| Text | 367462 2017 10.1002/mrm.26584 ISI Web of Science WOS 000416390700014 PubMed 28019018 neuromelanin MRI magnetization transfer relaxation Contrast mechanisms associated with neuromelanin MRI Trujillo P.; Summers P.E.; Ferrari E.; Zucca F.A.; Sturini M.; Mainardi L.T.; Cerutti S.; Smith A.K.; Smith S.A.; Zecca L.; Costa A. Trujillo, Paula; Summers, Paul E.; Costa, Antonella Department of Neuroradiology, Fondazione IRCCS Ca Granda Ospedale Maggiore Policlinico, Milan, Italy; Trujillo, Paula; Mainardi, Luca T.; Cerutti, Sergio Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy; Ferrari, Emanuele; Zucca, Fabio A.; Zecca, Luigi Institute of Biomedical Technologies, National Research Council of Italy, Segrate, Italy; Sturini, Michela Department of Chemistry, University of Pavia, Pavia, Italy; Smith, Alex K.; Smith, Seth A. Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA; Smith, Alex K.; Smith, Seth A. Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA; Smith, Seth A. Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA. Trujillo, P reprint author , Fondazione IRCCS Ca Granda Ospedale Maggiore Policlinico, Department of Neuroradiology, Via F. Sforza 35, 20122, Milan, Italy; e mail paula.trujillo@polimi.it Purpose To investigate the physical mechanisms associated with the contrast observed in neuromelanin MRI. Methods Phantoms having different concentrations of synthetic melanins with different degrees of iron loading were examined on a 3 Tesla scanner using relaxometry and quantitative magnetization transfer MT . Results Concentration dependent T1 and T2 shortening was most pronounced for the melanin pigment when combined with iron. Metal free melanin had a negligible effect on the magnetization transfer spectra. On the contrary, the presence of iron laden melanins resulted in a decreased magnetization transfer ratio. The presence of melanin or iron or both did not have a significant effect on the macromolecular content, represented by the pool size ratio. Conclusion The primary mechanism underlying contrast in neuromelanin MRI appears to be the T1 reduction associated with melanin iron complexes. The macromolecular content is not significantly influenced by the presence of melanin with or without iron, and thus the MT is not directly affected. However, as T1 plays a role in determining the MT weighted signal, the magnetization transfer ratio is reduced in the presence of melanin iron complexes. 78 Published version Publication date 2017 Nov. Epub 2016 Dec 26. Articolo in rivista Academic Press, 0740 3194 Magnetic resonance in medicine Print Magnetic resonance in medicine Print Magn. reson. med. Print Magnetic resonance in medicine Print MRM Print emanuele.ferrari FERRARI EMANUELE luigi.zecca ZECCA LUIGI fabioandrea.zucca ZUCCA FABIO ANDREA |
