The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Katherine Zukotynski - One of the best experts on this subject based on the ideXlab platform.
-
exploratory evaluation of mr permeability with 18f fdg pet mapping in pediatric brain tumors a report from the pediatric brain tumor consortium
The Journal of Nuclear Medicine, 2013Co-Authors: Katherine Zukotynski, Frederic H Fahey, Sridhar Vajapeyam, Mehmet Kocak, Sridharan Gururangan, Larry E Kun, Tina Young PoussaintAbstract:The purpose of this study was to develop a method of registering 18F-FDG PET with MR permeability images for investigating the correlation of 18F-FDG uptake, permeability, and cerebral blood volume (CBV) in children with pediatric brain tumors and their relationship with outcome. Methods: Twenty-four children with brain tumors in a phase II study of bevacizumab and irinotecan underwent brain MR and 18F-FDG PET within 2 wk. Tumor types included supratentorial high-grade astrocytoma (n = 7), low-grade glioma (n = 9), brain stem glioma (n = 4), medulloblastoma (n = 2), and ependymoma (n = 2). There were 33 cases (pretreatment only [n = 12], posttreatment only [n = 3], and both pretreatment [n = 9] and posttreatment [n = 9]). 18F-FDG PET images were registered to MR images from the last time point of the T1 perfusion time series using mutual information. Three-dimensional regions of interest (ROIs) drawn on permeability images were automatically transferred to registered PET images. The quality of ROI registration was graded (1, excellent; 2, very good; 3, good; 4, fair; and 5, poor) by 3 independent experts. Spearman Rank correlations were used to assess correlation of maximum tumor permeability (Kpsmax), maximum CBV (CBVmax), and maximum 18F-FDG uptake normalized to white matter (T/Wmax). Cox proportional hazards models were used to investigate associations of these parameters with progression-free survival (PFS). Results: The quality of ROI registration between PET and MR was good to excellent in 31 of 33 cases. There was no correlation of baseline Kpsmax with CBVmax (Spearman Rank correlation = 0.018 [P = 0.94]) or T/Wmax (Spearman Rank correlation = 0.07 [P = 0.76]). Baseline CBVmax was correlated with T/Wmax (Spearman Rank correlation = 0.47 [P = 0.036]). Baseline Kpsmax, CBVmax, and T/Wmax were not significantly associated with PFS (P = 0.42, hazard ratio [HR] = 0.97, 95% confidence interval [CI] = 0.90–1.045, and number of events [nevents] = 15 for Kpsmax; P = 0.41, HR = 0.989, 95% CI = 0.963–1.015, and nevents = 14 for CBVmax; and P = 0.17, HR = 1.49, 95% CI = 0.856–2.378, and nevents = 15 for T/Wmax). Conclusion:18F-FDG PET and MR permeability images were successfully registered and compared across a spectrum of pediatric brain tumors. The lack of correlation between metabolism and permeability may be expected because these parameters characterize different molecular processes. The correlation of CBV and tumor metabolism may be related to an association with tumor grade. More patients are needed for a covariate analysis of these parameters and PFS by tumor histology.
Tina Young Poussaint - One of the best experts on this subject based on the ideXlab platform.
-
exploratory evaluation of mr permeability with 18f fdg pet mapping in pediatric brain tumors a report from the pediatric brain tumor consortium
The Journal of Nuclear Medicine, 2013Co-Authors: Katherine Zukotynski, Frederic H Fahey, Sridhar Vajapeyam, Mehmet Kocak, Sridharan Gururangan, Larry E Kun, Tina Young PoussaintAbstract:The purpose of this study was to develop a method of registering 18F-FDG PET with MR permeability images for investigating the correlation of 18F-FDG uptake, permeability, and cerebral blood volume (CBV) in children with pediatric brain tumors and their relationship with outcome. Methods: Twenty-four children with brain tumors in a phase II study of bevacizumab and irinotecan underwent brain MR and 18F-FDG PET within 2 wk. Tumor types included supratentorial high-grade astrocytoma (n = 7), low-grade glioma (n = 9), brain stem glioma (n = 4), medulloblastoma (n = 2), and ependymoma (n = 2). There were 33 cases (pretreatment only [n = 12], posttreatment only [n = 3], and both pretreatment [n = 9] and posttreatment [n = 9]). 18F-FDG PET images were registered to MR images from the last time point of the T1 perfusion time series using mutual information. Three-dimensional regions of interest (ROIs) drawn on permeability images were automatically transferred to registered PET images. The quality of ROI registration was graded (1, excellent; 2, very good; 3, good; 4, fair; and 5, poor) by 3 independent experts. Spearman Rank correlations were used to assess correlation of maximum tumor permeability (Kpsmax), maximum CBV (CBVmax), and maximum 18F-FDG uptake normalized to white matter (T/Wmax). Cox proportional hazards models were used to investigate associations of these parameters with progression-free survival (PFS). Results: The quality of ROI registration between PET and MR was good to excellent in 31 of 33 cases. There was no correlation of baseline Kpsmax with CBVmax (Spearman Rank correlation = 0.018 [P = 0.94]) or T/Wmax (Spearman Rank correlation = 0.07 [P = 0.76]). Baseline CBVmax was correlated with T/Wmax (Spearman Rank correlation = 0.47 [P = 0.036]). Baseline Kpsmax, CBVmax, and T/Wmax were not significantly associated with PFS (P = 0.42, hazard ratio [HR] = 0.97, 95% confidence interval [CI] = 0.90–1.045, and number of events [nevents] = 15 for Kpsmax; P = 0.41, HR = 0.989, 95% CI = 0.963–1.015, and nevents = 14 for CBVmax; and P = 0.17, HR = 1.49, 95% CI = 0.856–2.378, and nevents = 15 for T/Wmax). Conclusion:18F-FDG PET and MR permeability images were successfully registered and compared across a spectrum of pediatric brain tumors. The lack of correlation between metabolism and permeability may be expected because these parameters characterize different molecular processes. The correlation of CBV and tumor metabolism may be related to an association with tumor grade. More patients are needed for a covariate analysis of these parameters and PFS by tumor histology.
