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Neurodegenerative dementias are a group of clinical syndromes manifested with impairment of cognitive functions with various pathological etiologies. Neuroimaging along with clinical presentations can make etiological diagnoses and support differentiate diagnosis of various dementias. In this article, we briefly introduced the MRI, PET and SPECT differential patterns in the three most common neurodegenerative dementias including Alzheimer's disease, frontotemporal lobe dementia and Lewy body dementia.

As the deposition of elemental sulfur may cause severe corrosion perforation risk in heat exchanger tube, it is necessary to clarify the suitability of commonly used heat exchanger tube materials in elemental sulfur - containing environments. In this paper, the corrosion behaviors under high - temperature environment containing elemental sulfur of three commonly used materials for heat exchanger tube, including 20# steel, 316L austenitic stainless steel and 2205 duplex stainless steel, were investigated by immersion test with the help of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X - ray diffractometer (XRD). Results showed that: in the 220 ℃ medium of condensate water containing 2% (mass fraction ) elemental sulfur, the average corrosion rate of 20# steel could reach 10.520 mm/a, the pitting corrosion rate of 316L stainless steel could reach 0.470 mm/a, and the corrosion rate of 2205 duplex stainless steel was only 0.036 mm/a. In addition, the main corrosion product of all the three materials was FeS2. The corrosion film on the surface of 20# steel was loose and porous, thus could only provide a poor protection. The corrosion film of 316L stainless steel and 2205 duplex stainless steel had better uniformity and density than that of 20# steel. Furthermore, 2205 duplex stainless steel could meet the service requirements of heat exchanger tubes under the as - mentioned working condition.

Objective To evaluate the clinical and paraclinical features of Chinese patients with anti- LGI1 encephalitis. Methods Patients with memory deficits, psychiatric symptoms, seizures or altered level of consciousness, suspicious of encephalitis, at presentation to Peking Union Medical College Hospital were recruited between July 2013 and January 2018, and tested for anti-LGI1 antibodies in their serum and/or cerebrospinal fluid(CSF) samples. Patients with anti-LGI1 antibodies were enrolled. The demographic characteristics, clinical manifestations, laboratory examination results, neuroimaging features, immunotherapy, follow-up practices and outcomes for included patients were registered and analyzed. Results The study enrolled 120 patients, of whom 66.7% were male. The median age was 61 years (interquartile range [IQR]: 49-66 years). Seizures(65.0%) were the most common initial symptoms. Most patients developed seizures (95.0%), including faciobrachial dystonic seizures (54.2%), memory deficits (92.5%), and psychiatric symptoms (69.1%). Brain MRI and 18F-FDG PET / CT showed that the lesions were mainly located in unilateral or bilateral medial temporal lobes, and (or) basal ganglia. Of the patients, 95.0% received intravenous immunoglobulin (IVIg) or corticosteroids, 47.5% received mycophenolate mofetil as long-term immunotherapy, and no one received second-line immunotherapy. The median follow-up was 34.2 months(IQR: 22.0-45.6 months). 91.2% had a good outcome (modified Rankin Scale score≤2 points). Residual mild memory deficits were present in 47.8% of the patients. Nine deaths were documented. Relapses occurred in 24.8% of the patients in the first year. In total, 24 (20%)cases were young patients(onset age ≤45 years).There were fewer males among the younger patients(37.5% vs. 74.0%, P < 0.01). Besides, there were fewer younger patients with psychiatric symptoms(50.0% vs. 74.0%, P=0.02), hyponatremia(33.3% vs. 68.8%, P < 0.01), and abnormalities on brain 18F-FDG PET/CT(20.8% vs. 47.9%, P=0.02). The relapse-free survival rate was significantly higher in the young patients. Conclusions Elderly males were predominant in patients with anti-LGI1 encephalitis. Most patients developed symptoms of limbic encephalitis and/or FDBS during the disease course. Several patients were young adults and lacked typical symptoms. Neuroimaging features were consistent with the involvement of limbic system or basal ganglia. Patients with anti-LGI1 encephalitis respond well to immunotherapy, irrespective of the age.

