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Definitions
Fibrous stroma: a low signal band on T2-weighted images in the cervix that is continuous with the junctional zone of the uterine body and represents an important landmark in staging of cervical cancer.
Junctional zone: inner layer of myometrium appearing dark on T2-weighted images.
Müllerian anomalies: congenital uterine malformations that may be present with pelvic pain and/or history of infertility.
Submucosal leiomyoma: a fibroid with greater than 50% of its surface in contact with the endometrial lining.
T2 shading: high signal intensity on T1-weighted scans that becomes dark on T2-weighted images typical of endometriomas.
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The technologic advances in magnetic resonance imaging (MRI) in providing faster imaging techniques have further expanded the already important role of MRI for genitourinary and gynecologic imaging. Not only tissue characterization and tumor staging, but also pelvic floor relaxation, urinary incontinence, and fetal imaging using MRI have become mainstream in modern practice.
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Ultrasound (US) is cheaper, faster, and more easily accessible than MRI. However, US is hampered by a small field of view, obscured findings due to overlying bowel gas or fatty tissue, and its operator dependency. US can be limited for visualization of deep nodes and for imaging obese patients.
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MRI has superior contrast resolution, volumetric and multiplanar imaging capability, flow-sensitive sequences, and larger field of view than US. The increased cost of MRI and the lack of proficiency of some radiologists to implement it for body imaging have been impediments to wider usage.
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MRI is used as a problem solving tool after equivocal US (Figure 48-1). Although pelvic sonography is the study of choice for the initial evaluation of most pelvic conditions, some conditions are best evaluated by MRI. These include adenomyosis, large masses, dermoids, some endometrial disorders, and staging, but not screening, of pelvic malignancies. The interested reader is referred to specific texts that cover pelvic applications of MRI.1,2
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Three-dimensional ultrasound (3D US) has recently gained acceptance in clinical practice (see also Chapter 47). Three-dimensional US offers volumetric imaging with reconstruction in any imaging plane, thereby nearly eliminating operator dependence. A more accurate and reproducible volume data set enables accurate tumor volume measurements that can be used to judge response to therapy and the need for intervention with recurrence, or to guide biopsies. Although the larger data sets require additional training, and workstations with computer ...