Application of 13N-NH3 PET in the evaluation of hypometabolic brain lesions on 18F-FDG PET / 中华核医学与分子影像杂志

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.

Usefulness of (13)N-NH (3) PET in the evaluation of brain lesions that are hypometabolic on (18)F-FDG PET.

We investigated the usefulness of (13)N-NH(3) PET in characterizing brain lesions which show hypometabolism on (18)F-FDG PET. (13)N-NH(3) PET was performed in 18 patients with brain lesions (in 14 for initial diagnosis and in 4 for detection of astrocytoma recurrence) that showed hypometabolism compared with normal brain tissue on (18)F-FDG PET. The diagnoses were ten gliomas, one metastatic tumor, one dysembryoplastic neuroepithelial tumor (DNT), and six non-neoplastic lesions (including three cases of radiation necrosis, two cases of encephalitic foci, and one ischemic lesion). Diagnosis was verified by histopathological examination in 13 patients or was established by clinical follow-up and additional investigations in the remainder. Seven of 12 brain tumors (58%, sensitivity) showed increased (13)N-NH(3) uptake despite hypometabolism on (18)F-FDG PET. The three low-grade gliomas, one metastatic tumor, and one DNT showed decreased (13)N-NH(3) uptake. The mean (±SD) uptake ratio of (13)N-NH(3) was significantly higher than that of (18)F-FDG (1.24 ± 0.57 vs. 0.67 ± 0.21, P < 0.01) in the tumors. By contrast, all six non-neoplastic lesions showed decreased (13)N-NH(3) uptake (100% specificity). The mean (±SD) uptake ratio of (18)F-FDG and (13)N-NH(3) in the non-neoplastic lesions was 0.68 ± 0.15 and 0.70 ± 0.19, respectively, and there was no significant difference between them (P > 0.05). The mean (±SD) uptake ratio of (13)N-NH(3) in the tumors was significantly higher than that in the non-neoplastic lesions (1.24 ± 0.53 vs. 0.70 ± 0.19, P < 0.05). The preliminary results of this study suggest that (13)N-NH(3) PET may be helpful to detect and differentiate brain tumors which show hypometabolism on (18)F-FDG PET from non-neoplastic lesions with high specificity, especially for cerebral astrocytomas, but the sensitivity is relatively limited.

Analysis and Evaluation of the Nuclear Medicine Examination Scores / 中华医学教育探索杂志

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.

Dynamic 13N-ammonia PET: a new imaging method to diagnose hypopituitarism.

UNLABELLED: We have developed a new imaging method to evaluate the blood perfusion and ammonia metabolism of the pituitary gland, and we preliminarily assessed its role in the diagnosis of hypopituitarism. METHODS: Six female healthy volunteers (age range, 20-46 y) and 6 female patients (age range, 23-42 y) were enrolled in this study. Dynamic (13)N-NH(3) PET was performed. Time-activity curves for the pituitary gland and internal carotid artery were generated by setting regions of interest on the transverse planes of the pituitary gland. The standardized uptake value of the pituitary gland, the radioactive ratio of pituitary to thalamus (P/T), and the first-pass uptake rate of ammonia in the pituitary gland were calculated. RESULTS: (13)N-Ammonia was extracted rapidly by pituitary tissue in the first 120 s after injection and trapped in pituitary tissue in the healthy volunteers. Three to 20 min after injection, the pituitary gland was clearly seen in the healthy volunteers, and the mean (+/-SD) size of the pituitary gland on (13)N-ammonia PET images was (1.09 +/- 0.17 cm) x (1.08 +/- 0.14 cm) x (1.12 +/- 0.09 cm). However, in patients with hypopituitarism, the first-pass uptake rate of ammonia in the pituitary gland was significantly lower than that in healthy volunteers (0.35 +/- 0.10 vs. 0.75 +/- 0.07). On images of patients, the pituitary gland was absent or could not clearly be found, was small or malformed, and showed significantly lower uptake of (13)N-NH(3) than in healthy volunteers (standardized uptake value, 1.15 +/- 0.34 vs. 3.74 +/- 1.44; P/T, 0.65 +/- 0.23 vs. 1.24 +/- 0.34). CONCLUSION: Dynamic (13)N-ammonia PET can provide information on blood perfusion and metabolism of the pituitary gland and is useful in early monitoring of damage to the pituitary gland and in diagnosing hypopituitarism.

Gastric sensorimotor function in patients with functional dyspepsia / 中华消化杂志

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.