Sensitivity of Proton MRS in differentiation between tumor recurrence and radiation sequel

Abstract

Aim of work: The purpose of this study is to assess the sensitivity of Proton MRS to differentiate between tumor recurrence and newly contrast enhanced radiation sequel. Patients and methods: The study was conducted from May 2011 to June 2014 and the study population included 29 patients, 18 males and 11 females with age ranging from 10 to 68 years old (mean = 39) who had been initially diagnosed with an IC neoplasm. Results: Proton MRS performed over the recurrent contrast enhancing lesions resulted in quantifiable choline, creatine, NAA, and lactate peaks in 28 (97%) of the 29 patients. Lesions in the recurrent or residual tumor group had higher Cho/Cr ratios and higher Cho/Cr ratios. Lesions in the recurrent or residual tumor group also had higher Cho/NAA ratios and higher Cho/ NAA ratios than the normal-appearing white matter of 26 patients (p < 0.0001; SE, 0.08). Lesions in the recurrent or residual tumor group had lower NAA/Cr ratios (p < 0.0001; SE, 0.09) than those in the radiation injury group, and lower NAA/Cr ratios than the normal-appearing white matter of 26 patients (p = 0.075; SE, 0.09). Conclusion: We conclude that Proton MRS has the potential to discriminate between recurrent tumor and radiation sequel in patients with recurrent contrast-enhancing intracranial lesions.