Ovarian Torsion

A 24-year-old nulliparous woman presents with sudden-onset severe right lower quadrant pain radiating to the right flank and inner thigh, associated with nausea and vomiting. She has a known 6 cm right ovarian dermoid cyst. CT abdomen and pelvis with IV contrast shows an enlarged edematous right ovary with peripherally displaced follicles, deviation of the uterus toward the affected side, and mild pelvic free fluid. The structure marked **A** in the diagram represents the twisted vascular pedicle at the infundibulopelvic ligament. Which of the following best describes the pathognomonic imaging sign represented by structure **A** in acute ovarian torsion?