Combined ¹H and ³¹P MR spectroscopic imaging: Impaired energy metabolism in severe carotid stenosis and changes upon treatment

Object: To evaluate if combined ¹H and ³¹P MR spectroscopic imaging (MRSI) before and after treatment of severe internal carotid artery (ICA) stenosis detects significant changes in energy metabolism in the basal ganglia of both hemispheres. Materials and methods: A group of 14 patients with high-grade ICA stenosis and 11 healthy control subjects were examined with 2D ¹H MRSI and 3D ³¹P MRSI at 3 T before and after treatment of severe ICA stenosis. Spectroscopic data were processed with LCModel and jMRUI software. Changes of the phosphorylated metabolites, pH, N-acetyl-acetate, creatine and choline-containing compounds prior/post intervention were analyzed and patients' data were compared with that of control subjects. Results: Untreated patients had significantly higher Adenosindiphosphate (ADP) in basal ganglia ipsi- and contralateral to the side of ACI stenosis compared to controls. After treatment, ADP of both hemispheres significantly decreased by approximately 20% compared to the pre-treatment values. Further, significant decreases of phosphorylated metabolites prior/post intervention were found for patients compared to controls. Conclusion: This spectroscopic study reveals that unilateral high-grade ICA stenosis has an effect on cerebral high-energy metabolism of both hemispheres, which is at least partially reversible after treatment. Therefore the restoration of blood flow in high-grade ICA stenosis recovers the impaired energy balance of the brain.