A laser Doppler system for monitoring cerebral microcirculation: implementation and evaluation during neurosurgery

Rejmstad, Peter; Åkesson, Gustav; Åneman, Oscar; Wårdell, Karin

doi:10.1007/s11517-015-1332-5

Cited by 15 publications

(19 citation statements)

References 39 publications

(46 reference statements)

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“…In previous measurements during open brain tumor resection it has been shown that the tumor has a lower TLI than the white matter, but higher than or equal to the gray matter [43]. The stereotactic measurements, which are more accurate in terms of measurement position and probe distance to the tissue, confirm that the tumor has generally a lower TLI than the white matter.…”

Section: Autofluorescence and Tlimentioning

confidence: 70%

5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy

Haj‐Hosseini¹,

Richter²,

Milos³

et al. 2018

Biomed. Opt. Express

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A fiber optic probe was developed for guidance during stereotactic brain biopsy procedures to target tumor tissue and reduce the risk of hemorrhage. The probe was connected to a setup for the measurement of 5-aminolevulinic acid (5-ALA) induced fluorescence and microvascular blood flow. Along three stereotactic trajectories, fluorescence (n = 109) and laser Doppler flowmetry (LDF) (n = 144) measurements were done in millimeter increments. The recorded signals were compared to histopathology and radiology images. The median ratio of protoporphyrin IX (PpIX) fluorescence and autofluorescence (AF) in the tumor was considerably higher than the marginal zone (17.3 vs 0.9). The blood flow showed two high spots (3%) in total. The proposed setup allows simultaneous and realtime detection of tumor tissue and microvascular blood flow for tracking the vessels.

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Section: Autofluorescence and Tlimentioning

confidence: 70%

5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy

Haj‐Hosseini¹,

Richter²,

Milos³

et al. 2018

Biomed. Opt. Express

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“…(49) With the help of the oxygenated hemoglobin (HbO 2 ) and deoxygenated hemoglobin (Hb) spectra from brain tissue, an estimation of the oxygen saturation (SO 2 ) can be achieved by curve fitting to known absorption spectra. The present work in the Linköping group focuses on improving the oxygen saturation algorithm for in vivo on line recording in brain tissue (50) in relation to, for example, traumatic brain injury in the neuro-intensive care unit, and thus also adaptation and implementation of the methods for monitoring of both microcirculation (12) and tissue oxygenation during brain surgery. …”

Section: Drs As a Navigational Tool During Stereotactic Neurosurgerymentioning

confidence: 99%

“…Neuro-endoscopes are increasingly becoming additional tools for minimally invasive surgery in operating rooms (OR). (8) Other examples of optical techniques with great potential are laser Doppler flowmetry (LDF) (9)(10)(11)(12) and laser Doppler perfusion imaging, (13,14) laser speckle contrast imaging, (15) NIR spectroscopy, (16) and optical coherence tomography (OCT). (17) Another area where optical techniques have been introduced as intraoperative guidance tools is during stereotactic and functional neurosurgery.…”

Section: Introductionmentioning

confidence: 99%

Optical Monitoring Techniques for Navigation during Stereotactic Neurosurgery

2016

Sensors and Materials

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Optical techniques are becoming increasingly important in healthcare, as both therapeutic and diagnostic tools. In neurosurgery, photonic technologies such as the microscope have already found widespread use. The overall aim of this paper is to give an overview of optical monitoring methods and their implementation and use in stereotactic and functional neurosurgery. The development steps presented in this paper range from radiofrequency-lesion size estimation using optics to a system adapted for neurosurgical intraoperative navigation during stereotactic deep brain stimulation (DBS) lead implantations. The two main optical methods implemented as intraoperative guidance tools are laser Doppler flowmetry and diffuse reflectance spectroscopy. By combining these fundamental methods with probe designs adapted to stereotactic systems, vessels can be tracked and "bar-codes" of tissue type along pre-defined trajectories used for DBS implantations identified. Examples of the optical methods used in relation to stereotactic DBS implantations are given.

