1,720,996 research outputs found
FDG-PET/CT:Whither I go, thou canst not follow me now; but thou shalt follow me afterwards
No full textGallium-68 DOTATATE PET/CT in Neuroendocrine Tumors
No full textThe general metadata -- e.g., title, author, abstract, subject headings, etc. -- is publicly available, but access to the submitted files is restricted to UT Southwestern campus access and/or authorized UT Southwestern users.BACKGROUND: Ga-68 DOTATATE PET/CT has been increasingly used for diagnosis and therapy response assessment of patients with neuroendocrine tumors (NETs). Point spread function (PSF) modeling is a partial volume correction method that can be used within PET imaging reconstruction. However, little is known about the effects of PSF reconstruction on quantitative measurements of Ga-68 DOTATATE PET/CT.
OBJECTIVE: The objective is to investigate the impact of PSF reconstruction and lesion size on Ga-68 DOTATATE PET/CT quantitative parameters.
METHODS: A total of 38 patients with 42 Ga-68 DOTATATE PET/CT scans and 125 lesions were included. Scans were reconstructed with and without PSF modulation. For each lesion, maximum and peak standardized uptake value (SUVmax, SUVpeak), metabolic tumor volume (MTV), total lesion somatostatin avidity (TLS), and tumor somatostatin receptor expression heterogeneity (TH) using area under the curve method were measured. Intraclass correlation coefficients (ICC) and Bland-Altman analyses were used to compare PSF and non-PSF values. Subgroup analysis was performed to determine the impact of lesion size.
RESULTS: Of the 125 lesions, 51 were in the liver, 31 in lymph nodes, 17 in bone, 8 in pancreas, 4 in lung, and 14 in other sites. ICC between PSF and non-PSF values were excellent for SUVmax, SUVpeak, MTV, and TLS (0.97-0.99), and was good for TH (0.81). Comparison of PSF with non-PSF values showed a bias (mean percent change ± standard deviation) of +27.5 ± 14.7% for SUVmax, +15.5 ± 9.5% for SUVpeak, -18.6 ± 37.6% for MTV, +0.8 ± 28.1% for TLS, and -7.1 ± 11.0% for TH. For lesions less than 2 cm in size (n=75), comparison of PSF with non-PSF values showed corresponding biases larger than for lesions greater than 2 cm.
CONCLUSION: PSF reconstruction effected higher values for SUVmax and SUVpeak, lower values for TH, and had a variable effect on MTV and TLS depending on lesion size. Clinical readers of Ga-68 DOTATATE PET/CT should be aware of such effects, as comparison between baseline and post-treatment follow-up scans can result in spurious artifact without any true change if different reconstruction methods are used between two time points
Intratumoral Metabolic Heterogeneity and Other Quantitative 8FFDG PET/CT Parameters for Prognosis Prediction in Esophageal Cancer
Get PDFThe 58th Annual Medical Student Research Forum at UT Southwestern Medical Center (Tuesday, January 21, 2020, 3-6 p.m., D1.600)PURPOSE: To evaluate the impact of intratumoral metabolic heterogeneity and other quantitative FDG PET/CT parameters for predicting patient outcomes in esophageal cancer.
METHODS AND MATERIALS: This IRB and HIPPA compliant retrospective study included a total of 71 patients with biopsy proven adenocarcinoma or squamous cell carcinoma of the esophagus who had a FDG PET/CT for initial staging. Automated gradient-based segmentation method was used to assess the primary tumor standardized uptake value maximum and peak (SUV max and SUV peak), metabolic tumor volume (MTV) and metabolic intratumoral heterogeneity index, calculated as the area under cumulative SUV-volume histograms (AUC-CSH), with lower AUC-CSH indexes corresponding to higher degrees of tumor heterogeneity. Patient's demographics and tumor staging were also collected. Median follow up time was 28.2±30.3 months. Overall survival (OS) and progression free survival (PFS) were calculated using univariate cox regression with the adjustment of age, gender, staging, treatment and histological grade. All pet measurements were normalized and the hazard ratios change was equivalent to one standard deviation.
RESULTS: The patients' mean age was 64±10.3 years and there were 6 patients with stage I, 11 with stage II, 31 with stage III, 21 with stage IV disease, and 2 with unknown staging. Median survival was 16.1 months. Forty-six patients died and 15 were alive as of the end of the study (for 10 patients no recent information on survival was available). Eighteen patients had recurrence as of the end of the study. Higher MTV was significantly associated with reduced PFS for every standard deviation increase (HR=0.193, 95% CI=0.052-0.711, p=0.0134). Higher AUC-CSH (lower tumor heterogeneity, homogeneous tumor) was significantly associated with increased PFS for every standard deviation increase in the area under the curve (HR=10.779, 95% CI=1.306-88.957, p=0.0272).
CONCLUSION: There was a significant association of MTV and tumor heterogeneity with progression free survival for patients with esophageal cancer.
CLINICAL RELEVANCE: FDG PET/CT quantitative parameters, particularly intramural metabolic heterogeneity, can provide prognostic information on initial staging scan, potentially leading to a more personalized approach for patient's treatment.Southwestern Medical Foundatio
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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