Assessment of periapical lesions by 7T magnetic resonance imaging and micro-CT - experimental study

Introduction: The currently existing imaging methods provide the opportunity to investigate even deeply the periapical lesions (PL). The objective of the study was to highlight the qualitative changes detected on 7 T MRI and micro-CT in model rats with experimentally induced PL. Material and methods: Four groups of animals were used: control group (C), experimentally induced PL group (PL), diabetes mellitus and PL group (PLD) and postmenopausal osteoporosis treated with zoledronic acid and PL group (PLO). All the animals were investigated at 14, 30 and 60 days by using MRI at a magnetic field strength of 7 Tesla and by micro-CT scanning and histopathological examination only for the group with PL, at 30 days. Results: The PL was identified based on the MRI and micro-CT images. The periapical inflammation was visible early in the axial and coronal MRI sections and appeared in marked hypersignal in the PLD group compared with the other groups of animals. Conclusion: MRI is a non-radiating method that allows in vivo early detection of PL and offers the possibility to study its evolutions in a continuous manner. Micro CT has the advantage of a high-resolution, providing detailed images of teeth and periapical structures, but it is expensive, time consuming and can only be used in vitro. Mostly micro-CT that are used in laboratories are for in vitro studies. If the two imaging modality would allow in vivo PL investigation, both can offfer complementary views on the PL evolution.