Functional High-Resolution 3D Examinations of the Cervical Spine with MRI and the NeuroSwing Device*

K. E. W. Eberhardt1, R. Schindler2, J. Liebisch1
1University, Erlangen, Germany, 2Inside, Functional Diagnostic Technology GmbH, Schweinfurt, Germany
 |  31.05.2007

Fig. 1 Demonstrates the procedure of an X-ray myelography.

Fig. 3 Functional range of movement of a volunteer. Neurtral position (A) Anteflexion (B) Retroflexion (C) Lateroflexion (D, E) Rotation (F, G).

Table 1 presents the results for the segmental mobility,
i. e., the maximum range of movement between inclination and reclination. The total range of movement was 106.16°, with a standard deviation of 4.96 °. The segmental mobility, in contrast, deviated substantially (SDev: 2.89-6.79°) and was distinctly greater in the cranial segments of the cervical spine than in the cranial segments (C0/1: 6.79°; C7/8: 5.51°). The values were determined from 25 young and healthy subjects. The functional mobility for lateroflexion was 25.3° on the left side and 22.5° on the right side, with small standard deviations (left: 1.3°;
right: 0.9°). In contrast with the sagittal plane of motion, the mobility varies less among the individual segments (2.3° and 5.4°). The deviation is substantial (1.3°–4.3°), as in the sagittal plane.

The total range of motion of the axial plane was 59.1° to the right and 56.9° to the left. The standard deviation is somewhat higher than in the sagittal and coronal planes (right: 12.5°; left: 13.6°). The segmental mobility deviates less and appears to be more uniform without great differences between the sides.
In summary, our results show clearly that although the total ranges of motion are comparable for the individual subjects, there are different segmental ranges of motion.
Reproducibility: Reproducibility tests were done with 5 subjects. Our results show that repeated examinations at defined functional positions are possible with high repetitive accuracy. In inclination, the standard deviation was from 1.5% to 3% of the initial value. In reclination, deviations from the expected value are between 3% and 8%. They are from 2.5% to 5% in lateroflexion and between 2% and 3% in rotation. In summary, our results show high reliability for functional examinations with the device used.
 

Discussion

Numerous publications have appeared in recent years which treat functional examinations of the cervical spine in various conditions, especially degenerative, inflammatory, and posttraumatic conditions [1–6]. In these cases, functional examinations of the cervical spine are performed in the end position, i.e., at the maximum for movement, or in firmly defined stages [5, 6, 11]. One group used a device, which was continuously adjustable in the sagittal plane. To date, there have been no studies regarding the extent to which functional examinations of the cervical spine are reproducible; or at least they have not been reported in the applicable literature. Although body coils were required in the past for measurement, it is now possible to use surface coils with better signal-to-noise ratio. One group has reported on the related possibility of improved spatial resolution [12]. In that case, however, gradient echo sequences were used (with all the associated disadvantages including high susceptibility to artifacts) to attain sufficiently high spatial resolution. Our group selected a sequence in (turbo) spin-echo technique for a high-resolution examination, and utilized parameters optimized for the examination. The spatial resolution obtained by other groups [12] using the gradient echo technique is limited, especially in the sliceselection direction. Multiplanar reconstructions have just as many limitations in application, because of voxel anisotropy, as do the more sophisticated visualization techniques such as VRT [12]. Until now, it has not yet been possible to establish a method comparable to the visualization aspect of conventional myelography. The same group presented 2D evaluations (diameter of subarachnoid space, myelon and neuroforamen) in functional studies [12]. Limitation to one plane, usually the sagittal plane, has been another limitation of functional MR examinations. Examinations in rotation have indeed been reported [ 12 ], but they are limited to a few stages of motion. Reports on reproducibility of the examinations are lacking.

Fig. 4 Former whiplash injury of a young male volunteer with a cryptic lesion. Real time imaging (TrueFISP) detects pathological movement in anteflexion (marked). A: anteflexion. B: retroflexion. 2D-FLASH (C, D) visualized a subluxation and a anterolisthesis (red lines mark an increasing angle between the superior and inferior process of the facet joints, D). 2D-MEDIC demonstrates a lesion of the flavum ligament (E).

Fig. 5 Former whiplash injury and disc herniation. Retrolisthesis (marked) could be detected only in retroflexion (TSE).

Fig. 6 Degeneration of the left facet joint. Only in lateroflexion to the left side (A) a compression of the CSF space and the posterior radix (E, marked with red arrow) caused by a hypertrophy of the facet joint (C) could be detected. Endoscopy of the CSF (VESAS) visualized an extradural mass (marked with yellow arrows) with contact to the posterior radix (G, marked with red arrow).
TSE (A, B). 2D-MEDIC (C, D). 3D-HASTE (E), VESAS (F, G).