Intracranial arteriovenous malformations: quantitative analysis of magnitude contrast MR angiography versus gradient-echo MR imaging versus conventional angiography.

Abstract

To quantitatively analyze magnitude contrast (MC) magnetic resonance (MR) angiography and gradient-echo (GRE) MR imaging for evaluation of persistent transnidal blood flow in intracranial arteriovenous malformations (AVMs) of various sizes before or after stereotaxic radiosurgery. Thirty-three patients with AVMs underwent 42 MC MR angiographic (maximum intensity projection [MIP] and source imaging), GRE imaging with and without flow compensation, and conventional angiographic studies within 90 days of each other. For MIP, source, and GRE images, the sensitivities for detection of large AVMs (> 1 cm) were 95%, 100%, and 100%, respectively, and for small AVMs (< or = 1 cm) were 27%, 50%, and 67%, respectively. MC MR angiography and GRE imaging depicted all eight nidi that were completely thrombosed on conventional angiograms. GRE imaging and MC MR angiography reliably depict AVMs larger than 1 cm. GRE is more sensitive for detection of small residual nidi (< 1 cm). Source images must be evaluated to accurately assess low-flow lesions. Neither GRE nor MR angiography is reliable for detection of mean nidus diameters less than 0.36 cm.