Imaging description

Non-traumatic vertebral compression fractures (VCF) are common and often secondary to either osteoporosis or metastasis. Radiologists should try to determine the benign or malignant nature of the fracture each time they diagnose a VCF, as this has obvious implications for treatment and prognosis. MRI has the greatest accuracy among imaging modalities in this regard. Bone SPECT scan and FDG-PET are very sensitive but their specificity is markedly limited [1,2].

There are various signal changes, morphologic features and quantitative measurements that can help differentiate benign and malignant VCF [3]. Perhaps the most important signal characteristic is the T1 signal within the fractured vertebra: replacement of marrow fat by metastasis is almost always complete, whereas in osteoporotic VCF there are often areas of preserved marrow signal (Fig. 88.1). Identification of normal marrow signal on T1-weighted images, even in a small portion of the vertebral body, is a good indicator of a benign fracture. Abnormal marrow signal in the pedicles of vertebral bodies can be seen in both malignant and benign fractures, but abnormal signal within the posterior elements is more specific for malignant fracture. Linearly oriented band-like signal changes on either T1- or T2-weighted images favor benign fractures, as does fluid signal within the vertebral body (Fig. 88.1). The posterior border of the vertebral body provides important clues as to the nature of the fracture: a rounded bulge of the posterior border is suggestive of malignant fracture, whereas a triangular bulge is more consistent with benign fracture (Figs. 88.1, 88.2). Presence of paraspinal and/or epidural masses suggests metastasis, although benign fractures may have considerable hematoma when they are acute, which mimics soft tissue mass.