CT angiography and MR angiography in the evaluation of carotid cavernous sinus fistula prior to embolization: a comparison of techniques

Abstract

Background and purpose: This study compared CT angiography (CTA), MR angiography (MRA), and digital subtraction angiography (DSA) in elucidating the size and location of carotid cavernous sinus fistulas (CCFs) before embolization treatment.

Methods: This was a retrospective study of 53 patients with angiographically confirmed CCF. All patients underwent pre- and postcontrast-enhanced CTA and DSA, and 50 patients also underwent MRA. Two neuroradiologists rated detectability of the fistula tract as "good," "moderate," or "poor" in source images obtained by using each procedure. The chi(2) test was used to compare the imaging modalities with respect to their ability to detect fistulas.

Results: CTA did not differ significantly from DSA (P = .155), and both CTA (P = .001) and DSA (P = .007) performed significantly better than MRA in the population as a whole. Differences in performance among the methods, however, depended upon the segmental location of the fistula along the internal carotid artery (ICA). CTA and MRA were similar in detection of CCFs in patients with a fistula at segment 3. CTA significantly outperformed MRA in patients with a fistula at segment 4, who accounted for approximately half of the population.

Conclusions: CTA source imaging has proved itself as useful as DSA for detecting CCFs. Of the 2 noninvasive techniques, CTA performed better than MRA in the population as a whole and in most patients whose fistula was located at segment 4 or 5 of the ICA.

Fig 1.

Segmental division of the cavernous carotid artery (after Debrun et al [10]).

Fig 2.

Detectability of CCFs by location according to segmental division (SD) of the ICA, by using each technique. Panels A, B, and C show results for CTA, MRA, and DSA, respectively. Bars indicate percentage of images having detectability ratings of poor (hatched), moderate (stippled), or good (open). P values indicate statistical significance for comparisons between locations by using the χ² test, for each technique.

Fig 3.

Detectability of CCFs by using CTA, MRA, and DSA, by location according to segmental division (SD) of the ICA. Panels A, B, and C show results for fistulas found at SD 3, SD 4, and SD 5, respectively. Bars indicate percentage of images having detectability ratings of poor (hatched), moderate (stippled) or good (open). P values indicate statistical significance for comparisons between modalities by using the χ² test, for each location.

Fig 4.

SD 3, DSA = CTA > MRA. Left CCF with left SOV drainage. Images were made by using CTA (panels A–C), MRA (panels D–F), and vertebral DSA (posterior-anterior view in panel H, lateral view in panel I) before embolization. The fistula ostium (panels B and E), proximal portion (panels A and D), and distal portion (panels C and F) are shown. A CTA source image made following embolization (panel G) shows the detachable balloon located at the previous fistula site. CS, cavernous sinus; DB, detachable balloon; F, fistula tract; SD, segmental division of the ICA.

Fig 5.

SD 3, DSA = CTA = MRA. Right CCF with transection of ICA. Images were made by using CTA (panels A–C), MRA (panels D–F), and carotid DSA (lateral view, panel H) before embolization. The fistula ostium (panels B and E), proximal portion (panels A and D) and distal portion (panels C and F) are shown. Panel G shows an image made by using MIP reconstruction MRA. CS, cavernous sinus; F, fistula tract; MIP, maximal intensity projection; SD, segmental division of the ICA.