Focal Node Research Articles

WE-D-BRB-05: Novel Post-Lumpectomy Breast Cancer Brachytherapy with the Capability of Simultaneous Focal Lymph Node Irradiation

Purpose: A new technique of post‐lumpectomy breast cancerbrachytherapy using beta‐emitting therapeutic radionuclides, rhenium‐188 (Re‐188) and rhenium‐186 (Re‐186), carried within lipidnanoparticles(liposomes) was investigated. This therapy strategy is advantageous regarding: 1) mm‐range focal radiation by beta‐particles ensures localized brachytherapy; 2) sustained high local retention within the lumpectomy cavity and accumulation in associated lymph nodes enables simultaneous cavity and lymph node focal radiation therapy; and 3) ease and flexibility of this modality to treat various locations and cavity shapes in the breast with minimal invasiveness. Method and Materials: Breast cancer surgical model in nude rats, gamma camera imaging, and animal organ dissection were used to study local and lymph node retention of radioactive liposomes. EGSnrc Monte Carlo code system was used to compare dose point kernels (DPK) for Re‐188 and Re‐186 in breast tissue, water, and other soft tissues. The DPK were then used for dose calculations of uniformly distributed liposomal Re‐188 or Re‐186 injected to the lumpectomy site within ellipsoid and spherical cavities. The dose calculation for lymph nodes modeled as a disk shape with exponentially decreased activity from the cortex was also performed. Results: High and sustained intracavitary retention of radioactive liposomes accompanied by lymph node accumulation was observed. Different human tissues showed very similar dose curves for Re‐188 and Re‐186. The therapeutic ranges in the cavity could be about 5 and 2.5 mm with Re‐188 and Re‐186, respectively, while radiationdoses beyond 1 cm sharply dropped to minimal. Also, the entire lymph node could receive therapeuticdose.Conclusion: The promise of a new post‐lumpectomy breast cancerbrachytherapy technique is presented. A rapid fall‐off in radiationdose with distance allows this treatment modality to spare substantial healthy tissue with reduced complications. It is also favorable through simultaneous focal treatment of microscopic tumor cells spreading to downstream lymphatics.

Conflictive sustainability landscapes: the neoliberal quagmire of urban environmental planning in Buenos Aires

This article examines a local, state-led attempt in Buenos Aires, Argentina, to conceptualise and implement a programme resembling priorities in recent scholarship on sustainable development that integrates a justice imperative, which encompasses environmental, sociopolitical, and economic concerns. In a context of transnationally circulating paradigms where the discourse on sustainable development has become hegemonic and coupled with neoliberal orientations in policy, the effort to enact the Urban Environmental Plan in Buenos Aires faces challenges of prioritisation among conflicting goals. The focus is on how planning revolves around three neoliberal keywords implicated in sustainable development – sustainability, participation, and competitiveness – and the way these lead to the projection of incompatible material-symbolic landscapes, as examined in the redevelopmental site of Puerto Madero, a focal node of the Urban Environmental Plan in the Argentine capital where many of its projects converge.

Trophic field overlap: A new approach to quantify keystone species

It is a current challenge to better understand the relative importance of species in ecosystems, and the network perspective is able to offer quantitative tools for this. It is plausible to assume, in general, that well-linked species, being key interactors, are also more important for the community. Recently a number of methods have been suggested for quantifying the network position of species in ecological networks (like the topological importance metric, TI). Most of them are based on node centrality indices and it may happen that the two most important species in a food web have very similar interaction structure and they can essentially replace each other if one becomes extinct. For conservation considerations it is a challenge to identify species that are richly connected and, at the same time, have a relatively unique and irreplaceable interaction pattern. We present a new method and illustrate our approach by using the Kuosheng Bay trophic network in Taiwan. The new method is based on the interaction matrix, where the strength of the interaction between nodes i and j depends only on topology. By defining a threshold separating weak and strong interactors, we define the effective range of interactions for each graph node. If the overlaps between pairs of these ranges are quantified, we gain a metric expressing how unique is the interaction pattern of a focal node (TO). The combination of centrality (TI) and uniqueness (TO) is called topological functionality (TF). We compare the nodal importance rank provided by this metric to others based on a variety of centrality measures. The main conclusion is that shrimps seem to have the most unique interaction pattern despite that their structural importance has been underestimated by all conventional centrality indices. Also, our network analysis suggests that fisheries disturb the ecosystem in a more critical network position than the impingement by the local power plant.

