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Reproducibility Study (reproducibility + study)
Selected AbstractsA UK-based investigation of inter- and intra-observer reproducibility of Gleason grading of prostatic biopsiesHISTOPATHOLOGY, Issue 6 2006J Melia Aims:, The frequency of prostatic core biopsies to detect cancer has been increasing with more widespread prostate specific antigen (PSA) testing. Gleason score has important implications for patient management but morphological reproducibility data for British practice are limited. Using literature-based criteria nine uropathologists took part in a reproducibility study. Methods:, Each of the nine participants submitted slides from consecutive cases of biopsy-diagnosed cancer assigned to the Gleason score groups 2,4, 5,6, 7 and 8,10 in the original report. A random selection of slides was taken within each group and examined by all pathologists, who were blind to the original score. Over six circulations, new slides were mixed with previously read slides, resulting in a total of 47 of 81 slides being read more than once. Results:, For the first readings of the 81 slides, the agreement with the consensus score was 78% and overall interobserver agreement was , 0.54 for Gleason score groups 2,4, 5,6, 7, 8,10. Kappa values for each category were 0.33, 0.56, 0.44 and 0.68, respectively. For the 47 slides read more than once, intra-observer agreement was 77%, , 0.66. The study identified problems in core biopsy interpretation of Gleason score at levels 2,4 and 7. Patterns illustrated by Gleason as 2 tended to be categorized as 3 because of the variable acinar size and unassessable lesional margin. In slides with consensus Gleason score 7, 13% of readings were scored 6 and in slides with consensus 6, 18% of readings were scored 7. Conclusions:, Recommendations include the need to increase objectivity of the Gleason criteria but limits of descriptive morphology may have to be accepted. [source] Assessing normal pulse wave velocity in the proximal pulmonary arteries using transit time: A feasibility, repeatability, and observer reproducibility study by cardiovascular magnetic resonanceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2007MRCP, William M. Bradlow BM Abstract Purpose To calculate pulse wave velocity (PWV) in the proximal pulmonary arteries (PAs) by cardiovascular magnetic resonance (CMR) using the transit-time method, and address respiratory variation, repeatability, and observer reproducibility. Materials and Methods A 1.9-msec interleaved phase velocity sequence was repeated three times consecutively in 10 normal subjects. Pulse wave (PW) arrival times (ATs) were determined for the main and branch PAs. The PWV was calculated by dividing the path length traveled by the difference in ATs. Respiratory variation was considered by comparing acquisitions with and without respiratory gating. Results For navigated data the mean PWVs for the left PA (LPA) and right PA (RPA) were 2.09 ± 0.64 m/second and 2.33 ± 0.44 m/second, respectively. For non-navigated data the mean PWVs for the LPA and RPA were 2.14 ± 0.41 m/second and 2.31 ± 0.49 m/second, respectively. No statistically significant difference was found between respiratory non-navigated data and navigated data. Repeated on-table measurements were consistent (LPA non-navigated P = 0.95, RPA non-navigated P = 0.91, LPA navigated P = 0.96, RPA navigated P = 0.51). The coefficients of variation (CVs) were 12.2% and 12.5% for intra- and interobserver assessments, respectively. Conclusion One can measure PWV in the proximal PAs using transit-time in a reproducible manner without respiratory gating. J. Magn. Reson. Imaging 2007;25:974,981. © 2007 Wiley-Liss, Inc. [source] Morphometric characterization of murine articular cartilage,Novel application of confocal laser scanning microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 9 2009Kathryn S. Stok Abstract A new technique for characterization of the three-dimensional morphology of murine articular cartilage is proposed. The technique consists of a novel application of confocal laser scanning microscopy (CLSM), where the objective was to develop and validate it for cartilage measurements in murine joints. Murine models are used in arthritis research, because they are well-described for manipulating the disease pathophysiology, facilitating our understanding of the disease, and identifying new targets for therapy. A calibration and reproducibility study was carried out to provide a consistent testing methodology for quantification of murine joints. The proximal tibial condyles from male C57BL/6 mice were scanned using a CLS microscope with an isotropic voxel size of 5.8 ,m. Measurements and analyses were repeated three times on different days, and in a second step the analysis was repeated three times for a single measurement. Calculation of precision errors (coefficient of variation) for cartilage thickness and volume was made. The bias of the system was estimated through comparison with histology. This technique showed good precision, with errors in the repeated analysis ranging from 0.63% (lateral thickness) to 3.48% (medial volume). The repeated analysis alone was robust, with intraclass correlations for the different compartments between 0.918 and 0.991. Measurement bias was corrected by scaling the confocal images to 32% of their width to match histology. CLSM provided a fast and reproducible technique for gathering 3D image data of murine cartilage and will be a valuable tool in understanding the efficacy of arthritis treatments in murine models. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source] Latent Class Modeling Approaches for Assessing Diagnostic Error without a Gold Standard: With Applications to p53 Immunohistochemical Assays in Bladder TumorsBIOMETRICS, Issue 2 2001Paul S. Albert Summary. Improved characterization of tumors for purposes of guiding treatment decisions for cancer patients will require that accurate and reproducible assays be developed for a variety of tumor markers. No gold standards exist for most tumor marker assays. Therefore, estimates of assay sensitivity and specificity cannot be obtained unless a latent class model-based approach is used. Our goal in this article is to estimate sensitivity and specificity for p53 immunohistochemical assays of bladder tumors using data from a reproducibility study conducted by the National Cancer Institute Bladder Tumor Marker Network. We review latent class modeling approaches proposed by previous authors, and we find that many of these approaches impose assumptions about specimen heterogeneity that are not consistent with the biology of bladder tumors. We present flexible mixture model alternatives that are biologically plausible for our example, and we use them to estimate sensitivity and specificity for our p53 assay example. These mixture models are shown to offer an improvement over other methods in a variety of settings, but we caution that, in general, care must be taken in applying latent class models. [source] | ||||||||||