Publications by authors named "Jeff Liticker"

4 Publications

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Hyperpolarized C MR Spectroscopy Depicts in Vivo Effect of Exercise on Pyruvate Metabolism in Human Skeletal Muscle.

Radiology 2021 Jun 22:204500. Epub 2021 Jun 22.

From the Advanced Imaging Research Center (J.M.P., C.E.H., J.M., J.C., J.R., J.L., G.D.R., A.C., C.R.M.), Department of Radiology (J.M.P., A.C., C.R.M.), Department of Neurology and Neurotherapeutics (R.G.H.), and Department of Internal Medicine (C.R.M.), University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8568; Department of Electrical and Computer Engineering, University of Texas at Dallas, Dallas, Tex (J.M.P.); Department of Diagnostic Imaging and Radiology, Developing Brain Institute, Children's National Hospital, Washington, DC (Z.Z.); Department of Pediatrics and Radiology, George Washington University, Washington, DC (Z.Z.); GE Healthcare, Dallas, Tex (G.D.R.); Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, Calif (T.J.); and Veterans Affairs North Texas Healthcare System, Dallas, Tex (C.R.M.).

Background Pyruvate dehydrogenase (PDH) and lactate dehydrogenase are essential for adenosine triphosphate production in skeletal muscle. At the onset of exercise, oxidation of glucose and glycogen is quickly enabled by dephosphorylation of PDH. However, direct measurement of PDH flux in exercising human muscle is daunting, and the net effect of covalent modification and other control mechanisms on PDH flux has not been assessed. Purpose To demonstrate the feasibility of assessing PDH activation and changes in pyruvate metabolism in human skeletal muscle after the onset of exercise using carbon 13 (C) MRI with hyperpolarized (HP) [1-C]-pyruvate. Materials and Methods For this prospective study, sedentary adults in good general health (mean age, 42 years ± 18 [standard deviation]; six men) were recruited from August 2019 to September 2020. Subgroups of the participants were injected with HP [1-C]-pyruvate at resting, during plantar flexion exercise, or 5 minutes after exercise during recovery. In parallel, hydrogen 1 arterial spin labeling MRI was performed to estimate muscle tissue perfusion. An unpaired test was used for comparing C data among the states. Results At rest, HP [1-C]-lactate and [1-C]-alanine were detected in calf muscle, but [C]-bicarbonate was negligible. During moderate flexion-extension exercise, total HP C signals (tC) increased 2.8-fold because of increased muscle perfusion ( = .005), and HP [1-C]-lactate-to-tC ratio increased 1.7-fold ( = .04). HP [C]-bicarbonate-to-tC ratio increased 8.4-fold ( = .002) and returned to the resting level 5 minutes after exercise, whereas the lactate-to-tC ratio continued to increase to 2.3-fold as compared with resting ( = .008). Conclusion Lactate and bicarbonate production from hyperpolarized (HP) [1-carbon 13 {C}]-pyruvate in skeletal muscle rapidly reflected the onset and the termination of exercise. These results demonstrate the feasibility of imaging skeletal muscle metabolism using HP [1-C]-pyruvate MRI and the sensitivity of in vivo pyruvate metabolism to exercise states. © RSNA, 2021
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June 2021

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

Magn Reson Med 2021 07 5;86(1):157-166. Epub 2021 Feb 5.

Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.

Purpose: This study aimed to investigate the role of regional inhomogeneity in spiral hyperpolarized C image quality and to develop measures to alleviate these effects.

Methods: Field map correction of hyperpolarized 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 [ 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 [ 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.
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July 2021

Imaging Acute Metabolic Changes in Patients with Mild Traumatic Brain Injury Using Hyperpolarized [1-C]Pyruvate.

iScience 2020 Dec 30;23(12):101885. Epub 2020 Nov 30.

Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.

Traumatic brain injury (TBI) involves complex secondary injury processes following the primary injury. The secondary injury is often associated with rapid metabolic shifts and impaired brain function immediately after the initial tissue damage. Magnetic resonance spectroscopic imaging (MRSI) coupled with hyperpolarization of C-labeled substrates provides a unique opportunity to map the metabolic changes in the brain after traumatic injury in real-time without invasive procedures. In this report, we investigated two patients with acute mild TBI (Glasgow coma scale 15) but no anatomical brain injury or hemorrhage. Patients were imaged with hyperpolarized [1-C]pyruvate MRSI 1 or 6 days after head trauma. Both patients showed significantly reduced bicarbonate (HCO ) production, and one showed hyperintense lactate production at the injured sites. This study reports the feasibility of imaging altered metabolism using hyperpolarized pyruvate in patients with TBI, demonstrating the translatability and sensitivity of the technology to cerebral metabolic changes after mild TBI.
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December 2020