<qa>  What is the sign rank test used to compare lesion detection rates?For assessment of characterization efficacy the McNemar test will be used to compare the rates of correct diagnosis for lesions on unenhanced ultrasound, CEUS and unenhanced CT or MRI. For assessment of detection efficacy, Wilcoxons signed rank test will be used to compare the lesion detection rates obtained with unenhanced ultrasound, CEUS, and unenhanced CT or MRI. For all tests, p0.05 will be considered a statistically significant difference. 