Mapping and correcting hyperpolarized magnetization decay with radial keyhole imaging.

Journal Article (Journal Article)


Hyperpolarized (HP) media enable biomedical imaging applications that cannot be achieved with conventional MRI contrast agents. Unfortunately, quantifying HP images is challenging, because relaxation and radio-frequency pulsing generate spatially varying signal decay during acquisition. We demonstrate that, by combining center-out k-space sampling with postacquisition keyhole reconstruction, voxel-by-voxel maps of regional HP magnetization decay can be generated with no additional data collection.

Theory and methods

Digital phantom, HP 129 Xe phantom, and in vivo 129 Xe human (N = 4 healthy; N = 2 with cystic fibrosis) imaging was performed using radial sampling. Datasets were reconstructed using a postacquisition keyhole approach in which 2 temporally resolved images were created and used to generate maps of regional magnetization decay following a simple analytical model.


Mean, keyhole-derived decay terms showed excellent agreement with the decay used in simulations (R2 = 0.996) and with global attenuation terms in HP 129 Xe phantom imaging (R2 > 0.97). Mean regional decay from in vivo imaging agreed well with global decay values and displayed spatial heterogeneity that matched expected variations in flip angle and oxygen partial pressure. Moreover, these maps could be used to correct variable signal decay across the image volume.


We have demonstrated that center-out trajectories combined with keyhole reconstruction can be used to map regional HP signal decay and to quantitatively correct images. This approach may be used to improve the accuracy of quantitative measures obtained from hyperpolarized media. Although validated with gaseous HP 129 Xe in this work, this technique can be generalized to any hyperpolarized agent.

Full Text

Duke Authors

Cited Authors

  • Niedbalski, PJ; Willmering, MM; Robertson, SH; Freeman, MS; Loew, W; Giaquinto, RO; Ireland, C; Pratt, RG; Dumoulin, CL; Woods, JC; Cleveland, ZI

Published Date

  • July 2019

Published In

Volume / Issue

  • 82 / 1

Start / End Page

  • 367 - 376

PubMed ID

  • 30847967

Pubmed Central ID

  • PMC6491256

Electronic International Standard Serial Number (EISSN)

  • 1522-2594

International Standard Serial Number (ISSN)

  • 0740-3194

Digital Object Identifier (DOI)

  • 10.1002/mrm.27721


  • eng