The potential role of magnetic resonance brain relaxometry in veterinary medicine: a preliminary study

Magnetic Resonance (MR) is a non-invasive modality of choice for the evaluation of brain morphology, with superior performance as compared to other techniques. However, MR images are typically assessed qualitatively, thus relying on the experience of the involved radiologist. This may lead to errors of interpretation in the presence of subtle alterations and does not exploit the full potential of this technique as a quantitative diagnostic tool. To this end Magnetic Resonance Relaxometry (MRR), which is able to quantitively characterize the tissues under investigation through their relaxation rates, seems extremely promising. Many studies assessed the feasibility of relaxometry as a diagnostic tool in human brain disorders, with the most promising results obtained in the evaluation of neurodegenerative diseases and in the oncologic field. However, despite such extensive literature in human medicine, due to the lack of standardized protocols and the need of high-field MRI scanners, to date few studies have been performed on companion animals. In this work, first we describe relaxometry applications in human neuropathology and their possible extension to companion animals both in the experimental and clinical fields. Then, we present two experiments performed on a typical standard clinical scanner operating at 0.25 T to show that, despite the low field intensity, this technique may be promising even in the clinical setup. We tested the relaxometry protocol in a phantom study and then applied it to a real clinical case study. The results showed that this protocol used on a phantom led to a higher contrast, as compared to the standard approach. Furthermore, when applied to a real case study, this protocol revealed brain lesions undetected by the standard technique which were confirmed by a histopathological examination. These preliminary results are encouraging and support the development of this approach as an advanced diagnostic tool even in a clinical setting where low field MRI scanners are typically employed.