Background The usefulness of in-phase/opposed-phase imaging and diffusion weighted imaging （DWI） in differentiating benign and neoplastic vertebral fractures has been described. In this study, we aimed to evaluate t...Background The usefulness of in-phase/opposed-phase imaging and diffusion weighted imaging （DWI） in differentiating benign and neoplastic vertebral fractures has been described. In this study, we aimed to evaluate the influence of the severity of vertebral damage on the diagnostic performance of these two technologies. Methods Totally 59 patients with 68 acute benign vertebral fractures and 43 patients with 79 vertebral metastases were included in this study. The MR protocol included DWls and sagittal in-phase/opposed-phase gradient recalled sequence. The severity of vertebral damage was expressed by lesion ratio （LR, the ratio of lesion area to vertebral area on the slices of largest abnormal signal area in the Tl-weighted sequence）. Quantitative （signal intensity ratio （SIR） defined as signal intensity （SI） on opposed-phase gradient recalled echo （GRE） images divided by SI on in-phase; apparent diffusion coefficient （ADC） value derived from DWl analysis was performed, the relationships between LR and the measurements of these two technologies were analyzed using linear regression. The covariate-specific receiver operating characteristic （ROC） curves were also fitted to evaluate the influence of LR on the diagnostic performance of ADC and SIR. Results The difference in both SIR and ADC for vertebral metastasis and acute benign vertebral fractures was significant （P 〈0.001）. A positive correlation between the LR and the SIR was found in benign fractures （P 〈0.05）. The severity of vertebral damage had a significant influence on the AUC （area under ROC curve） for SIR （P 〈0.05） but ADC （P 〉0.05）. More severe cases were associated with increased AUC for SIR. Conclusions LR is capable of affecting the diagnostic performances of chemical shift imaging. Thus, when applying these tests to make diagnoses on vertebral fractures, the severity of the vertebral damage should be taken into account. The covariate-specific ROC model is recommended because it substantially展开更多
The value of the combined in-phase (IP) and opposed-phase (OP) T1-weighted (T1-W) breath-hold FLASH sequences for hepatic imaging, especially for fat content, was evaluated. Non- contrast-enhanced IP and OP T1-W GRE ...The value of the combined in-phase (IP) and opposed-phase (OP) T1-weighted (T1-W) breath-hold FLASH sequences for hepatic imaging, especially for fat content, was evaluated. Non- contrast-enhanced IP and OP T1-W GRE breath-hold images were obtained in 76 patients refereed for abdominal MRI at 1. 5T. 76 patients were divided into three groups for analysis: (1) liver with- out mass (n=8); (2) liver with hepatoma (n=34); (3) liver with haemangioma or cyst (n=34). Liver/spleen and liver/lesion signal-to-noise (SNR) and contrast-to-noise ratio (CNR) were assessed for lesion detection. Images between IP and OP sequences were compared quantitatively. The results showed that there was not statistically significant difference in liver/spleen and liver/lesion SNR be- tween IP and OP sequences. In the patients with fatty infiltration, the OP sequences yielded substan- tially lower values for liver/spleen and liver/lesion SNR than those of the IP sequences. Further- more, OP imaging showed fatty infiltration in 14 cases and demonstrated hyperintense peritumor rim in 4 cases. In 14 cases of fatty infiltration, many lesions were identified using IP images. The use of IP and OP GRE sequences provides complementary diagnostic information for hepatic lesions and fat content. Focal hepatic lesions may be obscured in the setting of fatty infiltration if only OP sequences are employed. A complete assessment of the liver with MR should include both IP and OP imaging.展开更多
AIM To investigate the repeatability of proton magnetic resonance spectroscopy in the in vivo measurement of human cerebral levels of choline-containing compounds(Cho).METHODS Two consecutive scans were carried out in...AIM To investigate the repeatability of proton magnetic resonance spectroscopy in the in vivo measurement of human cerebral levels of choline-containing compounds(Cho).METHODS Two consecutive scans were carried out in six healthy resting subjects at a magnetic field strength of 1.5 T. On each occasion, neurospectroscopy data were collected from 64 voxels using the same 2 D chemical shift imaging(CSI) sequence. The data were analyzed in the same way, using the same software, to obtain the values for each voxel of the ratio of Cho to creatine. The Wilcoxon related-samples signed-rank test, coefficient of variation(CV), repeatability coefficient(RC), and intraclass correlation coefficient(ICC) were used to assess the repeatability. RESULTS The CV ranged from 2.75% to 33.99%, while the minimum RC was 5.68%. There was excellent reproducibility, as judged by significant ICC values, in 26 voxels. Just three voxels showed significant differences according to the Wilcoxon related-samples signed-rank test. CONCLUSION It is therefore concluded that when CSI multivoxel proton neurospectroscopy is used to measure cerebral choline-containing compounds at 1.5 T, the reproducibility is highly acceptable.展开更多
