A comparison of angiographic CT and multisection CT in lumbar myelographic imaging

Abstract

Background and purpose: The purpose of this work was to provide an intraindividual comparison of angiographic CT (ACT) and multisection CT (MSCT) in lumbar myelographic imaging and to evaluate possible benefits of ACT, which is a further development of rotational angiography providing image data of high spatial and CT-like contrast resolution.

Materials and methods: In 26 patients with degenerative lumbar spine disease a lumbar ACT was performed in combination with conventional lumbar myelography and followed by postmyelographic MSCT. Conventional lumbar myelography and lumbar ACT were performed with a flat panel detector-equipped angiographic device. Postmyelographic MSCT was performed with a 16-section CT scanner. Three experienced neuroradiologists rated anonymized sets of multiplanar reformatted CT and ACT images regarding diagnostic and technical parameters. The ratings were repeated after 2 months. Weighted kappa statistics were calculated to describe the levels of intraobserver and interobserver agreement.

Results: The analysis shows that MSCT achieves higher ratings than ACT in all of the parameters asked. An adequate diagnostic quality was only assigned to 80% of the ACT acquisitions compared with 97% of the MSCT acquisitions. All of the mean kappa values were above 0.60, demonstrating a substantial intraobserver and interobserver agreement for MSCT, as well as for ACT.

Conclusion: Using ACT, radiographic myelography and myelographic CT can be performed at the same imaging system. However, the results of our study show that the current myelographic ACT image quality fails to apply diagnostic standards. We, therefore, cannot recommend ACT as a general alternative to postmyelographic MSCT.

Fig 1.

Images from a 58-year-old woman with persistent back pain. The left lateromedial prolapsed intervertebral disk in the segment L2/3 is equally well visible in both ACT (A and C) and MSCT (B and D) images. ACT images in the left posterior oblique position are displayed as 3D-MIP (E) and 3D-VRT (F). G, The myelographic projection was derived by transferring the position of the 3D volume from the workstation to the C-arm. Hence, no additional fluoroscopy was necessary to determine the optimal angles for projection myelographies.

Fig 2.

Images from a 62-year-old man with symptoms of spinal claudication. Coronal MPR planes of ACT (A) and MSCT (B) are of equal quality. C, A curved coronal reconstruction of the ACT provides an appropriate depiction of the segmental nerve roots.

Fig 3.

MPR images from a 75-year-old woman with persistent back pain after multisegmental laminectomy. In the sagittal sections (A, ACT; B, MSCT), the relevant degenerative changes can be depicted equally well: ligamental hyperplasia in the segment L1/2, ventral osteochondrosis in the segment L2/3, and the slight listhesis in the segment L4/5. A, Note the loss of detail and the enhanced image noise in the ACT section at the level from L5 to S2 due to the high attenuation of contrast media in the thecal sac. The transverse sections through the vertebral body of L4 (C, ACT; D, MSCT) show the hypertrophic facet joints and the thecal sac herniating into the laminectomy site. Both techniques show a well-defined L4 nerve root of the right side and an increase of tissue around the L4 nerve root of the contralateral side.