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Key Terms
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) that provide faster imaging techniques have further expanded the already important role of MRI for genitourinary and gynecologic imaging. Pelvic MRI is an accurate modality for evaluating congenital uterine anomalies, staging most gynecologic malignancies, evaluating pelvic pain (including appendicitis in pregnant patients), problem solving in ectopic pregnancies, and fetal imaging. Additionally, dynamic/cine MRI can be helpful to evaluate pelvic floor relaxation. Ultrasonography (US) is cheaper, faster, and more easily accessible than MRI. However, US is hampered by a relatively 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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Although MRI remains far more expensive than US, it has many advantages, including superior contrast resolution, volumetric and multiplanar imaging capability, flow-sensitive sequences, and a larger field of view than US. MRI is frequently used as a problem-solving tool after an equivocal US (Figure 50-1). Although pelvic sonography is the study of choice for the initial evaluation of most pelvic conditions, some conditions are best evaluated by MRI. These conditions include: adenomyosis, large pelvic 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 (3DUS) has been more extensively utilized in clinical practice (see also Chapter 49). 3DUS offers volumetric imaging with reconstruction in any imaging plane, thereby minimizing operator dependence. A more accurate and reproducible volume data set enables precise tumor volume measurements that can be used to assess response to therapy and the need for intervention with recurrence, or to guide biopsies. Although the larger data sets require additional ...