Temperature Cycling Enables Efficient 13C SABRE-SHEATH Hyperpolarization and Imaging of [1-13C]Pyruvate

02 August 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Current metabolic imaging in humans is dominated by positron emission tomography (PET) methods. An emerging non-ionizing alternative for molecular imaging is hyperpolarized MRI. In particular, imaging of hyperpolarized 13C-pyruvate is a leading candidate because pyruvate is innocuous and has a central role in metabolism. However, simi-lar to PET, hyperpolarized MRI with dynamic nuclear polarization (DNP) is complex, costly and requires complex in-frastructure. In contrast, signal amplification by reversible exchange (SABRE) is a fast, cheap, and scalable hyperpo-larization technique. In particular, SABRE in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) transfers polarization from parahydrogen to 13C in pyruvate, however, to date, SABRE-SHEATH of 13C-pyruvate was limited in polarization levels relative to DNP (1.7% with SABRE-SHEATH vs. ~60% with DNP). Here we introduce a temperature cycling method for SABRE-SHEATH that enables >10% polarization on [1-13C]pyruvate, sufficient for successful in vivo experiments. First, at lower temperatures, ~20% polarization is accumulated on SABRE-catalyst bound pyruvate, which is subsequently released into free pyruvate in solution at elevated temperatures. We take ad-vantage of the achieved polarization to demonstrate first 13C pyruvate images with a cryogen-free MRI system operat-ed at 1 T. This illustrates that inexpensive hyperpolarization methods can be combined with low-cost MRI systems to obtain a broadly available, yet highly sensitive metabolic imaging platform.


Contrast agents

Supplementary materials

Supporting Information
Additional results, figures, and calculations as described in the main text.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.