Multispectral Diffuse Reflectance Imaging of Rat Cerebral Blood Flow and Tissue Structure

Abstract

Source: Nishidate, I., et al. Simultaneous Evaluation of Cerebral Hemodynamics and Light Scattering Properties of the In Vivo Rat Brain Using Multispectral Diffuse Reflectance Imaging. J. Vis. Exp. (2017)

This video demonstrates the use of multispectral diffuse reflectance imaging to analyze cerebral blood flow, oxygen levels, and tissue structure changes in an anesthetized rat, providing insights into brain hemodynamics and morphology under varying conditions.

Protocol

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Acquisition of sample images
   Note: Images of diffusely-reflected light intensity of exposed rat brain at nine wavelengths are captured and saved on the hard drive of a personal computer using the same acquisition conditions.
   1. Gently place the rat on the stage and slowly adjust the stage level so that the camera can focus on the surface of the rat's brain.
   2. Select the "save" command from the file menu to save an image to a file.
   3. Change the filter location by rotating the filter wheel.
   4. Save an image at the other wavelengths according to the process described above. The file name should identify the sample and the wavelength (e.g., R500, R520, R540 … R760).
2. Acquisition of dark images
   NOTE: The CCD (charged-coupled device) camera can generate a light intensity in response to an electrical signal. However, there is some minor output due to noise in the electric circuits and detectors, even if light does not enter the detector; this is called dark current noise. To accurately measure the spectral intensity of light, the dark current component should be recorded as a dark image and then subtracted from the measured signal. The dark image is an image taken with the light path blocked.
   1. Turn off the halogen lamp light source.
   2. Block the light path to the CCD camera system using a shielding plate.
   3. Select the "save" command from the file menu to save an image to a file. The file name should identify the sample (e.g., Dark).

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
150-W halogen-lamp light source	Hayashi Watch Works Co., Ltd, Tokyo, Japan	LA-150SAE
Light guide	Hayashi Watch Works Co., Ltd, Tokyo, Japan	LGC1-5L1000
Collecting lens	Hayashi Watch Works Co., Ltd, Tokyo, Japan	SH-F16
Interference filters l@500nm	Edmund Optics Japan Ltd, Tokyo, Japan	#65088
Interference filters l@520nm	Edmund Optics Japan Ltd, Tokyo, Japan	#65093
Interference filters l@540nm	Edmund Optics Japan Ltd, Tokyo, Japan	#65096
Interference filters l@560nm	Edmund Optics Japan Ltd, Tokyo, Japan	#67766
Interference filters l@570nm	Edmund Optics Japan Ltd, Tokyo, Japan	#67767
Interference filters l@580nm	Edmund Optics Japan Ltd, Tokyo, Japan	#65646
Interference filters l@600nm	Edmund Optics Japan Ltd, Tokyo, Japan	#65102
Interference filters l@730nm	Edmund Optics Japan Ltd, Tokyo, Japan	#65115
Interference filters l@760nm	Edmund Optics Japan Ltd, Tokyo, Japan	#67777
Motorized filter wheel	Andover Corporation, NH, USA	FW-MOT-12.5
16-bit cooled CCD camera	Bitran, Japan	BS-40
Video zoom lens	Edmund Optics Japan Ltd, Tokyo, Japan	VZMTM300i
Spectralon white standard with 99% diffuse reflectance	Labsphere Incorporated, North Sutton, NH, USA	SRS-99-020