7 Tesla Chlorine (35Cl) and Sodium (23Na) MR Imaging of an Enchondroma

We demonstrated the feasibility of 7 Tesla sodium (²³Na) and chlorine (³⁵Cl) MRI of a solitary enchondroma. For this, we established dedicated sequences on a 7-Tesla whole-body system with the following key parameters for ³⁵Cl MRI: TE/TR = 0.35/60 ms, T_RO = 5 ms, α = 90°, Δx³ = (6 mm)³, 3 averages, T_acq = 30 min and for ²³Na MRI: TE/TR = 0.4/101 ms, T_RO = 10ms; α = 90°; Δx³ = (1.9 mm)³, 3 averages, T_acq = 30 min 18 s. The measured apparent Na⁺ concentration was 255 mmol/l and was approximately 7-fold higher than the apparent Cl^- concentration with about 36 mmol/l. Additionally, repeated proton MRI examinations demonstrated constant but subtle growth (≈ 0.65 ml/year) over 14 years. In conclusion, enchondromas obviously have a high contrast-to-noise ratio when compared with the normal bone marrow in ²³Na and ³⁵Cl MRI, which may contribute to detection and differentiation in unclear or subtle cases. KEY POINTS:: · High magnetic field strengths (e. g., 7 Tesla) enable sodium (23Na) and chlorine (35Cl) MRI of solitary cartilage-forming tumors like enchondromas with nominal spatial resolutions of (1.9 mm)3 (23Na MRI) and (6 mm)3 (35Cl MRI).. · Measured median tumoral apparent Na+ and Cl- concentrations were nearly 13 times higher and 3 times higher than in normal muscle tissue, respectively.. · Enchondromas have a high contrast-to-noise-ratio when compared with the normal bone marrow in 23Na and 35Cl MRI, which may contribute to detection and differentiation in unclear or subtle cases.. CITATION FORMAT: · Weber M, Seyler L, Nagel AM. 7 Tesla Chlorine (35Cl) and Sodium (23Na) MR Imaging of an Enchondroma. Fortschr Röntgenstr 2021; 193: 1207 - 1211.