title: Bond-selective imaging of deep tissue through the optical window between 1600 and 1850 nm.
abstract: We report the employment of an optical window between 1600 nm and 1850 nm for bond-selective deep tissue imaging through harmonic vibrational excitation and acoustic detection of resultant pressure waves. In this window where a local minimum of water absorption resides, we found a 5 times enhancement of photoacoustic signal by first overtone excitation of the methylene group CH(2) at 1730 nm, compared to the second overtone excitation at 1210 nm. The enhancement allows 3D mapping of intramuscular fat with improved contrast and of lipid deposition inside an atherosclerotic artery wall in the presence of blood. Moreover, lipid and protein are differentiated based on the first overtone absorption profiles of CH(2) and methyl group CH(3) in this window.
authors: Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.
authors: Pu
authors: P
authors: Wang
authors: Han-Wei
authors: HW
authors: Wang
authors: Michael
authors: M
authors: Sturek
authors: Ji-Xin
authors: JX
authors: Cheng
mesh_terms: D000042:Absorption; D000162:Acoustics; D000818:Animals; D050197:Atherosclerosis / Q000175:diagnosis* / Q000473:pathology; D003287:Contrast Media; D006041:Goats; D021621:Imaging, Three-Dimensional; D008055:Lipids / Q000032:analysis; D057054:Molecular Imaging / Q000379:methods*; D055095:Optics and Photonics / Q000379:methods*; D019047:Phantoms, Imaging; D011506:Proteins / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013552:Swine; D014732:Vibration
chemical_list: D003287:Contrast Media; D008055:Lipids; D011506:Proteins