Tissue perfusion modelling in optical coherence tomography.
BACKGROUND
Optical coherence tomography (OCT) is a well established imaging technique with different applications in preclinical research and clinical practice. The main potential for its application lies in the possibility of noninvasively performing "optical biopsy". Nevertheless, functional OCT imaging is also developing, in which perfusion imaging is an important approach in tissue function study. In spite of its great potential in preclinical research, advanced perfusion imaging using OCT has not been studied. Perfusion analysis is based on administration of a contrast agent (nanoparticles in the case of OCT) into the bloodstream, where during time it specifically changes the image contrast. Through analysing the concentration-intensity curves we are then able to find out further information about the examined tissue.


METHODS
We have designed and manufactured a tissue mimicking phantom that provides the possibility of measuring dilution curves in OCT sequence with flow rates 200, 500, 1000 and 2000 μL/min. The methodology comprised of using bolus of 50 μL of gold nanorods as a contrast agent (with flow rate 5000 μL/min) and continuous imaging by an OCT system. After data acquisition, dilution curves were extracted from OCT intensity images and were subjected to a deconvolution method using an input-output system description. The aim of this was to obtain impulse response characteristics for our model phantom within the tissue mimicking environment. Four mathematical tissue models were used and compared: exponential, gamma, lagged and LDRW.


RESULTS
We have shown that every model has a linearly dependent parameter on flow ([Formula: see text] values from 0.4914 to 0.9996). We have also shown that using different models can lead to a better understanding of the examined model or tissue. The lagged model surpassed other models in terms of the minimisation criterion and [Formula: see text] value.


CONCLUSIONS
We used a tissue mimicking phantom in our study and showed that OCT can be used for advanced perfusion analysis using mathematical model and deconvolution approach. The lagged model with three parameters is the most appropriate model. Nevertheless, further research have to be performed, particularly with real tissue.
Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic. stohanzlova@phd.feec.vutbr.cz.
Petra
P
Stohanzlova
Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic.
Radim
R
Kolar
D003287:Contrast Media / Q000737:chemistry; D004867:Equipment Design; D006046:Gold / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D053768:Metal Nanoparticles / Q000737:chemistry; D008962:Models, Theoretical; D043942:Nanotubes / Q000737:chemistry; D019047:Phantoms, Imaging; D066330:Printing, Three-Dimensional; D054457:Tissue Scaffolds / Q000737:chemistry*; D041623:Tomography, Optical Coherence / Q000379:methods*
D003287:Contrast Media; D006046:Gold
Deconvolution; Impulse response; Model; Optical coherence tomography; Perfusion analysis; Phantom