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Imaging brain vasculature with BOLD microscopy: MR detection limits determined by in vivo two‐photon microscopy
Author(s) -
Park SungHong,
Masamoto Kazuto,
Hendrich Kristy,
Kanno Iwao,
Kim SeongGi
Publication year - 2008
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21573
Subject(s) - microscopy , two photon excitation microscopy , nuclear magnetic resonance , biomedical engineering , chemistry , materials science , pathology , fluorescence , medicine , optics , physics
Rat brain vasculature was imaged at 9.4T with blood oxygenation level‐dependent (BOLD) microscopy. Data were acquired without exogenous contrast agent in <35 min using 3D gradient‐echo imaging with 78‐μm isotropic resolution. Detailed vascular patterns including intracortical veins and some branches were observed in simple magnitude‐contrast data acquired at an experimentally optimized echo time. The venous origin of the dark patterns was confirmed by oxygenation‐dependent studies, and when the systemic arterial oxygen saturation level was <80% BOLD microscopy revealed additional intracortical vessels presumed to be of arterial origin. Quantification shows a decrease of intracortical venous density with depth. The full width at half‐minimum intensity was 90–190 μm for most intracortical venous vessels identifiable by BOLD venography. Since actual diameters are not directly quantifiable by BOLD, we also measured diameter‐dependent intracortical venous density in vivo by two‐photon excitation fluorescent microscopy. Density comparisons between the two modalities, along with computer simulations, show that venous vessels as small as ≈16–30 μm diameter are detectable with 9.4T BOLD microscopy under our experimental conditions. Magn Reson Med 59:855–865, 2008. © 2008 Wiley‐Liss, Inc.