title: Wavelength-dependent penetration depth of near infrared radiation into cartilage.
abstract: Articular cartilage is a hyaline cartilage that lines the subchondral bone in the diarthrodial joints. Near infrared (NIR) spectroscopy is emerging as a nondestructive modality for the evaluation of cartilage pathology; however, studies regarding the depth of penetration of NIR radiation into cartilage are lacking. The average thickness of human cartilage is about 1-3 mm, and it becomes even thinner as OA progresses. To ensure that spectral data collected is restricted to the tissue of interest, i.e. cartilage in this case, and not from the underlying subchondral bone, it is necessary to determine the depth of penetration of NIR radiation in different wavelength (frequency) regions. In the current study, we establish how the depth of penetration varies throughout the NIR frequency range (4000-10 000 cm(-1)). NIR spectra were collected from cartilage samples of different thicknesses (0.5 mm to 5 mm) with and without polystyrene placed underneath. A separate NIR spectrum of polystyrene was collected as a reference. It was found that the depth of penetration varied from ∼1 mm to 2 mm in the 4000-5100 cm(-1) range, ∼3 mm in the 5100-7000 cm(-1) range, and ∼5 mm in the 7000-9000 cm(-1) frequency range. These findings suggest that the best NIR region to evaluate cartilage with no subchondral bone contribution is in the range of 4000-7000 cm(-1).
authors: Department of Bioengineering, Temple University, Philadelphia, PA, USA. npleshko@temple.edu.
authors: M V
authors: MV
authors: Padalkar
authors: N
authors: N
authors: Pleshko
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000737:chemistry*; D002417:Cattle; D061848:Optical Imaging; D011137:Polystyrenes / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared
chemical_list: D011137:Polystyrenes
references: Arch Orthop Trauma Surg. 2011 Mar;131(3):377-81
references: 21249375
references: Eur J Radiol. 2012 May;81(5):923-7
references: 21392912
references: Osteoarthritis Cartilage. 2012 Nov;20(11):1367-73
references: 22820498
references: Med Eng Phys. 2013 Jan;35(1):88-95
references: 22824725
references: Rheum Dis Clin North Am. 2013 Feb;39(1):1-19
references: 23312408
references: J Mech Behav Biomed Mater. 2013 Apr;20:249-58
references: 23384759
references: Arch Orthop Trauma Surg. 2013 Jul;133(7):997-1002
references: 23636317
references: Ann Biomed Eng. 2013 Nov;41(11):2426-36
references: 23824216
references: Appl Spectrosc. 2014;68(10):1168-75
references: 25197817
references: Matrix Biol. 2014 Sep;38:3-11
references: 25083813
references: Magn Reson Imaging. 2000 May;18(4):423-30
references: 10788720
references: Invest Radiol. 2000 Oct;35(10):573-80
references: 11041151
references: Clin Orthop Relat Res. 2001 Oct;(391 Suppl):S26-33
references: 11603710
references: Skin Res Technol. 2004 May;10(2):113-21
references: 15059179
references: Clin Phys Physiol Meas. 1991 Nov;12(4):353-8
references: 1778034
references: J Rheumatol. 1994 Jul;21(7):1310-8
references: 7966075
references: Clin Orthop Relat Res. 1997 Sep;(342):254-69
references: 9308548
references: Ann Rheum Dis. 1999 Jan;58(1):27-34
references: 10343537
references: Osteoarthritis Cartilage. 2005 May;13(5):368-78
references: 15882560
references: Adv Drug Deliv Rev. 2005 Jun 15;57(8):1144-70
references: 15885850
references: Clin Biomech (Bristol, Avon). 2005 Aug;20(7):736-44
references: 15963613
references: AJR Am J Roentgenol. 2005 Oct;185(4):899-914
references: 16177408
references: Osteoarthritis Cartilage. 2007 Feb;15(2):198-204
references: 16949313
references: Biomaterials. 2007 May;28(15):2465-78
references: 17175021
references: BMC Musculoskelet Disord. 2007;8:47
references: 17535439
references: Nat Clin Pract Rheumatol. 2008 Jan;4(1):4-5
references: 18030296
references: Br Med Bull. 2007;84:5-23
references: 17785279
references: Med Eng Phys. 2008 Apr;30(3):285-92
references: 17553725
references: Arch Orthop Trauma Surg. 2009 Aug;129(8):1117-21
references: 19367409
references: Phys Med Biol. 2009 Sep 21;54(18):5579-94
references: 19717892
references: Appl Spectrosc. 2010 Oct;64(10):1160-6
references: 20925987