Imaging evaluation of patients with spinal deformity.

CT myelography and MRI provide the best means of preoperatively assessing patients with spinal deformities. Owing to its noninvasive nature and its superior soft-tissue contrast, MRI represents the single best modality in the evaluation of a patient with any deformity. MRI allows complete preoperative surgical planning and obviates the need for any additional studies. Screening of the entire cord in a patient with a deformity is best accomplished with sagittal and coronal (as needed) T1W images. These images allow assessment of the cord for compression, tethering, syrinx, enlargement, and Arnold-Chiari malformation. Evaluation of cord compression at the apex of a curve is the single most important consideration other than the diagnosis of intrinsic cord abnormality. Subsequent sagittal or axial T2W images may be helpful if specific abnormalities are noted on T1W screening images. Coronal images are particularly helpful in patients with prominent curves or in those with vertebral anomalies. Additionally, coronal images may be useful in assessing patients with suspected diastematomyelia. Advances in hardware and software design have resulted in marked improvements in the ability to satisfactorily image all aspects of patients with spinal deformities. New phased array coils allow rapid imaging of larger portions of the spine. For instance, a complete MRI of the spine can be performed in a child in the same length of time that would have been necessary for a single lumbar examination when MRI was in it's infancy. The use of fast spin-echo imaging also permits more rapid acquisition times. CT myelography remains useful for those patients who cannot undergo MRI or for those with specific abnormalities such as multilevel central spinal stenosis when dynamic information obtained during the myelogram might be helpful. CT myelography represents the only means of assessing the central spinal canal of patients with metallic instrumentation in place. With the exception of these limited applications, MRI has replaced CT myelography as the imaging study of choice in the evaluation and examination of patients with spinal deformities.