23Na Distribution at 7T in a Patient with Transmural Myocardial Infarction

Description of Clinical Presentation: A 57-year-old female patient was admitted after an episode of severe chest pain, with an initial diagnosis of acute coronary syndrome. Invasive coronary angiography demonstrated coronary occlusion, and subsequent 1.5T cardiac MRI revealed transmural late gadolinium enhancement in the lateral wall of the left ventricle, consistent with myocardial fibrosis.

Diagnostic Techniques and Their Most Important Findings: As part of a research protocol, 7T cardiac MRI was performed using a dual-tuned (1H/23Na) coil and a dedicated protocol (Table 1). This approach enabled the acquisition of both proton and sodium images (Figure 1). Focal 23Na accumulation was identified in the lateral wall, corresponding to the fibrotic area previously detected by 1.5T CMR. The increased sodium signal is linked to cell death and extracellular remodeling after infarction. Despite technical limitations such as field inhomogeneity and restricted spatial resolution, the ultra-high field strength provided sufficient SNR gain to enable myocardial sodium detection.

Learning Points from this Case: Learning Points from this Case

This case emphasizes the potential of 23Na imaging at 7T as a viable alternative to gadolinium for the detection of myocardial fibrosis. The spatial concordance between sodium accumulation and fibrosis detected by late gadolinium enhancement suggests that 23Na may serve as a surrogate biomarker, especially valuable for patients with contraindications to contrast agents. Although still confined to research settings and facing technical challenges, ultra-high field sodium MRI holds promise for advanced myocardial tissue

Summary configuration of the protocol for 23Na cardiac MRI acquisition at 7T.

Sequence	TR (ms)	TE (ms)	Pulse Sequence	Trigger	Slice Thickness	Flip Angle	SNR	Acquisition Time
Sodium	37	1,36	GRE	Retrospective gating	8 mm	112°	1	8.14 min

Images acquired at 7 Tesla. On the left, proton (¹H) images; on the right, sodium (²³Na) distribution maps.(A1) Right and left ventricles.(B1) Interventricular septum.(C1) Left ventricle.(A2) Right and left ventricles.(B2) Interventricular septum.(C2) Left ventricle.
(A) Late gadolinium enhancement sequence at 1.5T showing transmural fibrosis in the lateral wall. (B) Sodium distribution map acquired at 7T, demonstrating focal 23Na accumulation in the corresponding region. (C) Signal intensity curve from the fibrotic area, illustrating increased gadolinium uptake. (D) Reproduced pattern of sodium accumulation in the same region, with concordant hyperintense signal. (E) Signal curve from normal septal myocardium, representing reference tissue pattern. (F) Sodium distribution in the septal region, showing a consistent normal pattern, similar to that observed in conventional tissue characterization.