Flat panel catheter angiotomography of the spinal venous system: an enhanced venous phase for spinal digital subtraction angiography

Abstract

Background and purpose: While spinal DSA remains the reference standard technique for spinovascular imaging, visualizing spinal veins remains challenging due to their small size and motion artifacts. This study evaluates the ability of FPCA to overcome these obstacles.

Materials and methods: Sixty-three FPCAs, performed by intersegmental artery injections in 57 patients, were prospectively evaluated. Entrance skin doses were compared with standard spinal DSA runs, including a venous phase and cerebral FPCAs. FPCA contributions were stratified as 1) provided no added information, 2) complemented spinal DSA findings, 3) assisted therapy planning, and 4) contributed principal diagnostic findings.

Results: No complications were observed. Diagnoses included vascular malformations (44%), stroke (9%), venous anomalies (10%), other (9%), and unremarkable (28%). Mean entrance skin doses were of 419 mGy for FPCA, 161 mGy for spinal DSA with venous phase, and 309 mGy for cerebral FPCAs. FPCA contributed the principal diagnostic finding in 16 cases (25.4%), assisted therapy planning in 13 cases (20.6%), complemented spinal DSA findings in 12 cases (19.1%), and provided no additional information in 20 cases (31.7%). In 8 of these 20 cases, FPCA documented a spinal venous anatomy that was poorly visualized or not visualized on spinal DSA.

Conclusions: Spinal FPCA is safe, with a moderate increase in radiation dose, compared with spinal DSA with venous phase or cerebral FPCA. It proved particularly valuable for therapy planning and the diagnosis of venous abnormalities. This study suggests that FPCA has an important role to play in the evaluation of the spinal venous system.

Fig 1.

47-year-old woman investigated for progressive myelopathy. A, Spinal DSA, left T10 injection, arterial phase, documenting the artery of the lumbosacral enlargement (artery of Adamkiewicz). B, Spinal DSA, left T10 injection, venous phase, illustrating the typical appearance of the perimedullary venous system during spinal angiography performed under optimal conditions, that is, with a lean patient able to hold breath long enough to prevent motion artifacts. The anterior spinal venous axis is seen (arrowheads), as well as a medullary vein (short arrow) draining into the internal vertebral venous plexus (long arrow). C, FPCA, left T10 injection, sagittal MIP, voxel size = 0.4, section thickness = 1.8. The anterior and posterior perimedullary venous systems are easily differentiated. On FPCA, depending on the level of injection, overlapping may exist between arterial and venous structures related to the length of the rotational acquisition (20 seconds). D, FPCA, left T10 injection, axial MIP, voxel size = 0.1, section thickness = 4.0. The axial projection best characterizes this anastomosis, showing its course over the lateral of the spinal cord, connecting the anterior spinal vein (gray arrowhead) to a right posterior-lateral vein (white arrowhead), separate from the posterior spinal vein (black arrowhead). Because of their close topographic relationship and the thickness of the section (4.0 mm), the anterior spinal vein (gray arrowhead) and the anterior spinal artery are particularly difficult to separate in this image. The lack of dynamic information in FPCA can render the distinction between adjoining arteries and veins difficult; correct interpretation is helped by the analysis of the course and connection pattern of the vessels, the use of different reconstruction planes, or the correlation with the spinal DSA information.

Fig 2.

57-year-old man with a perimedullary arteriovenous fistula of the conus medullaris. A, MR imaging, sagittal T2-weighted image of the thoracic spine, showing diffuse spinal cord swelling and hyperintensity; B, MR imaging, sagittal T1-weighted image after gadolinium administration of the lumbar spine. Note the presence of enhancing venous structures around the conus medullaris and along the filum terminale. C, Spinal DSA, left T10 injection, anteroposterior view, early arterial phase, showing a prominent descending ramus of the anterior spinal artery (white arrowheads) reaching the level of the conus medullaris, where a small tangle of blood vessels may be seen (arrow). D, Spinal DSA, left T10 injection, anteroposterior view. In the late arterial phase, while the vascular tangle is still visible, extensive opacification of the perimedullary venous system is noted (black arrowheads). E, FPCA, left T10 injection, sagittal MIP, voxel size = 0.4, section thickness = 3.0, demonstrating the anterior spinal artery (white arrowheads) ending at the tip of the conus medullaris (L1/L2) into a Type I perimedullary arteriovenous fistula (arrow). The posterior location of the enlarged draining veins detected by spinal DSA is well documented on this sagittal reconstruction (gray arrowhead).

Fig 3.

58-year-old woman with a history of severe midscapular pain. A, MR imaging, sagittal T1-weighted images after gadolinium administration, showing prominent venous structures along the dorsal surface of the spinal cord between T8 and T12. A tangle of veins at the upper aspect of T10 was considered particularly suspicious for a vascular malformation (arrow). B, Spinal DSA, left T11 injection, anteroposterior view centered at T10/T11, arterial phase, documenting the artery of the lumbosacral enlargement (artery of Adamkiewicz). C, Spinal DSA, left T11 injection, anteroposterior view centered at T10/T11, venous phase. In this venous phase, the anterior spinal axis can be seen (arrowheads), without evidence of enlarged or abnormal veins. D, FPCA, left T11 injection, sagittal MIP, voxel size = 0.4, section thickness = 3.0, demonstrating the thoracolumbar perimedullary venous system, including the dorsal venous structures documented by MR imaging. E, FPCA, left T11 injection, coronal MIP, voxel size = 0.4, section thickness = 2.0. This coronal projection is an enlarged but otherwise unremarkable venous segment ending in a tangle of veins at the upper aspect of T10 (arrow), matching the suspicious structure seen by MR imaging (A, left). F, FPCA, left T10 injection, oblique MIP, voxel size = 0.1, section thickness = 1.0. This high-resolution reconstruction depicts the fine morphology of the right medullary vein exiting the dural sac at T10/T11. Note the narrowing of the vein as it pierces the dura (arrow) to join the internal vertebral venous plexus (epidural plexus; arrowhead).