Quantitative assessment of HCC wash-out on CT is a predictor of early complete response to TACE

OBJECTIVES: To investigate the predictive value of four-phase contrast-enhanced CT (CECT) for early complete response (CR) to drug-eluting-bead transarterial chemoembolization (DEB-TACE), with a particular focus on the quantitatively assessed wash-in and wash-out. METHODS: A retrospective analysis of preprocedural CECTs was performed for 129 HCC nodules consecutively subjected to DEB-TACE as first-line therapy. Lesion size, location, and margins were recorded. For the quantitative analysis, the following parameters were computed: contrast enhancement ratio (CER) and lesion-to-liver contrast ratio (LLC) as estimates of wash-in; absolute and relative wash-out (WO(abs) and WO(rel)) and delayed percentage attenuation ratio (DPAR) as estimates of wash-out. The early radiological response of each lesion was assessed by the mRECIST criteria and dichotomized in CR versus others (partial response, stable disease, and progressive disease). RESULTS: All quantitatively assessed wash-out variables had significantly higher rates for CR lesions (WO(abs) p = 0.01, WO(rel) p = 0.01, and DPAR p = 0.00002). However, only DPAR demonstrated an acceptable discriminating ability, quantified by AUC = 0.80 (95% CI0.73–0.88). In particular, nodules with DPAR ≥ 120 showed an odds ratio of 3.3(1.5–7.2) for CR (p = 0.0026). When accompanied by smooth lesion margins, DPAR ≥ 120 lesions showed a 78% CR rate at first follow-up imaging. No significative association with CR was found for quantitative wash-in estimates (CER and LLC). CONCLUSIONS: Based on preprocedural CECT, the quantitative assessment of HCC wash-out is useful in predicting early CR after DEB-TACE. Among the different formulas for wash-out quantification, DPAR has the best discriminating ability. When associated, DPAR ≥ 120 and smooth lesion margins are related to relatively high CR rates. KEY POINTS: • A high wash-out rate, quantitatively assessed during preprocedural four-phase contrast-enhanced CT (CECT), is a favorable predictor for early radiological complete response of HCC to drug-eluting-bead chemoembolization (DEB-TACE). • The arterial phase of CECT shows great dispersion of attenuation values among different lesions, even when a standardized protocol is used, limiting its usefulness for quantitative analyses. • Among the different formulas used to quantify the wash-out rate (absolute wash-out, relative wash-out, and delayed percentage attenuation ratio), the latter (DPAR), based only on the delayed phase, is the most predictive (AUC = 0.80), showing a significant association with complete response for values above 120

A multi-element psychosocial intervention for early psychosis (GET UP PIANO TRIAL) conducted in a catchment area of 10 million inhabitants: study protocol for a pragmatic cluster randomized controlled trial

Multi-element interventions for first-episode psychosis (FEP) are promising, but have mostly been conducted in non-epidemiologically representative samples, thereby raising the risk of underestimating the complexities involved in treating FEP in 'real-world' services

Overcoming the memory limits of network devices in SDN-enabled data centers

Abstract: In extremely connected and dynamic environments, such as data centers, SDN network devices can be exploited to simplify the management of network provisioning. However, they leverage on TCAMs to implement the flow tables, i.e., on size-limited memories that can be quickly filled up when fine-grained traffic control is required, eventually preventing the installation of new forwarding rules. In this work, we demonstrate how this issue can be mitigated by means of a novel flow rule swapping mechanism. Specifically, we first show the negative effects of a full TCAM on a video streaming service provided by an SDN-enabled data center. Then, we show that our swapping mechanism helps in overcoming the inability to properly access a media content available in the data center, by temporarily moving the least matched flow rules from the TCAM to a larger memory outside the SDN device

An effective swapping mechanism to overcome the memory limitation of SDN devices

Thanks to its 1-cycle lookup performance, the Ternary Content Addressable Memory (TCAM) is considered an essential hardware component for the deployment of high-performance Software-Defined Networks (SDN). Unfortunately, in many network scenarios, TCAMs can quickly fill due to their limited memory size, thus preventing the installation of new flow-rules and leading to inefficient traffic forwarding. This issue has already been addressed in computer programming, where Virtual Memory is offered to applications to mimic a much larger physical memory, by swapping memory pages to disk. In a previous work, we proposed and discussed the architecture of a Memory Management System (MMS) for SDN controllers that, like the analogous process for computer Operating Systems, optimizes the memory usage and prevents anomalies due to lack of memory space. This work proposes a memory swapping mechanism for SDN controllers, a function of the MMS which gives SDN applications the illusion of unlimited memory space in the forwarding devices, without requiring any hardware modification or changes in the control protocol. The paper discusses the memory swapping mechanism design, its implementation and proves its quality using real traffic traces, demonstrating lower TCAM memory utilization and potentially increased network performance in terms of end-to-end throughput. A prototype of the MMS is available for testing as an open source project

Generalizing virtual network topologies in OpenFlow-based networks

Network Virtualization (NV) is one of the most promising technique to enable innovation in today's network. A recent approach toward NV has been proposed through FlowVisor, whose aim is to leverage on the specific features of an OpenFlow-controlled network to share the same hardware forwarding plane among multiple logical networks. However, FlowVisor lacks some features to enable a full implementation of a NV architecture: the virtual topologies that can be established are restricted to subsets of the physical topology and it has no way for two slices to share flowspace and simultaneously prevent them from interfering with each other's traffic. In this work, an innovative system called ADVisor (ADvanced FlowVisor) which enhances FlowVisor while overcoming its major constraints is presented and a set of experimental results discussed to demonstrate its capability to provide an effective support toward a Network Virtualization architecture

Empowering Network Operating Systems with Memory Management Techniques

Similarly to computer operating systems which guarantee safe access to memory resources, Network Operating Systems shall grant SDN applications a reliable access to neatly organized flow table resources. This paper presents the architecture for a controller-agnostic Memory Management System and some of its functionalities that aim at improving flow table usage and preventing network misconfigurations. From the implementation perspective, this work discusses the applicability of the proposed system, a strategy to evaluate it and current open challenges