Diffusion-weighted imaging of gynecologic tumors: diagnostic pearls and potential pitfalls

Conventional magnetic resonance (MR) imaging has an established role in gynecologic imaging. However, increasing clinical demand for improved lesion characterization and disease mapping to optimize patient management has resulted in the incorporation of newer sequences, such as diffusion-weighted (DW) imaging, into routine protocols for pelvic MR imaging. DW imaging provides functional information about the microenvironment of water in tissues, hence augmenting the morphologic information derived from conventional MR images. It can depict shifts of water from extracellular to intracellular compartments, altered cell membrane permeability, disruption of cell membrane depolarization, and increased cellular density. Such changes may be associated with tumors. DW imaging has emerged as an important cancer biomarker and takes the role of the radiologist from the level of mere macroscopic diagnosis to more active participation in determining patient prognosis and management through a better understanding of the tumor microenvironment. With the growing acknowledgment of DW imaging as a pivotal tool in the radiologist's armamentarium, radiologists must be familiar with the appearances of various gynecologic tumors at DW imaging and understand the implications of this sequence for improving diagnostic accuracy and predicting and monitoring treatment response. Although positron emission tomography/computed tomography is extremely useful for detecting tumor recurrence in cervical and ovarian carcinomas, it has a limited specificity in the immediate posttreatment setting. DW imaging may aid in detection of residual or recurrent tumors in such situations. DW imaging is a potentially useful adjunct to conventional MR imaging for evaluation of gynecologic tumors, thus improving overall diagnostic accuracy, tumor staging, prediction of response to therapy, and treatment follow-up.