High-Resolution Diffusion Tensor MR Imaging for Evaluating Myocardial Anisotropy and Fiber Tracking at 3T: the Effect of the Number of Diffusion-Sensitizing Gradient Directions

Objective: We wanted to evaluate the effect of the number of diffusion-sensitizing gradient directions on the image quality for evaluating myocardial anisotropy and fiber tracking by using in vitro diffusion tensor MR imaging (DT-MRI). Materials and Methods: The DT-MR images, using a SENSE-based echo-planar imaging technique, were acquired from ten excised porcine hearts by using a 3T MR scanner. With a b-value of 800 S/mm(2), the diffusion tensor images were obtained for 6,15 and 32 diffusion-sensitizing gradient directions at the mid-ventricular level. The number of tracked fibers, the fractional anisotropy (FA), and the length of the tracked fibers were measured for the quantitative analysis. Two radiologists assessed the image quality of the fiber tractography for the qualitative analysis. Results: By increasing the number of diffusion-sensitizing gradient directions from 6 to 15, and then to 32, the FA and standard deviation were significantly reduced (p < 0.01), and the number of tracked fibers and the length of the tracked fibers were significantly increased (p < 0.01). The image quality of the fiber tractography was significantly increased with the increased number of diffusion-sensitizing gradient directions (p < 0.01). Conclusion: The image quality of in vitro DT-MRI is significantly improved as the number of diffusion-sensitizing gradient directions is increased. ; Jiang Y, 2007, AM J PHYSIOL-HEART C, V293, pH2377, DOI 10.1152/ajpheart.00337.2007 ; Wu EX, 2007, MAGN RESON MED, V58, P687, DOI 10.1002/mrm.21350 ; Wu EX, 2007, MAGN RESON IMAGING, V25, P1048, DOI 10.1016/j.mri.2006.12.008 ; Wu MT, 2006, CIRCULATION, V114, P1036, DOI 10.1161/CIRCULATIONHAHA.105.545863 ; Lee JW, 2006, INVEST RADIOL, V41, P553 ; Okada T, 2006, RADIOLOGY, V238, P668, DOI 10.1148/radiol.2382042192 ; CHANG YM, 2005, J KOREAN RADIOL SOC, V52, P87 ; Tanenbaum LN, 2004, AM J NEURORADIOL, V25, P1626 ; Nagae-Poetscher LM, 2004, AM J NEURORADIOL, V25, P1325 ; Jones DK, 2004, MAGNET RESON MED, V51, P807, DOI 10.1002/mrm.20033 ; Jaermann T, 2004, MAGNET RESON MED, V51, P230, DOI 10.1002/mrm.10707 ; Naganawa S, 2004, EUR RADIOL, V14, P234, DOI 10.1007/s00330-003-2163-6 ; Zhai GH, 2003, RADIOLOGY, V229, P673, DOI 10.1148/radiol.2293021462 ; Cercignani M, 2003, AM J NEURORADIOL, V24, P1254 ; Tseng WYI, 2003, J MAGN RESON IMAGING, V17, P31, DOI 10.1002/jmri.10223 ; Jeong AK, 2001, KOREAN J RADIOL, V2, P21 ; Holmes AA, 2000, MAGNET RESON MED, V44, P157 ; Choi SI, 2000, RADIOLOGY, V215, P863 ; Spotnitz HM, 2000, J THORAC CARDIOV SUR, V119, P1053 ; Pruessmann KP, 1999, MAGNET RESON MED, V42, P952 ; Tseng WI, 1999, MAGNET RESON MED, V42, P393 ; Scollan DF, 1998, AM J PHYSIOL-HEART C, V275, pH2308 ; Pierpaoli C, 1996, MAGNET RESON MED, V36, P893 ; Taber LA, 1996, J BIOMECH, V29, P745 ; REESE TG, 1995, MAGNET RESON MED, V34, P786 ; EDELMAN RR, 1994, MAGNET RESON MED, V32, P423 ; RADEMAKERS FE, 1994, CIRCULATION, V89, P1174 ; STREETER DD, 1969, CIRC RES, V24, P339 ; 1