Exploration of Networks using overview+detail with Constraint-based cooperative layout

A standard approach to large network visualization is to provide an overview of the network and a detailed view of a small component of the graph centred around a focal node. The user explores the network by changing the focal node in the detailed view or by changing the level of detail of a node or cluster. For scalability, fast force-based layout algorithms are used for the overview and the detailed view. However, using the same layout algorithm in both views is problematic since layout for the detailed view has different requirements to that in the overview. Here we present a model in which constrained graph layout algorithms are used for layout in the detailed view. This means the detailed view has high-quality layout including sophisticated edge routing and is customisable by the user who can add placement constraints on the layout. Scalability is still ensured since the slower layout techniques are only applied to the small subgraph shown in the detailed view. The main technical innovations are techniques to ensure that the overview and detailed view remain synchronized, and modifying constrained graph layout algorithms to support smooth, stable layout. The key innovation supporting stability are new dynamic graph layout algorithms that preserve the topology or structure of the network when the user changes the focus node or the level of detail by in situ semantic zooming. We have built a prototype tool and demonstrate its use in two application domains, UML class diagrams and biological networks.

Cryptococcal Lymphadenitis and Massive Splenomegaly in an Immunocompromised Patient

Abstract: We report an unusual case of lymphadenitis and splenitis in a hemophiliac with AIDS. Splenomegaly without focal lesions was shown by CT and MRI. A Ga-67 scan demonstrated markedly increased activity in the spleen and increased focal activity in the left supraclavicular region. Cryptococcus neoformans was cultured from blood. A fine needle aspirate of a supraclavicular lymph node revealed budding yeast. After therapy, a repeat gallium scan showed no supraclavicular activity and markedly reduced splenic uptake. Cryptococcal infection should be in the differential diagnosis of markedly increased Ga-67 uptake in splenomegaly and focal lymph node uptake in an immunocompromised patient.

Hepatic Toxocariasis: US, CT and MRI Findings

Visceral larva migrans (VLM) most commonly occurs as a febrile disease of childhood particularly affecting children between 1 and 7 years of age. Pulmonary, dermatological, hepatic, lymphatic, cardiac, rheumatological and neurological manifestations may occur. VLM seems to be a rare disease in adults. We report the imaging findings of a woman with hepatic toxocariasis. Ultrasonography showed a solitary hepatic lesion measuring 4 x 3 cm, displaying a hypoechoic-heterogeneous pattern with ill-defined borders and distal acoustic enhancement, located in the right sub-diaphragmatic area. Two enlarged periportal lymph nodes and moderately dilated intrahepatic biliary ducts were also noted. The probability of toxocariasis was discussed, based on sonographic and biopsy findings, and the final diagnosis was confirmed by a specific ELISA test. In summary, a clinical picture of cholestasis initially resembling hepatitis or malignancy should be further evaluated by imaging techniques, and the ultrasound examiner should be familiar with the possible findings of hepatic toxocariasis, which consist of focal ill-defined hepatic lesions, hepato-splenomegaly, biliary dilatation, sludge and periportal lymph node enlargement.

Standardized Uptake Values in 2-Deoxy-2-[ 18F]Fluoro-D-Glucose with Positron Emission Tomography : Clinical Significance of Iterative Reconstruction and Segmented Attenuation Compared with Conventional Filtered Back Projection and Measured Attenuation Correction

Purpose: To evaluate the clinical significance of differences in 2-deoxy-2-[ 18F]fluoro-D-glucose positron emission tomography (FDG-PET) lymph node standardized uptake values (SUV) in human immunodeficiency virus (HIV) infection using iterative reconstruction with segmented attenuation correction (IR SAC) compared to filtered back-projection with measured attenuation correction (FBP MAC). Procedures: Seven patients with HIV infection and multiple focal lymph node abnormalities were investigated with whole-body FDG-PET. Mean and maximum SUVs from lymph node regions of interest (n = 961) were compared for quantitative differences between reconstruction techniques. Results: IR MAC resulted in significantly lower mean SUV [0.06; 95% (confidence interval (CI)) = 0.04–0.07] and maximum SUV (0.82; 95% CI = 0.77–0.88) values compared to FBP MAC. With IR, segmentation of attenuation correction (AC) resulted in significantly higher mean SUV (0.12; 95% CI = 0.11–0.13) and maximum SUV (0.21; 95% CI = 0.18–0.23) values compared to IR MAC. The overall effect of both IR and SAC was a slight but significant increase in mean SUV (0.06; 95% CI = 0.06–0.08; bias = 2.1%) and a significant decrease in maximum SUV (0.62; 95% CI = 0.56–0.67) compared to FBP MAC. Conclusions: With our reconstruction parameters, significant differences in mean and maximum SUV values were observed. The magnitude of the mean SUV difference, however, was small. IR SAC is a promising method to accurately quantify standardized uptake values for clinical use.

