Improved SNR efficiency in gradient echo coronary MRA with high temporal resolution using parallel imaging

Abstract

Contemporary coronary magnetic resonance angiography techniques suffer from signal-to-noise ratio (SNR) constraints. We propose a method to enhance SNR in gradient echo coronary magnetic resonance angiography by using sensitivity encoding (SENSE). While the use of sensitivity encoding to improve SNR seems counterintuitive, it can be exploited by reducing the number of radiofrequency excitations during the acquisition window while lowering the signal readout bandwidth, therefore improving the radiofrequency receive to radiofrequency transmit duty cycle. Under certain conditions, this leads to improved SNR. The use of sensitivity encoding for improved SNR in three-dimensional coronary magnetic resonance angiography is investigated using numerical simulations and an in vitro and an in vivo study. A maximum 55% SNR enhancement for coronary magnetic resonance angiography was found both in vitro and in vivo, which is well consistent with the numerical simulations. This method is most suitable for spoiled gradient echo coronary magnetic resonance angiography in which a high temporal and spatial resolution is required. Magn Reson Med 62:1211-1220, 2009.

Practical signal‐to‐noise ratio quantification for sensitivity encoding: Application to coronary MR angiography

“…One may notice that SNR obtained with a SENSE acceleration factor of 2 is higher than that with factor of 1 for both cardiac and skeletal muscles. As previously reported, this is attributable to a longer TR, a lower receiver bandwidth and an improved RF transmit to receive duty cycle used in the sequence with a SENSE acceleration factor of 2 (26,32). …”

“…Coronary MRA data obtained in ten healthy adult subjects (26) were analyzed. The study protocol was approved by our Institutional Review Board and all subjects gave written informed consent to participate.…”

MRI and CT in the diagnosis of coronary artery disease: indications and applications

“…The latter allows for either the improvement of spatial resolution or the reduction of imaging time with the use of higher acceleration factors (e.g. applying parallel imaging techniques) [76]. Yang et al [77] recently were able to demonstrate a sensitivity of 93% and a specificity of 89% for >50% stenosis on a per-vessel basis, and 94% and 82%, respectively, on a per-patient basis.…”

Cardiovascular PET/MR: Potential Role and Challenges

“…However, whole-heart coverage (to mimic CT angiography) still requires relatively long acquisition times (~ 15 min), so further refinements in are needed. (7,8) Beyond development of new acquisition protocols, other challenges must be overcome. Currently, N-13 ammonia is the only PET perfusion radiopharmaceutical that can be used clinically since the Rubidium-82 infusion system is not MR compatible.…”