Objective To observe the correlation between brain abnormal glucose metabolism and striatal dopaminergic neuron damage in early-stage Parkinson disease(PD)patients.Methods Thirty-two early-stage PD patients(PD group)and 18 healthy individuals(control group)were prospectively enrolled,and 18F-FDG and 18F-9-fluoropropyl-(+)-dihydrotetrabenazine(18 F-FP-DTBZ)PET/MR brain imaging were performed.The degrees of uptake were compared between groups,and the correlation between brain abnormal glucose metabolism and striatal dopaminergic neuron damage was analyzed.Results Compared with control group,18F-FDG PET showed that in PD group glucose metabolism decreased in bilateral frontal and parietal lobes but increased in bilateral putamen,pons and bilateral cerebellum(all P＜0.05),while18 F-FP-DTBZ PET showed that in PD group glucose metabolism decreased in bilateral caudate nucleus,anterior putamen and posterior putamen(all P＜0.05).In PD group,the mean standard uptake value(SUVmean)of putamen was positively correlated with the standard uptake value ratio(SUVR)of contralateral caudate nucleus(r=0.305,P=0.014),while SUVmean of frontal cortex was positively correlated with SUVR of contralateral and symptomatic caudate nucleus(r=0.352,0.324,both P＜0.05)as well as anterior putamen(r=0.300,0.314,both P＜0.05),SUVmean of the partial cortex in parietal lobe was positively correlated with SUVR of contralateral and symptomatic caudate nucleus and contralateral anterior putamen(r=0.329,0.303,0.330,all P＜0.05).Conclusion Brain abnormal glucose metabolism had certain correlation with striatal dopaminergic neuron damage in early-stage PD patients.

Objective:To explore the value of 18F-FDG PET brain glucose metabolism imaging in the subtype differential diagnosis and prognosis evaluation of autoimmune encephalitis (AE). Methods:A retrospective analysis was conducted on PET/CT brain glucose metabolism imaging data from 58 patients with AE (from August 2020 to June 2023, Xuanwu Hospital, Capital Medical University; 31 males, 27 females; age (47.4±16.9) years). Patients were divided into 4 groups: anti-leucine-rich glioma-inactivated protein 1(LGI1) antibody-related encephalitis group, anti- N-methyl- D-aspartate receptor (NMDAR) encephalitis group, anti-γ-amino butyric acid type B receptor (GABA BR) antibody-related encephalitis group, and other types of AE group. In addition, 20 cases were included in control group (6 males and 14 females, age (58.8±7.5) years). Visual assessment was performed to evaluate changes in brain glucose metabolism among patients with different subtypes of AE, and abnormal glucose metabolism brain regions were compared by independent-sample t test between different groups. Spearman rank correlation analysis was conducted between SUV ratio (SUVR) of abnormal brain regions and modified Rankin Scale (mRS) scores at six months later. Results:Among 58 patients, 21 were diagnosed with anti-LGI1 antibody-related encephalitis, 18 were diagnosed with anti-NMDAR encephalitis, 7 were diagnosed with anti-GABA BR antibody-related encephalitis, and 12 were diagnosed with other subtypes of AE. Compared with anti-NMDAR encephalitis group: patients with anti-LGI1 antibody-related encephalitis showed increased glucose metabolism in the right occipital lobe and bilateral hippocampi, and decreased glucose metabolism in the right frontal lobe, right precentral gyrus, and bilateral superior marginal gyrus ( t values: from -5.13 to 4.89, all P<0.001); patients with anti-GABA BR antibody-related encephalitis exhibited increased glucose metabolism in the bilateral hippocampi and right fusiform gyrus, and decreased glucose metabolism in the left middle frontal gyrus ( t values: from -3.82 to 3.91, all P<0.001). Anti-NMDAR encephalitis was characterized by decreased metabolism in the bilateral parietal lobes, occipital lobes, local frontal-temporal lobes, and bilateral thalami, as well as increased metabolism in the limbic lobe and local frontal-temporal-parietal lobes ( t values: from -8.30 to 7.30, all P<0.001), and the SUVR of the right occipital lobe was negatively correlated with mRS score at six months later ( rs=-0.64, P=0.014). Other subtypes of AE showed decreased glucose metabolism in different cerebral lobes. Conclusion:18F-FDG PET/CT can evaluate brain glucose metabolism in different subtypes of AE diseases and prognosis.

