Hemispatial neglect is a kind of cognitive impairment characterized by failure to report,respond or orient to stimuli presented in ipsi-or contra-lateral space after brain injury,which cannot be attributed to sensory or motor defects.Although there are various diagnosis and assessment methods,none is regarded as standard.The paper and pencil test is commonly used in routine clinical workup.The mechanism is controversial and the most accepted opinion is due to visuospatial attention defect.Imaging study focuses on exploring the functional regions leading to the hemispatial neglect.As functional imaging,SPECT and PET have capability to evaluate the perfusion,glucose metabolism and cellular vitality,which have been found increasingly useful and applicable clinically in the field of diagnosis for cognitive impairment diseases.They are likely to have potential for contribution in the study of hemispatial neglect.

There exist many studies on the radioligands for imaging of nicotinic acetylcholine receptors (nAChRs) in the human brain and the most common one is the radioligand binding to α4β2-nAChRs,the main subtype of cerebral nAChRs.There are few data published in the literature on the radioligands for the imaging of α7-nAChRs,another important subtype of cerebral nAChRs.This review summarizes recent work on PET radioligands for the imaging of cerebral nAChRs.

Neuronal nicotinic acetylcholine receptors (nAChRs) are involved in a spectrum of cognitive functions and related to some psychiatric and neurodegenerative disorders such as AD,PD,autosomal dominant nocturnal frontal lobe epilepsy and schizophrenia.Nuclear medicine imaging of neuronal nAChRs in living human is a relatively new field.Halogenated analogs of 3 (2 (S)-2-azetidinylmethoxy) pyridine (A-85380) are the most widely used brain imaging radiotracers.In this review,the progress on the latest research on SPECT and PET using the analogs of A-85380 is summarized.

Objective To explore the changes in regional cerebral blood flow(rCBF)and cerebral hemodynamics in patients with CCVI.Methods Twenty patients diagnosed as CCVI were enrolled to undergo single photon emission computed tomography(SPECT)rCBF imaging or transcranial Doppler uhrasonography(TCD)examination.All the patients were free from cerebral structural abnormalities as demonstrated by X-CT or magnetic resonance imaging(MRI).Cranial arteries blood flow velocity,pulsating index(PI)were measured by TCD and compared with the mean of rCBF as measured by SPECT.Results On SPECT images, decreased rCBF lesions were found in 95 percent of patients(19/20).The areas of hypoperfusion were mainly located in frontal,temporal,parietal lobes and fondues nodus.Increased cranial arteries blood flow velocity was found in the anterior cerebral artery(ACA)and middle cerebral artery(MCA)in 80 percent of patients (16/20).There were no correlations among rCBF,the decreased percentage of rCBF,average velocity,and PI of cranial arteries.Conclusions By performing SPECT rCBF and TCD on CCVI patients,the degree of changes in rCBF and hemodynamics Can be evaluated easily,which is valuable for early clinical diagnosis and treatment of CCVI.

Objective To compare the imaging features of 18F-FDG PET/CT in malignant pleural effusion (MPE) and tuberculosis pleural effusion (TPE).Methods From January 2012 to December 2014,93 patients (52 males,41 females,and average age (66.7±12.7) years) with unexplained pleural effusion who underwent 18F-FDG PET/CT were retrospectively studied.MPE and TPE were confirmed by histology,cytology or clinical follow-up.Lesion SUVmax and T/NT were calculated.Both lesion size and density (in Hounsfield units) of pleural abnormalities on CT images were measured.The difference of images between MPE and TPE was analyzed.Diagnostic efficiency of 18F-FDG PET/CT for detecting MPE and TPE were estimated.Two-sample t test and x2 test were used to analyze the data.Results The lesion SUVmax of 66 patients with MPE and 27 patients with TPE was higher than that in normal tissues (7.72±6.50,8.43±4.92;t=7.81 and 7.15,both P＜0.01),but there was no statistical difference between the TPE and MPE (t=0.56,P＞0.05).T/NT was not significantly different between MPE and TPE (5.40±4.29,5.20±2.73 respectively,t=-0.22,P＞0.05) either.The uptake features of 18F-FDG were different between MPE and TPE (x2=29.3,P＜0.01).When the nodular 18F-FDG uptake increase in pleura was taken as the malignancy,diffuse 18F-FDG uptake increase in pleura as tuberculosis,the sensitivity,specificity,positive predictive value,and negative predictive value of 18F-FDG PET/CT were 78.8％ (52/66),81.5％ (22/27),91.2％ (52/57),61.1％ (22/36),respectively,for differentiation of MPE from TPE.Primary cancers were found in 43 patients.When the nodular uptake increase in pleura,or primary cancer associated with increased pleural uptake found by PET was taken as the malignancy,the above mentioned parameters were95.5％(63/66),81.5％(22/27),92.6％(63/68),88.0％(22/25),respectively.Conclusions The 18FFDG uptake in MPE and TPE is higher than that in normal tissues.18F-FDG PET/CT is helpful in the search for the primary tumor of MPE.Qualitative method of 18F-FDG PET/CT has a good value in the differentiation of MPE from TPE.

