Exploiting sparsity to accelerate noncontrast MR angiography in the context of parallel imaging

Pippa Storey, Ricardo Otazo, Ruth P. Lim, Sooah Kim, Lazar Fleysher, Niels Oesingmann, Vivian S. Lee, Daniel K. Sodickson

Research output: Contribution to journalArticlepeer-review


Noncontrast techniques for peripheral MR angiography are receiving renewed interest because of safety concerns about the use of gadolinium in patients with renal insufficiency. One class of techniques involves subtraction of dark-blood images acquired during fast systolic flow from bright-blood images obtained during slow diastolic flow. The goal of this work was to determine whether the inherent sparsity of the difference images could be exploited to achieve greater acceleration without loss of image quality in the context of generalized autocalibrating partially parallel acquisition (GRAPPA). It is shown that noise amplification at high acceleration factors can be reduced by performing subtraction on the raw data, before calculation of the GRAPPA weights, rather than on the final magnitude images. Use of the difference data to calculate the GRAPPA weights decreases the geometry factor (g-factor), because the difference data represent a sparse image set. This demonstrates an inherent property of GRAPPA and does not require the use of compressed sensing. Application of this approach to highly accelerated data from healthy volunteers resulted in similar depiction of large arteries to that obtained with low acceleration and standard reconstruction. However, visualization of very small vessels and arterial branches was compromised.

Original languageEnglish (US)
Pages (from-to)1391-1400
Number of pages10
JournalMagnetic resonance in medicine
Issue number5
StatePublished - May 2012


  • noncontrast MR angiography
  • parallel imaging
  • sparsity

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


Dive into the research topics of 'Exploiting sparsity to accelerate noncontrast MR angiography in the context of parallel imaging'. Together they form a unique fingerprint.

Cite this