1,721,008 research outputs found
Histogram analysis of magnetic resonance images: evaluation of intra-tumoral heterogeneity and correlation with pathological findings in solid pancreatic tumors.
Full text linkObjectives To evaluate magnetic resonance (MR)-derived whole-tumor histogram analysis parameters in predicting aggressiveness of pancreatic ductal adenocarcinomas (PDACs) and neuroendocrine neoplasms (panNENs). Methods Pre-operative MR of 169 consecutive patients with PDAC or panNEN were retrospectively analyzed. T1-/T2-weighted images and apparent diffusion coefficient (ADC) maps were analyzed. Histogram-derived parameters were compared to several pathological features (grade, vascular infiltration, nodal and hepatic metastases) using Mann-Whitney U test. Diagnostic accuracy was assessed by receiver operating characteristic area under curve (ROC-AUC) analysis; sensitivity and specificity were assessed for each histogram parameter. Results No significant differences were found among histogram parameters for prediction of PDACs grade. ADCentropy was significantly higher in G2-3 panNENs with ROC-AUC 0.757; sensitivity was 83.3%. ADCentropy was significantly higher in PDACs with vascular involvement (p=.022; AUC=.641), with specificity of 92.2%. ADCskewness was significantly higher in PDACs with nodal metastases (p=.027; AUC=.642), with 72% specificity. ADCkurtosis was higher in panNENs with vascular involvement, nodal and hepatic metastases (p= .008, .021, and .008; ROC-AUC= 0.820, 0.709, and 0.820); sensitivity and specificity were: 85.7/74.3%; 36.8/96.5%; and 100/62.8%. No significant differences between groups were found for other histogram-derived parameters (p >.05). Conclusions Whole-tumors histogram analysis of ADC values is a valuable tool for predicting aggressiveness of PDACs and panNENs. Our results indicate that histogram metrics related to intra-tumor heterogeneity, as ADCentropy, ADCkurtosis and ADCskewness are the most accurate parameters for the identification of PDACs and panNENs with higher biological aggressiveness. Further and larger studies are needed to incorporate the results of the histogram analysis within decision support models and to mine these data to detect possible correlations with genomic patterns
Advanced Imaging of Pancreatic Neoplasms
No full textImaging has a pivotal role in pancreatic neoplasms, ranging from diagnosis to treatment monitor. It is crucial, especially for pancreatic ductal adenocarcinoma (PDAC), to obtain an early diagnosis, since the therapeutic approach is mainly surgical and may be curative only in early-stage disease. For this reason, every advance in imaging should be evaluated and tested to produce a step forward in lesion identification
Single-Energy Low-Voltage Arterial Phase Scanning for the Detection of Adenocarcinoma of the Pancreas
No full textPURPOSE: To test a single-energy low-voltage arterial phase protocol for the diagnosis of adenocarcinoma of the pancreas.METHOD AND MATERIALS: 19 patients (10 M, 9 F, mean age 64 years) with pathology proven adenocarcinoma of the adenocarcinoma underwent triphasic abdominal CTwith arterial phase at 80 kVp and 370 mAs (test group) on a 64-row MDCT. These were compared to a similar group of 19 patients (12 M, 7 F, mean age 57 years)scanned on the same scanner with a 120 kVp arterial phase protocol with automatic tube current modulation (control group). Except for tube parameters, all otherscan parameters were kept constant. Scans were compared for quantitative image parameters (attenuation and standard deviation in the liver, pancreas, aorta andadenocarcinoma of the pancreas) and for dose parameters (CTDI and DLP) using an unpaired t-test. Contrast/noise ratio (CNR) was calculated for normalparenchyma and adenocarcinoma in both groups. Image noise was also measured as the standard deviation of the HU from 3 ROIs drawn outside the body.Unpaired t-test was used for statistical analysis.RESULTS: Mean attenuation was significantly higher in the test group than in the control group in the aorta (547.92±140.84 vs 281.90±101.23 HU; p<0.0001),liver (92.63±18.11 vs 78.45±15.48 HU; p=0.0004) and normal pancreas (168.90±45.64 vs 97.86±14.99 HU; p<0.0001), while no significant difference wasobserved for adenocarcinoma attenuation (83.77±41.18 vs 57.77±23.63 HU; p=n.s.). Radiation dose was significantly lower in the test group than in the controlgroup (CTDI 6.64±0 vs 9.41±2.79 mGy, p=0.0016; DLP 196.02±40.94 vs 365.07±138.30 mGy x cm; p=0.0003). CNR was not significantly different between thetest and the control group both for normal parenchyma (8.3±1.3 vs 6.1±0.5; p=n.s.) and carcinoma (3.3±0.5 vs 3.4±0.5; p=n.s.). Tumor conspicuity, calculatedas the difference in attenuation between carcinoma and normal pancreas, was significantly higher in the test group (85.12±41.60 vs 40.10±23.92 HU). Meanimage noise was significantly higher in the test group than in control group (12.14±4.03 vs 10.13±3.23 HU; p=0.0174).CONCLUSION: The use of 80 kVp arterial phase for abdomen CT increases the conspicuity of adenocarcinoma thus potentially improving its identification.CLINICAL RELEVANCE/APPLICATION: The use of a low-voltage scan for the pancreatic phase increases the conspicuity of adenocarcinoma thus potentiallyimproving its identification
Malignant obstructive jaundice: Imaging and percutaneous intervention
No full textiliary obstruction is a common clinical problem. Malignant obstructive jaundice is frequently caused by cholangiocarcinoma and pancreatic head adenocarcinoma, which are often inoperable at presentation and carry a dismal prognosis; less common causes include metastatic lymph nodes at the hepatic hilum and gallbladder cancer. The management of patients with a suspected malignant biliary obstruction ultimately depends on local expertise, availability, cost, and the multidisciplinary cooperation. An adequate assessment of malignant obstructive jaundice requires the use of various noninvasive imaging modalities, as ultrasound, computed tomography and magnetic resonance imaging to identify the level and the cause of the obstruction and to plan the treatment. Percutaneous intervention is an effective method of palliation in such patients, thereby improving their quality of life. It may also be an adjunct to surgical management by improving hepatic function before surgical resection or neoadjuvant therapy. This chapter reviews standards of care in terms of non-invasive diagnosis and percutaneous treatment of malignant biliary obstruction
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
Ablazione percutanea con radiofrequenza dell'adenocarcinoma del pancreas
No full textnon disponibile; poster scientific
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
Analisi radiomica delle modificazioni dopo radioterapia neoadiuvante in pazienti con adenocarcinoma del pancreas
No full textNo abstract availabl
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