Tissue characterization in the female pelvis by means of MR imaging

Pelvic imaging techniques such as computed tomography and ultrasonography provide a limited capability for tissue characterization. Fat, fluid, and calcification, for example, can be identified on the basis of parameters such as x-ray attenuation, echogenicity, and sound attenuation. Because of the many tissue parameters, such as T1, T2, magnetic susceptibility, and chemical shift, that contribute to signal intensity, magnetic resonance (MR) imaging may afford an ability to identify a wider array of specific tissues. The purpose of this article is to review the ability of MR imaging to help identify various types of soft tissue and to provide an approach to interpretation of MR images of the female pelvis through tissue characterization. Lipid, fluid, hemorrhage, smooth muscle, fibrosis, solid malignant tissue, and hydrated soft tissue (including edema, mucin, and myxomatous tissue) have typical MR imaging properties, and their presence in a mass can often be established on MR images. Consideration of the tissue composition of various pathologic processes in the pelvis can result in more systematic approaches to image interpretation and thus narrow the differential diagnosis.