Method of photoacoustic microscopy with lateral resolution of microvasculature

Abstract

A method for obtaining a 3-D OR-PAM image of microvasculature within a region of interest of a subject is provided. The method includes: focusing a first light pulse at a first depth beneath a first surface position within the region of interest; receiving a first PA signal in response to the first light pulse; focusing a second light pulse at a second depth beneath the first surface position within the region of interest; receiving a second PA signal in response to the second light pulse; and forming the 3-D OR-PAM image by combining the first PA signal and the second PA signal.

What is claimed is: 
     
         1 . A method of obtaining a 3-D OR-PAM image of microvasculature within a region of interest of a subject, the method comprising:
 focusing a first light pulse at a first depth beneath a first surface position within the region of interest;   receiving a first PA signal in response to the first light pulse;   focusing a second light pulse at a second depth beneath the first surface position within the region of interest;   receiving a second PA signal in response to the second light pulse; and   forming the 3-D OR-PAM image by combining the first PA signal and the second PA signal.   
     
     
         2 . The method of  claim 1 , wherein the first depth is less than the second depth. 
     
     
         3 . The method of  claim 2 , wherein the second depth is up to about 2 mm. 
     
     
         4 . The method of  claim 2 , wherein the second depth is up to about 1 mm. 
     
     
         5 . The method of  claim 1 , further comprising:
 focusing at least one additional first light pulse at the first depth beneath at least one additional surface position within the region of interest;   receiving at least one additional first PA signal in response to the at least one additional first light pulse;   focusing at least one additional second light pulse at a second depth beneath at least one additional surface position within the region of interest;   receiving at least one additional second PA signal in response to the at least one additional second light pulse, wherein the first surface position and the at least one additional surface position comprise locations within a scanning pattern defined over the region of interest.   
     
     
         6 . The method of  claim 5 , wherein the 3-D OR-PAM image is formed by combining the first PA signal, the at least one additional first PA signal, the second PA signal, and the at least one additional first PA signal. 
     
     
         7 . The method of  claim 2 , wherein a first wavelength of the first light pulse is equal to a second wavelength of the second light pulse. 
     
     
         8 . The method of  claim 7 , wherein the first wavelength is shorter than the second wavelength. 
     
     
         9 . The method of  claim 8 , wherein the region of interest is a port wine stain on the subject. 
     
     
         10 . The method of  claim 9 , wherein the region of interest comprises one or more sample regions within the port wine stain. 
     
     
         11 . A method of monitoring a treatment of a port wine stain of a subject, the method comprising:
 obtaining a baseline 3-D OR-PAM image of the port wine stain prior to the treatment;   obtaining at least one additional 3-D OR-PAM image of the port wine stain after at least a portion of the treatment; and   comparing the baseline and the at least one additional 3-D OR-PAM images to detect changes within the port wine stain after at least a portion of the treatment;   wherein each of the baseline and at least one additional 3-D OR-PAM images are obtained by:
 focusing at least one first light pulse at a first depth beneath at least one surface position within the port wine stain; 
 receiving at least one first PA signal in response to the at least one first light pulse; 
 focusing at least one second light pulse at a second depth beneath the at least one surface position within the port wine stain; 
 receiving at least one second PA signal in response to the at least one second light pulse; and 
 forming the first 3-D OR-PAM image by combining the at least one first PA signal and the at least one second PA signal. 
   
     
     
         12 . The method of  claim 11 , further comprising identifying at least one region of the port wine stain for treatment from the baseline 3-D OR-PAM image. 
     
     
         13 . The method of  claim 11 , further comprising :
 obtaining a post-treatment 3-D OR-PAM image of the port wine stain after completion of the treatment; and   comparing the baseline and the post-treatment 3-D OR-PAM images to assess the effectiveness of the treatment.   
     
     
         14 . The method of  claim 11 , wherein the first depth is less than the second depth. 
     
     
         15 . The method of  claim 14 , wherein the second depth is up to about 2 mm. 
     
     
         16 . The method of  claim 11 , wherein the at least one surface position comprises locations within a scanning pattern defined over the port wine stain. 
     
     
         17 . The method of  claim 16 , wherein the scanning pattern is defined over the entire port wine stain. 
     
     
         18 . The method of  claim 17 , wherein the scanning pattern is defined over at least one portion of the port wine stain. 
     
     
         19 . The method of  claim 11 , wherein a first wavelength of the first light pulse is equal to a second wavelength of the second light pulse. 
     
     
         20 . The method of  claim 17 , wherein the first wavelength is shorter than the second wavelength.