Rapid eye movement sleep behavior disorder（RBD）， as a sleep disorder with unique clinical manifestations， is currently widely regarded as a precursor marker for α-synucleinopathies （Parkinson disease， dementia with Lewy bodies， and multiple system atrophy）. In recent years， great achievements have been made in radiological studies on isolated RBD and RBD comorbid with various α-synucleinopathies. This article reviews the research findings in RBD in terms of magnetic resonance imaging and radionuclide imaging and discusses the significance of radiological features in the diagnosis and prognosis of RBD， so as to provide a reference for subsequent research and clinical practice.

Objective To observe the correlation between brain abnormal glucose metabolism and striatal dopaminergic neuron damage in early-stage Parkinson disease(PD)patients.Methods Thirty-two early-stage PD patients(PD group)and 18 healthy individuals(control group)were prospectively enrolled,and 18F-FDG and 18F-9-fluoropropyl-(+)-dihydrotetrabenazine(18 F-FP-DTBZ)PET/MR brain imaging were performed.The degrees of uptake were compared between groups,and the correlation between brain abnormal glucose metabolism and striatal dopaminergic neuron damage was analyzed.Results Compared with control group,18F-FDG PET showed that in PD group glucose metabolism decreased in bilateral frontal and parietal lobes but increased in bilateral putamen,pons and bilateral cerebellum(all P＜0.05),while18 F-FP-DTBZ PET showed that in PD group glucose metabolism decreased in bilateral caudate nucleus,anterior putamen and posterior putamen(all P＜0.05).In PD group,the mean standard uptake value(SUVmean)of putamen was positively correlated with the standard uptake value ratio(SUVR)of contralateral caudate nucleus(r=0.305,P=0.014),while SUVmean of frontal cortex was positively correlated with SUVR of contralateral and symptomatic caudate nucleus(r=0.352,0.324,both P＜0.05)as well as anterior putamen(r=0.300,0.314,both P＜0.05),SUVmean of the partial cortex in parietal lobe was positively correlated with SUVR of contralateral and symptomatic caudate nucleus and contralateral anterior putamen(r=0.329,0.303,0.330,all P＜0.05).Conclusion Brain abnormal glucose metabolism had certain correlation with striatal dopaminergic neuron damage in early-stage PD patients.

Objective:To explore the value of 18F-FDG PET brain glucose metabolism imaging in the subtype differential diagnosis and prognosis evaluation of autoimmune encephalitis (AE). Methods:A retrospective analysis was conducted on PET/CT brain glucose metabolism imaging data from 58 patients with AE (from August 2020 to June 2023, Xuanwu Hospital, Capital Medical University; 31 males, 27 females; age (47.4±16.9) years). Patients were divided into 4 groups: anti-leucine-rich glioma-inactivated protein 1(LGI1) antibody-related encephalitis group, anti- N-methyl- D-aspartate receptor (NMDAR) encephalitis group, anti-γ-amino butyric acid type B receptor (GABA BR) antibody-related encephalitis group, and other types of AE group. In addition, 20 cases were included in control group (6 males and 14 females, age (58.8±7.5) years). Visual assessment was performed to evaluate changes in brain glucose metabolism among patients with different subtypes of AE, and abnormal glucose metabolism brain regions were compared by independent-sample t test between different groups. Spearman rank correlation analysis was conducted between SUV ratio (SUVR) of abnormal brain regions and modified Rankin Scale (mRS) scores at six months later. Results:Among 58 patients, 21 were diagnosed with anti-LGI1 antibody-related encephalitis, 18 were diagnosed with anti-NMDAR encephalitis, 7 were diagnosed with anti-GABA BR antibody-related encephalitis, and 12 were diagnosed with other subtypes of AE. Compared with anti-NMDAR encephalitis group: patients with anti-LGI1 antibody-related encephalitis showed increased glucose metabolism in the right occipital lobe and bilateral hippocampi, and decreased glucose metabolism in the right frontal lobe, right precentral gyrus, and bilateral superior marginal gyrus ( t values: from -5.13 to 4.89, all P<0.001); patients with anti-GABA BR antibody-related encephalitis exhibited increased glucose metabolism in the bilateral hippocampi and right fusiform gyrus, and decreased glucose metabolism in the left middle frontal gyrus ( t values: from -3.82 to 3.91, all P<0.001). Anti-NMDAR encephalitis was characterized by decreased metabolism in the bilateral parietal lobes, occipital lobes, local frontal-temporal lobes, and bilateral thalami, as well as increased metabolism in the limbic lobe and local frontal-temporal-parietal lobes ( t values: from -8.30 to 7.30, all P<0.001), and the SUVR of the right occipital lobe was negatively correlated with mRS score at six months later ( rs=-0.64, P=0.014). Other subtypes of AE showed decreased glucose metabolism in different cerebral lobes. Conclusion:18F-FDG PET/CT can evaluate brain glucose metabolism in different subtypes of AE diseases and prognosis.

