Fast functional MRA using time-resolved projection MR angiography with correlation analysis

Most recently, time-resolved 2D MRA after injection of a contrast agent:bol us for various applications has been proposed. Similar to conventional digi tal subtraction angiography (DSA), 2D MR DSA offers the ability to observe the dilution of the bolus in the,vascular system during the passage with a temporal resolution considerably below 1 sec. The purpose of this paper is to present strategies to improve the inherent low signal-to-noise ratio of 2D angiograms while retaining some temporal resolution. This can be achieve d by applying algorithms for time series analysis as used in functional MRI , The significantly improved image quality is demonstrated on examples from clinical studies from bronchial MRA as well as cardiovascular MRA. In addi tion to the increased signal-to-noise ratio, correlation analysis leads to suppression of background signals and to a better discrimination of overlap ping vessels. Further improvements in the temporal discrimination of vessel s is afforded by the use of consecutive multiple contrast agent boli as dem onstrated by numerical simulations and experiments. (C) 2000 Wiley-Liss, In c.