Characterization and compensation of f0 inhomogeneity artifact in spiral hyperpolarized (13) C imaging of the human heart.

Affiliation

Reed GD(1), Ma J(2), Park JM(2)(3)(4), Schulte RF(5), Harrison CE(2), Chen AP(6), Pena S(2), Baxter J(2), Derner K(2), Tai M(2), Raza J(7), Liticker J(2)(8), Hall RG 2nd(7), Dean Sherry A(2)(9), Zaha VG(2)(10)(11), Malloy CR(2)(3)(10)(12).
Author information:
(1)GE Healthcare, Dallas, TX, USA.
(2)Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
(3)Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
(4)Department of Electrical Engineering, University of Texas at Dallas, Richardson, TX, USA.
(5)GE Healthcare, Munich, Germany.
(6)GE Healthcare, Toronto, Canada.
(7)Department of Pharmacy Practice, Texas Tech University Health Sciences Center, Dallas, TX, USA.
(8)Astrazeneca, Dallas, TX, USA.
(9)Department of Chemistry, University of Texas at Dallas, Richardson, TX, USA.
(10)Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
(11)Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
(12)VA North Texas Health Care System, Dallas, TX, USA.

Abstract

PURPOSE: This study aimed to investigate the role of regional f0 inhomogeneity in spiral hyperpolarized 13 C image quality and to develop measures to alleviate these effects. METHODS: Field map correction of hyperpolarized 13 C cardiac imaging using spiral readouts was evaluated in healthy subjects. Spiral readouts with differing duration (26 and 45 ms) but similar resolution were compared with respect to off-resonance performance and image quality. An f0 map-based image correction based on the multifrequency interpolation (MFI) method was implemented and compared to correction using a global frequency shift alone. Estimation of an unknown frequency shift was performed by maximizing a sharpness objective based on the Sobel variance. The apparent full width half at maximum (FWHM) of the myocardial wall on [13 C]bicarbonate was used to estimate blur. RESULTS: Mean myocardial wall FWHM measurements were unchanged with the short readout pre-correction (14.1 ± 2.9 mm) and post-MFI correction (14.1 ± 3.4 mm), but significantly decreased in the long waveform (20.6 ± 6.6 mm uncorrected, 17.7 ± 7.0 corrected, P = .007). Bicarbonate signal-to-noise ratio (SNR) of the images acquired with the long waveform were increased by 1.4 ± 0.3 compared to those acquired with the short waveform (predicted 1.32). Improvement of image quality was observed for all metabolites with f0 correction. CONCLUSIONS: f0 -map correction reduced blur and recovered signal from dropouts, particularly along the posterior myocardial wall. The low image SNR of [13 C]bicarbonate can be compensated with longer duration readouts but at the expense of increased f0 artifacts, which can be partially corrected for with the proposed methods.