Prepolarized MRI of hard tissues and solid‐state matter

• Published in: NMR in biomedicine 2022-08, Vol.35 (8), p.e4737-n/a
• Main Authors: Borreguero Morata, Jose, González, José M., Pallás, Eduardo, Rigla, Juan P., Algarín, José M., Bosch, Rubén, Galve, Fernando, Grau‐Ruiz, Daniel, Pellicer, Rubén, Ríos, Alfonso, Benlloch, José M., Alonso, Joseba
• Format: Article
• Language: English
• Subjects: Biological products; Field strength; hard tissues; low field; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Magnetics; Magnets; Models, Theoretical; MRI; prepolarization; Signal-To-Noise Ratio; solid state; Tissues; Vibrations
• ISSN: 0952-3480; 1099-1492; 1099-1492
• DOI: 10.1002/nbm.4737

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 μs. To this end, we have used resin, dental and bone samples, all with T1 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. Prepolarized MRI (PMRI) is a long‐established technique conceived to counteract the loss in signal strength 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 hard‐tissue prepolarization is possible with a 0.29 T scanner designed for dental MRI. These results can be applied to clinical dental imaging, making a low‐field PMRI scanner a possible replacement for hazardous X‐ray systems.