<div dir="ltr">Hi everybody, and thank you for previous answers.<div><br></div><div style>I have two questions today. First, I am comparing the gradient table obtained by PAR/REC and DICOM files. They are very different, I can't find similar lines. However, the final statistics on fiber tracking look similar. Below you can find the two gradient tables and the fiber statistics. Can you please tell me whether the difference in gradient tables is normal, and if one is more precise than the other (the PAR/REC table was calculated by a Matlab script developed at the John Hopkins).</div>
<div style><br></div><div style>Second question: Given a fixed time is available on a 1.5T, is it better to obtain 2 scans of 16 directions or one scan of 32 directions? I can imagine the SNR is much better with two, but not sure whether more directions compensate for SNR too.</div>
<div style><br></div><div style>Thank you.</div><div style>Dorian</div><div style><br></div><div style><br></div><div style><div>Gradient table calculated from Philips PAR file:</div><div><br></div><div>0: -0.44136, -0.57117, -0.69207</div>
<div>1: -0.56394, -0.42335, 0.70905</div><div>2: 0.69797, -0.70323, 0.13526</div><div>3: -0.59198, -0.34304, -0.72931</div><div>4: -0.15274, -0.74584, -0.64838</div><div>5: 0.074435, -0.77687, -0.62525</div><div>6: 0.47574, -0.63875, -0.60471</div>
<div>7: 0.74718, -0.22799, -0.62429</div><div>8: -0.5922, -0.34308, -0.7291</div><div>9: -0.24242, -0.7705, -0.58954</div><div>10: 0.34275, -0.76982, -0.53843</div><div>11: 0.56981, -0.55721, -0.60402</div><div>12: 0.75753, -0.35855, -0.54552</div>
<div>13: -0.66312, -0.52489, -0.53364</div><div>14: -0.43153, -0.75822, -0.48876</div><div>15: 0.59311, -0.69541, -0.40574</div><div>16: 0.74571, -0.52489, -0.41038</div><div>17: -0.71084, -0.70326, 0.011793</div><div>18: -0.75432, -0.41491, 0.50878</div>
<div>19: 0.65451, -0.41491, 0.63204</div><div>20: 0.41865, -0.64824, 0.63602</div><div>21: -0.71152, -0.70239, 0.019779</div><div>22: -0.69363, -0.35558, 0.62645</div><div>23: -0.71454, -0.69646, 0.066208</div><div>24: -0.354, -0.63595, 0.68575</div>
<div>25: 0.22954, -0.63595, 0.7368</div><div>26: 0.69727, -0.70239, 0.14303</div><div>27: 0.64596, -0.224, 0.72977</div><div>28: -0.71425, -0.69728, 0.060467</div><div>29: -0.033138, -0.62847, 0.77712</div><div>30: 0.69693, -0.70198, 0.14667</div>
<div>31: 0.64313, 0.073913, 0.76219</div><div>32: 0, 0, 0</div><div>33: 100, 100, 100</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div>Gradient table obtined by DICOM file:</div><div><br>
</div><div>0: 0.000000, 0.000000, 0.000000, 0.000000</div><div>1: -0.499998, -0.499998, -0.707110, 850.000000</div><div>2: -0.499998, -0.499998, 0.707110, 850.000000</div><div>3: 0.707107, -0.707107, 0.000000, 850.000000</div>
<div>4: -0.653288, -0.270606, -0.707098, 850.000000</div><div>5: -0.208664, -0.675630, -0.707095, 850.000000</div><div>6: 0.019658, -0.706829, -0.707112, 850.000000</div><div>7: 0.421225, -0.567950, -0.707109, 850.000000</div>
<div>8: 0.689925, -0.154927, -0.707108, 850.000000</div><div>9: -0.653495, -0.270675, -0.706880, 850.000000</div><div>10: -0.292882, -0.707102, -0.643604, 850.000000</div><div>11: 0.294515, -0.706411, -0.643619, 850.000000</div>
<div>12: 0.514993, -0.486072, -0.706056, 850.000000</div><div>13: 0.707102, -0.292882, -0.643604, 850.000000</div><div>14: -0.707102, -0.472486, -0.526084, 850.000000</div><div>15: -0.472486, -0.707102, -0.526084, 850.000000</div>
<div>16: 0.555492, -0.643950, -0.526077, 850.000000</div><div>17: 0.707102, -0.472486, -0.526084, 850.000000</div><div>18: -0.707107, -0.707107, -0.000212, 850.000000</div><div>19: -0.707102, -0.472486, 0.526084, 850.000000</div>
<div>20: 0.707102, -0.472486, 0.526084, 850.000000</div><div>21: 0.472486, -0.707102, 0.526084, 850.000000</div><div>22: -0.707085, -0.707085, 0.007849, 850.000000</div><div>23: -0.636392, -0.425181, 0.643604, 850.000000</div>
<div>24: -0.706047, -0.706047, 0.054730, 850.000000</div><div>25: -0.292882, -0.707102, 0.643604, 850.000000</div><div>26: 0.292882, -0.707102, 0.643604, 850.000000</div><div>27: 0.707085, -0.707085, 0.007849, 850.000000</div>
<div>28: 0.707102, -0.292882, 0.643604, 850.000000</div><div>29: -0.706260, -0.706260, 0.048932, 850.000000</div><div>30: 0.034719, -0.706256, 0.707105, 850.000000</div><div>31: 0.707060, -0.707060, 0.011526, 850.000000</div>
<div>32: 0.707107, -0.000000, 0.707107, 850.000000</div><div>33: 100.000000, 100.000000, 100.000000, 850.000000</div><div><br></div><div style>Fiber statistics for each:</div><div><a href="http://img580.imageshack.us/img580/2887/capturenbh.jpg">http://img580.imageshack.us/img580/2887/capturenbh.jpg</a><br>
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