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.

Subpubic cartilaginous cyst: a rare cause of vulvar lesion

“…Imaging exams, MRI in particular, have garnered increasing attention in the assessment of pelvic diseases (6)(7)(8)(9)(10) . A diagnosis of SCC, which is based on clinical and imaging findings, depends on the amount of mucinous and cartilaginous material, which results in a heterogeneous aspect on MRI (2,11) .…”

Diffusion-weighted imaging of the female pelvis: how to avoid pitfalls

“…Consequently, the technique has been routinely used in MRI scans of the pelvis. However, these advances have brought new challenges, because there are physiological and benign conditions of the female pelvis that can present restricted diffusion, despite not representing malignant tissue, as detailed and demonstrated by Duarte et al ( 3 ) , in their article published in the previous issue of Radiologia Brasileira. The authors pointed out that 22% of female pelvic lesions exhibiting restricted diffusion are benign-either cystic lesions, such as abscesses, or solid lesions, such as cellular leiomyomas-with high signal intensity on DWI and low signal intensity on apparent diffusion coefficient (ADC) mapping.…”

“…Duarte et al ( 3 ) also describe physiological pelvic conditions, such as those observed in the endometrium and myometrium, which can show variable ADCs throughout the menstrual cycle and different ADCs for women using oral contraceptives. Normal ovaries can also exhibit high signal intensity on DWI, especially during the luteal phase.…”

“…Duarte et al. ( 3 ) highlight several examples of such pitfalls. The authors of a study characterizing lesions in the uterus highlighted the behavior of hyalinized uterine leiomyoma, in which collagen deposition results in the "T2 blackout effect", decreasing signal intensity in DWI sequences and in ADC mapping ( 4 ) .…”

“…Duarte et al ( 3 ) further note that benign ovarian lesions can mimic malignancy on DWI because of other factors, such as intracellular or extracellular edema (due to torsion with infarction), bleeding (due to endometrioma or a hemorrhagic corpus luteum cyst), and increased viscosity (due to teratoma or abscess). Therefore, in this context, the clinical implications of DWI depend on the tissue under investigation and the interpretation of the images must begin with the conventional sequences ( 9 - 11 ) .…”