Feasibility of 39-potassium MR imaging of a human brain at 9.4 Tesla

Abstract

Purpose: To demonstrate the feasibility of performing 39-potassium MR imaging of a human brain. Methods: 39-Potassium magnetic resonance imaging of a human brain was performed at 9.4 T using a flexible twisted projection imaging acquisition with a nominal isotropic spatial resolution of 10 mm in 40 min using a single-tuned birdcage radiofrequency coil. Co-registered sodium imaging with a nominal isotropic spatial resolution of 3.5 mm was performed on the same subject in 10 min. Results: The 39-potassium flexible twisted projection imaging imaging had a signal-to-noise ratio of 5.2 in brain paranchyma. This qualitative imaging showed the expected features when compared to co-registered high-and low-resolution sodium imaging of the same subject. Conclusion: Potassium MR images may offer complementary information to that of sodium MR images by sampling the intracellular rather that interstitial environment. Quantification will require additional improvement in signal-to-noise ratio to produce clinically useful bioscales as are developing for sodium MR imaging.

X‐nuclei imaging: Current state, technical challenges, and future directions

“…, respectively. State‐of‐the‐art coils for 35 Cl, 17 O, and 39 K imaging are transmit‐and‐receive birdcage coils.…”

“…Three decades after the first in vivo 23 Na images, the first 39 K and 35 Cl MR images in humans were shown . Compared with 39 K and 35 Cl MRI, the first in vivo 17 O image was published earlier .…”

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).…”

Toward 20 T magnetic resonance for human brain studies: opportunities for discovery and neuroscience rationale

“…Quantification of the ion concentrations has the potential to map ion gradients between different compartments of the brain. Sodium imaging [77–81], potassium imaging [82, 83], and chloride imaging [84] have been accomplished in the human brain at 7 T and 9.4 T. However, to exploit multiple quantum imaging methods to determine the separate concentrations of these ions in the intra- and extracellular compartments, the sensitivity must increase substantially. A field increase from 7 to 20 T can realize an increase in SNR of 6 that reflects a 36-fold decrease in acquisition time based on the theoretical prediction of the 7/4 power-dependence of field strength [43].…”