Sodium MRI of the human heart at 7.0 T: preliminary results

Abstract

The objective of this work was to examine the feasibility of three-dimensional (3D) and whole heart coverage (23)Na cardiac MRI at 7.0 T including single-cardiac-phase and cinematic (cine) regimes. A four-channel transceiver RF coil array tailored for (23)Na MRI of the heart at 7.0 T (f = 78.5 MHz) is proposed. An integrated bow-tie antenna building block is used for (1)H MR to support shimming, localization and planning in a clinical workflow. Signal absorption rate simulations and assessment of RF power deposition were performed to meet the RF safety requirements. (23) Na cardiac MR was conducted in an in vivo feasibility study. 3D gradient echo (GRE) imaging in conjunction with Cartesian phase encoding (total acquisition time T(AQ) = 6 min 16 s) and whole heart coverage imaging employing a density-adapted 3D radial acquisition technique (T(AQ) = 18 min 20 s) were used. For 3D GRE-based (23)Na MRI, acquisition of standard views of the heart using a nominal in-plane resolution of (5.0 × 5.0) mm(2) and a slice thickness of 15 mm were feasible. For whole heart coverage 3D density-adapted radial (23)Na acquisitions a nominal isotropic spatial resolution of 6 mm was accomplished. This improvement versus 3D conventional GRE acquisitions reduced partial volume effects along the slice direction and enabled retrospective image reconstruction of standard or arbitrary views of the heart. Sodium cine imaging capabilities were achieved with the proposed RF coil configuration in conjunction with 3D radial acquisitions and cardiac gating. Cardiac-gated reconstruction provided an enhancement in blood-myocardium contrast of 20% versus the same data reconstructed without cardiac gating. The proposed transceiver array enables (23)Na MR of the human heart at 7.0 T within clinical acceptable scan times. This capability is in positive alignment with the needs of explorations that are designed to examine the potential of (23)Na MRI for the assessment of cardiovascular and metabolic diseases.

Cardiorenal sodium MRI at 7.0 Tesla using a 4/4 channel 1H/23Na radiofrequency antenna array

“…The 4/4 channel 1 H/ 23 Na RF antenna array implemented in our work affords cardiorenal MRI and supports the study of the heart–kidney interdependence. Our work builds on the first report on 23 Na MRI of the heart at 7.0 T, which employed a 4‐element RF antenna array in conjunction with a single 1 H dipole bow‐tie element . This approach severely limited anatomic coverage for 1 H MRI and was not suited for renal MRI.…”

“…In this renal imaging study, a 6‐channel transmit–receive sodium array tailored for spine‐imaging was used . For 23 Na MRI of the heart at 7.0 T, a 4‐element RF antenna array was previously developed . This early cardiac configuration was retrofitted with a single proton ( 1 H) dipole bow‐tie element, which severely limited anatomic coverage and transmission uniformity.…”

Agreement Between 24-Hour Salt Ingestion and Sodium Excretion in a Controlled Environment

“…Alternative approaches, such as direct non-invasive measurements of tissue sodium content in humans may provide more concise information on the relationship between salt and health. 25–28, 31, 32 Effective and conclusive intervention studies may require particularly unique environmental situations, 33 or nationwide “prescribed” salt reduction in processed foods. 29 Should an intervention study be entertained to test the notion that salt reduction lowers hard endpoints, the long-term physiological regulatory patterns of sodium balance could be carefully considered in the design of such an intervention.…”

Electrodynamics and radiofrequency antenna concepts for human magnetic resonance at 23.5 T (1 GHz) and beyond

“…Some of the benefits are already clear: we have already seen progress in remotely probing local concentrations of fluorine, sodium, potassium and chlorine in human tissues (9)(10)(11)(12)(13)(14), in assessing bioenergetic conditions (15)(16)(17) and oxygen consumption (18) in vivo along with the advances in 9.4 T human MR (15,(19)(20)(21)(22)(23)(24). Pioneering reports on MR physics, radiofrequency (RF) power deposition considerations and novel RF antenna designs (25,26) spurred the installation of a 10.5 T whole-body MR system at the Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, USA (27).…”