Embedded MR fluoroscopy: High temporal resolution real-time imaging duringhigh spatial resolution 3D MRA acquisition

A method termed "embedded fluoroscopy" for simultaneously acquiring a real- time sequence of 2D images during acquisition of a 3D image is presented. T he 2D images are formed by periodically sampling the central phase encodes of the slab-select direction during the 3D acquisition. The tradeoffs in sp atial and temporal resolution are quantified by two parameters: the "redund ancy" (R), the fraction of the 3D acquisition sampled more than once; and t he "effective temporal resolution" (T), the time between temporal updates o f the central views. The method is applied to contrast-enhanced MR angiogra phy (CE-MRA). The contrast bolus dynamics are portrayed in real time in the 2D image sequence while a high-resolution 3D image is being acquired. The capability of the 2D acquisition to measure contrast enhancement with only a 5% degradation of the spatial resolution of the 3D CE-MR angiogram is sho wn theoretically, The method is tested clinically in 15 CE-MRA patient stud ies of the carotid and renal arteries. (C) 2001 Wiley-Liss, Inc.