Vascular intracranial lesions: applications of gradient-echo MR imaging

To investigate the role of the gradient-echo (GRE) technique in clinical intracranial magnetic resonance (MR) imaging, 63 patients with a variety of vascular intracranial lesions were examined at 1.5 T with the use of spin-echo (SE) and GRE sequences. In all cases, the sequential section acquisition technique called gradient recalled acquisition in the steady state (GRASS) was employed; a repetition time of 150-200 msec, an echo time of 13-16 msec, and a flip angle of 50 degrees-60 degrees were used to optimize the depiction of blood flow as high intensity and the depiction of stationary fluid as low intensity. In 61 of 63 cases, gradient moment nulling was utilized to compensate for first-order flow effects. Although GRE images rapidly demonstrated flow in vascular intracranial lesions as high intensity, the vascular nature of these lesions was also clearly evident on SE images in most cases. In some cases, GRE images can be used to clarify the vascular nature of a lesion or to characterize a neoplasm. Other applications include the detection of vascular thrombosis, occult vascular malformations, and hemorrhagic complications of vascular lesions.