Below are shown two videos. Both are from an MRI set to reveal standing fluid as bright white. On the left are axial sections with the iliacus (i) and psoas major (pm) labelled in sections 1 and 2. On the right are coronal sections with the iliacus (i) and psoas major (pm) labelled in sections 14 - 21. Play the videos frame by frame, paying particular attention to structures indicated by the green and red arrows. The blue arrows point to the same structure on the right side as do the red arrows on the left. The diagnosis is presented in the box below the images.