Colorectal cancer is the second leading cause of cancer death in the United States. According to American Cancer society, the overall lifetime risk of developing colorectal cancer is about 4.7% for men and 4.4% for women. We have developed a rigid, endoscopic photoacoustic microscopy (PAM) probe for imaging of in vivo human colorectal cancers. In order to accommodate colon sections with different size (typically from 50 to 70mm), our 10mm diameter rigid probe uses an off-optical-axis, external mechanical scanning mechanism with a speed of 35deg/s instead of an on-optical-axis, internal mechanical scan mechanism. 532-nm pulsed laser light enters the ridged probe through a photonic crystal single mode fiber before it is collimated and refocused by a water-immersed objective lens onto the colon surface. A focused ultrasound ring transducer (40.5 MHz, 6.5mm focal length) receives photoacoustic signal from chromophores excited by laser beam. Imaging system performance specifications including resolution (6μm) and signal-to-noise ratio are quantified and verified from phantom imaging tests. Ex vivo human colon samples are studied to reveal microscopic features of normal colon, benign polyps, adenocarcinoma and cancer.
Xiandong Leng, Bin Rao, and Quing Zhu, "Endoscopic photoacoustic microscopy probe for human colorectal cancer imaging (Conference Presentation)," Proc. SPIE 10494, Photons Plus Ultrasound: Imaging and Sensing 2018, 1049419 (Presented at SPIE BiOS: January 29, 2018; Published: 15 March 2018); https://doi.org/10.1117/12.2292016.5752212564001.
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