High resolution MR venography technique in patients with cerebral arteriovenous malformations

Purpose. The purpose of this study was to evaluate the diagnostic potential of a high resolution MR venography technique in patients with cerebral art eriovenous malformations (AVM). A high-resolution 3D gradient echo sequence was used with a long echo time TE to obtain venous information down to sub -pixel sized vessel diameters of several hundred microns. The method is bas ed on the paramagnetic property of deoxyhemoglobin and the resulting develo ping phase difference between veins and brain parenchyma at long echo times which leads to signal cancellation. The reconstructed venograms were compa red with TOF-MR angiography using qualitative and quantitative criteria wit h the conventional DSA serving as the reference gold standard. Methods. In 17 patients with angiographically proven cerebral AVM the metho d indicates its potential in clinical applications. Venography was able to detect all AVM whereas TOF-MRA failed in three patients. In the delineation of venous drainage patterns MR venography was superior to TOF-MRA, however , as expected the method detected only about half of the main feeding arter ies. Due to susceptibility artifacts at air/tissue boundaries or interferen ce with paramagnetic hemosiderin, MR venography was limited with respect to the delineation of the exact nidus sizes and shapes in ten patients with A VM located close to the skull base or in patients having suffered from prev ious bleeding. Results. Although the visualization of draining veins represents an importa nt prerequisite in the surgical and radiosurgical treatment planning of cer ebral AVM,there exist limitations of the technique in regions where strong induced static field inhomogeneities are present. Conclusions. Due to its high sensitivity the method may be of special impor tance in the early detection and assessment of small AVM which are difficul t to diagnose with other MR methods.