Objective To investigate the variabihty of absolute and relative biochemical concenstrations at different repetition time(TR) in quantifying normal brain by single voxel proton MR spectroscopy.Methods Thirty normal volunteers signed informed consent were recruited for the study.Short echo time(TE=35 ms)single voxel spectroscopy of the left parieto-occipital white matter were performed on a 1.5 T MR scanner by using point-resolved selective spectroscopy(PRESS)sequence.Two spectra were obtained using the same voxel placement and acquisition parameters but at different TRs:first at TR=1500 ms then at TR=5000 ms.Raw data of spectra were processed on a commercial software Liinear combination model(LCModel)normalized to spectral date obtained from a reference phantom of known metabolite quantities.Measured metabohtes included total creatine(tCr,creatine and phosphocreatine),glutamate(Glu),myo-inositol(mI),N-acytalaspartate(NAA),glycerophosphorylcholine(GPC),glutamate and glutamine(Glx).The t test was performed by using SPSS 11.5 for windows.Results Both the absolute and relative concentrations of normal white matter were significanth different between spectra obtafined at TR=1500 ms and that at TR=5000 ms(P＜0.05).The absolute concentrations(mmol/L)at TR=1500 ms were tCr,3.0±0.2;Glu,4.4±0.7;ml,3.0±0.3;NAA,5.0±0.4;GPC,1.1±0.1:Glx,5.9±0.6;compared to concentration at TR=5000 ms,tCr,4.2±0.4;Gitu,5.3±0.5;mI.3.7±0.5;NAA,6.7±0.7;GPC,1.4±0.1;Glx,6.6±0.6;respectively.The concentrations relatively to tCr at TR=1500 ms,were Glu,1.47±0.27;mI,1.00±0.11;NAA,1.69±0.17;GPC,0.36±0.05;Glx,1.95±0.22;and relative concentrations at TR=5000 ms were Glu,1.25±0.12;mI,0.89±0.09;NAA,1.60±0.16;GPC,0.33±0.04;Glx,1.58±0.17;respectively.Conclusion Proton MR spectroscopy can accurately quantify absolute and relative concentrations of brain metabolites.Metabolites concentrations may be significant underestimated when using shorter repetition time in short TE spectroscopic study.

Objective To evaluate the diagnostic value of CT guided percutaneous transthoracic core needle biopsy (TCNB). Methods CT guided TCNB were performed on 121 cases who had suffered from pulmonary diseases. Cook QC 18G, 19G, or 20 gauge needles were used. The diameter of the pulmonary lesions was ranged from 0.8cm to 9.5cm, mean (3.4?1.9)cm. Postbiopsy complications were observed by routine CT scan. Results According to the Westcott's method, the final diagnosis of 86 cases of malignancy and 35 cases of benignancy had been established. Seventy nine malignant and 32 benign ones could be accurately diagnosed by TCNB. The overall diagnostic accuracy was 91.7%(111/121). The sensitivity of TCNB in the malignancy was 91.9%(79/86) with 7 cases of false negative, and the specificity was 100%. Seventy cases of malignancy could be made definitely. The sensitivity of benignancy was 91.4%(32/35). Complication of pneumothorax in 22 cases (18.2%) and pulmonary hemorrhage in 19 cases (15.7%) resolving spontaneously. Conclusions CT guided TCNB is a safe, reliable method with high accuracy in diagnosis and less complications, especially for non lung cancer malignancy and benign lesions.