Imaging methods

The bony pelvis and lower limb are increasingly examined using the full armoury of imaging modalities as these become more widely available. Plain radiography remains as important as ever, and its more detailed applications will be discussed further in the relevant anatomical subsections.

Computed tomography (CT)

Scanning is now available in the majority of hospitals, finding particular favour in the further examination of complex skeletal trauma, where it is often capable of contributing valuable additional information.

Magnetic resonance imaging (MRI)

This is revolutionizing the investigation of bone, joint and soft tissue abnormalities. Multiplanar imaging capability and high contrast resolution mean that the presence and extent of pathology can be defined far more accurately. This capacity is enhanced with the use of phased array surface detection coils, which greatly improve the signal-to-noise ratio (SNR).

The exact choice of sequences and imaging planes varies greatly, depending on the clinical problem, the anatomical location and individual radiological preference. In bony structures, the relatively high signal of bone marrow fat may mask pathology on T2-weighted images, so the use of techniques for abolishing the signal from fat is a valuable adjunct. Increasingly, chemical fat saturation techniques are available in conjunction with T2-weighted imaging. Alternatively, STIR (short tau inversion recovery) sequences may also be used. The principal limitation of MRI is that cortical bone and calcification have no signal at all, which can make abnormalities difficult to interpret. More specific applications of MRI will be dealt with in the appropriate sections.