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Quantitative imaging features (radiomics) extracted from apparent diffusion coefficient (ADC) maps of rectal cancer patients can provide additional information to support treatment decision. Most available radiomic computational packages allow extraction of hundreds to thousands of features. However, two major factors can influence the reproducibility of radiomic features: interobserver variability, and imaging filtering applied prior to features extraction. In this exploratory study we seek to determine to what extent various commonly-used features are reproducible with regards to the mentioned factors using ADC maps from two different clinics (56 patients). Features derived from intensity distribution histograms are less sensitive to manual tumour delineation differences, noise in ADC images, pixel size resampling and intensity discretization. Shape features appear to be strongly affected by delineation quality. On the whole, textural features appear to be poorly or moderately reproducible with respect to the image pre-processing perturbations we reproduced.

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Background Ultrasound elastography is increasingly available in clinical practice. Recent studies showed higher velocity stiffness in testicular tumors compared to normal testicles. Purpose To evaluate ultrasound elastography in combination with the apparent diffusion coefficient measurements in diffusion weighted (DW) magnetic resonance imaging (MRI) in testicles. DW can be a useful tool in evaluating testicular malignancies. However, the relationship between velocity stiffness and MRI diffusion is not well established. Material and Methods We prospectively included 132 patients with testicular microlithiasis (n = 53), or normal testicular tissue (n = 53), or suspected for testicular cancer (n = 26). All 132 patients underwent ultrasonography including shear wave elastography and MRI diffusion coefficient examination of the scrotum. Results No clinically relevant difference in velocity stiffness was found between normal and testicles with microlithiasis. There was a significant difference in stiffness between patients with testicular microlithiasis (0.78 m/s), normal testicular tissue (0.77 m/s), and patients with testicular cancer (1.95 m/s) ( P ≤ 0.001). Similarly, there was a statistically significant difference in MRI diffusion values between patients with testicular microlithiasis (0.978 × 10mms), normal testicular tissue (0.929 × 10mms), and testicular cancers (0.743 × 10mms) ( P < 0.01). Conclusion Patients with testicular microlithiasis had no malignant characteristics measured with shear wave elastography or MRI diffusion. MRI diffusion and elastography may be useful to preoperatively differentiate benign from malignant testicular lesions.