Qiong Song MD, Presenter: Nothing to Disclose

LiMing Xia, Abstract Co-Author: Nothing to Disclose

To evaluate the diagnostic value of 1H-MRS in the cerebral hyper acute injury induced by radiation after the radiotherapy of nasopharyngeal carcinoma

18 patients with nasopharyngeal carcinoma were performed radiotherapy for the first time. Bilateral temporal lobes of all patients underwent conventional MRI and 1H-MRS before and after radiotherapy with radiant dose of 20Gy、40Gy and 60Gy respectively. The main metabolic products observed were N-acetylaspartate (NAA), choline-containing compounds (Cho), creatine (Cr). The change of the spectroscopic morphology and the ratios of these metabolites were observed at different stages. The ratios of Cho/Cr、NAA/Cr and NAA/Cho at different stages were analyzed by ANOVA, with statistical significance ( P<0.001).

There weren’t change of signal in the temporal lobes with conventional MRI after radiotherapy, but the peak height of NAA and Cho began to decrease obviously in the inferior half of the temporal lobes with 1H-MRS after radiotherapy accepting 20Gy. The peak value of NAA, compared to Cho, began to fall earlier to a lower level. Cho/Cr, NAA/Cr and NAA/Cho decreased in the same position too. The peak values of NAA, Cho and ratios of Cho/Cr、NAA/Cr and NAA/Cho decreased progressively with the increase of accepting radiant dose. There was positive correlation between the ratios of metabolites and the dose of radiotherapy. The ratios of Cho/Cr、NAA/Cr and NAA/Cho showed significant difference( P<0.001) at different stages.

1H-MRS can detect and evaluate in vivo the metabolic effects in the cerebral hyper acute injury induced by radiation after the radiotherapy of nasopharyngeal carcinoma. During the period, NAA and Cho descended obviously in the inferior half of the temporal lobes. Cho/Cr, NAA/Cr and NAA/Cho descended in the same position too.

1H-MRS can provide objective evidence to make early diagnosis for radiation-induced brain injury.

Song, Q, Xia, L, The Study of 1H-MRS on Cerebral Hyper Acute Injury Induced by Radiation after Nasopharyngeal Carcinoma Radiotherapy.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4435624.html