic composite with negligible Brownian motion. The calculations of the relative particle trajectories are based on direct computations of the hydrodynamic interactions among rigid spheres in the regime of low particle Reynolds number. Depending on the relative importance of the interparticle forces and gravity, the collisions may result in aggregation or simply in a breaking of the particle relative trajectory time reversibility. After summing over all possible encounters, the transverse self-diffusion and down-gradient diffusion coefficients that describe the cross-flow migration of the particles are calculated. Our calculation shows first evidence and the significance of the diffusion process arising from magnetic interactions in dilute non-Brownian suspensions.
