In:
Journal of Magnetic Resonance Imaging, Wiley, Vol. 36, No. 6 ( 2012-12), p. 1273-1286
Abstract:
The introduction of digital subtraction angiography (DSA) in 1980 provided a method for real time 2D subtraction imaging. Later, 4D magnetic resonance (MR) angiography emerged beginning with techniques like Keyhole and time‐resolved imaging of contrast kinetics (TRICKS) that provided frame rates of one every 5 seconds with limited spatial resolution. Undersampled radial acquisition was subsequently developed. The 3D vastly undersampled isotropic projection (VIPR) technique allowed undersampling factors of 30–40. Its combination with phase contrast displays time‐resolved flow dynamics within the cardiac cycle and has enabled the measurement of pressure gradients in small vessels. Meanwhile similar accelerations were achieved using Cartesian acquisition with projection reconstruction (CAPR), a Cartesian acquisition with 2D parallel imaging. Further acceleration is provided by constrained reconstruction techniques such as highly constrained back‐projection reconstruction (HYPR) and its derivatives, which permit acceleration factors approaching 1000. Hybrid MRA combines a separate phase contrast, time‐of flight, or contrast‐enhanced acquisition to constrain the reconstruction of contrast‐enhanced time frames providing exceptional spatial and temporal resolution and signal‐to‐noise ratio (SNR). This can be extended to x‐ray imaging where a 3D DSA examination can be used to constrain the reconstruction of time‐resolved 3D volumes. Each 4D DSA (time‐resolved 3D DSA) frame provides spatial resolution and SNR comparable to 3D DSA, thus removing a major limitation of intravenous DSA. Similar techniques have provided the ability to do 4D fluoroscopy. J. Magn. Reson. Imaging 2012; 36:1273–1286. © 2012 Wiley Periodicals, Inc.
Type of Medium:
Online Resource
ISSN:
1053-1807
,
1522-2586
Language:
English
Publisher:
Wiley
Publication Date:
2012
detail.hit.zdb_id:
1497154-9
Permalink