Magnetic resonane imaging (MRI) has already been widely used in medical diagnosis,but its potential application to material science has not been fully acknowledged yet. AsMRI is highly sensitive to protons, and organi...Magnetic resonane imaging (MRI) has already been widely used in medical diagnosis,but its potential application to material science has not been fully acknowledged yet. AsMRI is highly sensitive to protons, and organic materials contain abundant protons, thereis ample scope of its application. It is gradually becoming a powerful tool for studyingmaterials because it is rich in content and noninvasive to samples under investigation.展开更多
文摘Background The usefulness of in-phase/opposed-phase imaging and diffusion weighted imaging （DWI） in differentiating benign and neoplastic vertebral fractures has been described. In this study, we aimed to evaluate the influence of the severity of vertebral damage on the diagnostic performance of these two technologies. Methods Totally 59 patients with 68 acute benign vertebral fractures and 43 patients with 79 vertebral metastases were included in this study. The MR protocol included DWls and sagittal in-phase/opposed-phase gradient recalled sequence. The severity of vertebral damage was expressed by lesion ratio （LR, the ratio of lesion area to vertebral area on the slices of largest abnormal signal area in the Tl-weighted sequence）. Quantitative （signal intensity ratio （SIR） defined as signal intensity （SI） on opposed-phase gradient recalled echo （GRE） images divided by SI on in-phase; apparent diffusion coefficient （ADC） value derived from DWl analysis was performed, the relationships between LR and the measurements of these two technologies were analyzed using linear regression. The covariate-specific receiver operating characteristic （ROC） curves were also fitted to evaluate the influence of LR on the diagnostic performance of ADC and SIR. Results The difference in both SIR and ADC for vertebral metastasis and acute benign vertebral fractures was significant （P 〈0.001）. A positive correlation between the LR and the SIR was found in benign fractures （P 〈0.05）. The severity of vertebral damage had a significant influence on the AUC （area under ROC curve） for SIR （P 〈0.05） but ADC （P 〉0.05）. More severe cases were associated with increased AUC for SIR. Conclusions LR is capable of affecting the diagnostic performances of chemical shift imaging. Thus, when applying these tests to make diagnoses on vertebral fractures, the severity of the vertebral damage should be taken into account. The covariate-specific ROC model is recommended because it substantially
文摘The value of the combined in-phase (IP) and opposed-phase (OP) T1-weighted (T1-W) breath-hold FLASH sequences for hepatic imaging, especially for fat content, was evaluated. Non- contrast-enhanced IP and OP T1-W GRE breath-hold images were obtained in 76 patients refereed for abdominal MRI at 1. 5T. 76 patients were divided into three groups for analysis: (1) liver with- out mass (n=8); (2) liver with hepatoma (n=34); (3) liver with haemangioma or cyst (n=34). Liver/spleen and liver/lesion signal-to-noise (SNR) and contrast-to-noise ratio (CNR) were assessed for lesion detection. Images between IP and OP sequences were compared quantitatively. The results showed that there was not statistically significant difference in liver/spleen and liver/lesion SNR be- tween IP and OP sequences. In the patients with fatty infiltration, the OP sequences yielded substan- tially lower values for liver/spleen and liver/lesion SNR than those of the IP sequences. Further- more, OP imaging showed fatty infiltration in 14 cases and demonstrated hyperintense peritumor rim in 4 cases. In 14 cases of fatty infiltration, many lesions were identified using IP images. The use of IP and OP GRE sequences provides complementary diagnostic information for hepatic lesions and fat content. Focal hepatic lesions may be obscured in the setting of fatty infiltration if only OP sequences are employed. A complete assessment of the liver with MR should include both IP and OP imaging.
文摘AIM To investigate the repeatability of proton magnetic resonance spectroscopy in the in vivo measurement of human cerebral levels of choline-containing compounds(Cho).METHODS Two consecutive scans were carried out in six healthy resting subjects at a magnetic field strength of 1.5 T. On each occasion, neurospectroscopy data were collected from 64 voxels using the same 2 D chemical shift imaging(CSI) sequence. The data were analyzed in the same way, using the same software, to obtain the values for each voxel of the ratio of Cho to creatine. The Wilcoxon related-samples signed-rank test, coefficient of variation(CV), repeatability coefficient(RC), and intraclass correlation coefficient(ICC) were used to assess the repeatability. RESULTS The CV ranged from 2.75% to 33.99%, while the minimum RC was 5.68%. There was excellent reproducibility, as judged by significant ICC values, in 26 voxels. Just three voxels showed significant differences according to the Wilcoxon related-samples signed-rank test. CONCLUSION It is therefore concluded that when CSI multivoxel proton neurospectroscopy is used to measure cerebral choline-containing compounds at 1.5 T, the reproducibility is highly acceptable.
基金Project supported by the Chinese Academy of Sciences and the State Science and Technology Commission of China.
文摘Magnetic resonane imaging (MRI) has already been widely used in medical diagnosis,but its potential application to material science has not been fully acknowledged yet. AsMRI is highly sensitive to protons, and organic materials contain abundant protons, thereis ample scope of its application. It is gradually becoming a powerful tool for studyingmaterials because it is rich in content and noninvasive to samples under investigation.