Parkinson's disease(PD)is a common neurodegenerative disease,which seriously affects the quality of life of patients.The early and accurate diagnosis of PD is still a major medical problem.Positron computed tomography(PET)can be used to monitor noninvasively the pathophysiological changes in the early stage of PD in vivo,which has good clinical application value.18F-FDG PET cerebral glucose metabolism imaging is the most convenient and widely used detection method.At present,a variety of specific cerebral metabolic patterns of PD have been found,which have good guidance for the early diagnosis,differential diagnosis,disease monitoring and curative efficacy judgment of PD.Therefore,this paper focuses on the review of the 18F-FDG PET cerebral glucose metabolism model related to PD,aiming to enable a better application of this technique to the diagnosis of PD.

Levodopa is the standard therapy for Parkinson disease(PD),however,with the progression of the disease and long-term treatment,levodopa-induced dyskinesia(LID)can occur,greatly reducing the quality of patients'life.PET brain molecular imaging can detect the uptake and distribution of imaging agents at the molecular level in vivo,thereby reflecting the brain function and metabolism of patients with PD complicated with LID,which is helpful for early clinical diagnosis and treatment.The research progresses of PET molecular imaging for PD complicated with LID were reviewed in this article.

Parkinson disease (PD) is a common neurodegenerative disease. PET has special advantages in early identification, diagnosis and evaluation of PD. The main PET tracers contain 18F-FDG and dopaminergic neuron function targeting imaging tracers. The research status and progresses of 18F-FDG PET brain imaging and dopaminergic neuron function targeting imaging on evaluation of PD were reviewed in this article.

Objective: T To investigate the distribution and occurrence probability of artifact of "hot air spot" in integrated PET/MR examination, and the role of time of flight (TOF) in alleviating the artifact of "hot air spot ". Methods: The occurrence sites and probability of artifact of "hot air spot" in 105 examinees who underwent integrated whole-body PET/MR examination were retrospectively analyzed, and the occurrence of heat organ sign in integrated PET/MR without TOF technology and TOF-PET/MR images were evaluated. Results: The artifacts of "hot air spot" were distributed in sinus, trachea, gastric sinus, colon and rectum, and most commonly in trachea in the integrated PET/MR examination, and the incidence rates were 60.00%(63/105), 68.57%(72/105), 8.57%(9/105), 20.00%(21/105) and 16.19%(17/105), respectively. The SUVmax of different parts on PET/MR images without TOF technology were 4.09±2.17, 1.77±0.81,1.75±0.85,3.73±0.51 and 11.77±8.39, respectively. The SUVmean of different parts on integrated TOF-PET/MR images were 3.19±1.87, 1.38±0.70, 1.44±0.85, 2.68±0.46 and 6.78±4.19, respectively. The SUVmax and SUVmean of artifact of "hot air spot" on PET/MR images without TOF technology were higher than those on integrated TOF-PET/MR images (all P<0.01). Conclusion: The artifact of "hot air spot " mainly exists in the sinuses, trachea and digestive tract in integrated whole-body PET/MR examination. The artifact of "hot air spot" in the trachea is the most commonly happened among them. TOF technology can obviously help to reduce the "hot air spot" artifact on the integrated PET/MR examination without TOF technology, thus significantly improving the quality of the integrated PET/MR image.

Objective To explore the consistency of time-of-flight (TOF) technology of PET/MRI and PET/CT for max standardized uptake value (SUVmax) of body malignant tumors.Methods A retrospective analysis of TOF-PET/CT and TOF-PET/MR imaging data about twenty patients with body malignant tumors was performed.Patients were divided into two groups (each n=10),including PET/CT first and sequentially PET/MR group and PET/MR first and sequentially PET/CT group.Bland-Altman figure was used to evaluate consistency of SUVmax of malignant lesions between TOF-PET/CT and TOF-PET/MR.Multi-way ANOVA was used to analysis effect of machine type and exam order on SUVmaxof malignant lesions in TOF-PET/CT and TOF-PET/MR.Results SUVmax of malignant lesions in TOF-PET/CT and TOF-PET/MR had good consistency in two groups (PET/CT first and sequentially PET/MR group:Mean difference was 3.06,95％CI was [-7.5,13.6];PET/MR first and sequentially PET/CT group:Mean difference was 3.0,95％CI was [-2.4,8.3]).SUVmax was not influenced by machine type (F=0.005,P=0.95),but exam order (F=46.00,P＜0.001).Conclusion PET/MR and PET/CT with TOF technology have comparative diagnostic value in SUVmaxof body malignant lesions.SUVmax of body malignant lesions increases in delay time,which is not related to machine type,but exam time.