Validating Minimally Invasive Laser Doppler Flowmetry for Serial Bone Perfusion Measurements in Mice

AbstractIn vivo laser Doppler flowmetry (LDF) has previously been used to quantify blood perfusion accurately at a single timepoint in the murine tibial metaphysis. However, this procedure entailed substantial disruption to soft tissues overlying the bone and caused notable localized inflammation for several weeks after the procedure, impeding serial measurements in the same mouse. In this study, we tested a less invasive technique to measure perfusion in the tibia with LDF and validated that it can be used serially in the same mouse without causing inflammation or gait perturbations. Twenty 14-week-old C57Bl/6J mice were evenly divided into groups that either had daily treadmill exercise or remained sedentary. Within these activity groups, mice were evenly subdivided into groups that received LDF measurements either weekly or only once at the study endpoint. Bone perfusion was measured with LDF in the anteromedial region of the right tibial metaphysis. Serum concentrations of interleukin 6, incision site wound area, and interlimb coordination during gait were measured weekly for four weeks. Tibial perfusion did not differ significantly between exercise and sedentary groups within the weekly or endpoint-only LDF groups at any timepoint. Perfusion was significantly increased in the third week in the weekly LDF group relative to measurements in the second and fourth weeks. Ligation of the femoral artery caused consistent, rapid reductions in tibial perfusion, validating that LDF is sensitive to changes in tibial blood supply. Weekly LDF procedures did not adversely affect gait, as interlimb coordination during treadmill locomotion was similar between weekly and endpoint-only LDF groups at every timepoint. Images of the incision site show wound closure within one week, and serum concentrations of interleukin 6 were not significantly different between weekly and endpoint-only groups. Together, these findings demonstrate that our minimally invasive LDF technique can be used for serial in vivo measurements of intraosseous blood perfusion without inducing localized inflammation or negatively affecting gait patterns in mice.HighlightsModified, minimally invasive laser Doppler flowmetry (LDF) technique was validated for serial measures of tibial perfusion in mice.Weekly LDF procedures did not induce inflammation or alter gait patterns that could confound metrics of interest in bone studies.Ligation of the femoral artery confirmed the LDF technique measures functional perfusion within the bone.

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Fiber-Optic System for Intraoperative Study of Abdominal Organs during Minimally Invasive Surgical Interventions

Applied Sciences ◽

10.3390/app9020217 ◽

2019 ◽

Vol 9 (2) ◽

pp. 217 ◽

Cited By ~ 6

Author(s):

Ksenia Kandurova ◽

Viktor Dremin ◽

Evgeny Zherebtsov ◽

Elena Potapova ◽

Alexander Alyanov ◽

...

Keyword(s):

Minimally Invasive ◽

Laser Doppler Flowmetry ◽

Blood Perfusion ◽

Optical Probe ◽

Diagnostic Methods ◽

Laser Doppler ◽

Doppler Flowmetry ◽

Abdominal Organs ◽

Minimally Invasive Operation

The paper presents the results of experimental measurements of endogenous fluorescence and blood perfusion in patients with pathology of the organs of hepatopancreatoduodenal area in vivo. A custom setup combining channels for fluorescence spectroscopy (excitation wavelengths of 365 nm and 450 nm) and laser Doppler flowmetry (1064 nm) with fibre optical probe for nondestructive laparoscopic measurements has been developed and applied during minimally invasive operation procedure. Preliminary measurements with two aforementioned channels have been performed at specified excitation wavelengths. The possibility of obtaining fluorescence spectra and laser Doppler flowmetry signals in vivo during minimally invasive interventions was shown. Obtained data show perspectives of further research on technical and methodological development of optical diagnostic methods for minimally invasive surgery. The obtained results can be used to provide a deeper understanding of pathological processes influence on optical properties of abdominal organs tissues, which will ultimately help surgeons to determine the state of vitality in tissues and mucous membranes directly during the process of surgical intervention.

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A Minimally Invasive Technique for Serial Intraosseous Perfusion Measurements in the Murine Tibia Using Laser Doppler Flowmetry

10.1101/708453 ◽

2019 ◽

Cited By ~ 1

Author(s):

Nicholas J Hanne ◽

Elizabeth D Easter ◽

Sandra Stangeland-Molo ◽

Jacqueline H Cole

Keyword(s):

Minimally Invasive ◽

Laser Doppler Flowmetry ◽

Laser Doppler ◽

Invasive Technique ◽

List Type ◽

Current Standard ◽

Preclinical Research ◽

Modified Technique ◽

Doppler Flowmetry

AbstractIn biomedical and preclinical research, the current standard method for measuring blood perfusion inside murine bone, radiolabeled microspheres, is a terminal procedure that cannot be used to monitor longitudinal perfusion changes. Laser Doppler flowmetry (LDF) can quantify perfusion within the proximal tibial metaphysis of mice in vivo but requires a surgical procedure to place the measurement probe directly onto the bone surface. Sustained inflammation for over a month following this technique was previously reported, and previous studies have used LDF as an endpoint-only procedure. We developed a modified, minimally invasive LDF procedure to measure intraosseous perfusion in the murine tibia without stimulating local or systemic inflammation or inducing gait abnormalities. This modified technique can be used to measure perfusion weekly for up to at least a month. Unlike previous endpoint-only techniques, this modified LDF procedure can be performed weekly to monitor serial changes to intraosseous perfusion in the murine tibiaThe modified LDF technique utilizes a smaller, more localized incision to minimize invasiveness and speed recovery

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Fractal Dimension Characterization of in-vivo Laser Doppler Flowmetry signals

Physics Procedia ◽

10.1016/j.phpro.2011.06.124 ◽

2011 ◽

Vol 19 ◽

pp. 49-54 ◽

Cited By ~ 2

Author(s):

Gayathri Srinivasan ◽

N. Sujatha

Keyword(s):

Fractal Dimension ◽

Laser Doppler Flowmetry ◽

Laser Doppler ◽

Doppler Flowmetry

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Laser Doppler Flowmetry versatile acquisition system with low quantization error

Journal of Biomedical Engineering and Informatics ◽

10.5430/jbei.v4n1p25 ◽

2018 ◽

Vol 4 (1) ◽

pp. 25

Author(s):

Francesco Marrazzi ◽

Frederic Truffer ◽

Martial Geiser

Keyword(s):

Laser Doppler Flowmetry ◽

Analog Circuit ◽

Scattered Light ◽

Blood Perfusion ◽

Electrical Signal ◽

Laser Doppler ◽

Physical Models ◽

Acquisition System ◽

Invasive Technique ◽

Doppler Flowmetry

The Laser Doppler Flowmetry (LDF) is a non-invasive technique used to evaluate blood perfusion of various human tissues like the skin or the fundus of the eye. It is based on the scattering of light on moving red blood cells in tissue. Frequency shifted scattered light is detected and provide an electrical signal. Physical models for LDF use the DC and AC components of this signal. If AC is small relative to the DC, digitalization becomes an issue, and if more than two LDF signal acquisitions and analysis have to be done simultaneously, the device becomes expensive and bulky. We propose here a versatile and inexpensive acquisition system, which overcomes quantization errors issue by first separating DC from AC, then amplifying AC and finally recombining both signals before digitalization. We designed an analog circuit combined with a 12 bit analog-to-digital converter, a microcontroller unit and a Raspberry Pi2 (Rpi2) for the signal processing. Results are accessed remotely from the Rpi2 through HTTP protocol. Multiple systems can easily be used simultaneously for multichannel acquisitions.

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