Nagahiro Saijo - One of the best experts on this subject based on the ideXlab platform.
-
effect of the introduction of minimum lesion size on interobserver reproducibility using recist guidelines in non small cell lung cancer patients
Cancer Science, 2006Co-Authors: Hirokazu Watanabe, Hideo Kunitoh, Seiichiro Yamamoto, Shin Kawasaki, Akira Inoue, Katsuyuki Hotta, Kazu Shiomi, Masahiko Kusumoto, Kazuro Sugimura, Nagahiro SaijoAbstract:We evaluated interobserver reproducibility for the response evaluation criteria in solid tumors (RECIST) guidelines and the influence of minimum lesion size (MLS) on reproducibility. The 110 consecutive patients with non-small cell lung cancer were treated with platinum-based chemotherapy. Five observers measured target lesions according to both the World Health Organization (WHO) criteria and RECIST. The percentage changes for unidimensional measurements (UD; RECIST type) and bidimensional measurements (BD; WHO type) were calculated for each patient. Interobserver reproducibility among five observers, that is 10 pairs, was expressed as the Spearman's correlation coefficient for the percentage changes, the proportion of agreement and the kappa statistics for response categories. The same analysis was carried out using MLS. BD was more reproducible than UD (Spearman Rank correlation coefficient, 0.84 vs 0.81; proportion of agreement, 84.4% vs 82.5%; kappa value, 0.69 vs 0.61). When MLS was applied to UD, eligible cases decreased by 6.4% and the number of target lesions by 44.6%, whereas interobserver reproducibility for UD improved (Spearman Rank correlation coefficient, 0.81-0.84; proportion of agreement, 82.5-84.2%; kappa value, 0.61-0.65). The introduction of MLS to UD could also improve intercriteria reproducibility between WHO and RECIST. It is important to apply the MLS when using RECIST for the comparable interobserver reproducibility attained with WHO.
Xie Jun - One of the best experts on this subject based on the ideXlab platform.
-
reduction in ordered decision system based on Spearman Rank correlations
Journal of Computer Applications, 2009Co-Authors: Xie JunAbstract:Reduction is an important knowledge discovery process.The original rough set theory based on equivalence relations does not consider attributes with preference-ordered domains and is sensitive to data noise.Based on Spearman Rank correlation analysis,a method was introduced to reduction ordered decision systems.This method computes the reduction according to the impact of certain attributes on the Spearman Rank correlations between objects.Experimental results show that this method is effective as it not only takes into account the preference relationship,but also improves noise immunity,and thus is more suitable for practical application.
S P Vriend - One of the best experts on this subject based on the ideXlab platform.
-
spearmen a dbase program for computation and testing of Spearman Rank correlation coefficient distributions
Computers & Geosciences, 1991Co-Authors: G Frapporti, L A M Linnartz, S P VriendAbstract:Abstract Large “hierarchical” datasets, that is a dataset that consists of identifiable subsamples of a population, offer the possibility to calculate a statistic per subsample. Together they form a sample distribution of that statistic. This distribution may be compared to some null hypothesis distribution and tested for deviations. To determine whether two variables are related, some type of correlation statistic usually is calculated. If the assumption for a normal distribution is not true necessarily the nonparametric Spearman Rank correlation coefficient is better suited to estimate the existence of a relation than the Pearson product-moment correlation coefficient. The Spearman Rank correlation coefficient thus has more general applicability at the cost of only a marginal loss in efficiency in the situation of normality. The dBase program SPEARMEN calculates Spearman Rank correlation coefficients for all the subsamples of a “hierarchical” dataset and tests the sample distribution of this statistic against the null hypothesis H o : r s = 0 by using the Kolmogorov-Smirnov one sample test. This approach has the advantage that it is sensitive to deviations for the entire range of observations and not only at critical tail-end values. For subsample sizes under 14 the theoretical null hypothesis permutation distribution is used, whereas above this value the distribution is approximated by a Student- t distribution. The program uns under dBaseIII + , dBaseIV, Foxbase + , and Clipper and can be used for virtually unlimited datasets.
