Spin‐labeling angiography of the carotids by presaturation and simplified adiabatic inversion

Abstract

A new adiabatic inversion pulse is tested for a spin-labeling subtraction angiography method. Adiabatic nature of the pulse is achieved by ramping the gradient during the RF pulse. In addition, with cardiac triggering, any irregularity of the heartbeat would decrease cancellation of the static tissue after subtraction. A 90 degree presaturation pulse applied to prevent this suppresses the background intensity from the static tissue by a factor greater than 2. Slice angiograms of carotid arteries are presented.

Fast projective carotid MR angiography using arterial spin‐labeled balanced SSFP

“…The presented MRA technique is a pulsed ASL (pulsed ASL) method that interleaves the acquisition of two image sets and uses signal subtraction to generate an angiogram, in a manner analogous to the signal targeting with alternating radiofrequency (STAR) method (8,9,14). The two image sets are similar except that one image set is acquired after application of a 180°adia-batic RF pulse (Fig.…”

“…The adiabatic labeling pulse was of the hyperbolic-secant shape ( ϭ 4, ␤ ϭ 372 s -1 ) (15) and was applied over a 30-cm-thick region upstream of the carotid artery to label inflowing arterial spins. On both image sets, a 90°saturation RF pulse was applied over the imaging slice to suppress background signal (8). Imaging was performed using a bSSFP sequence preceded with a linear flip angle preparation (16).…”

“…Although projective methods for angiography do not allow for retrospective review of vascular morphology along arbitrary views, as allowed with the aforementioned MRA methods, they may allow for fast depiction of long portions of the carotid vessels. Previous studies have reported that projective MRA of the carotid arteries can be performed with arterial spin-labeling (ASL) methods using thick two-dimensional slices (7)(8)(9). These encouraging studies, however, were performed years ago on MR systems that were far less capable than current MR systems, as the imaging scans took several minutes to complete and were prone to artifacts.…”

2121 spin-labeled projection MR angiography of the carotid arteries

“…The imaging method is similar to that described by Sardashti [2] and Edelman [3] and consists of acquiring two images sets that, upon conclusion of the scan, are subtracted. The first image set is acquired after blood upstream of the imaging volume is tagged by an RF pulse, while the second image set is acquired without application of a tagging RF pulse.…”

The Role of 3 Tesla MRA in the Detection of Intracranial Aneurysms

“…Time-of-flight (TOF) MRA sequences provide optimal vascular contrast [36, 37]. Dixon et al initially used a method that selectively targeted common carotid artery inflow at the carotid bifurcation, with suppression of the stationary tissue using low amplitude gradient pulses [37].…”