title: Quantification of cervical spine muscle fat: a comparison between T1-weighted and multi-echo gradient echo imaging using a variable projection algorithm (VARPRO).
abstract: BACKGROUND
  Previous data using T1-weighted MRI demonstrated neck muscle fat infiltration (MFI) in patients with poor functional recovery following whiplash. Such findings do not occur in those with milder symptoms of whiplash, chronic non-traumatic neck pain or healthy controls, suggesting traumatic factors play a role. Muscle degeneration could potentially represent a quantifiable marker of poor recovery, but the temporal constraints of running a T1-weighted sequence and performing the subsequent analysis for muscle fat may be a barrier for clinical translation. The purpose of this preliminary study was to evaluate, quantify and compare MFI for the cervical multifidus muscles with T1-weighted imaging and a more rapid quantitative 3D multi-echo gradient echo (GRE) Dixon based method in healthy subjects.
  
  
  METHODS
  5 asymptomatic participants with no history of neck pain underwent cervical spine MRI with a Siemens 3 Tesla system. The muscle and fat signal intensities on axial spin-echo T1-weighted images were quantitatively classified for the cervical multifidii from C3-C7, bilaterally. Additional axial GRE Dixon based data for fat and water quantification were used for comparison via paired t-tests. Inter-tester reliability for fat and water measures with GRE images were examined using 1) Pearson's Intra-class correlation coefficient 2) Bland-Altman Plots and 3) Lin's-Concordance Coefficient. P < 0.05 was used to indicate significance.
  
  
  RESULTS
  Total mean (SD) MFI (C3-C7) for the multifidii obtained with T1-weighted imaging and GRE were 18.4% (3.3) (range 14-22%) and 18.8% (2.9) (range 15-22%), respectively. The Pearson correlation coefficients for inter-tester reliability on the GRE sequences for the C3-C7 multifidii ranged from .83 - .99, indicating high levels of agreement with segmental MFI measures. Bland-Altman Plots revealed all data points were within 2 SDs and concordance was established between 2-blinded raters, suggesting good agreement between two raters measuring fat and water with GRE imaging.
  
  
  CONCLUSIONS
  Results of this preliminary study demonstrate reliability between 2 raters of varying experience for MRI analysis of MFI with 3D GRE MRI. The quantification of MFI for healthy cervical musculature is comparable to T1-weighted images. Inclusion of larger samples of symptomatic data and histological comparison with the reference standard biopsy is warranted.
authors.affiliation: Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, 645 North Michigan Avenue, Suite 1100 room 1139, Chicago, IL 60611, USA. j-elliott@northwestern.edu.
authors.forename: James M
authors.initials: JM
authors.lastname: Elliott
authors.forename: David M
authors.initials: DM
authors.lastname: Walton
authors.forename: Alfred
authors.initials: A
authors.lastname: Rademaker
authors.forename: Todd B
authors.initials: TB
authors.lastname: Parrish
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000473:pathology*; D050154:Adiposity / Q000502:physiology*; D000328:Adult; D000465:Algorithms; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000502:physiology*; D017352:Echo-Planar Imaging; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
references.citation: Clin Radiol. 2005 Mar;60(3):355-63
references.pmid: 15710139
references.citation: J Back Musculoskelet Rehabil. 2011;24(1):23-30
references.pmid: 21248397
references.citation: J Manipulative Physiol Ther. 1997 Jan;20(1):24-9
references.pmid: 9004119
references.citation: Radiology. 1993 Apr;187(1):213-8
references.pmid: 8451416
references.citation: J Comput Assist Tomogr. 1985 Nov-Dec;9(6):1084-9
references.pmid: 4056142
references.citation: AJR Am J Roentgenol. 2005 Jun;184(6):1868-72
references.pmid: 15908544
references.citation: Clin Radiol. 2000 Feb;55(2):145-9
references.pmid: 10657162
references.citation: Radiology. 2006 Sep;240(3):786-92
references.pmid: 16926328
references.citation: Magn Reson Med. 2004 Jan;51(1):35-45
references.pmid: 14705043
references.citation: Muscle Nerve. 1998 Oct;21(10):1350-3
references.pmid: 9736071
references.citation: Muscle Nerve. 2000 Sep;23(9):1431-4
references.pmid: 10951448
references.citation: Spine (Phila Pa 1976). 2011 Nov 1;36(23):1961-8
references.pmid: 21289551
references.citation: AJR Am J Roentgenol. 2006 Jan;186(1):130-5
references.pmid: 16357391
references.citation: Am J Phys Med Rehabil. 1998 Nov-Dec;77(6):545-9
references.pmid: 9862543
references.citation: Stat Med. 1998 Jan 15;17(1):101-10
references.pmid: 9463853
references.citation: Radiology. 1984 Oct;153(1):189-94
references.pmid: 6089263
references.citation: J Shoulder Elbow Surg. 2007 Nov-Dec;16(6):691-6
references.pmid: 17931904
references.citation: Spine (Phila Pa 1976). 2010 Apr 20;35(9):948-54
references.pmid: 20118837
references.citation: Spine (Phila Pa 1976). 2006 Oct 15;31(22):E847-55
references.pmid: 17047533
references.citation: Phys Med Biol. 1985 Apr;30(4):341-4
references.pmid: 4001160
references.citation: Radiology. 2011 May;259(2):487-94
references.pmid: 21324839
references.citation: J Am Osteopath Assoc. 1994 Dec;94(12):1032-8
references.pmid: 7852102
references.citation: PLoS One. 2011;6(6):e21194
references.pmid: 21698170
references.citation: Magn Reson Med. 2005 Sep;54(3):636-44
references.pmid: 16092103
references.citation: Magn Reson Med. 2008 Mar;59(3):571-80
references.pmid: 18306409
references.citation: Pain. 2006 May;122(1-2):102-8
references.pmid: 16527397
references.citation: Clin Radiol. 2008 Jun;63(6):681-7
references.pmid: 18455560
references.citation: Phys Med Rehabil Clin N Am. 2005 Nov;16(4):1033-51, x
references.pmid: 16214058
references.citation: AJR Am J Roentgenol. 2007 Nov;189(5):W284-91
references.pmid: 17954627
references.citation: Pain. 2005 Mar;114(1-2):141-8
references.pmid: 15733639
references.citation: Biometrics. 1989 Mar;45(1):255-68
references.pmid: 2720055