The data were fit using both the correction factor originally derived by Svaasand^{11} and stated concisely by van Veen et al.,^{15} as well to our correction factor. The Svaasand correction factor is given by Eq. (11). In Eq. (11), $\u03f5(\lambda )$ is as defined previously in Eq. (9), and $r$ is the vessel radius. Both methods have the same number of fit parameters, six. Several of them are the same: $c0$ is the relative vessel size, $c1$ is the oxygenation, $c2$, $c3$, and $c4$ are used in the parameterization of the measured backscattering signal in the absence of absorption [Eq. (10)]. The fit parameter, $c5$, however, is different. When the Svaasand correction factor is used, it is the blood volume fraction as in Eq. (12). When our correction factor is used, $c5$ controls the density of blood vessels through the equation $L=c5\xd783\u2009\u2009\mu m$ and the tissue $\mu a,eff$ is given by Eq. (13) Display Formula
$CSv=\mu a,eff\mu a=1\u2212e\u22122\u03f5(\lambda )Cbr2\u03f5(\lambda )Cbr,$(11)
Display Formula$\mu a,eff=c5\u03f5(\lambda )CSv,$(12)
Display Formula$\mu a,eff=\pi r2L2Cb\u03f5(\lambda )Cthis\u2009work$(13)