title: A method for quantitative measurement of lumbar intervertebral disc structures: an intra- and inter-rater agreement and reliability study.
abstract: BACKGROUND
  There is a shortage of agreement studies relevant for measuring changes over time in lumbar intervertebral disc structures. The objectives of this study were: 1) to develop a method for measurement of intervertebral disc height, anterior and posterior disc material and dural sac diameter using MRI, 2) to evaluate intra- and inter-rater agreement and reliability for the measurements included, and 3) to identify factors compromising agreement.
  
  
  METHODS
  Measurements were performed on MRIs from 16 people with and 16 without lumbar disc herniation, purposefully chosen to represent all possible disc contours among participants in a general population study cohort. Using the new method, MRIs were measured twice by one rater and once by a second rater. Agreement on the sagittal start- and end-slice was evaluated using weighted Kappa. Length and volume measurements were conducted on available slices between intervertebral foramens, and cross-sectional areas (CSA) were calculated from length measurements and slice thickness. Results were reported as Bland and Altman's limits of agreement (LOA) and intraclass correlation coefficients (ICC).
  
  
  RESULTS
  Weighted Kappa (Kw (95% CI)) for start- and end-slice were: intra-: 0.82(0.60;0.97) & 0.71(0.43;0.93); inter-rater: 0.56(0.29;0.78) & 0.60(0.35;0.81). For length measurements, LOA ranged from [-1.0;1.0] mm to [-2.0;2.3] mm for intra-; and from [-1.1; 1.4] mm to [-2.6;2.0] mm for inter-rater. For volume measurements, LOA ranged from [-293;199] mm3 to [-582;382] mm3 for intra-, and from [-17;801] mm3 to [-450;713] mm3 for inter-rater. For CSAs, LOA ranged between [-21.3; 18.8] mm2 and [-31.2; 43.7] mm2 for intra-, and between [-10.8; 16.4] mm2 and [-64.6; 27.1] mm2 for inter-rater. In general, LOA as a proportion of mean values gradually decreased with increasing size of the measured structures. Agreement was compromised by difficulties in identifying the vertebral corners, the anterior and posterior boundaries of the intervertebral disc and the dural sac posterior boundary. With two exceptions, ICCs were above 0.81.
  
