Advancing techniques in spinal MR imaging: but are they necessary for spinal leptomeningeal tumor?

Sugahara et al, in this issue of the American Journal of Neuroradiology (page 1773), compare the 2D spin-echo (2D-SE) technique with the 3D gradient-echo (3D-GE) technique after contrast injection in order to determine which sequence is superior for the evaluation of suspected leptomeningeal tumor in the spine. The authors found that the 2D-SE technique depicted the fewest lesions. The 3D-GE technique depicted a greater number of lesions, but the best lesion depiction was achieved with the 3D-GE technique combined with multiplanar reconstruction. In addition, the authors found that the use of reconstruction was helpful in distinguishing vascular enhancement. Therefore, they suggest that the 3D-GE technique in combination with multiplanar reconstruction should be used for detecting intradural tumor dissemination. This article is the first to compare the use of 2D-SE and 3D-GE techniques in the evaluation of contrast-enhancing lesions in the spine. Certainly, 3D techniques are now routinely used in imaging of the spine and in other applications. In particular, 3D-GE or 3D fast spin-echo imaging techniques are commonly used for the evaluation of extradural disorders, such as disk disease. Typically, with the 3D-GE technique, low flip angles are used to create hyperintensity in the CSF, allowing differentiation and delineation of disk from CSF. The use of 3D-GE techniques with spoiler gradients , to achieve an essentially T1-weighted effect, in combination with contrast material, has been much less common. Up to now, the primary use of 3D-GE techniques has been limited to the examination of patients with degenerative changes (1). Here again, the use of the 3D-GE technique, in combination with contrast enhancement and spoiler gradients, has been shown to provide good delineation of small disks. In these cases, however, it is often vascular enhancement that is being examined rather than enhancement of the lesion itself. The current study used a 3D-GE technique in combination with spoiler gradients and contrast enhancement to detect enhancing tumors. While work of this sort has not been performed in the spine, it has been done in the brain. There, the technique has had mixed results. Some have advocated its advantages. For example , the 3D technique has been shown to offer better spatial resolution because much thinner sections can be achieved. In addition, such thin sections have allowed reformations to be performed. If a patient has been imaged in one plane but examination of the lesion in another plane is desired, reformations are easy to …