Objective To compare the metabolism pattern of the brain in patients with cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD), and to evaluate the value of brain imaging of 18F-fluorodeoxy glucose (FDG) positron emission tomography/computed tomography (PET/CT) in differentiating CAA and AD. Methods We retrospectively recruited patients with probable CAA (revised Boston diagnostic criteria) and AD of similar age from December 2020 to June 2021 at Peking Union Medical College Hospital. Patients with normal cognition that underwent 18F-FDG PET/CT during the same period were randomly included as controls. We performed visual analysis and quantitative analysis of PET/CT imaging in the three groups. Results Ten patients with probable CAA (CAA group), 10 patients with AD (AD group), and 11 control subjects with normal cognitive function (control group) that met the inclusion and exclusion criteria were enrolled. Visual analysis showed that, compared with the control group, the AD group showed mostly bilateral symmetrical hypometabolism in temporoparietal lobes, with the most significant hypometabolism in the medial temporal lobe and posterior cingulate gyrus; the CAA group exhibited unspecific cortical hypometabolic areas corresponding to hemorrhage. Quantitative analysis of voxel-based brain metabolism images showed that metabolism in the posterior cingulate gyrus, parahippocampal gyrus, parietal lobe, and medial temporal lobe was significantly reduced in the AD group compared with the control group (P < 0.01); metabolism was significantly reduced in the extensive white matter areas, as well as in the caudate nucleus head, corpus callosum, anterior cingulate gyrus, and lateral temporal cortex in the CAA group (P < 0.01). Quantitative analysis based on brain regions showed that the standardized uptake value ratio (SUVr) of 18F-FDG in the occipital/posterior cingulate (O/PC) was significantly lower in the CAA group than in the AD group (0.91±0.05 vs. 1.07±0.08, P < 0.001); the area under the curve for O/PC SUVr identification of probable CAA and AD was 0.98 (95% CI: 0.93-1.00), with an optimal threshold of 0.96, exhibiting sensitivity of 100% and specificity of 90%. Conclusions Probable CAA and AD patients exhibited distinct brain hypometabolism patterns. O/PC SUVr can be a sensitive indicator for differential diagnosis between CAA and AD.

Objectives: Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytic proliferative disorder. We performed a retrospective study to characterize the clinical and [18F]FDG PET/CT features of RDD. Methods: We retrospectively recruited 38 RDD patients with [18F]FDG PET/CT scan in our center. [18F]FDG PET/CT features were assessed, and clinical and follow-up data were recorded. Results: In the recruited patients, 20/38 (52.6%) patients had single-system disease, while others (18/38, 47.4%) had disease affecting multiple system. RDD most commonly involved the upper respiratory tract (47.4%), followed by cutaneous/subcutaneous lesion (39.5%), lymph node (36.8%), bone (31.6%), central nervous system (28.9%), and cardiovascular system (13.2%) in the recruited patients. In PET/CT, the RDD lesions were FDG-avid, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels (r = 0.418, p = 0.014), and negatively correlated with hemoglobin levels (r = −0.359, p = 0.036). The overall response rate of the first-line treatment was 80.8% in newly diagnosed RDD patients, and for patients with relapsed/progressive RDD, the overall response rate was 72.7%. Conclusion: [18F]FDG PET/CT could be a useful tool for evaluating RDD. Key Points: • About half of the patients with Rosai-Dorfman disease had single-system disease, while others had disease affecting multiple system. Rosai-Dorfman disease most commonly involved the upper respiratory tract, followed by cutaneous/subcutaneous lesion, lymph node, bone, central nervous system, and cardiovascular system. • In [18F]FDG PET/CT, Rosai-Dorfman disease was usually hypermetabolic, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels. • Rosai-Dorfman disease usually has a high overall response rate after treatment. [ABSTRACT FROM AUTHOR]