  
  CONCLUSIONS
  Length measurements and calculated CSAs of disc morphology and dural sac diameter from MRIs showed acceptable intra- and inter-rater agreement and reliability. However, caution should be taken when measuring very small structures and defining anatomical landmarks.
authors: Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, Odense M DK-5230, Denmark. pkjaer@health.sdu.dk.
authors: Andreas
authors: A
authors: Tunset
authors: Per
authors: P
authors: Kjaer
authors: Shadi
authors: S
authors: Samir Chreiteh
authors: Tue
authors: T
authors: Secher Jensen
references: Neuroradiology. 2000 Jun;42(6):451-4
references: 10929308
references: Mil Med. 2005 Nov;170(11):926-30
references: 16450819
references: Eur Spine J. 2004 Jul;13(4):325-9
references: 14714243
references: Acta Anaesthesiol Belg. 2011;62(1):37-45
references: 21612144
references: Magn Reson Imaging. 2005 Apr;23(3):475-9
references: 15862649
references: Eur Spine J. 2002 Dec;11(6):575-81
references: 12522716
references: J Bone Joint Surg Br. 2006 Sep;88(9):1192-6
references: 16943471
references: Lancet. 1986 Feb 8;1(8476):307-10
references: 2868172
references: AANA J. 1996 Jun;64(3):261-8
references: 9095698
references: Neurol Med Chir (Tokyo). 2009 Jun;49(6):242-7; discussion 247
references: 19556732
references: Spine (Phila Pa 1976). 2000 Feb 15;25(4):487-92
references: 10707396
references: Spine (Phila Pa 1976). 2008 Jan 1;33(1):61-7
references: 18165750
references: Spine (Phila Pa 1976). 2006 Jun 15;31(14):1605-12; discussion 1613
references: 16778696
references: Surg Radiol Anat. 2010 Jul;32(6):581-5
references: 19967536
references: Spine (Phila Pa 1976). 2011 Jan 15;36(2):160-9
references: 20739918
references: Spine J. 2005 Nov-Dec;5(6):608-14
references: 16291099
references: Spine (Phila Pa 1976). 2008 Mar 1;33(5):E140-4
references: 18317181
references: Spine (Phila Pa 1976). 2008 Apr 20;33(9):991-8
references: 18427321
references: Skeletal Radiol. 2000 Apr;29(4):217-23
references: 10855470
references: Spine (Phila Pa 1976). 1997 Jul 15;22(14):1650-60
references: 9253102
references: Spine (Phila Pa 1976). 2008 Jun 1;33(13):1484-90
references: 18475246
references: Clin J Pain. 2004 Nov-Dec;20(6):455-61
references: 15502690
references: J Clin Epidemiol. 2010 Aug;63(8):854-61
references: 20056381
references: Spine (Phila Pa 1976). 2008 Oct 15;33(22):2464-72
references: 18923325
references: J Am Geriatr Soc. 2011 Mar;59(3):423-9
references: 21391933
references: Ophthalmic Physiol Opt. 2011 Jul;31(4):330-8
references: 21615445
references: Echocardiography. 2012 Apr;29(4):385-90
references: 22150607
references: Radiology. 1987 Nov;165(2):517-25
references: 3659376
references: J Orthop Sci. 2012 Jul;17(4):341-5
references: 22538438
references: J Spinal Disord. 1994 Oct;7(5):388-93
references: 7819638
references: J Spinal Disord. 1996 Jun;9(3):251-6
references: 8854282
references: J Spinal Disord Tech. 2002 Apr;15(2):157-63
references: 11927827
references: Phys Ther. 1986 Sep;66(9):1431
references: 3749277
references: PLoS One. 2012;7(5):e37908
references: 22662248
references: J Clin Epidemiol. 2006 Oct;59(10):1033-9
references: 16980142
references: Skeletal Radiol. 2011 Aug;40(8):1033-9
references: 21286714
references: Spine (Phila Pa 1976). 1999 May 15;24(10):1015-22
references: 10332795
references: Minim Invasive Neurosurg. 2006 Aug;49(4):220-6
references: 17041833
references: Nat Rev Rheumatol. 2010 Mar;6(3):139-45
references: 20142811
references: Spine (Phila Pa 1976). 2006 Nov 15;31(24):2836-42
references: 17108838
references: Eur Spine J. 2011 Apr;20(4):513-22
references: 20949289
references: J Spinal Disord Tech. 2006 Jun;19(4):249-56
references: 16778658
references: J Magn Reson Imaging. 2000 Sep;12(3):439-43
references: 10992311
references: AACN Adv Crit Care. 2008 Apr-Jun;19(2):223-34
references: 18560291
references: Spine (Phila Pa 1976). 2002 Sep 1;27(17):1918-25; discussion 1924-5
references: 12221358
references: Int J Clin Pract. 2010 Jan;64(1):13-8
references: 20089014
references: Pain Physician. 2008 May-Jun;11(3):311-26
references: 18523502
references: Spine (Phila Pa 1976). 2003 Jul 1;28(13):1418-23
references: 12838100
references: Spine (Phila Pa 1976). 2006 May 15;31(11):1247-52
references: 16688039
references: Yonsei Med J. 2011 Jan;52(1):137-44
references: 21155046
references: Spine (Phila Pa 1976). 1999 May 1;24(9):918-20
references: 10327517
references: Spine (Phila Pa 1976). 2008 Dec 1;33(25):2789-800
references: 19018250
references: Magn Reson Imaging. 2007 Apr;25(3):386-91
references: 17371729
references: Phys Med Rehabil Clin N Am. 2011 Feb;22(1):1-5
references: 21292142
references: Spine (Phila Pa 1976). 1993 Sep 1;18(11):1433-8
references: 8235813
references: Acta Orthop Scand Suppl. 1970;129:1-76
references: 5269867
references: Spine (Phila Pa 1976). 2007 Feb 15;32(4):E136-40
references: 17304123
references: J Manipulative Physiol Ther. 1991 Feb;14(2):119-32
references: 2019821
references: Arch Dis Child Fetal Neonatal Ed. 2012 Nov;97(6):F434-8
references: 22447988
references: Spine (Phila Pa 1976). 2005 May 15;30(10):1173-80
references: 15897832
references: Pract Neurol. 2012 Dec;12(6):367-70
references: 23144299
references: IEEE Trans Med Imaging. 2011 Jan;30(1):1-10
references: 20378464
references: Spine (Phila Pa 1976). 1989 Apr;14(4):431-7
references: 2718047
references: Spine (Phila Pa 1976). 2008 Sep 1;33(19):2094-100
references: 18758366
references: Spine (Phila Pa 1976). 1990 Jul;15(7):683-6
references: 2218716
references: J Manipulative Physiol Ther. 2001 Jun;24(5):317-26
references: 11416821
references: Radiology. 2005 May;235(2):562-7
references: 15858095
references: Acta Radiol. 2006 Nov;47(9):947-53
references: 17077047
references: Spine (Phila Pa 1976). 2010 Oct 1;35(21):1919-24
references: 20671589
references: Spine (Phila Pa 1976). 1983 Mar;8(2):131-40
references: 6857385
references: Spine (Phila Pa 1976). 1992 Aug;17(8):934-9
references: 1523495
references: Sports Med. 1998 Oct;26(4):217-38
references: 9820922
references: Biometrics. 1977 Mar;33(1):159-74
references: 843571
references: J Spinal Disord Tech. 2005 Apr;18(2):121-6
references: 15800427
references: Int J Nurs Stud. 2011 Jun;48(6):661-71
references: 21514934
references: Radiology. 2005 Nov;237(2):597-604
references: 16244269
references: Physiol Meas. 2012 Aug;33(8):1313-21
references: 22813922
references: Stat Med. 2002 May 15;21(9):1331-5
references: 12111881
references: Pediatr Radiol. 2005 Apr;35(4):419-24
references: 15635468
references: Spine (Phila Pa 1976). 2002 May 15;27(10):1082-6
references: 12004176