Abstract: A highly elastic stent is made of an alloy that exhibits superelasticity at body temperature. At least a part of the highly elastic stent has such a property that load increases with displacement without exhibiting a distinct yield on a load-displacement curve obtained by a compression test and a bending test.

Abstract: An object of the present invention is to provide a compound represented by formula (I) which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or undetected toxicity.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.

Abstract: An object of the present invention is to provide a probe for imaging a ?-sheet structure protein which can be used for the diagnosis of conformational diseases, particularly disease (tauopathy) having a cardinal symptom such as intracerebral accumulation of tau protein, for example, Alzheimer's disease. Another object of the present invention is to provide a compound which is highly specific to tau and can image tau with satisfactory sensitivity, and also has high brain transition, low or non-recognized bone-seeking properties and low or non-recognized toxicity. According to the present invention, the above problems are solved by providing a compound of a formula I (wherein A, R1, R2, R3, R4, R5, R6, Ra and Rb are as defined in the present description) or a pharmaceutically acceptable salt or solvate thereof.