Background and purpose:The proportion of incidental thyroid cancer in PET imaging was sig-niifcantly increased with the wide application of18F-FDG PET/CT. The correlation between the glucose metabolism of thyroid incidental thyroid cancer and pathological changes is unclear. The objective of this study is to analyze the relationship between the glucose metabolism by18F-FDG PET/CT and tumor differentiation or lymph node metastasis in patients with incidental thyroid cancer.Methods:A total of 195 patients with focal FDG-avid thyroid incidentaloma during cancer evaluation were enrolled. Fifty-three patients were diagnosed as having thyroid cancer by the pathology. The SUVmax of thyroid cancer foci, lesion size, lesion number, and SUVmax of normal thyroid tissue were quantiifed. The tumor pathological grades and lymph node metastasis were analyzed by the pathology. The patients were broken down into 4 groups (G1, G2, G3 and G4) according to the tumor pathological grades and lymph node metastasis (differentiated thyroid cancer, non-differentiated thyroid cancer, without lymph node metastasis and with lymph node metastasis). The differences of glucose metabolism between G1and G2groups, G3 and G4 groups were analyzed.Results:Fifty-three foci were found by PET imaging. Sixty-two foci were found by the pathology (37 papillary thyroid carcinoma, 4 follicular thyroid carcinoma, 9 medullary thyroid carcinoma, 3 poorly differentiated thyroid cancer). The SUVmax in the normal thyroid tissue, G1and G2were 1.51±0.30, 4.25±1.70 and 6.34±2.45, respectively. The SUVmax in the G1and G2were signiifcantly higher than in the normal thyroid tissue (t=11.0,t=7.10,P<0.01). The SUVmax of G3was 4.77±2.15, and the SUVmax of G4group was 4.67±2.02. The differences between G1and G2groups, G3 and G4groups were not statisti-cally signiifcant (t=3.61,P>0.05;t=0.33,P=0.56).Conclusion:The differentiated incidental thyroid carcinoma and non-differentiated incidental thyroid carcinoma had high glucose metabolism, and there was no signiifcant difference in the levels of glucose metabolism in different differentiation degree and metastasis ability cancer.

OBJECTIVETo explore the correlations between the occurrence and severity of neglect and the region, range or extent of the decrease in regional cerebral blood flow (rCBF).

METHODSNineteen dextromanual patients who were diagnosed as unilateral stroke clinically and hemispatial neglect by a neglect test battery received single photon emission computed tomography (SPECT) scans.

RESULTSOn images, the damages of patients with neglect were seen most frequently in the frontal cortex, and then in turn in the parietal cortex, occipital cortex, temporal cortex, basal ganglia and thalamus. Most patients with neglect had two or more regions damaged. The most significant region was temporal-parietal-occipital (TPO) junction. The correlation coefficient between rCBF and the severity of neglect was -0.34 (t = -1.5, P > 0.05), and that between the decrease percentage of rCBF and the severity of neglect was 0.34 (t = 1.47, P > 0.05). The correlation coefficients between the range, number of foci, the flow deficit size and the severity of neglect were 0.71 (t = 4.13, P < 0.01), 0.70 (t = 4.07, P < 0.01) and 0.64 (t = 3.40, P < 1.01), respectively.

CONCLUSIONSThe severity of neglect correlates with rCBF and the decrease percentage of rCBF insignificantly, but correlates positively with the range, number of foci and the flow deficit size significantly. Hemispatial neglect is caused by the damage of multiple sites and combined damage results in more severe neglect.

