Intracranial aneurysm is ranked as the third highest pathogenic factor of stroke. Compared to DSA, CTA, and contrast enhanced MRA [1,2], TOF-MRA has the advantage of being radiation and contrast free. However, its vulnerability to system imperfection and hemodynamics may lead to signal voids in the angiograms and aneurysms, which may consequently lead to bias in the assessment of the dimensions of the lesions. In comparison, continuous arterial spin labeling based (ASL) MRA uses labeled blood as contrast bolus and places no constraint on the direction of blood flow, combining with a zero TE radial acquisition further minimizes the sensitivity to filed inhomogeneity and eddy current. In this study, we compare the use of zTE MRA to TOF in the assessment of intracranial aneurysm, using DSA as gold standard.Total of 10 patients (4 male, 6 female, mean age 55 years) diagnosed with aneurysm in DSA were enrolled in this study, consent forms were obtained prior to the scan. All the patients received both 3D TOF and zTE MRA on a whole body 3.0T scanner (GE, Discovery 750w) with the following parameters: in zTE MRA, FOV/Matrix 180mm/180, bandwidth 31.25 kHz, and flip angle 3°; in TOF MRA, TR/TE 25/3.4 ms, flip angle 15°, FOV/Matrix 220mm/320, slice thickness 1.4 mm, and bandwidth 41.67 kHz. The assessment and delineation of aneurysm (neck, sac) were performed by two experienced neuroradiologists independently. The diagnostic quality was judged using a cored on a 5-point Likert scale (1=worst, 3=sufficient for diagnosis, 5=best) for delineation, intraluminal signal homogeneity, comfort degree, and diagnostic confidence. The dimensions of the aneurysm were assessed using the long and short axis of the identified lesion regions, and the measurements made based on the MRA images were respectively correlated to those made using DSA based on Pearson analysis.There were 14 aneurysms detected by DSA in 10 patients and all the aneurysms were successfully detected (score≥3) using both TOF and zTE MRA. In comparison, the signal within aneurysm is much more homogenous in that of zTE MRA as compared to TOF MRA (Fig.1), likely attributed to the turbulent flow within the lesion. This observation was more obvious in larger lesions (an example of <3mm shown in Fig.2). The improved signal homogeneity benefited diagnostic confidence, accuracy and dimension assessment of the aneurysms. The overall diagnostic confidence in detecting intracranial aneurysms using zTE and TOF MRA were 89.7% and 85.2% respectively (P>0.05). Accuracies using zTE and TOF MRA for lesions smaller than 3mm were 85.9% and 80.2%, and those for lesions smaller than 3mm were 95.4% and 96.1% (no statistical significance). Fig.2 shows the long axis measurement of the aneurysms made using zTE and TOF MRA plotted against those made using DSA respectively. The calculated correlation coefficients were 0.95 and 0.81 for the two cases. In this work, the recently developed zTE MRA, combining continuous ASL labeling zero TE read out, was used to depict characterization of cerebral aneurysm and compared to the results using TOF MRA. For the diagnosis of aneurysm, both the qualitative depiction of the lesion and quantitative measure of their dimensions are important. In this preliminary study, it was observed that zTE MRA surpassed TOF MRA in both aspects for lesions of larger sizes, taking the results from DSA as the reference. In addition, zTE also offers other advantages such as isotropic resolution, increased spatial coverage and being completely silent. Overall, zTE has the potential of being a replacement for TOF MRA in imaging of cerebral aneurysm.