Intracranial Arteriovenous Shunting: Detection with Arterial Spin-Labeling and Susceptibility-Weighted Imaging Combined

Abstract

Background and purpose: Arterial spin-labeling and susceptibility-weighted imaging are 2 MR imaging techniques that do not require gadolinium. The study aimed to assess the accuracy of arterial spin-labeling and SWI combined for detecting intracranial arteriovenous shunting in comparison with conventional MR imaging.

Materials and methods: Ninety-two consecutive patients with a known (n = 24) or suspected arteriovenous shunting (n = 68) underwent digital subtraction angiography and brain MR imaging, including arterial spin-labeling/SWI and conventional angiographic MR imaging (3D TOF, 4D time-resolved, and 3D contrast-enhanced MRA). Arterial spin-labeling/SWI and conventional MR imaging were reviewed separately in a randomized order by 2 blinded radiologists who judged the presence or absence of arteriovenous shunting. The accuracy of arterial spin-labeling/SWI for the detection of arteriovenous shunting was calculated by using the area under receiver operating curve with DSA as reference standard. κ coefficients were computed to determine interobserver and intermodality agreement.

Results: Of the 92 patients, DSA showed arteriovenous shunting in 63 (arteriovenous malformation in 53 and dural arteriovenous fistula in 10). Interobserver agreement was excellent (κ =0.83-0.95). In 5 patients, arterial spin-labeling/SWI correctly detected arteriovenous shunting, while the conventional angiographic MR imaging did not. Compared with conventional MR imaging, arterial spin-labeling/SWI was significantly more sensitive (0.98 versus 0.90, P = .04) and equally specific (0.97) and showed significantly higher agreement with DSA (κ = 0.95 versus 0.84, P = .01) and higher area under the receiver operating curve (0.97 versus 0.93, P = .02).

Conclusions: Our study showed that the combined use of arterial spin-labeling and SWI may be an alternative to contrast-enhanced MRA for the detection of intracranial arteriovenous shunting.

Fig 1.

Flow chart illustrating patient selection.

Fig 2.

Patient 62 with a complex developmental venous anomaly. ASL raw data (A) and right internal carotid artery angiogram, venous phase, lateral view (B). Increased signal-intensity is visible on ASL images within the right frontal lobe and deep brain nuclei (A, arrows). ASL images were considered suggestive of AVS by 1 blinded reader. Developmental venous anomaly was correctly diagnosed (and thus absence of AVS) by using SWI and a combination of SWI and ASL (not shown). DSA confirms the diagnosis of developmental venous anomaly by revealing a classic umbrella-shaped aspect at the venous phase with medullary veins (B, arrowheads) draining into an enlarged collector (B, arrows), which further drains into the superficial Sylvian vein and cavernous sinus.

Fig 3.

A 60-year-old patient with a right paracentral AVM. ASL raw data (A) demonstrates a strong hypersignal at the anterior part of the right paracentral region (A, arrow). The slight venous hypersignal related to AVS was initially missed by the blinded readers by using SWI alone (B, arrowhead) but was correctly identified by using ASL and SWI combined (C, ASL/SWI merged image, arrow). Findings of time-resolved 4D contrast-enhanced MRA (D) were considered negative by the blinded readers. DSA reveals a small pial AVM in the right paracentral region (E, arrow).

Fig 4.

A 52-year-old patient with a right cerebellar AVM draining into the right transverse sinus and the right periclival plexus. ASL raw data demonstrate a strong hypersignal within the right periclival plexus (A, arrows) and the right lateral sinus (B, arrowhead). With SWI alone, the slight venous hypersignal within the right periclival plexus and related to AVS was initially missed by the blinded readers (C, arrowhead) but correctly identified by using ASL and SWI combined (D, ASL/SWI merged image, arrow). Findings of time-resolved and high-resolution contrast-enhanced MRA were negative. Anteroposterior (E) and lateral (F) views from the right vertebral conventional angiograms show a small nidus (E, long arrow) draining into the right lateral sinus through the right superior petrosal sinus (E and F, arrowheads) and into the periclival plexus through a lateropontine vein (E and F, arrow).

Fig 5.

Patient 26 with a previously treated AVM and residual AVS according to DSA. SWI (A) and left internal carotid artery angiogram, arterial phase, lateral view (B). An increased signal intensity is visible with SWI within a deep vein adjacent to the treated nidus (A, arrows), suggestive of AVS. Of note, findings of ASL and contrast-enhanced MR images were considered negative (not shown). DSA confirms the presence of dysplastic vessels around the cast of the embolic agent (B, arrows) and an early opacification of venous drainage (B, arrowheads) coursing toward the deep venous system at the anterior and inferior pole of the embolized AVM.