Adult ; Aged ; Cerebral Cortex ; blood supply ; Female ; Frontal Lobe ; blood supply ; Humans ; Male ; Middle Aged ; Perceptual Disorders ; diagnostic imaging ; physiopathology ; Regional Blood Flow ; Tomography, Emission-Computed, Single-Photon

Nicotinic acetylcholine receptors (nAChRs) play an important role in cognitive function.Vascular cognitive impairment (VCI) seriously affects the health and quality of life.Early diagnosis and timely effective intervention of VCI may delay or even prevent the occurrence of dementia.The development of nAChRs agents and molecular imaging,such as PET/CT or PET/MR,may promote research on the early diagnosis and treatment of VCI.This review summarizes the pathogenesis of VCI,the relationship between nAChRs and VCI,the progress on nAChRs receptor imaging,and the treatment of VCI.

Objective:To investigate the value of 18F-FDG PET/CT imaging in the diagnosis of suspected autoimmune encephalitis (AE) in children with epilepsy and negative MRI. Methods:From May 2019 to August 2022, 94 suspected AE children (49 males, 45 females; age 1-15 years) with epilepsy and negative MRI who underwent brain 18F-FDG PET/CT imaging at Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were retrospectively analyzed. All patients were divided into AE and non-AE groups based on clinical final diagnosis. The effectiveness of visual diagnosis was evaluated. The cortical lesion extent score (S), and SUV max, SUV mean and minimum of SUV (SUV min) of cortical lesions (L), basal ganglia (B) and thalamus (T) were measured and SUV ratios (SUVR) of L/B or L/T were obtained. Independent-sample t test or Mann-Whitney U test was used to analyze data. Binary logistic regression analysis was used to screen the diagnostic factors of AE, and a diagnostic model was established. The diagnostic efficiency was evaluated by ROC curve analysis and Delong test. Results:There were 53 cases in AE group and 41 cases in non-AE group. Based on visual analysis, the sensitivity, specificity and accuracy of 18F-FDG PET/CT for AE were 100%(53/53), 43.9%(18/41) and 75.5%(71/94), respectively. Differences of LSUV max, LSUV mean, LSUV min, L/BSUVR max, L/BSUVR mean, L/BSUVR min, L/TSUVR max, L/TSUVR mean, L/TSUVR min and S between AE and non-AE groups were statistically significant ( z=-6.74, t values: from -8.51 to -3.97, all P<0.001). ROC curve analysis showed that the AUC of L/BSUVR max was the highest (0.914) among visual analysis and semi-quantitative parameters. Logistic regression analysis showed that S (odds ratio ( OR)=11.40, 95% CI: 2.18-59.52, P=0.004), L/BSUVR max( OR=13.19, 95% CI: 2.11-82.51, P=0.006) and L/TSUVR max( OR=9.66, 95% CI: 1.57-59.55, P=0.015) were independent diagnostic factors for AE. Regression model was established: P=1/(1+ e - x), x=2.433×S+ 2.580×L/BSUVR max+ 2.267×L/TSUVR max-3.802. The AUC of this model was 0.948, with the sensitivity, specificity and accuracy of 98.1%(52/53), 90.2%(37/41) and 94.7%(89/94), respectively. The diagnostic efficacy of the optimized scoring system was consistent with the pre-optimization model, and were both superior to L/BSUVR max(both z=2.01, both P=0.040). Conclusion:The diagnostic model and scoring system based on the semi-quantitative analysis of 18F-FDG PET/CT have better diagnostic efficacy for AE and are superior to semi-quantitative parameters alone.

The important role of TDP-43 proteinopathy in Alzheimer's disease (AD) has been gradually revealed. High proportion of AD patients have TDP-43 proteinopathy on their postmortem diagnosis. Patients with TDP-43 proteinopathy show more sever hippocampal atrophy and cognitive dysfunction, suggesting that TDP-43 proteinopathy can serve as an important target in AD diagnosis and treatment. Evaluation of TDP-43 proteinopathy in vivo would hold great promise in AD diagnosis, drug development and treatment. In this review, we describe the pathological characteristics of TDP-43 proteinopathy in AD, and summarize the recent progress of TDP-43 proteinopathy in the diagnosis and treatment of AD.