Abstract
Phosphorous MR spectroscopy (31P-MRS) forms a powerful, non-invasive research tool to quantify the energetics of the heart in diverse patient populations. 31P-MRS is frequently applied alongside other radiological examinations, many of which use various contrast agents that shorten relaxation times of water in conventional proton MR, for a better characterisation of cardiac function, or following prior computed tomography (CT). It is, however, unknown whether these agents confound 31P-MRS signals, for example, 2,3-diphosphoglycerate (2,3-DPG). In this work, we quantitatively assess the impact of non-ionic, low osmolar iodinated CT contrast agent (iopamidol/Niopam), gadolinium chelates (linear gadopentetic acid dimeglumine/Magnevist and macrocyclic gadoterate meglumine/Dotarem) and superparamagnetic iron oxide nanoparticles (ferumoxytol/Feraheme) on the nuclear T1 and T2 of 31P metabolites (ie, 2,3-DPG), and 1H in water in live human blood and saline phantoms at 11.7 T. Addition of all contrast agents led to significant shortening of all relaxation times in both 1H and 31P saline phantoms. On the contrary, the T1 relaxation time of 2,3-DPG in blood was significantly shortened only by Magnevist (P = .03). Similarly, the only contrast agent that influenced the T2 relaxation times of 2,3-DPG in blood samples was ferumoxytol (P = .02). Our results show that, unlike conventional proton MR, phosphorus MRS is unconfounded in patients who have had prior CT with contrast, not all gadolinium-based contrast agents influence 31P-MRS data in vivo, and that ferumoxytol is a promising contrast agent for the reduction in 31P-MRS blood-pool signal.
Highlights
Cardiac MR (CMR) imaging is the gold-standard noninvasive technique used to diagnose heart disease
The PCr/adenosine triphosphate (ATP) ratio remains a biomarker of high interest, as it changes in most cardiac pathologies,[2,3,4,5] predicts mortality in patients with dilated cardiomyopathy,[2] and decreases even in systemic diseases, such as obesity[6] and type-II diabetes.[7]
As this effect persists for a length of time that is variable depending upon pathology, late gadolinium enhancement (LGE) scans are typically performed after all other proton (1H) CMR sequences, in order to avoid any potential confounding effects of gadolinium on the native contrast
Summary
Cardiac MR (CMR) imaging is the gold-standard noninvasive technique used to diagnose heart disease. It can quantify cardiac structure, function, viability as well as myocardial metabolism directly.[1] The latter is commonly probed by in vivo phosphorus MR spectroscopy (31P-MRS), which allows the assessment of high-energy metabolites, for example, adenosine triphosphate (ATP) and phosphocreatine (PCr). Cine imaging, providing cardiac volumes and function,[8] and late gadolinium enhancement (LGE) assessment of tissue viability[9] are the most commonly used cardiac MR methods. As the effect of gadolinium on 31P metabolites is not well characterized, as a potentially unnecessary precaution 31P-MRS data sets are acquired before LGE
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
