[EN] Prepolarized MRI (PMRI) is a long-established technique conceived to counteract the loss in signal-to-noise ratio (SNR) inherent to low-field MRI systems. When it comes to hard biological tissues and solid-state matter, PMRI is severely restricted by their ultra-short characteristic relaxation times. Here we demonstrate that efficient hard-tissue prepolarization is within reach with a special-purpose 0.26 T scanner designed for ex vivo dental MRI and equipped with suitable high-power electronics. We have characterized the performance of a 0.5 T prepolarizer module, which can be switched on and off in 200 mu s. To this end, we have used resin, dental and bone samples, all with T1T1 times of the order of 20 ms at our field strength. The measured SNR enhancement is in good agreement with a simple theoretical model, and deviations in extreme regimes can be attributed to mechanical vibrations due to the magnetic interaction between the prepolarization and main magnets.Agencia Valenciana de la Innovaci~o; European Regional Development Fund; Ministerio de Ciencia e Innovacion; This work was supported by the Ministerio de Ciencia e Innovaci~on of Spain through research grant PID2019-111436RBC21. Action co-financed by the European Union through the Programa Operativo del Fondo Europeo de Desarrollo Regional (FEDER) of the Comunitat Valenciana 2014-2020 (IDIFEDER/2018/022). JMG and JB acknowledge support from the Innodocto program of the Agencia Valenciana de la Innovacion (INNTA3/2020/22 and INNTA3/2021/17); Ministerio de Ciencia e Innovaci~on of Spain, Grant/Award Number: PID2019-111436RB-C21; Programa Operativo del Fondo Europeo de Desarrollo Regional (FEDER) of the Comunitat Valenciana, Grant/Award Number: IDIFEDER/2018/022; Innodocto program of the Agencia Valenciana de la Innovacion, Grant/Award Numbers: INNTA3/2020/22, INNTA3/2021/17Borreguero-Morata, J.; González Hernández, JM.; Pallás Lodeiro, E.; Rigla, JP.; Algarín-Guisado, JM.; Bosch-Esteve, R.; Galve, F.... (2022). Prepolarized MRI of Hard Tissues and Solid-State Matter. NMR in Biomedicine. 35(8):1-10. https://doi.org/10.1002/nbm.473711035