31P-MR spectroscopy of the brain in patients with anorexia nervosa: characteristic differences in the spectra between patients and healthy control subjects

Purpose: To investigate whether 31P-MR spectroscopy can detect reduced concentrations of high-energy phosphates, like PCr and NTP, caused by decreased metabolic activity in the brain of patients with anorexia nervosa (AN) and, furthermore, whether any impairment of the cerebral membrane metabolism can be derived from the spectra. Material and Methods: 10 female patients, age range 12 - 20 years and mean BMI (body mass index) of 14.8 ± 1.6 kg/m2, with clinically diagnosed AN (ICD-10, F50.0) and 10 healthy control subjects, age range 12 - 21 years and mean BMI 19.0 ± 2.1 kg/m2, without nutritional disturbances: were investigated. 31P-MR spectroscopy was performed with a 1.5 T MRI unit using single volume selection in the frontal/prefrontal region of brain. Relative metabolic concentrations were quantified by normalizing the peak areas of the metabolites with the total area of the complete phosphorous spectrum, Ptot, as well as with the peak area of β;-NTP. Results: Significant differences between the two groups were observed for the metabolic ratios PDE/Ptot, PDE/β;-NTP and α-NTP/Ptot which were lower in the patient group except for α-NTP/Ptot. These ratios also revealed a statistically significant correlation with the BMI (rPDE/Ptot = 0.747, rPDE/β;-NTP = 0.57, rα-NTP/Ptot = -0.56; p ≤ 0.1). Reduced relative concentrations of PCr/Ptot, β;-NTP/Ptot or Pi/Ptot were not encountered. Conclusion: The lowered PDE/Ptot ratio for patients with AN and its correlation with BMI suggests that decreased BMI induces compositional changes of the phospholipids in the brain, which decrease the fraction of mobile phospholipids. (orig.)