Tissue Sodium Concentration in Myocardial Infarction in Humans: A Quantitative²³Na MR Imaging Study¹

Abstract

Purpose To prospectively determine whether the absolute tissue sodium concentration (TSC) increases in myocardial infarctions (MIs) in humans and whether TSC is related to infarct size, infarct age, ventricular dysfunction, and/or electrophysiologic inducibility of ventricular arrhythmias. Materials and Methods Delayed contrast material-enhanced 1.5-T hydrogen 1 (1H) magnetic resonance (MR) imaging was used to measure the size and location of nonacute MIs in 20 patients (18 men, two women; mean age, 63 years ± 9 [standard deviation]; age range, 48-82 years) examined at least 90 days after MI. End-systolic and end-diastolic volumes, ejection fraction, and left ventricle (LV) mass were measured with cine MR imaging. The TSC in normal, infarcted, and adjacent myocardial tissue was measured on sodium 23 (23Na) MR images coregistered with delayed contrast-enhanced 1H MR images. Programmed electric stimulation to induce monomorphic ventricular tachycardia (MVT) was used to assess arrhythmic potential, and myocardial TSC was compared between the inducible MVT and noninducible MVT patient groups. Results The mean TSC for MIs (59 μmol/g wet weight ± 10) was 30% higher than that for noninfarcted (remote) LV regions (45 μmol/g wet weight ± 5, P < .001) and that for healthy control subjects, and TSC did not correlate with infarct age or functional and morphologic indices. The mean TSC for tissue adjacent to the MI (50 μmol/g wet weight ± 6) was intermediate between that for the MI and that for remote regions. The elevated TSC measured in the MI at 23Na MR imaging lacked sufficient contrast and spatial resolution for routine visualization of MI. Cardiac TSC did not enable differentiation between patients in whom MVT was inducible and those in whom it was not. Conclusion Absolute TSC is measurable with 23Na MR imaging and is significantly elevated in human MI; however, TSC increase is not related to infarct age, infarct size, or global ventricular function. In regions adjacent to the MI, TSC is slightly increased but not to levels in the MI.

K + -dependent paradoxical membrane depolarization and Na + overload, major and reversible contributors to weakness by ion channel leaks

“…In particular, paradoxical depolarization and loss of function may arise when these tissues become leaky (e.g., because of ischemia, hypertrophy, hormones, or drugs) (28)(29)(30) or exhibit [Na ϩ ] i overload (14). Serum K ϩ values in the lower-normal range therefore should be avoided, as demonstrated by the first clinical studies in which continuous K ϩ supplementation was proven to be beneficial in hypertensive and postinfarction states (31).…”

Comparing anisotropic diffusion filters for the enhancement of sodium magnetic resonance images

“…Regarding further areas of application, sodium imaging of the human heart [34][35][36][37], brain [38][39][40][41], tumors [42] or cartilage [43] as well as other X-nuclei imaging techniques [44,45] all suffer from low resolution and low SNR and could possibly be enhanced by anisotropic diffusion filtering.…”

The Agfa Mayneord lecture: MRI of short and ultrashortT2andT2* components of tissues, fluids and materials using clinical systems

“…Sodium imaging has a long history, with the principal applications in the brain [133][134][135][136][137][138], heart [139], kidney [140,141] and musculoskeletal system [142][143][144]. Phosphorus imaging has also been performed with UTE sequences [145,146].…”