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Characterization and compensation of inhomogeneity artifact in spiral hyperpolarized 13 C imaging of the human heart

2021; Wiley; Volume: 86; Issue: 1 Linguagem: Inglês

10.1002/mrm.28691

1522-2594

Galen D. Reed, Junjie Ma, Jae Mo Park, Rolf F. Schulte, Crystal Harrison, Albert P. Chen, Salvador Peña Martín, Jeannie Baxter, Kelly Derner, Maida Tai, Jaffar Ali Raza, Jeff Liticker, Ronald G. Hall, A. Dean Sherry, Vlad G. Zaha, Craig R. Malloy,

Electron Spin Resonance Studies

Purpose This study aimed to investigate the role of regional 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 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 correction. Conclusions ‐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 artifacts, which can be partially corrected for with the proposed methods.