BACKGROUND: 31P magnetic resonance spectroscopy (31P MRS) can be used to non-injuredly and dynamicly detect various metabolites including phosphorus in organis and reflect changes of phospholipid metabolism and energy metabolism in tissue and pH value in cells.OBJECTIVE: To observe changes of pH value, phospholipid metabolism and energy metabolism of various cerebral tumors and normal brain tissue with 31P MRS.DESIGN: Semi-quantitative contrast observation.PARTICIPANTS: A total of 44 patients with cerebral tumor diagnosed with surgery operation were selected from the Department of Magnetic Resonance, Central South Hospital, Wuhan University from September 2004 to June 2006. All the subjects had complete 31P MRS data before steroid and operation. Among them,16 patients had glioma of grade Ⅱ-Ⅲ, 12 spongioblastoma and 16 meningioma. The mean age was (45±6)years. Another 36 subjects without focus on cerebral MRI were regarded as normal group, including 19 males and 18 females, and the mean age was (41±4) years. Included subjects were consent.METHODS: Eclipse1.5T MRS (Philips Company) was used to collect wave spectrum; jMRUI(1.3) was used to analyze experimental data and calculate pH value in voxel and ratios of phosphocreatine (PCr)/inorganic phosphate (Pi), PCr/phosphodiesterase (PDE) and phosphomonoesterase (PME)/β-adenosine triphosphate (β-ATP) of various metabolites. 31P MRS results were compared with t test between tumor patients and normal subjects.MAIN OUTCOME MEASURES: Changes of phospholipid metabolism (PME/PDE), energy metabolism (PCr/ATP) and pH value of various cerebral tumors and normal brain tissues.RESULTS: A total of 44 cases with cerebral tumor and 36 normal subjects were involved in the final analysis. pH value and semi-quantitative measurements of normal brain tissues and various cerebral tumors: ① pH value at top occipital region and temple occipital region of normal brain tissue was 7.04±0.02;PCt/β-ATP was 1.51 ±0.03; PCt/Pi was 2.85±0.20; PDE/β-ATP was 2.70±0.40; PME/β-ATP was 1.01 ±0.03.② Glioma of grade Ⅱ -Ⅲ: Tumor tissue was alkalized. The pH value was 7.09±0.01, which was higher than that in normal group (t=1.823, P ＜ 0.05); PCr/β-ATP, PME/β-ATP and PCr/ Pi were 1.50±0.04, 1.04±0.07and 2.49±0.21, respectively, which was close to that in normal group (P ＞ 0.05); PDE/β-ATP was 1.73±0.20, which was lower than that in normal group (t=2.168, P ＜ 0.05). ③ Spongioblastoma: Tumor tissue was alkalized. The pH value was 7.12±0.02, which was higher than that in normal group (t=2.170,P ＜ 0.05); PCr/β-ATP and PCr/ Pi were 1.48±0.05 and 2.39±0.23, respectively, which was lower than that in normal group, but the difference was not significant (P ＞ 0.05); PDE/β-ATP was 1.61±0.25, which was lower than that in normal group (t=3.582, P ＜ 0.01); PME/β-ATP was 1.64±0.05, which was higher than that in normal group (t=3.930, P ＜ 0.01). ④ Meningioma: Tumor tissue was alkalized. The pH value was 7.16±0.03, which was higher than that in normal group (t=2.978, P ＜ 0.01); PCr/β-ATP, PCr/Pi and PDE/β-ATP were 0.46±0.04, 1.08±0.16 and 0.82±0.10, respectively, which was lower than that in normal group (t=3.132, 3.983, 3.985, P ＞ 0.01); PME/β-ATP was 2.05±0.03, which was higher than that in normal group (t=3.007, P＜ 0.01).CONCLUSION : 31P MRS can provide informations about pH value of cerebral tumor, phospholipid metabolism and energy metabolism. Changes of pH value, PCr, PME and PDE can reflect metabolic characteristics of various cerebral tumors.