Proton magnetic resonance spectroscopy of normal human brain and glioma: a quantitative in vivo study.

BACKGROUND: In vivo proton magnetic resonance spectroscopy (MRS) provides a noninvasive method of examining a wide variety of cerebral metabolites in both healthy subjects and patients with various brain diseases. Absolute metabolite concentrations have been determined using external and internal standards with known concentrations. When an external standard is placed beside the head, variations in signal amplitudes due to B1 field inhomogeneity and static field inhomogeneity may occur. Hence an internal standard is preferable. The purpose of this study was to quantitatively analyze the metabolite concentrations in normal adult brains and gliomas by in vivo proton MRS using the fully relaxed water signal as an internal standard. METHODS: Between January 1998 and October 2001, 28 healthy volunteers and 16 patients with gliomas were examined by in vivo proton MRS. Single-voxel spectra were acquired using the point-resolved spectroscopic pulse sequence with a 1.5 T scanner (TR/TE/Ave = 3000 ms/30 ms/64). RESULTS: The calculated concentrations of N-acetyl-asparatate (NAA), creatine (Cre), choline (Cho), and water (H2O) in the normal hemispheric white matter were (23.59 +/- 2.62) mmol/L, (13.06 +/- 1.8) mmol/L, (4.28 +/- 0.8) mmol/L, and (47,280.96 +/- 5414.85) mmol/L, respectively. The metabolite concentrations were not necessarily uniform in different parts of the brain. The concentrations of NAA and Cre decreased in all gliomas (P < 0.001). The ratios of NAA/Cho and NAA/H2O showed a significant difference between the normal brain and gliomas, and also between the high and low grades (P < 0.001). CONCLUSIONS: Quantitative analysis of in vivo proton MR spectra using the fully relaxed water signal as an internal standard is useful. The concentrations of NAA and the ratios of NAA/H2O and NAA/Cho conduce to discriminating between the glioma and normal brain, and also between the low-grade glioma and high-grade glioma.

[Value and economic analysis of emergency endoscopy in the diagnosis and treatment of massive upper gastrointestinal hemorrhage].

OBJECTIVE: To study the application value of emergency endoscopy in the diagnosis and treatment of massive upper gastrointestinal hemorrhage, and to evaluated by the economic analysis whether the emergency endoscopy was safe and effective,or shorten the hospitalization days and reduced the medical costs. METHODS: Ninety-one patients with massive upper gastrointestinal hemorrhage were randomly divided into emergency endoscopy group (group A) and non-emergency endoscopy group (group B). The patients in group A underwent endoscopy as soon as the blood pressures were normal and the patients of group B underwent endoscopy at 24-48 hours after hospitalization. They would be treated depending on the conditions by endoscopy. Then the correct diagnosis rates, rebleeding rates, complication rates, mean hospitalization days, the endoscopy costs, the blood transfusion costs, the drugs costs and the total hospitalization costs of two groups were evaluated and the cost-effect ratio (C/E) was calculated. RESULTS: The correct diagnosis rates and the endoscopy costs of group A were higher than the group B (100.0 percent vs.90.2 percent, P<0.05; (714.78+/-263.54) yuan vs. (383.57+/-251.72) yuan, P<0.01), and the rebleeding rates, the mean hospitalizations days, the blood transfusion costs and the drugs costs and the total hospitalization costs were all lower compared to the group B (6.1 percent vs. 26.8 percent, P<0.05; (5.42+/-1.70) days vs. (8.51+/-2.30) days, P<0.01; (791.80+/-258.35) yuan vs. (1270.29+/-569.21) yuan, P<0.01; (945.22+/-125.82) yuan vs. (1223.81+/-254.44) yuan, P<0.01; (2785.76+/-353.26) yuan vs. (3 527.76+/-555.62)yuan, P<0.01. The C/E of group A was lower than the group B (2785.76 yuan per patient vs. 3527.76 yuan per patient, P<0.01). CONCLUSION: Emergency endoscopy is not only safe and effective but also economical in the diagnosis and treatment of massive upper gastrointestinal hemorrhage.