[Attenuation correction methods in PET and PET/CT: basic principles and validity].
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Biomedical subjects
Shoichi Watanuki
Publications and source records attributed to Shoichi Watanuki.
Decreased striatal D2 receptor density associated with severe behavioral abnormality in Alzheimer's disease.
OBJECTIVES: Since patients manifesting behavioral and psychological symptoms of dementia (BPSD) are a burden for their families and caregivers, the underlying neurobiological mechanism of this condition should be clarified. Using positron emission tomography (PET), we previously reported that wandering behavior in dementia was associated with a disturbed dopaminergic neuron system. We herein investigated the relationship between the severity of BPSD and the striatal D2 receptor density in Alzheimer's disease (AD). METHODS: Ten patients with probable AD as per the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) and the AD and Related Disorders Association (ADRDA) criteria and five normal subjects were examined with PET. The tracer used was [11C]raclopride (D2 antagonist). The uptake of [11C] raclopride was calculated as the estimation of binding potential (BP) of the striatum to the cerebellum. The AD patients were institutionalized in multiple nursing homes, and their BPSD were evaluated by the Behavioral Pathology in AD Frequency Weighted Severity Scale (BEHAVE-AD-FW) scale (Reisberg). RESULTS: There was a significant inverse Spearman's correlation between BEHAVE-AD-FW score and the BP, especially between the score of the behavioral domain and the BP values. The BP was found to be lower in severer BPSD patients. CONCLUSIONS: Patients with AD who manifest severe BPSD may have some dysfunction of striatal dopamine metabolism compared with those without BPSD.
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[Reliability of a positron emission tomography system (CTI:PT931/04-12)].
PURPOSE: The maintenance data of a PET system (PT931/04-12 CTI Inc.) was analyzed to evaluate its reliability. METHOD: We examined whether the initial performance for the system resolution and efficiency is kept. The reliability of the PET system was evaluated from the value of MTTF (mean time to failure) and MTBF (mean time between failures) for each part of the system obtained from the maintenance data for 13 years. RESULTS: The initial performance was kept for the resolution, but the efficiency decreased to 72% of the initial value. The 83% of the troubles of the system was for detector block (DB) and DB control module (BC). The MTTF of DB and BC were 2,733 and 3,314 days, and the MTBF of DB and BC per detector ring were 38 and 114 days. The MTBF of the system was 23 days. We found seasonal dependence for the number of troubles of DB and BC. This means that the trouble may be related the humidity. CONCLUSION: The reliability of the PET system strongly depends on the MTBF of DB and BC. The improvement in quality of these parts and optimization of the environment in operation may increase the reliability of the PET system. For the popularization of PET, it is effective to evaluate the reliability of the system and to show it to the users.
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