Studio RM Fast Spin-Echo dei traumi vertebro-midollari acuti Fast spin echo MR imaging in acute spinal trauma

This paper describes the technical features of fast spin echo sequences in assessing acute spinal trauma using high and medium field MR systems. The series comprises 56 patients with spinal trauma investigated in the acute phase with T2-weighted fast spin echo myelographic sequences as well as T1-weighted morphologic sequences. Spinal injuries were divided into cord lesions (9 concussion, 28 focal and/or diffuse oedema, 3 haematomyelia, 4 lacerations with transection) and perimedullary lesions (6 extramedullary haematoma), vertebral injury (36 vertebral fractures, 14 impaired statics, 3 vertebral dislocation/spondylexarthrosis, 2 joint dislocation, 28 instability) and cord lesions (58 ligamentous damage, 10 haematoma, 23 spinal cord and root compression, 3 disc protrusion, 14 disc herniation). The shorter acquisition times of fast spin echo with respect to traditional spin echo led to faster classification of spinal injury. The two imaging techniques are similar, but slight differences must be taken into account for optimum image interpretation: an enhanced myelographic effect, reduced sensitivity to the effects of magnetic susceptibility and persistent fat hyperintensity. The enhanced myelographic effect improved the contrast between CSF and epidural structures and between CSF and cord. The reduced sensitivity to the effects of magnetic susceptibility helped to attenuate the artifacts caused by ferromagnetic foreign bodies or metal stabilizers. Persistence of fat hyperintensity, however, may be a major drawback, especially in elderly patients (who have a mainly yellow marrow), masking the 'oedema pattern' following trauma. In these cases fast spin echo techniques must be combined with fat suppression. The fast acquisition times and maintained spin echo contrast and hence the pattern of spinal lesions make this sequence a valid alternative to traditional spin echo at least on sagittal planes. On axial planes gradient echo is superior to fast spin echo given the improved contrast between cord white matter and grey matter and the lack of artifacts produced by CSF pulsation.