Objective:To reveal the abnormal topology of brain network in Alzheimer′s disease (AD), and evaluate the laterality of tau protein deposition in brains of AD patients based on 18F-APN-1607 PET brain imaging combined with graph theory. Methods:From November 2018 to January 2020, 23 clinically diagnosed AD patients (9 males, 14 females; age (61.3±10.7) years) and 13 normal controls (NC) (9 males, 4 females; age (61.6±4.5) years) who underwent 18F-APN-1607 PET imaging in Huashan Hospital, Fudan University were analyzed in this cross-sectional study. The brain network analysis method based on graph theory was used to construct the tau network of the NC group and the AD group, the network attributes (clustering coefficient, shortest path length, local efficiency, and small-worldness) were calculated, and the asymmetry index (AI) of each group to evaluate the laterality of tau protein deposition was obtained. Permutation test (1 000 times) was used to analyze the differences in brain network parameters between the NC group and the AD group. Results:The tau network of the AD group had obvious topological disorder, and the connections in the olfactory cortex and temporal lobe were weakened, while in the posterior cingulate gyrus, anterior wedge, and parietal occipital lobe, the connections were enhanced. Compared with NC group, clustering coefficient ( t values: 2.28-2.69), local efficiency ( t values: 2.34-3.06) and small-worldness ( t values: 2.26-3.32) were significantly decreased in AD group (all P<0.05) with the sparsity of 20%-50%, while the shortest path length was significantly increased ( t values: 2.13-2.85; all P<0.05). There was significant tau laterality in the posterior cingulate gyrus, superior parietal gyrus, paracentral lobule, superior temporal gyrus and middle temporal gyrus (AI: 10.5%(8.1%, 13.9%), 14.1%(7.6%, 20.3%), -12.4%(-15.7%, -7.8%), -10.8%(-15.3%, -2.1%) , -12.1%(-17.9%, -6.6%), respectively). Conclusion:The tau network analysis based on 18F-APN-1607 may be used to reveal abnormal topological changes of AD patients, and the tau deposition in the posterior cingulate gyrus, superior parietal gyrus, paracentral lobule, superior temporal gyrus and middle temporal gyrus has obvious laterality in AD patients.

Objective:To investigate characteristics and differences of cerebral glucose metabolism in patients with anti- N-methyl- D-aspartate receptor (NMDAR) encephalitis from the perspective of different trigger factors of antibodies. Methods:A total of 15 patients (8 males, 7 females, age (30.5±17.7) years) with anti-NMDAR encephalitis between January 2016 and January 2019 in Huashan Hospital, Fudan University were recruited retrospectively. All patients underwent resting state cerebral 18F-FDG PET imaging. The characteristics of brain glucose metabolism were analyzed, and the SUV ratio (SUVR) was semi-quantitatively compared with that in 12 healthy subjects (HS; 7 males, 5 females, age (51.5±9.6) years). Independent-sample t test was used to analyze the data. Results:Among 15 patients, 5 patients were viral encephalitis-related anti-NMDAR encephalitis, showing focal decreased metabolism in unilateral temporal lobe or basal ganglia (SUVR: patients: 0.659±0.219; HS: 1.754±0.203; t=-9.58, P<0.001), with increased metabolism in contralateral temporal lobe or basal ganglia (SUVR: patients: 2.275±0.244; HS: 1.960±0.227; t=2.55, P=0.022) in 18F-FDG PET imaging. Six patients were cryptogenic anti-NMDAR encephalitis, showing asymmetric increased metabolism in frontal, temporal, parietal and basal ganglia (SUVR: patients: 2.482±0.395; HS: 1.754±0.203; t=5.23, P<0.001), with decreased metabolism in bilateral occipital lobes. The remaining 4 cases were paraneoplastic origin accompanied by teratoma, showing increased metabolism in bilateral temporal and basal ganglia (SUVR: patient: 2.359±0.181; HS: 1.960±0.227; t=3.16, P=0.007), with mild decreased metabolism in bilateral occipital lobe. Conclusions:The abnormal changes of cerebral glucose metabolism in patients with anti-NMDAR encephalitis can be divided into at least three patterns according to different trigger factors. A comprehensive understanding of these characteristic metabolic changes is helpful for detecting disease, and may provide potential value in indicating different causes.

