Measurement of cerebral blood volume in mouse brain regions using micro-computed tomography.
Micro-computed tomography (micro-CT) is an X-ray imaging technique that can produce detailed 3D images of cerebral vasculature. This paper describes the development of a novel method for using micro-CT to measure cerebral blood volume (CBV) in the mouse brain. As an application of the methodology, we test the hypotheses that differences in CBV exist over anatomical brain regions and that high energy demanding primary sensory regions of the cortex have locally elevated CBV, which may reflect a vascular specialization. CBV was measured as the percentage of tissue space occupied by a radio-opaque silicon rubber that fills the vasculature. To ensure accuracy of the CBV measurements, several innovative refinements were made to standard micro-CT specimen preparation and analysis procedures. Key features of the described method are vascular perfusion under controlled pressure, registration of the micro-CT images to an MRI anatomical brain atlas and re-scaling of micro-CT intensities to CBV units with selectable exclusion of major vessels. Histological validation of the vascular perfusion showed that the average percentage of vessels filled was 93+/-3%. Comparison of thirteen brain regions in nine mice revealed significant differences in CBV between regions (p<0.0001) while cortical maps showed that primary visual and auditory areas have higher CBV than primary somatosensory areas.
Mouse Imaging Centre, The Hospital for Sick Children, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada. brige@phenogenomics.ca
Brige P
BP
Chugh
Jason P
JP
Lerch
Lisa X
LX
Yu
Martin
M
Pienkowski
Robert V
RV
Harrison
R Mark
RM
Henkelman
John G
JG
Sled
D000818:Animals; D001810:Blood Volume / Q000502:physiology*; D001811:Blood Volume Determination / Q000379:methods*; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D021621:Imaging, Three-Dimensional / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL; D055420:Perfusion Imaging / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000662:veterinary*