Biology Reference
In-Depth Information
Chapter 41
Laser Speckle Imaging
Nils Hecht , Ulf C. Schneider , Johannes Woitzik , and Peter Vajkoczy
Abstract
Impaired cortical cerebral blood fl ow (CBF) is a main indicator for hemodynamic perfusion defi cits of the
brain. After aneurysmal subarachnoid hemorrhage (SAH), vasospasm may cause hemodynamic hypoperfu-
sion and subsequent cortical border zone infarction. In order to provide dynamic real-time assessment of
cortical CBF after experimental SAH, Laser Speckle Contrast Analysis (LASCA) serves as a novel tool for
semiquantitative and noninvasive cortical perfusion measurement with high spatial and temporal resolu-
tion. This chapter describes the principle of LASCA, technique and procedure, pitfalls and limitations of
the technique on the basis of a mouse model of aneurysmal SAH.
Key words:
Aneurysmal subarachnoid hemorrhage, Cerebral blood fl ow, Cortical perfusion imaging,
Laser speckle contrast analysis
1. Introduction
Cerebral blood fl ow (CBF) measurement techniques with high
spatial resolution such as autoradiography (
11
), magnetic resonance
imaging (
4
), and positron emission tomography (
8
) are not capa-
ble of continuous fl ow assessment and hampered by low temporal
resolution. For this purpose, Laser Doppler Flowmetry (LDF) has
been established as a routine experimental and clinical tool for
noninvasive monitoring of blood fl ow velocity, traditionally
expressed through the arbitrary blood fl ow-unit “fl ux.” LDF allows
to assess changes in cortical microcirculatory fl ow (
5, 10
) with a high
temporal resolution, but remains spatially limited to small sampling
volumes in the brain and is prone to nonrepresentative measure-
ments and sampling errors. Only if the LDF probe is not reposi-
tioned during the measurement period, blood fl ow changes can be
measured in a comparative fashion, for example, before and after
an intervention expected to cause variations in regional blood fl ow.
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