ABSTRACT

We aimed to investigate the clinical and magnetic resonance imaging (MRI) characteristics of uterine adenomyosis, in which there is an extensive area of high signal intensity in the myometrium on T2-weighted MRI.

This retrospective radiographic study reviewed a case series of six patients (mean age, 36 years) with adenomyosis. These patients were selected because, unlike in classical adenomyosis, T2-weighted images showed a larger area of high signal intensity than that of low signal intensity in the myometrium. The morphology of the myometrial lesions, patterns of contrast enhancement (n=4), intramyometrial hemorrhaging, diffusion restriction (n=5), endometrial lesions, and imaging findings after treatment (n=3) were evaluated on MRI.

The patients’ clinical symptoms included vaginal bleeding and severe anemia. Four were administered hormonal therapy, one underwent hysterectomy, and one underwent enucleation. On T2-weighted images, all showed endometrial thickening and a high signal intensity area in the myometrium that was divided up by a mesh of low signal intensity bands, with an appearance reminiscent of a fish caught in a net. Other findings included gradual centripetal enhancement with contrast defects in multicystic areas (4/4), an intramyometrial hemorrhage (1/6), and increased diffusion (5/5). Following hormonal therapy, the uteruses decreased in size and were similar to those of classical adenomyosis on MRI (3/3). The lesions were diagnosed as adenomyosis with a proliferation of adenomyotic glandular tissue and a proliferative endometrial polyp.

This case series suggests that there is a subgroup of uterine adenomyosis that shows a characteristic “fish-in-a-net” appearance on T2-weighted images.