US-guided retrograde tibial artery puncture for recanalization of complex infrainguinal arterial occlusions

PURPOSEWe aimed to describe the technical aspects and outcomes of the retrograde tibial approach and balloon predilation for recanalization of complex infrainguinal arterial occlusions and determine the efficacy of this approach in minimizing failure rates. MATERIALS AND METHODSBetween September 2006 and April 2011, antegrade revascularization failed in 22 limbs with complex total occlusions within the infrainguinal arterial territory. For each of these antegrade failure cases in 22 patients, a retrograde tibial puncture had been attempted. Percutaneous recanalization and predilation were initially performed through tibial access, and final balloon dilatation or stent placement was performed from antegrade femoral access. The patients were followed up for functionality and wound healing. RESULTSAccess from the tibial artery was successfully obtained for all patients (100%). Successful recanalization was obtained in 18 patients (82%). Retrograde access was performed from the anterior tibial/dorsalis pedis artery in 12 patients and posterior tibial artery in 10 patients. One major and one minor complications were documented. CONCLUSIONRetrograde tibial recanalization technique in the infrainguinal complex arterial occlusion safely increases the success rates of percutaneous recanalization in the failed traditional approach and is a feasible endovascular option to avoid more invasive, time-consuming, and high-risk procedures

Use of shear-wave elastography to distinguish complex and complicated fibroadenomas from simple fibroadenomas

PURPOSESimple fibroadenomas (SFAs), complex fibroadenomas (CFAs), and cellular fibroadenomas (CeFAs) are variants of fibroadenomas. Additionally, some degenerative, hyperplastic, and metaplastic changes may occur in fibroadenomas, forming complicated fibroadenomas. Distinctive ultrasonography (US) features in variants of fibroadenomas and complicated fibroadenomas have not been reported. Shear-wave elastography (SWE) can be applied to effectively discriminate between these variants and complicated fibroadenomas. In this study, we aimed to evaluate SWE findings to discriminate between SFAs and other variants.METHODSIn total, 48 patients (26 with SFAs, 16 with CFAs, 3 with CeFAs, and 3 with complicated fibroadenomas) participated in this study. The lesions were classified into two groups according to histopathologic diagnoses. The SWE evaluation and lesion elasticity scores (Emax, Emean, and Emin) were both assessed in m/s and k/Pa, respectively. Two observers measured Emax, Emean, and Emin. Brightness (B)-mode US findings based on the Breast Imaging Reporting and Data System categorization and elasticity scores were recorded. In the statistical analyses, the chi-square test and non-parametric tests were performed. Fisher’s exact test was used to compare independent groups, and Spearman’s correlation coefficients were used to correlate the SWE data between the two observers. Additionally, receiver operating characteristic curves were analyzed to evaluate the diagnostic performance of the elasticity values.RESULTSThe B-mode US features in both groups showed no statistical significance. The set of SWE values of both observers demonstrated strong statistical significance in discriminating between group 1 (SFAs) and Group 2 (CFAs, CeFAs, and complicated fibroadenomas).CONCLUSIONAs the fibroadenoma variants and complicated fibroadenomas have similar US findings, SWE in addition to a conventional B-mode examination can increase the diagnostic performance to discriminate SFAs from other complex and complicated forms of fibroadenomas

Subtypes of renal cell carcinoma: MRI and pathological features

Renal cell carcinoma (RCC) is the most common malignant tumor involving the kidney. Determining the subtypes of renal cell carcinoma is among the major goals of preoperative radiological work-up. Among all modalities, magnetic resonance imaging (MRI) has several advantages, such as inherent soft tissue contrast, detection of lipid and blood products, and excellent sensitivity to detect small amounts of intravenous contrast, which facilitate the discrimination of subtypes of RCC. In this article, we review MRI and pathological features used for determining the main histologic subtypes of RCC, including clear cell, papillary, collecting duct, chromophobe, multilocular cystic, and unclassified RCC

Introduction to The Limits of Westernization: A Cultural History of America in Turkey

Perin E. Gürel, introduction to The Limits of Westernization: A Cultural History of America in Turkey (New York: Columbia University Press, 2017), 1–15

Shear Thinning from Bond Orientation in Model Unentangled Bottlebrush Polymer Melts

The rheology of molecular brushes remains challenging to control due to the multiple length scales and relaxation processes involved and the lack of direct observation of molecular conformation during flow. We use molecular dynamics simulations to determine the shear thinning of unentangled bottlebrush polymers with varying architecture, from linear chains to combs, to densely grafted bottlebrushes, to star-like and star polymers. We find shear thinning exponents in line with theoretical and experimental results and characterize the shape and orientation of bottlebrushes in steady-state flow. Many shape parameters derived from the gyration tensor show molecular alignment with the flow for all systems. Yet, the orientation of individual bonds is what most strongly correlates with the architecture-dependent shear-thinning exponents. In densely grafted bottlebrushes, the packing of side chains prevents alignment with the flow, causing a reduction in shear thinning. The molecular insight from our simulations is useful to tune the architecture of bottlebrushes to control their rheology