Carpal Tunnel Median Nerve

A 48-year-old female administrative assistant presents with a 6-month history of bilateral numbness and tingling in the thumb, index, and middle fingers, worst at night and relieved by shaking her hand. She has a history of hypothyroidism, type 2 diabetes mellitus, and previous gestational carpal tunnel syndrome. On examination, she demonstrates a positive Phalen maneuver, Tinel sign at the wrist, and mild thenar eminence atrophy with weakness of thumb abduction. High-resolution ultrasound of the wrist in transverse section at the pisiform level shows the structure marked **A** with a cross-sectional area of 15 mm² and loss of normal fascicular pattern. Which of the following best describes the sonographic finding at the structure marked **A** in carpal tunnel syndrome?