title: Reproducibility analysis of diffusion tensor indices and fiber architecture of human calf muscles in vivo at 1.5 Tesla in neutral and plantarflexed ankle positions at rest.
abstract: OBJECTIVE
  To investigate the reproducibility of diffusion tensor imaging (DTI) -derived indices and fiber architecture of calf muscles at 1.5 Tesla (T), to establish an imaging based method to confirm ankle position, and to compare fiber architecture at different ankle positions.
  
  
  METHODS
  Six subjects were imaged at 1.5T with the foot in neutral and plantarflexed positions. DTI indices were calculated in four muscle compartments (medial and lateral gastrocnemius [MG, LG], superficial and deep anterior tibialis [AT-S, AT-D]). Two subjects were scanned on 3 days to calculate the coefficient of variability (CV) and the repeatability coefficient (RC).
  
  
  RESULTS
  DTI indices were close to the values obtained in earlier 3T and 1.5T studies. Fractional anisotropy decreased significantly in the MG and increased significantly in the AT-S and AT-D compartments while fiber orientation with respect to the magnet Z-axis increased significantly in the MG and decreased significantly in the AT-S compartment with plantarflexion. The CV and RC for the DTI indices and fiber orientations were comparable to 3T studies. Fiber lengths and orientation angles in the MG matched corresponding measures from ultrasound studies.
  
  
  CONCLUSIONS
  DTI at 1.5T provides reproducible measures of diffusion indices and fiber architecture of calf muscle at different muscle lengths.
authors: Muscle Imaging and Modeling Laboratory, Department of Radiology, University of California, San Diego, California 92121-0852, USA. shsinha@ucsd.edu
authors: Shantanu
authors: S
authors: Sinha
authors: Usha
authors: U
authors: Sinha
references: Lancet. 1986 Feb 8;1(8476):307-10
references: 2868172
references: J Biomech. 1990;23(5):495-501
references: 2373722
references: J Anat. 2001 Oct;199(Pt 4):429-34
references: 11693303
references: Eur Radiol. 2008 Oct;18(10):2303-10
references: 18463875
references: NMR Biomed. 2010 Apr;23(3):294-303
references: 20099372
references: NMR Biomed. 2005 Dec;18(8):489-98
references: 16075414
references: Magn Reson Med. 2004 Apr;51(4):807-15
references: 15065255
references: NMR Biomed. 2010 Aug;23(7):803-20
references: 20886566
references: NMR Biomed. 2008 Jul;21(6):566-73
references: 18041804
references: J Magn Reson Imaging. 2008 Jan;27(1):212-7
references: 18022843
references: Magn Reson Med Sci. 2010;9(1):1-8
references: 20339260
references: Biophys J. 2001 Jun;80(6):2968-75
references: 11371469
references: NMR Biomed. 2009 Dec;22(10):1047-53
references: 19618408
references: J Appl Physiol (1985). 2007 Aug;103(2):673-81
references: 17446411
references: Magn Reson Med. 2008 Oct;60(4):934-44
references: 18816814
references: J Magn Reson Imaging. 2007 Aug;26(2):375-85
references: 17622966
references: J Magn Reson Imaging. 2006 Aug;24(2):402-8
references: 16823776
references: Radiology. 2007 May;243(2):413-21
references: 17384238
references: Magn Reson Med. 1999 Sep;42(3):515-25
references: 10467296
references: Magn Reson Med. 2002 Jul;48(1):97-104
references: 12111936
references: Eur J Appl Physiol. 2004 Dec;93(3):253-62
references: 15322853
references: Magn Reson Med. 2006 Aug;56(2):272-81
references: 16826605
references: J Magn Reson Imaging. 2006 Jul;24(1):182-90
references: 16729262
references: IEEE Trans Med Imaging. 2007 Nov;26(11):1472-82
references: 18041263
references: Magn Reson Med Sci. 2008;7(2):59-63
references: 18603836
references: Eur Radiol. 2007 Dec;17(12):3079-85
references: 17639406
references: Magn Reson Imaging. 2006 Jan;24(1):19-25
references: 16410174
references: Comput Methods Programs Biomed. 2006 Feb;81(2):106-16
references: 16413083
references: NMR Biomed. 2002 Nov-Dec;15(7-8):456-67
references: 12489095
references: J Magn Reson Imaging. 2007 Feb;25(2):245-61
references: 17260407
references: Clin Anat. 2003 May;16(3):215-23
references: 12673816
references: J Magn Reson. 2000 Dec;147(2):340-52
references: 11097823