A peer-to-peer zone-based two-level link state routing for mobile ad hoc networks

A new global positioning system (GPS)-based routing protocol for ad hoc networks, called zone-based hierarchical link state (ZHLS) routing protocol, is proposed. In this protocol, the network is divided into nonoverlapping zones. Each node only knows the node connectivity within its zone and the zone connectivity of the whole network. The link state routing is performed on two levels: focal node and global zone levels. Unlike other hierarchical protocols, there is no cluster head in this protocol. The zone level topological information is distributed to all nodes. This "peer-to-peer" manner mitigates traffic bottleneck, avoids single point of failure, and simplifies mobility management. Since only zone ID and node ID of a destination are needed for routing, the route from a source to a destination is adaptable to changing topology. The zone ID of the destination is found by sending one location request to every zone. Simulation results show that our location search scheme generates less overhead than the schemes based on flooding. The results also confirm that the communication overhead for creating and maintaining the topology in the proposed protocol is smaller than that in the flat LSR protocol. This new routing protocol provides a flexible, efficient, and effective approach to accommodate the changing topology in a wireless network environment.

HISTOPLASMOSIS IN THE ACQUIRED IMMUNODEFICIENCY SYNDROME (AIDS)

This case report describes a 50-year-old man from South America with AIDS who developed disseminated histoplasmosis with focal lymph node involvement. Treatment with ketoconazole was initially successful. Six weeks after cessation of ketoconazole he died of what was thought to be relapse of histoplasmosis.

Proceedings: Recurrent pheochromocytoma.

Seven of 28 patients had well-established recurrent disease following a primary operation for control of pheochromocytoma. Two of these recurrences were in 23 patients whose primary operation had been performed by us. The other five were referred to us with recurrent pheochromocytoma. A broad range of pathologic entities is represented in these patients. One patient had an asymptomatic biochemical recurrence of disease and one multiple benign primary pheochromocytoma. A third had a local recurrence with negative lymph nodes and a fourth focal lymph node recurrences. Long-term resolution of disease has occurred in three of these patients following another exploratory operation. Three patients had disseminated disease, one had abdominal recurrences, and two had miliary pulmonary disease that escaped pre-operative detection on conventional posteroanterior roentgenographic views of the chest. The latter two patients died after fruitless surgical exploration and represent the only deaths in our series.

Intergeneric Hybrids in the Lychnideae (Caryophyllaceae)

Debate on the objectivity of the genus rarely has reached the intensity of that generated over the category of species. Taxonomists-alpha and omega, plant and animal-have nearly all agreed that the genus is a category of convenience where generic limits are blurred (Mayr 1942, Stebbins 1950). Where extinction, isolation, or adaptive specialization has resulted in an abrupt and sharp discontinuity, the genus becomes a focal node in phylogeny and may be defined with a greater degree of objectivity. Clearly then, the degree of evolutionary divergence between related generic phylads will determine their distinctness. The tribe Lychnideae of the family Caryophyllaceae binds together a number of generic tendencies, some of which have achieved undisputed taxonomic status, while others continue to undergo reapportionment decade after decade. Drypsis, Cucubalus, Petrocopttis, and Agrostemma are lineages of such undisputed generic status; all are small genera, each with its own distinct and divergent pattern. The remaining genera of the tribe (Silene, Heliosperma, Melandrium, Lychnis, and VTiscaria) are the troublesome ones; they have defied clearcut delineation for many years. Certain members of the three largest generaSilene (ca. 500 species), Lychnis (ca. 10 species), and Melandrium (ca. 60 species)-have slipped in and out of these three repeatedly. What follows in this paper concerns results of intentional crosses made among various species usually placed in Silene, Lychnis, or Melandriu,m. The results of interspecific hybridization often lead to the answering of questions regarding genetic relationship among species. The technique of deliberate hybridizing yields data on crossability, hybrid fertility, and the nature of genetic control of phenotype, all of which are useful in assessing the degree of relationship between species. For the past several years, I have carried on such a program, mainly involving the North American species of Silene (Kruckeberg 1955, 1961). A number of taxa traditionally treated as species of Lychnis and Melandrium were also included in the crossing program. Intergeneric hybridizations pose several questions. Are crosses between species of different genera significantly different from those between species of the same genus? In other words, are we justified in expecting that crossability and hybrid fertility will be lower in the intergeneric hybrids? If there is a significant difference between intraand intergeneric crosses for these criteria, then evidence from crossings would reinforce the taxonomic judgments of separate generic status for the species in question. We would also want to know how the "key" characters traditionally used to separate the genera fare phenotypically in the hybrids. In a word, are the key morphological differences separating the genera oligogenically controlled (as simple Mendelian traits) or are they under polygenic control? The plants used for hybridizing were either collected in the wild or were obtained from botanical gardens and private collectors. Table 1 gives the origins and chromosome. numbers of theplants used; seventeen taxa are represented.