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Imaging of temperature dependent hemodynamics in the rat sciatic nerve by functional photoacoustic microscopy.

Liao LD, Orellana J, Liu YH, Lin YR, Vipin A, Thakor NV, Shen K, Wilder-Smith E - Biomed Eng Online (2013)

Bottom Line: Our main results show that the relative functional total hemoglobin concentration (HbT) is more significantly correlated with localized temperature changes than the hemoglobin oxygen saturation (SO2) changes in the sciatic nerve.Our results show that fPAM is a promising candidate for in vivo imaging of peripheral nerve hemodynamics without the use of contrast agents.Additionally, this technique may shed light on the neuroprotective effect of hypothermia on peripheral nerves by visualizing their intrinsic hemodynamics.

View Article: PubMed Central - HTML - PubMed

Affiliation: Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, 28 Medical Drive, #05-COR, Singapore 117456, Singapore. kqshen@gmail.com.

ABSTRACT

Background: Vascular hemodynamics is central to the regulation of neuro-metabolism and plays important roles in peripheral nerves diseases and their prevention. However, at present there are only a few techniques capable of directly measuring peripheral nerve vascular hemodynamics.

Method: Here, we investigate the use of dark-field functional photoacoustic microscopy (fPAM) for intrinsic visualizing of the relative hemodynamics of the rat sciatic nerve in response to localized temperature modulation (i.e., cooling and rewarming).

Results and conclusion: Our main results show that the relative functional total hemoglobin concentration (HbT) is more significantly correlated with localized temperature changes than the hemoglobin oxygen saturation (SO2) changes in the sciatic nerve. Our study also indicates that the relative HbT changes are better markers of neuronal activation than SO2 during nerve temperature changes. Our results show that fPAM is a promising candidate for in vivo imaging of peripheral nerve hemodynamics without the use of contrast agents. Additionally, this technique may shed light on the neuroprotective effect of hypothermia on peripheral nerves by visualizing their intrinsic hemodynamics.

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Related in: MedlinePlus

PA imaging results. (A)In vivo relative I(570) (i.e., HbT; upper panel) and IF(560) (i.e., SO2; lower panel) PA B-scan images of selected position at different times of temperature modulation protocol. Note that the I(570) and IF(560) are specifically sensitive to relative HbT and SO2 changes, respectively. The red scale bar is equivalent to 100 μm and applies to all images in panel A. Mean functional (B) HbT (i.e., RHbT) and (C) SO2 (i.e., ) changes resulting from in vivo temperature modulation of the rat sciatic nerve as a function of time. The error bars indicate standard deviation (n = 10).
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Figure 3: PA imaging results. (A)In vivo relative I(570) (i.e., HbT; upper panel) and IF(560) (i.e., SO2; lower panel) PA B-scan images of selected position at different times of temperature modulation protocol. Note that the I(570) and IF(560) are specifically sensitive to relative HbT and SO2 changes, respectively. The red scale bar is equivalent to 100 μm and applies to all images in panel A. Mean functional (B) HbT (i.e., RHbT) and (C) SO2 (i.e., ) changes resulting from in vivo temperature modulation of the rat sciatic nerve as a function of time. The error bars indicate standard deviation (n = 10).

Mentions: A selected cross-section region of the sciatic nerve was examined for relative side-to-side PA signal differences in response to localized temperature modulation. The thermoregulation protocol was designed to quantitatively compare the relative HbT and SO2 changes in vascular structures of the sciatic nerve between three localized temperature modulation stages: baseline, cooling and rewarming (Figure 2D). Figure 3A and Additional file 1: Movie S1 show the response for both relative HbT changes as function of time under the thermoregulation protocol.


Imaging of temperature dependent hemodynamics in the rat sciatic nerve by functional photoacoustic microscopy.

Liao LD, Orellana J, Liu YH, Lin YR, Vipin A, Thakor NV, Shen K, Wilder-Smith E - Biomed Eng Online (2013)

PA imaging results. (A)In vivo relative I(570) (i.e., HbT; upper panel) and IF(560) (i.e., SO2; lower panel) PA B-scan images of selected position at different times of temperature modulation protocol. Note that the I(570) and IF(560) are specifically sensitive to relative HbT and SO2 changes, respectively. The red scale bar is equivalent to 100 μm and applies to all images in panel A. Mean functional (B) HbT (i.e., RHbT) and (C) SO2 (i.e., ) changes resulting from in vivo temperature modulation of the rat sciatic nerve as a function of time. The error bars indicate standard deviation (n = 10).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4225521&req=5

Figure 3: PA imaging results. (A)In vivo relative I(570) (i.e., HbT; upper panel) and IF(560) (i.e., SO2; lower panel) PA B-scan images of selected position at different times of temperature modulation protocol. Note that the I(570) and IF(560) are specifically sensitive to relative HbT and SO2 changes, respectively. The red scale bar is equivalent to 100 μm and applies to all images in panel A. Mean functional (B) HbT (i.e., RHbT) and (C) SO2 (i.e., ) changes resulting from in vivo temperature modulation of the rat sciatic nerve as a function of time. The error bars indicate standard deviation (n = 10).
Mentions: A selected cross-section region of the sciatic nerve was examined for relative side-to-side PA signal differences in response to localized temperature modulation. The thermoregulation protocol was designed to quantitatively compare the relative HbT and SO2 changes in vascular structures of the sciatic nerve between three localized temperature modulation stages: baseline, cooling and rewarming (Figure 2D). Figure 3A and Additional file 1: Movie S1 show the response for both relative HbT changes as function of time under the thermoregulation protocol.

Bottom Line: Our main results show that the relative functional total hemoglobin concentration (HbT) is more significantly correlated with localized temperature changes than the hemoglobin oxygen saturation (SO2) changes in the sciatic nerve.Our results show that fPAM is a promising candidate for in vivo imaging of peripheral nerve hemodynamics without the use of contrast agents.Additionally, this technique may shed light on the neuroprotective effect of hypothermia on peripheral nerves by visualizing their intrinsic hemodynamics.

View Article: PubMed Central - HTML - PubMed

Affiliation: Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, 28 Medical Drive, #05-COR, Singapore 117456, Singapore. kqshen@gmail.com.

ABSTRACT

Background: Vascular hemodynamics is central to the regulation of neuro-metabolism and plays important roles in peripheral nerves diseases and their prevention. However, at present there are only a few techniques capable of directly measuring peripheral nerve vascular hemodynamics.

Method: Here, we investigate the use of dark-field functional photoacoustic microscopy (fPAM) for intrinsic visualizing of the relative hemodynamics of the rat sciatic nerve in response to localized temperature modulation (i.e., cooling and rewarming).

Results and conclusion: Our main results show that the relative functional total hemoglobin concentration (HbT) is more significantly correlated with localized temperature changes than the hemoglobin oxygen saturation (SO2) changes in the sciatic nerve. Our study also indicates that the relative HbT changes are better markers of neuronal activation than SO2 during nerve temperature changes. Our results show that fPAM is a promising candidate for in vivo imaging of peripheral nerve hemodynamics without the use of contrast agents. Additionally, this technique may shed light on the neuroprotective effect of hypothermia on peripheral nerves by visualizing their intrinsic hemodynamics.

Show MeSH
Related in: MedlinePlus