Osirix workstation

The MR-DTI volumes were reformatted to match the NC-MRV images. An experienced radiologist (DJL) assessed the NC-MRV images using an Osirix workstation (Pixmeo, Berne, CH) to determine the location and length of the venous occlusion (complete or partial, above-knee only). This assessment was performed principally using the subtracted NC-MRV images; however, the arterial images, as well as the unsubtracted bright- and dark-vein images, were also available to aid the diagnosis where needed.
Subsequently, an assessment of the location and length of any high-signal regions on the matching MR-DTI images was performed and these were compared with the NC-MRV images to evaluate to what extent thrombus length and location matched on both techniques. The individual-slice images were evaluated with reference to curved-reformat images, as required where the thrombi curved significantly out of the image plane. Any mismatch in thrombus extent or location was recorded. All discontinuities in high signal T1 regions were noted and the tract lengths were summed over the affected region on the matching NC-MRV.

Shear wave elastography was performed using an Aixplorer ultrasound system (Supersonic Imagine, Aix-en-Provence, France) with ShearWave™ Elastography coupled with a 4–15 MHz linear transducer, as previously described in detail (Bercoff et al., 2004 (link); Tanter et al., 2008 (link); Andonian et al., 2016 (link)). Grayscale ultrasound was used to identify anatomical structures and to determine the location of the rectus femoris. Next, the user was positioned such that a fixed-size square region of interest (ROI) delimiting the elastographic field of view (SWE box), i.e., a ROI, where shear-wave propagation was analyzed within the muscle, was visible. Three successive SWE acquisitions were performed for the rectus femoris with the transducer in a fixed position (Figure 1B). Images were transferred to an OsiriX workstation (Pixmeo, Geneva, Switzerland) for analysis using a dedicated analysis plugin (QBox, 1.0, Supersonic Imaging). To avoid artifacts in the circular ROIs, five ROIs (5-mm diameter) were placed within a given square SWE color map (Figure 1B). As three SWE acquisitions were performed in succession for each rectus femoris, 15 stiffness measurements were available at each measurement time point for each subject. Same two observers making all SWE measurements in different site.

Images were evaluated on an OsiriX Workstation (Version 5.6, Pixmeo Inc., Geneva, Switzerland) by two independent radiologists. Three different measurements (BDM) in a single 2D image were used to evaluate the exact distance from the anal verge to the distal ending of the tumor. All geometric measurements were performed on the T2w sagittal scans. Diffusion-weighted images, DCE scans, and the high-resolution T2w axial scan were used for improved tumor identification. For the first measurement (MRI1), two unbowed lines, one from the anal verge (AV) to the upper ending of the anal canal and the other beginning at the upper ending of the anal canal to the lower border of the tumor, were drawn and both distances were added (Figure 1(a)). In the second measurement (MRI2), one straight line from the anal verge to the lower boarder of the tumor was measured (Figure 1(b)). The third measurement (MRI3) was a curved line beginning at the anal verge and following the course of the rectum wall ending at the lower border of the tumor (Figure 1(c)).