The evaluation of the efficacy of a drug is a fundamental step in the development of new treatments or in the personalized therapeutic strategies and management of patients. Ideally, this evaluation should be rapid, possibly in real time, simple to implement and reliable. Moreover, for patients, it should be accompanied by the least possible adverse effects. In this study, we present a device designed to meet these objectives for assessing therapeutic response. This theranostic device is based on the use of magnetic resonance imaging and spectroscopy for the diagnostic aspect and on the application of the convection-enhanced delivery technique for the therapeutic aspect. The miniaturized device is implantable and can be used in vivo in a target tissue. In this study, the device was applied on rodent glioma models with localized administration of choline kinase inhibitor and acquisition of magnetic resonance images and spectra at 7 Tesla. The variations of concentration of key metabolites measured by the device during the administration of the molecules demonstrate the relevance of the approach and the potential of the device.