1,720,958 research outputs found
Comparison of retrospective PET and MRI-DWI (PET/MRI-DWI) image fusion with PET/CT and MRI-DWI in detection of cervical and endometrial cancer lymph node metastases
No full textOBJECTIVES:
The aim of this study was to compare the accuracy of retrospective image fusion of PET/MRI-DWI with that of PET/CT and MRI-DWI alone in detecting metastatic lymph nodes in patients with cervical and endometrial carcinoma.
MATERIALS AND METHODS:
Twenty-seven patients with endometrial (n = 14) and cervical (n = 13) cancer who had undergone preoperative MRI-DWI and PET/CT for staging were retrospectively evaluated. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PET/CT, MRI-DWI, and PET/MRI-DWI image fusion were calculated on a per-patient basis and on a per-node basis. Histopathological and follow-up imaging results were used as the gold standard.
RESULTS:
On a per-patient basis PET/MRI-DWI had the same sensitivity (87.5 %), specificity (84.2 %), diagnostic accuracy (85.1 %), PPV (70 %), and NPV (94.1 %) as PET-CT, but on a per-node basis PET/MRI-DWI showed better sensitivity (89 vs 70.2 %), specificity (91.6 vs 90.5 %), diagnostic accuracy (91.2 vs 87 %), PPV (68.7 vs 60.4 %), and NPV (97.6 vs 93.6 %) than PET-CT. Comparison of the areas under the ROC curves for the detection of metastatic lymph nodes demonstrated a non-significant difference (p = 0.055) between PET/CT and fused PET/MRI-DWI.
CONCLUSION:
PET/MRI-DWI may be a valuable technique for N-staging patients with endometrial and cervical cancer, but more studies are needed to investigate its potential clinical utility
Combined multimodal co-registration of PET/CT and MRI images increases diagnostic accuracy in squamous cell carcinoma staging
No full textOBJECTIVES:
The purpose of our study was to assess the diagnostic value of multi-modal imaging through co-registration of short tau inversion recovery (STIR) and diffusion-weighted imaging (DWI) MRI with 18FDG-PET/CT in T and N staging of head and neck tumours.
MATERIALS AND METHODS:
25 patients with head and neck squamous cell carcinoma who had undergone MRI and PET/CT before treatment were retrospectively evaluated. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PET/CT, MRI and their combined use were assessed in T and N staging. Histopathology and follow-up imaging results were used as the gold standard.
RESULTS:
In assessing trans-compartmental extensions, PET-MRI showed 93 % sensitivity, 88 % specificity, 94 % PPV, and 88 % NPV, as compared to the 94 and 53 % sensitivity, 75 and 75 % specificity, 89 and 82 % PPV, and 86 and 43 % demonstrated by MRI and PET, respectively. In the identification of pathological lymph nodes, PET-MRI showed 92 % sensitivity, 89 % specificity, 96 % PPV, and 89 % NPV, whereas PET/CT displayed 72 % sensitivity, 89 % specificity, 95 % PPV and 53 % NPV. The corresponding figures for DWI and STIR sequences were 84 and 100 % sensitivity, 67 and 56 % specificity, 88 and 86 % PPV, and 60 and 100 % NPV, respectively.
CONCLUSIONS:
Multi-modal imaging assessment of co-registered MRI and PET/CT images provides more accurate results for trans-compartmental extensions in T and N staging than the individual techniques alone
Staging of Primary Abdominal Lymphomas: Comparison of Whole-Body MRI with Diffusion-Weighted Imaging and 18F-FDG-PET/CT
No full textBackground. The purpose of this study was to compare the accuracy of whole-body MRI with diffusion-weighted sequences (WB-DW-MRI) with that of 18F-FDG-PET/CT in the staging of patients with primary gastrointestinal lymphoma. Methods. This retrospective study involved 17 untreated patients with primary abdominal gastrointestinal lymphoma. All patients underwent 18F-FDG-PET/CT and WB-DW-MRI. Histopathology findings or at least 6 months of clinical and radiological follow-up was the gold standard. The Musshoff-modified Ann Arbor system was used for staging, and diagnostic accuracy was evaluated on a per-node basis. Results. WB-DW-MRI exhibited 100% sensitivity, 96.3% specificity, and 96.1% and 100% positive and negative predictive values (PPV and NPV), respectively. The sensitivity, specificity, and PPV and NPV of PET/CT were 95.9%, 100%, and 100% and 96.4%, respectively. There were no statistically significant differences between the two techniques . The weighted kappa agreement statistics with a 95% confidence interval were 0.97 (0.95–0.99) between the two MRI readers and 0.87 (0.82–0.92) between the two methods. Conclusions. WB-DW-MRI appears to have a comparable diagnostic value to 18F-FDG-PET/CT in staging patients with gastrointestinal lymphoma
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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