NSC683864 Structural MRI Structural MRI is increasingly accepted as a surrogate for anatomic phenotype in neuroscience research. In many areas, anatomic MRI has replaced the need for analysis of the postmortem brain in order to elucidate relationships between structure and function. It is not hard to find examples in which anatomic MRI has transformed the entire research landscape of a field: cerebrovascular disease, epilepsy, multiple sclerosis, and other inflammatory conditions, cerebral developmental disorders, to some extent psychiatric disorders, and neurodegenerative disorders. Animal model studies at high magnetic fields have made unique contributions to

this development. Morphological images of brain tissue rely largely on proton Inhibitors,research,lifescience,medical density, T1 and T2 differences between tissue types (eg, white matter vs. gray matter, cortex vs. subcortical nuclei etc.). Proton density is clearly a magnetic field independent parameter. However, relaxation times T1 and T2 are field dependent, Inhibitors,research,lifescience,medical generally increasing63,64 and decreasing1,9,65,66 respectively, with higher magnetic fields Inhibitors,research,lifescience,medical (see review in ref 67). It was recently shown that, contrary to expectations, the dispersion in T1 increases

with increasing magnetic fields in the brain, leading to superior T1-weighted structural Images at the higher magnetic fields.68 Lengthening of T1 with increasing magnetic field also holds true Inhibitors,research,lifescience,medical for blood. Blood T1 is virtually insensitive to its oxygenation state. Ex vivo measurements have shown that blood T1 varies linearly with field strength going from 1.5 T to 9.4 T according to T1= 1.226+ 0.134B0.69 This imparts a clear benefit in time-of-flight type vascular imaging, as well as perfusion imaging using spin labeling techniques. Mapping signals in all hemodynamic-based functional imaging

methods, such as fMRI and optical Inhibitors,research,lifescience,medical imaging with intrinsic signals, are mediated through the vasculature. Consequently, vascular components in these methods are of utmost significance in determining the ultimate spatial and temporal accuracy of the neural activity maps produced by these methods. Therefore, it is important to be able to image vasculature in great detail, and ideally together with functional data in order Thymidine kinase to understand more precisely the source of the fMRI signals and their spatial correlation with the volume of altered neuronal activity. Vascular imaging with high resolution is also of paramount importance in other fields of biomedical research such as tumor biology, where angiogenesis is a necessary component of tumor growth. Taking advantage of the gains in SNR and longer T1 values, the feasibility of obtaining high-resolution MR images of intracortlcal vessels was demonstrated in the cat brain.70 This accomplishment relied on a combination of time-of -flight MR angiography and T2*-weighted contrast based on both endogenous BOLD effect and exogenous iron-oxide particles.