ABSTRACT
Objective To investigate the usefulness of 13N-NH3 PET in detecting brain lesions which show hypometabolism on 18F-FDG PET.Methods 13N-NH3 PET imaging was performed for a prospective study in 18 patients with brain lesions that showed hypometabolism compared with normal brain tissue on 18F-FDG PET scans.Fourteen patients underwent 18 F-FDG PET imaging for initial diagnosis and 4 patients for detection of astrocytoma recurrence (13 males,5 females,age 20-68 (42.4 ± 12.6) years).Ten gliomas,1 metastatic tumor,1 dysembryoplastic neuroepithelial tumor (DNT) and 6 non-neoplastic lesions (including 3 cases of radiation necrosis,2 cases of encephalitic foci,and 1 case of ischemic lesion)were verified by histopathological examination (n =13) or clinical follow-up (n =5).The tumor-to-contralateral brain tissue ratios (T/C) were calculated by the ROI method.The diagnostic efficacy of 13N-NH3 PET was evaluated.Paired t test and two-sample t test were performed to analyze the differences of T/C between different groups.Results Seven (5 astrocytomas and 2 glioblastomas) of 12 brain tumors (sensitivity:58％,7/12) showed increased 13N-NH3 uptake (higher uptake than the contralateral brain tissue),while 3 low-grade gliomas,1 metastatic tumor,and 1 DNT showed decreased 13N-NH3 uptake (no uptake or lower uptake than the contralateral brain tissue).The uptake ratio of 13N-NH3 was significantly higher than that of 18 F-FDG (1.24 ± 0.66 vs 0.67 ± 0.24,t =-3.740,P ＜ 0.05) in the tumors.All six non-neoplastic lesions showed decreased 13N-NH3 uptake (specificity:6/6).The T/C ratios of 18F-FDG and 13N-NH3 in the non-neoplastic lesions were 0.68 ±0.15 and 0.70 ±0.19,respectively,and there was no significant difference between them (t =-0.246,P ＞ 0.05).The T/C ratio of 13N-NH3 in the tumors was significantly higher than that in the non-neoplastic lesions (1.24 ± 0.53 vs 0.70 ± 0.19,t =2.624,P ＜ 0.05).Conclusion 13N-NH3 PET imaging may be helpful to detect and differentiate brain tumors with hypometabolism as detected by 18 F-FDG PET imaging from non-neoplastic lesions with high specificity,especially for cerebral astrocytomas,but the sensitivity is relatively limited.
ABSTRACT
In order to evaluate our teaching results and improve the teaching quality,we designed this study to analyze the scores of nuclear medicine examination for the students of 2001 majoring in clinical medicine.There were 345 students participating in the examination.The results showed that the scores was Gassion distribution,the average score was 82.26,and the difficulty and discrimination of the test paper were appropriate.This analysis method as an objective index can be used to evaluate the response of teaching in nuclear medicine as well as improve the quality of test paper.
ABSTRACT
0.05). Conclusions Gastric hypersensitivity, impaired proximal gastric accommodation and delayed gastric emptying may be important but independent pathophysiological factors of FD. Different pathophysiological factors can coexist in one patient with FD.