Pitfalls of diffusion-weighted imaging of the female pelvis

Abstract

Diffusion-weighted imaging (DWI) is widely used in protocols for magnetic resonance imaging (MRI) of the female pelvis. It provides functional and structural information about biological tissues, without the use of ionizing radiation or intravenous administration of contrast medium. High signal intensity on DWI with simultaneous low signal intensity on apparent diffusion coefficient maps is usually associated with malignancy. However, that pattern can also be seen in many benign lesions, a fact that should be recognized by radiologists. Correlating DWI findings with those of conventional (T1- and T2-weighted) MRI sequences and those of contrast-enhanced MRI sequences is mandatory in order to avoid potential pitfalls. The aim of this review article is the description of the most relevant physiological and benign pathological conditions of the female pelvis that can show restricted diffusion on DWI.

Keywords: Diffusion magnetic resonance imaging; Magnetic resonance imaging; Pelvis/diagnostic imaging.

Figure 1

MRI of a female patient with cervical cancer. Sagittal DWI at b = 1000 s/mm² showing the low SI of the myometrium (arrowhead), the high SI of the endometrium (asterisk), and the high SI of the tumor (arrow).

Figure 2

MRI of a female patient with cellular leiomyoma. Axial DWI at b = 1000 s/mm² showing a large uterine tumor with high SI (arrows).

Figure 3

MRI of a female patient with leiomyosarcoma. Axial DWI at b = 1000 s/mm² showing a large uterine tumor with high SI (arrows).

Figure 4

MRI of a female patient with tubo-ovarian abscess. a: Axial DWI at b = 1000 s/mm² showing an area with high SI (circle). b: Axial T1W image with fat suppression after intravenous gadolinium-based contrast administration showing that this area did not enhance but exhibited a diffusely thickened wall that enhanced avidly (arrow).

Figure 5

MRI of a female patient with endometrioma. a: Axial DWI at b = 1000 s/mm² showing a right adnexal mass with relative high SI (arrow). b: Axial T1W images with fat suppression showing that the mass is spontaneously hyperintense (arrow).

Figure 6

MRI of a female patient with a hemorrhagic cyst. Axial DWI at b = 1000 s/mm² showing a left adnexal nodule with high SI (arrow).

Figure 7

MRI of a female patient with mature cystic teratoma. Axial DWI at b = 1000 s/mm² showing a tumor with areas of high SI (arrow).

Figure 8

MRI of a female patient with fibroma. Axial DWI showing that the tumor has relatively high SI (arrow).

Figure 9

MRI, at the level of the rectum, of the same female patient depicted in Figure 2. Axial DWI showing a large hyperintense uterine tumor (asterisk)- the known cellular leiomyoma-and a posterior hyperintense ring (circle)-the rectal mucosa.

Figure 10

MRI of a pelvic lymph node in a female patient. Axial DWI showing a bright ovoid nodule in the topography of the obturator foramen (circle).