A 28-year-old nulliparous woman with a 5-year history of progressive pelvic pain and dyspareunia is evaluated. Laparoscopy reveals peritoneal endometriosis with adhesions and a 3 cm ovarian endometrioma. A 35-year-old multiparous woman with 2 years of severe dysmenorrhea and infertility has a boggy, enlarged uterus on examination and heterogeneous myometrial echotexture on transvaginal ultrasound. Which imaging or clinical finding best distinguishes endometriosis from adenomyosis?