Comparison of retinal and cerebral blood flow between continuous arterial spin labeling MRI and fluorescent microsphere techniques.
OBJECTIVE
To compare basal retinal and cerebral blood flow (BF) values using continuous arterial spin labeling (CASL) MRI and fluorescent microspheres.


METHODS
A total of 41 animals were used. BF was measured using an established microsphere technique (a mixture of 2.5 million 8 μm green and 0.5 million 10 μm blue fluorescent microspheres) and CASL MRI blood flow measurement in the rat retina and brain at 7 Tesla (T) and 11.7T, respectively.


RESULTS
Retinal BF by MRI was 1.18 ± 0.57 mL/g/min and choroidal BF was 8.14 ± 1.8 mL/g/min (n = 6). Microsphere retinal BF was 9.12 ± 2.8 μL/min per tissue and choroidal BF was 73.38 ± 44 μL/min per tissue (n = 18), corresponding to a retinal BF value of 1.22 ± 0.36 mL/g/min by means of a wet weight conversion. The wet-weight of the choroid could not be determined. To corroborate our findings, cerebral BF (CBF) by MRI was also analyzed. In the cerebral cortices, CBF was 0.91 ± 0.29 mL/g/min (n = 14) by CASL MRI and 1.09 ± 0.37 mL/g/min (n = 6) by microspheres. There were no significant differences found between MRI and microsphere blood flow in the retina and brain.


CONCLUSIONS
BF values in the rat retina and cerebral cortex by MRI are in agreement with those obtained by the microsphere technique.
Departments of Neurology, Biomedical Research Imaging Center, and Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina, USA; Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
Yen-Yu I
YY
Shih
Bryan H
BH
De La Garza
Shiliang
S
Huang
Guang
G
Li
Lin
L
Wang
Timothy Q
TQ
Duong
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002829:Choroid / Q000098:blood supply; D005453:Fluorescence; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008863:Microspheres; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000502:physiology; D012171:Retinal Vessels / Q000502:physiology*; D013113:Spin Labels
D013113:Spin Labels
MRI; blood flow; brain; choroid; microsphere; rat; retina