A method for T1 and T2 relaxation times validation and harmonization as a support to MRI mapping

Quantitative analysis of MR T2 relaxation times in neck muscles

T2 relaxation times (T2 times) are different between resting and exercised muscles and between muscles of healthy subjects and subjects with muscle pathology. However, studies specifically focusing on neck muscles are lacking. Furthermore, normative neck muscle T2 times are not well defined and methodology used to analyse T2 times in neck muscles is not robust. We analysed T2 times in key neck muscles and explored factors affecting variability between muscles. 20 healthy subjects were recruited. Two circular regions of interest (ROIs) were drawn in two mutually exclusive regions within neck muscles on T2 weighted images and values averaged. ROI measurements were performed by a co-investigator, supervised by a neuro-radiologist. For the first ten subjects, measurements were done from C1-T1. For the remaining subjects, ROIs were drawn at two pre-determined levels. Two MRIs were repeated at 31 degrees acquisition to evaluate the effect of muscle fibre orientation. ROI values were translated into T2 times. Results showed semispinalis capitis had the longest T2 times (range 46.88-51.42 ms), followed by splenius capitis (range 47.37-48.33 ms), trapezius (range 45.27-47.46 ms), levator scapulae (range 43.17-45.63 ms) and sternocleidomastoid (range 38.45-42.91 ms). T2 times did not vary along length of muscles and were unaffected by muscle fibre orientation (P > 0.05). T2 times of splenius capitis correlated significantly with age at C2/C3 and C5/C6 levels and trapezius at C7/T1 level. Gender did not influence relaxation times (P > 0.05). In conclusion, results of normative neck muscle T2 time values and factors influencing the T2 times could serve as a reference for future MR analysis of neck muscles. The methodology used may also be useful for related studies of neck muscles.

Development and Evaluation of the Magnetic Properties of a New Manganese (II) Complex: A Potential MRI Contrast Agent

Magnetic resonance imaging (MRI) is a non-invasive powerful modern clinical technique that is extensively used for the high-resolution imaging of soft tissues. To obtain high-definition pictures of tissues or of the whole organism this technique is enhanced by the use of contrast agents. Gadolinium-based contrast agents have an excellent safety profile. However, over the last two decades, some specific concerns have surfaced. Mn(II) has different favorable physicochemical characteristics and a good toxicity profile, which makes it a good alternative to the Gd(III)-based MRI contrast agents currently used in clinics. Mn(II)-disubstituted symmetrical complexes containing dithiocarbamates ligands were prepared under a nitrogen atmosphere. The magnetic measurements on Mn complexes were carried out with MRI phantom measurements at 1.5 T with a clinical magnetic resonance. Relaxivity values, contrast, and stability were evaluated by appropriate sequences. Studies conducted to evaluate the properties of paramagnetic imaging in water using a clinical magnetic resonance showed that the contrast, produced by the complex [Mn(II)(L')₂] × 2H₂O (L' = 1.4-dioxa-8-azaspiro[4.5]decane-8-carbodithioate), is comparable to that produced by gadolinium complexes currently used in medicine as a paramagnetic contrast agent.