Glucose Positron Emission Tomography Imaging Research Articles

Functional and neuropathological changes induced by injection of distinct alpha-synuclein strains: A pilot study in non-human primates

The role of alpha-synuclein in Parkinson's disease has been heavily investigated since its discovery as a component of Lewy bodies. Recent rodent data demonstrate that alpha-synuclein strain structure is critical for differential propagation and toxicity.Based on these findings, we have compared, for the first time, in this pilot study, the capacity of two alpha-synuclein strains and patient-derived Lewy body extracts to model synucleinopathies after intra-putaminal injection in the non-human primate brain. Functional alterations triggered by these injections were evaluated in vivo using glucose positron emission tomography imaging. Post-mortem immunohistochemical and biochemical analyses were used to detect neuropathological alterations in the dopaminergic system and alpha-synuclein pathology propagation.In vivo results revealed a decrease in glucose metabolism more pronounced in alpha-synuclein strain-injected animals. Histology showed a decreased number of dopaminergic tyrosine hydroxylase-positive cells in the substantia nigra to different extents according to the inoculum used. Biochemistry revealed that alpha-synuclein-induced aggregation, phosphorylation, and propagation in different brain regions are strain-specific.Our findings show that distinct alpha-synuclein strains can induce specific patterns of synucleinopathy in the non-human primate, changes in the nigrostriatal pathway, and functional alterations that resemble early-stage Parkinson's disease.

Changing Landscapes in the Neuroimaging of Dementia.

Neuroimaging in dementia has advanced several folds in the past decade. It has evolved from diagnosing secondary causes of dementia to the current use in identifying primary dementia and aid in clinically perplexing situations. There has been a leap in the imaging technology that can virtually dissect the brain with a high degree of radiopathological correlation. The neuroimaging in dementia is classified into structural, functional, and molecular imaging. Structural imaging includes voxel-based morphometry and diffusion tensor imaging. Functional imaging includes 18F-fluorodeoxy glucose positron emission tomography imaging, 99mTc hexamethylpropyleneamineoxime single photon emission computed tomography imaging, and functional magnetic resonance imaging studies. Molecular imaging includes amyloid imaging, tau imaging, and translocated protein imaging. These advancements have led to using neuroimaging as a biomarker in assessing the progression and also in deciphering prognosis of the disease. In this article, we discuss the current clinical relevance of these neurological advancements.

Primary and Recurrent Early Stage Laryngeal Cancer: Preliminary Results of 2-[Fluorine 18]fluoro-2-deoxy-d-glucose PET Imaging

To evaluate the effectiveness of 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in the identification of early stage (T1-T2) primary and recurrent laryngeal cancer. Twelve patients with T1 or T2 laryngeal cancer underwent imaging prospectively with PET. Seven patients had new disease, and five had recurrent disease. All patients underwent imaging prior to planned therapy and tissue biopsy. PET images were evaluated by using standardized uptake ratios and visual analysis. Histopathologic evidence of early stage cancer was documented in the 12 patients. One had a carcinoma in situ, nine had T1 tumors, and two had T2 tumors. Of the 12 patients, 10 had vocal cord tumors, one had a hypopharyngeal tumor, and one had a preepiglottic tumor. Eleven (92%) patients with early stage cancer had standardized uptake ratios indicative of malignancy (mean, 4.6; SD, 1.8; 95% CI, 1.2; range, 2.8-7.6). One had false-negative results (standardized uptake ratio = 2.3). Nine underwent CT, and results in the larynx were normal in seven and abnormal in two. FDG PET can be used to identify primary and recurrent early stage laryngeal cancer. It may be useful for follow-up after therapy.