Target-specific contrast agents for magnetic resonance microscopy

High-resolution ex vivo magnetic resonance microscopy (MRM) can be used to delineate prominent architectonic features in the human brain, but increased contrast is required to visualize more subtle distinctions. The goal of this thesis is to employ target-specific MR contrast agents to regionally alter relaxation rates, resulting in increased contrast in ex vivo MRM of the human brain, with the aim of providing richer information about cyto- and/or myelo-architechtonics than is currently achievable. To accomplish this goal, a traditional optical myelin stain, luxol fast blue (LFB) MBSN with a paramagnetic copper core, has been introduced as a white-matter-selective MR contrast agent in ex vivo brain tissue. The solution relaxivity of LFB was measured at high (4.7 Tesla) and ultra-high (14 Tesla) field strengths. A methodology was developed for staining large tissue samples, enabling MR imaging. Longitudinal (R1) and transverse (R.2) relaxation rates in LFB-stained tissue increased proportionally with myelination at both field strengths. Ri changes produced larger contrast-to-noise ratios (CNR), per unit time, on Ti-weighted images between the deeper, more myelinated cortical layers (IV-VI) and adjacent, superficial layers (I-III) at both field strengths. Specifically, CNR for LFB-treated samples increased by 229± 13 per cent at 4.7T and 269± 25 per cent at 14T when compared to controls. Also, additional cortical layers (IVca, IVd, and Va) became resolvable in 14TMR images after en bloc staining with LFB. After imaging was completed, the LFB-stained sample was prepared for light microscopy.

Department dc:contributor.department

Harvard University--MIT Division of Health Sciences and Technology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Hepler Blackwell, Megan Leticia

Advisor dc:contributor.advisor

• Florian S. Eichler.

• Harvard University--MIT Division of Health Sciences and Technology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/42202

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/42202