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Random process estimator for laser speckle imaging of cerebral blood flow.

Miao P, Li N, Thakor NV, Tong S - Opt Express (2010)

Bottom Line: A new random process estimator is proposed and able to overcome these drawbacks.In an in-vitro study, random process estimator outperforms either spatial LASCA or temporal LASCA by providing much higher SNR (random process estimator vs. spatial LASCA vs. temporal LASCA: 33.64+/-6.87 (mean+/-s.t.d.) vs. 9.08+/-2.85 vs. 3.83+/-1.05).In an in-vivo structural imaging study, random process estimator efficiently suppresses the noise in contrast image and thus improves the distinguishability of small vessels.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China.

ABSTRACT
In this paper, we develop a random process theory to explain the laser speckle phenomena. The relation between the probability distribution of speckle's integrated intensity random process Y(t) and the relative velocity v(t) is derived. Based on the random process theory, traditional spatial or temporal laser speckle contrast analysis (i.e. spatial or temporal LASCA) can be derived as the spatial or temporal estimators respectively. Both spatial LASCA and temporal LASCA suffer from noise due to insufficient statistics and nonstationarity in either spatial or temporal domain. Furthermore, either LASCA results in a reduction of spatial or temporal resolution. A new random process estimator is proposed and able to overcome these drawbacks. In an in-vitro study, random process estimator outperforms either spatial LASCA or temporal LASCA by providing much higher SNR (random process estimator vs. spatial LASCA vs. temporal LASCA: 33.64+/-6.87 (mean+/-s.t.d.) vs. 9.08+/-2.85 vs. 3.83+/-1.05). In an in-vivo structural imaging study, random process estimator efficiently suppresses the noise in contrast image and thus improves the distinguishability of small vessels. In a functional imaging study of cerebral blood flow change in the somatosensory cortex induced by rat's hind paw stimulation, random process estimator provides much lower estimation errors in single trial data (random process estimator vs. temporal LASCA: 0.31+/-0.03 vs. 1.36+/-0.09) and finally leads to higher resolution spatiotemporal patterns of cerebral blood flow.

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The denoising performance of random process estimator: (a) one frame of raw images; (b) the estimation results of  using different methods; (c) the contrast image  estimated based on all 600 raw images using the random process estimator; (d) the estimated  using different methods.
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g001: The denoising performance of random process estimator: (a) one frame of raw images; (b) the estimation results of using different methods; (c) the contrast image estimated based on all 600 raw images using the random process estimator; (d) the estimated using different methods.

Mentions: The denoising performance of random process estimator is evaluated in the in-vitro simulation experiment. During the experiment, the blood flow velocity in the polyethylene tube was strictly maintained at using the syringe pump. According to Eq. (16) and Eq. (17), the noise parts and in the random process estimator would be very closed to zeros with. Therefore, for any pixel, and based on all 600 raw images were considered as the true and. Figure 1(a)Fig. 1


Random process estimator for laser speckle imaging of cerebral blood flow.

Miao P, Li N, Thakor NV, Tong S - Opt Express (2010)

The denoising performance of random process estimator: (a) one frame of raw images; (b) the estimation results of  using different methods; (c) the contrast image  estimated based on all 600 raw images using the random process estimator; (d) the estimated  using different methods.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369537&req=5

g001: The denoising performance of random process estimator: (a) one frame of raw images; (b) the estimation results of using different methods; (c) the contrast image estimated based on all 600 raw images using the random process estimator; (d) the estimated using different methods.
Mentions: The denoising performance of random process estimator is evaluated in the in-vitro simulation experiment. During the experiment, the blood flow velocity in the polyethylene tube was strictly maintained at using the syringe pump. According to Eq. (16) and Eq. (17), the noise parts and in the random process estimator would be very closed to zeros with. Therefore, for any pixel, and based on all 600 raw images were considered as the true and. Figure 1(a)Fig. 1

Bottom Line: A new random process estimator is proposed and able to overcome these drawbacks.In an in-vitro study, random process estimator outperforms either spatial LASCA or temporal LASCA by providing much higher SNR (random process estimator vs. spatial LASCA vs. temporal LASCA: 33.64+/-6.87 (mean+/-s.t.d.) vs. 9.08+/-2.85 vs. 3.83+/-1.05).In an in-vivo structural imaging study, random process estimator efficiently suppresses the noise in contrast image and thus improves the distinguishability of small vessels.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China.

ABSTRACT
In this paper, we develop a random process theory to explain the laser speckle phenomena. The relation between the probability distribution of speckle's integrated intensity random process Y(t) and the relative velocity v(t) is derived. Based on the random process theory, traditional spatial or temporal laser speckle contrast analysis (i.e. spatial or temporal LASCA) can be derived as the spatial or temporal estimators respectively. Both spatial LASCA and temporal LASCA suffer from noise due to insufficient statistics and nonstationarity in either spatial or temporal domain. Furthermore, either LASCA results in a reduction of spatial or temporal resolution. A new random process estimator is proposed and able to overcome these drawbacks. In an in-vitro study, random process estimator outperforms either spatial LASCA or temporal LASCA by providing much higher SNR (random process estimator vs. spatial LASCA vs. temporal LASCA: 33.64+/-6.87 (mean+/-s.t.d.) vs. 9.08+/-2.85 vs. 3.83+/-1.05). In an in-vivo structural imaging study, random process estimator efficiently suppresses the noise in contrast image and thus improves the distinguishability of small vessels. In a functional imaging study of cerebral blood flow change in the somatosensory cortex induced by rat's hind paw stimulation, random process estimator provides much lower estimation errors in single trial data (random process estimator vs. temporal LASCA: 0.31+/-0.03 vs. 1.36+/-0.09) and finally leads to higher resolution spatiotemporal patterns of cerebral blood flow.

Show MeSH
Related in: MedlinePlus