All parameters are analyzed as an independent unit. Statistical analysis will be calculated using the Stat View software package version 5.0 for Mac OS 9 (Stat View Software by Abacus C., Berkley, California) and Graph Pad Prism version 4 for Mac OS X (Graph Pad Software, San Diego, California). Results will be given in median and interquartile ranges. Comparison between visits in the same patients will be done by the non-parametric, paired Wilcoxon signed rank test or if more than two groups are involved the Kruskal Wallis test. A probability level of < 0.05 will be considered significant. The inter - reader agreement will be measured using the kappa value.