Detection of an intense resonance at 2.4 ppm in 1H MR spectra of patients with severe late-delayed, radiation-induced brain injuries.

ABSTRACT

Proton MRS and MRI were used to monitor the progression of severe cerebral radiation injuries in 10 patients over a period of 18 months. An unknown resonance (Px) in the 2.37-2.40 ppm region was consistently detected in the affected temporal lobes of four patients. The detection of Px was only confined to spectra with lactate (Lac) and in patients with the highest severity grading of radiation injury. The incidence of Px in Lac-positive spectra was 42.8% (15/35) and in lesions with highest injury grading was 46.8% (15/32). Lesions with Px had significantly higher Lac/creatine (Cr) ratios and more extensive mass effect changes when compared to lesions without Px. The probable identity of Px was examined in the context of anaerobic glycolysis producing pyruvate (2.37 ppm) and the model of metabolic changes in brain abscess formation implicating succinate (2.40 ppm).