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“…One source-detector (SD) pair was used for LDF and the other pair for DRS measurements. The protective outer cable was made of dark polyvinyl chloride and ended with a transparent 0.3 m long flexible tip of medical grade polyvinyl chloride with an outer diameter of 1.7 mm [106]. To enable a clear detection in CT imaging a thin steel thread (Ø = 0.12 mm, 6 cm long) was incorporated inside the measuring end of the probe.…”

Section: Fiber-optic Probementioning

confidence: 99%

“…The optical signals from LDF for tumor tissue compared with gray and white matter that showed a significant difference between tumor and white matter in terms of perfusion and TLI are seen in Paper II [106]. …”

Section: Tumor Surgerymentioning

confidence: 99%

Optical Monitoring of Cerebral Microcirculation

Rejmstad¹

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The cerebral microcirculation consists of a complex network of small blood vessels that support nerve cells with oxygen and nutrition. The blood flow and oxygen delivery in the microcirculatory blood vessels are regulated through mechanisms which may be influenced or impaired by disease or brain damage resulting from conditions such as brain tumors, traumatic brain injury or subarachnoid hemorrhage (SAH). Monitoring of parameters relating to the microvascular circulation is therefore needed in the clinical setting. Optical techniques such as diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) are capable of estimating the oxygen saturation (SO2) and tracking the microvascular blood flow (perfusion) using a fiber optic probe. This thesis presents the work carried out to adapt DRS and LDF for monitoring cerebral microcirculation in the human brain.A method for real-time estimation of SO2 in brain tissue was developed based on the P3 approximation of diffuse light transport and quadratic polynomial fit to the measured DRS signal. A custom-made fiberoptic probe was constructed for measurements during tumor surgery and in neurointensive care. Software modules with specific user interface for LDF and DRS were programmed to process, record and present parameters such as perfusion, total backscattered light, heart rate, pulsatility index, blood fraction and SO2 from acquired signals.The systems were evaluated on skin, and experimentally by using optical phantoms with properties mimicking brain tissue. The oxygen pressure (pO2) in the phantoms was regulated to track spectroscopic changes coupled with the level of SO2. Clinical evaluation was performed during intraoperative measurements during tumor surgery (n = 10) and stereotactic deep brain stimulation implantations (n = 20). The LDF and DRS systems were also successfully assessed in the neurointensive care unit for a patient treated for SAH. The cerebral autoregulation was studied by relating the parameters from the optical systems to signals from the standard monitoring equipment in neurointensive care.In summary, the presented work takes DRS and LDF one step further toward clinical use for optical monitoring of cerebral microcirculation. SammanfattningHjärnans mikrocirkulation består av ett komplext nätverk av små blodkärl som försörjer nervceller med syre och näring. Blodflödet och syretransporten i mikrocirkulationen regleras via olika mekanismer som kan påverkas eller försämras vid sjukdom eller hjärnskada som till exempel vid hjärntumörer, traumatisk hjärnskada eller subaraknoidalblödning (SAH). Diffus reflektansspektroskopi (DRS) och laserdopplerteknik (LDF) kan användas för att uppskatta syremättnaden (SO2) och övervaka det mikrocirkulatoriska blodflödet, också kallat perfusion, med hjälp av en fiberoptisk prob. Den här avhandlingen beskriver arbetet med att anpassa DRS och LDF för att övervaka den cerebrala mikrocirkulationen.En metod för realtidsuppskattning av SO2 i hjärnvävnad utvecklades baserat på P3 approximationen av diffus...

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A laser Doppler system for monitoring cerebral microcirculation: implementation and evaluation during neurosurgery

Cited by 15 publications

References 39 publications

5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy

5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy

Optical Monitoring Techniques for Navigation during Stereotactic Neurosurgery

Optical Monitoring of Cerebral Microcirculation

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