Identification of Venous Signal on Arterial Spin Labeling Improves Diagnosis of Dural Arteriovenous Fistulas and Small Arteriovenous Malformations

Patient 5. A 25-year-old man with sudden onset of headache while weightlifting, followed by confusion and loss of consciousness. A, Axial noncontrast CT scan shows a large right frontal hematoma with significant edema, mass effect, and brain herniation. The patient was immediately taken to the operating room for right frontal craniotomy decompression. B, Postdecompression time-of-flight MRA findings are normal, without MR imaging evidence of AVM or DAVF. C, Axial ASL image shows focal high signal intensity at the medial right frontal lobe (white arrow), concerning for the presence of a shunt lesion. Initial angiogram (not shown) obtained on the same day as the MR imaging study failed to demonstrate the presence of an AVM, likely due to edema and mass effect. D, Repeat angiogram after 4 weeks shows a small (<1 cm) right frontal lobe AVM (black arrow). The feeding vessel is the right anterior choroidal artery, with deep venous drainage into the right internal cerebral vein.

Patient 2. A 76-year-old man presenting with worsening headache and vomiting. A, Axial gradient recalled-echo MR image shows a left cerebellar hemorrhage. B, MRA does not reveal an obvious vascular lesion. C, ASL image shows high signal intensity within the venous confluence (white arrow) and left internal jugular vein (white arrowhead), suspicious for a shunt lesion. D, Frontal DSA confirms a small AVM, fed by a small branch of the left vertebral artery; venous drainage is to the venous confluence, left transverse sinus, and left internal jugular vein.

Histograms of pooled scores of the 3 readers regarding the likelihood of DAVF/AVM (1 = very unlikely, 2 = unlikely, 3 = neutral, 4 = likely, 5 = very likely) before and after reviewing the ASL images, for cases with both negative and positive findings on DSA. Note that the distribution before reviewing ASL was skewed toward the correct diagnosis, but this effect was magnified following ASL review. In particular, the number of cases deemed “neutral” (score of 3) markedly decreased following review of ASL, suggesting that the readers had higher confidence in their decisions post-ASL.

ROC curves for the pooled and individual readers pre- and postreview of the ASL images. The increase in the AUC was significant (P = .02). The post-ASL curve is a more well-rounded predictor and indicates that the readers' sensitivity for identifying a vascular malformation has increased after reviewing the ASL images. Reader 1 is a neurologist; readers 2 and 3 are neuroradiologists.