Initial experience with helical CT and 3D reconstruction in therapeutic planning of cerebral AVMs: comparison with 3D time-of-flight MRA and digital subtraction angiography.

PURPOSE

We report our initial experience with helical CT and CT angiography (CTA) in evaluating cerebral arteriovenous malformations (AVMs) in comparison with time-of-flight MR angiography (MRA) and digital subtraction angiography (DSA).

METHOD

Twelve AVMs were studied with CTA, non-gadolinium-enhanced MRA, and DSA. Reconstructed images were obtained in three display methods (maximum intensity projection, shaded surface black and white, shaded surface color). Shaded surface color display was obtained by assigning different colors to vessels and "presumed" nidus. The number of feeding arteries and draining veins associated with each AVM was independently counted in each modality. The relative ease of depicting the nidus and vessels was also determined in each display method. AVM nidus dimensions were measured on CTA and MRA source images and interobserver differences were compared.

RESULTS

CTA-reconstructed images depicted more veins but fewer arteries than MRA. Shaded-surface color displays best delineated vessels and nidus. Nidus dimension measurement was possible on CTA in all AVMs but impossible on MRA in four AVMs due to interference by methemoglobin (three AVMs) and phase artifact (one AVM). The interobserver difference in nidus dimension as measured on CTA was significantly smaller than that on MRA.

CONCLUSION

Reconstructed CTA images and CTA source images seem to be valuable adjuncts or alternatives to MRA.