Abstract: A nitroimidazole derivative represented by the following formula (1): [wherein R1 represents a hydrogen atom or a C1-C4 alkanoyl group; and X represents a fluorine atom or an isotope thereof], and a diagnostic imaging agent containing the derivative as an active ingredient. The derivative enables imaging of the ischemic sites of a circulatory organ or imaging of cancer cells, and thus the derivative can provide information about the position and the amount of the ischemic sites or the cancer cells. Therefore, the derivative contributes to selection of appropriate treatment of ischemia or cancer.

Abstract: Pyrrolo[3,2-e]pyrazolo[1,5-a]pyrimidine derivatives are disclosed. The compounds are represented by the formula (I), ##STR1## wherein R.sub.1 and R.sub.2 individually represent a hydrogen atom, a linear or branched alkyl group which may have a substituent, a cycloalkyl or phenyl group which may have a substituent, or a heterocyclic group which may have a substituent, and R.sub.3 is a hydrogen atom or a cyano group. The compounds have excellent circulatory disease curing activities as well as bronchodilation activities.