AJNR Am J Neuroradiol 21:1900–1907, November/December 2000 Contrast-enhanced MR Angiography of Intracranial Giant

vent adequate depiction of intracranial giant aneurysms on 3D time-of-flight (3D-TOF) MR angiography (MRA). Additional diagnostic difficulties may arise from T1 contamination arti-fact of an associated blood clot. Our aim was to assess whether contrast-enhanced MRA could improve the evaluation of giant aneurysms and to compare two different types of contrast-enhanced MRA. METHODS: We studied 11 aneurysms in 10 patients (age range, 31–77 years) with giant aneurysms of the anterior (n 5 9) and posterior (n 5 2) cerebral circulation by comparing 3D-TOF, first-pass dynamic contrast-enhanced MRA, and steady-state contrast-enhanced 3D-TOF sequences. Additional comparison with digital subtraction angiography (DSA) was per-formed in eight aneurysms. RESULTS: In nine of 11 aneurysms, 3D-TOF did not adequately show the lumen and exiting vessels. Contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA showed the aneu-rysm sac and exiting vessels in all of these cases. Dynamic contrast-enhanced MRA showed a better intravascular contrast than did contrast-enhanced 3D-TOF, which led to better delin-eation of the aneurysms. T1 contamination artifact from intra- or extraluminal blood clot wa