Photoacoustic characterisation of vascular tissue at NIR wavelengths

Photoacoustic spectroscopy has been shown to be able to discriminate between normal and atheromatous areas of arterial tissue in the visible range (410nm-680nm). However, at these wavelengths haemoglobin absorption is also very high. This makes it challenging to apply photoacoustic techniques using an intravascular probe, as a significant amount of the excitation light will be absorbed by the blood present in the artery. In this study we investigate the use of a wider range of excitation wavelengths (740-1800nm) for discriminating between normal arterial tissue and lipid rich plaques and minimise the effect of blood absorption. Special attention will be given to the near infra-red (NIR) wavelength range (900-1300nm) as in this region blood absorption is relatively weak and there are expected to be significant differences in the absorption spectrum of each tissue type. To investigate this, tissue samples were obtained and imaged at a range of wavelengths, the samples were illuminated first through water, then blood. This study demonstrated that the photoacoustic technique can discriminate between normal arterial tissue and lipid rich plaques, even when blood is present.

[1]  P. Beard,et al.  Characterization of post mortem arterial tissue using time-resolved photoacoustic spectroscopy at 436, 461 and 532 nm , 1997 .

[2]  J. Muller,et al.  Near-infrared spectroscopy for the detection of vulnerable coronary artery plaques. , 2006, Journal of the American College of Cardiology.

[3]  Cheng-Lun Tsai,et al.  Near-infrared Absorption Property of Biological Soft Tissue Constituents , 2001 .

[4]  K. Norris,et al.  Measurement of Hemoglobin in Unlysed Blood by Near-Infrared Spectroscopy , 1994 .

[5]  Francis A. Duck,et al.  Physical properties of tissue : a comprehensive reference book , 1990 .

[6]  R. Virmani,et al.  The thin-cap fibroatheroma: a type of vulnerable plaque: The major precursor lesion to acute coronary syndromes , 2001, Current opinion in cardiology.

[7]  R. de Caterina,et al.  Optical coherence tomography accurately identifies intermediate atherosclerotic lesions--an in vivo evaluation in the rabbit carotid artery. , 2007, Atherosclerosis.

[8]  E. Halpern,et al.  Characterization of Human Atherosclerosis by Optical Coherence Tomography , 2002, Circulation.

[9]  Jing Wang,et al.  Near-infrared spectroscopic characterization of human advanced atherosclerotic plaques. , 2002, Journal of the American College of Cardiology.

[10]  S. Emelianov,et al.  Intravascular photoacoustic imaging using an IVUS imaging catheter , 2007, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[11]  Shriram Sethuraman,et al.  Spectroscopic intravascular photoacoustic imaging to differentiate atherosclerotic plaques. , 2008, Optics express.

[12]  G. M. Hale,et al.  Optical Constants of Water in the 200-nm to 200-microm Wavelength Region. , 1973, Applied optics.

[13]  V. Fuster,et al.  Clinical Imaging of the High-Risk or Vulnerable Atherosclerotic Plaque , 2001, Circulation research.

[14]  L A Cassis,et al.  Near-IR imaging of atheromas in living arterial tissue. , 1993, Analytical chemistry.

[15]  P. Beard,et al.  Characterization of a polymer film optical fiber hydrophone for use in the range 1 to 20 MHz: A comparison with PVDF needle and membrane hydrophones , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[16]  Jan Laufer,et al.  Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration , 2007, Physics in medicine and biology.

[17]  Xu Xiao.  Photoacoustic imaging in biomedicine , 2008 .