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Updated: Aug 18, 2026
Simultaneous Brightfield, Fluorescence, and Optical Coherence Tomographic Imaging of Contracting Cardiac Trabeculae Ex Vivo
Published on: October 2, 2021
Measuring human cardiac tissue sodium concentrations using surface coils, adiabatic excitation, and twisted
Ronald Ouwerkerk1, Robert G Weiss, Paul A Bottomley
1Division of MR Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-0845, USA. rouwerke@mri.jhu.edu
Purpose:
To measure tissue sodium concentrations in the human heart with (23)Na MRI using a surface coil, thereby eliminating the effects of inhomogeneous excitation by surface coils and minimizing T(1) and T(2) relaxation.
Materials And Methods:
We combined fully relaxed, very short-echo, (23)Na twisted projection imaging (TPI) with adiabatic half passage (AHP) excitation and external referencing on subjects and comparing with a concentration reference phantom scan to quantify TSC with surface coils. (23)Na signal losses during hard (square), composite, and tanh/tan amplitude/frequency-modulated AHP excitation pulses were analyzed over a wide range of RF field strengths and T(2short) values.
Results:
AHP excitation yielded a homogeneous excitation flip angle and negligible losses compared to a 90 degrees hard pulse wherever the B1 field exceeded the adiabatic threshold, rendering this sequence suitable for applications that use surface coil excitation. An AHP (23)Na TPI sequence was used with a surface coil at 1.5 T to noninvasively quantify myocardial TSC in 10 normal volunteers. The mean TSC was 43 +/- 4, 53 +/- 12, and 17 +/- 4 micromol/g in the left ventricular (LV) free wall, septum, and adipose tissue, respectively, consistent with prior invasive measurements on biopsy and autopsy specimens.
Conclusion:
It is now possible to noninvasively quantify TSC in the human heart with surface coil (23)Na MRI.
