Imaging methods

Conventional radiography, ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) are all capable of providing detailed anatomical information.

The gross bony anatomy of the pelvis, as well as the detailed trabecular pattern of bone, are best demonstrated on conventional radiographs, which have higher spatial resolution than CT or MRI. However, CT with reconstruction of the data using a bone algorithm provides superior information regarding spatial relationships, for example, in the demonstration of bone fragments in pelvic fractures. Although MRI is not capable of demonstrating cortical or trabecular bone, the technique provides unique information regarding bone marrow components such as fat, haemopoietic tissue and bone marrow pathology.

The soft tissues of the pelvis are demonstrated using ultrasound, CT and MRI, which all provide complementary information. Ultrasound and MRI have the advantage of not utilizing ionizing radiation. Transabdominal ultrasound is useful as a basic screen, but requires a full bladder to act as an acoustic window and to displace gas-filled loops of bowel out of the pelvis, whereas endovaginal and transrectal ultrasound, though invasive, can provide exquisite detail of the internal anatomy of the male prostate and seminal vesicles and the female genital tract without the necessity of a full bladder. MRI provides similar detail, either by use of dedicated surface phased array coils or endocavitary coils. However, the hysterosalpingogram (HSG) still has an important role in the evaluation of the uterine cavity and Fallopian tubes.

Although ultrasound (with colour flow and pulsed wave Doppler techniques), MRI and contrast-enhanced CT (particularly helical CT), are able to visualize much of the pelvic vasculature, pelvic arteriography remains the gold standard investigation, particularly for delineating the internal iliac arterial tree.