Objective:To explore the abnormal brain metabolic pattern and connectivity in temporal lobe epilepsy (TLE) patients.Methods:18F-FDG PET images of 75 patients diagnosed as drug resistant unilateral TLE from January 2014 to December 2016 in Huashan Hospital of Fudan University were collected retrospectively, including 41 (22 males, 19 females, age (28.4±8.7) years) left TLE (LTLE) and 34 (13 males, 21 females, age (28.5±8.8) years) right TLE (RTLE). Forty-four healthy controls (24 males, 20 females, age (31.2±6.2) years) were also enrolled. The cerebral glucose metabolism in TLE patients and the controls were analyzed with statistical parametric mapping (SPM) 12. The brain connectivity based on glucose metabolism were analyzed with bilateral hippocampus and amygdala as seeds. Permutation test with 1 000 permutations was used to analyze data. Results:Compared to control group, in both LTLE and RTLE groups, hypometabolism was found in affected hippocampus, amygdala, insula and temporal gyrus and hypermetabolism was observed in health hippocampus, parahippocampal gyrus, amygdala, lenticular nucleus and thalamus. In addition, hypometabolism was also found in affected superior/middle frontal gyrus and hypermetabolism was also found in bilateral frontal-orbital gyrus, bilateral cerebellum, affected lenticular nucleus and thalamus in LTLE group. In both TLE groups, affected seeds exhibited increased connectivity with affected superior frontal gyrus, lingual gyrus, fusiform gyrus, superior/middle temporal gyrus and temporal pole (all P<0.05); affected seeds exhibited increased connectivity with health superior frontal gyrus ( P=0.005), lingual gyrus ( P=0.018) and transverse temporal gyrus ( P=0.016) in RTLE group in addition. Besides, affected seeds exhibited decreased connectivity with bilateral default mode network (DMN) (all P<0.05), affected caudate nucleus ( P=0.015) and health thalamus ( P=0.008), in a uniform distribution pattern in LTLE group, and with bilateral cerebral cortex in an irregular distribution pattern in RTLE group (all P<0.05). In LTLE group, health seeds exhibited more increased connections with superior ( P=0.005)/middle frontal gyrus ( P=0.042), health hippocampus ( P=0.038), parahippocampal gyrus ( P=0.019), amygdala ( P=0.038), posterior cingulate gyrus ( P=0.004), and bilateral fusiform gyrusand ( P=0.048) compared with RTLE group; while, in RTLE group, health seeds exhibited more decreased connections with health superior ( P=0.047), inferior frontal gyrus ( P<0.001), orbital frontal gyrus ( P<0.001) and rectus gyrus ( P=0.016) compared with LTLE group. Conclusion:Altered brain glucose metabolism and connectivity pattern are found and will elucidate the underlying metabolic pattern of TLE.

Objective:Exploring tau related disease pattern (tauRDP) in the brain of Alzheimer′s disease (AD) patients based on 18F-APN-1607 PET scan. Methods:18F-APN-1607 PET images were collected from 17 AD patients (6 males and 11 females, age: (61.7±12.3) years, Mini-Mental State Examination (MMSE) score: 17.6±7.9) and 10 normal controls (NC; 6 males and 4 females, age: (61.2±4.7) years) from Huashan Hospital of Fudan University. The scaled subprofile model (SSM) based on principal component analysis (PCA) technique was used to construct the tauRDP. Then the expression value of tauRDP in each sample was calculated. The differences on tauRDP expression values between AD patients and NC were compared by independent-sample t test. Pearson correlation analysis was used to analyze the correlation between tauRDP expression values and MMSE values in AD patients. Results:The tauRDP area mainly included: precentral gyrus, dorsolateral superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus of opercular part, inferior frontal gyrus of triangular part, supplementary motor area, medial superior frontal gyrus, left median cingulate and paracingulate gyri, right cuneus, superior occipital gyrus, middle occipital gyrus, postcentral gyrus, superior parietal gyrus inferior parietal, but supramarginal and angular gyri, supramarginal gyrus, angular gyrus, precuneus and middle temporal gyrus. There were significant differences ( t=4.395, P<0.001) between AD group (12.6±8.0) and NC group (0.0±1.0) in tauRDP expression values. The tauRDP expression values were correlated with MMSE values in AD group significantly ( r=-0.566, P=0.018). Conclusions:TauRDP established basing on SSM/PCA method can be used to quantitatively express the abnormal spatial distributions of tau deposition. Expression value of tauRDP has the potential to initially assess the severity of AD.

Objective To investigate the neural activity in the central auditory pathway by using a tinnitus an-imal model .Methods Twenty -four rats were randomly divided into the control ,acute salicylate treatment ,chronic salicylate treatment ,and recovery groups .The gap prepulse inhibition of acoustic startle test was used to confirm tinnitus -like behavior .After delivery of an intravenous bolus of fluorine -18 fluorodeoxyglucose (18F -FDG ) , small animal positron emission tomography scans were performed on rats .Results Only rats in chronic salicylate -treatment group showed evidence of experiencing tinnitus .The SUV ratios of the AC were significantly greater in the acute salicylate treatment group than in the control group (P<0 .01) ,suggesting relatively increased metabolism in the two brain regions of the rats in this group .The SUV ratios of the IC and AC (P<0 .01) ,but not of the CRB (P>0 .05) were greater in the chronic salicylate treatment group than in the control groups .There was a significant difference in whole brain SUVs between the control and acute salicylate treatment groups (P<0 .01) ,the whole brain SUVs in chronic salicylate treatment group were a little higher but showed no significant difference (P>0 .05) .There was no significant difference in the SUVs between the control and recovery groups (P>0 .05) .Conclu-sion These findings indicate that long -term salicylate administration induced tinnitus in rats and may have en-hanced neural activity corresponded to the up -regulated metabolic rate in our study .Alterations to neuroplasticity of the CNS may lead to tinnitus .