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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"><html><head> <title>Description of mni2tal_matrix</title> <meta name="keywords" content="mni2tal_matrix"> <meta name="description" content="MNI2TAL_MATRIX - Talairach to MNI coordinates (best guess)"> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="generator" content="m2html © 2003 Guillaume Flandin"> <meta name="robots" content="index, follow"> <link type="text/css" rel="stylesheet" href="../m2html.css"></head><body><a name="_top"></a><div><a href="../index.html">Home</a> > <a href="index.html">mri_toolbox</a> > mni2tal_matrix.m</div><!--<table width="100%"><tr><td align="left"><a href="../index.html"><img alt="<" border="0" src="../left.png"> Master index</a></td><td align="right"><a href="index.html">Index for mri_toolbox <img alt=">" border="0" src="../right.png"></a></td></tr></table>--><h1>mni2tal_matrix</h1><h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2><div class="box"><strong>MNI2TAL_MATRIX - Talairach to MNI coordinates (best guess)</strong></div><h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2><div class="box"><strong>function M2T = mni2tal_matrix() </strong></div><h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2><div class="fragment"><pre class="comment"> MNI2TAL_MATRIX - Talairach to MNI coordinates (best guess)
MNI2TALAIRACH = mni2tal_matrix
MNI2TALAIRACH is a struct containing rotation matrices
used by mni2tal and tal2mni
See also, <a href="mni2tal.html" class="code" title="function outpoints = mni2tal(inpoints)">MNI2TAL</a>, <a href="tal2mni.html" class="code" title="function outpoints = tal2mni(inpoints)">TAL2MNI</a> & http://www.mrc-cbu.cam.ac.uk/Imaging/mnispace.html</pre></div><!-- crossreference --><h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>This function calls:<ul style="list-style-image:url(../matlabicon.gif)"></ul>This function is called by:<ul style="list-style-image:url(../matlabicon.gif)"><li><a href="mni2tal.html" class="code" title="function outpoints = mni2tal(inpoints)">mni2tal</a> MNI2TAL - MNI to Talairach coordinates (best guess)</li><li><a href="tal2mni.html" class="code" title="function outpoints = tal2mni(inpoints)">tal2mni</a> TAL2MNI - Talairach to MNI coordinates</li></ul><!-- crossreference --><h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2><div class="fragment"><pre>0001 <a name="_sub0" href="#_subfunctions" class="code">function M2T = mni2tal_matrix()</a>0002 0003 <span class="comment">% MNI2TAL_MATRIX - Talairach to MNI coordinates (best guess)</span>0004 <span class="comment">%</span>0005 <span class="comment">% MNI2TALAIRACH = mni2tal_matrix</span>0006 <span class="comment">%</span>0007 <span class="comment">% MNI2TALAIRACH is a struct containing rotation matrices</span>0008 <span class="comment">% used by mni2tal and tal2mni</span>0009 <span class="comment">%</span>0010 <span class="comment">% See also, MNI2TAL, TAL2MNI &</span>0011 <span class="comment">% http://www.mrc-cbu.cam.ac.uk/Imaging/mnispace.html</span>0012 <span class="comment">%</span>0013 0014 <span class="comment">% $Revision: 1.5 $ $Date: 2004/02/07 01:41:51 $</span>0015 0016 <span class="comment">% Licence: GNU GPL, no express or implied warranties</span>0017 <span class="comment">% Matthew Brett 2/2/01, matthew.brett@mrc-cbu.cam.ac.uk</span>0018 <span class="comment">% modified 02/2003, Darren.Weber_at_radiology.ucsf.edu</span>0019 <span class="comment">% - removed dependence on spm_matrix by</span>0020 <span class="comment">% creating this function, thereby</span>0021 <span class="comment">% abstracting the important matrix</span>0022 <span class="comment">% transforms (easier to change if needed).</span>0023 <span class="comment">%</span>0024 <span class="comment">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span>0025 0026 0027 <span class="comment">% See notes below for explanations...</span>0028 0029 0030 <span class="comment">% rotn = spm_matrix([0 0 0 0.05]); % similar to Rx(eye(3),-0.05), DLW</span>0031 M2T.rotn = [ 1 0 0 0;0032 0 0.9988 0.0500 0;0033 0 -0.0500 0.9988 0;0034 0 0 0 1.0000 ];0035 0036 0037 <span class="comment">% upz = spm_matrix([0 0 0 0 0 0 0.99 0.97 0.92]);</span>0038 M2T.upZ = [ 0.9900 0 0 0;0039 0 0.9700 0 0;0040 0 0 0.9200 0;0041 0 0 0 1.0000 ];0042 0043 0044 <span class="comment">% downz = spm_matrix([0 0 0 0 0 0 0.99 0.97 0.84]);</span>0045 M2T.downZ = [ 0.9900 0 0 0;0046 0 0.9700 0 0;0047 0 0 0.8400 0;0048 0 0 0 1.0000 ];0049 0050 <span class="comment">% from original mni2tal...</span>0051 <span class="comment">%upT = spm_matrix([0 0 0 0.05 0 0 0.99 0.97 0.92]);</span>0052 <span class="comment">%downT = spm_matrix([0 0 0 0.05 0 0 0.99 0.97 0.84]);</span>0053 0054 0055 0056 <span class="keyword">return</span>0057 0058 0059 <span class="comment">% from http://www.mrc-cbu.cam.ac.uk/Imaging/mnispace.html</span>0060 <span class="comment">%</span>0061 <span class="comment">% Approach 2: a non-linear transform of MNI to Talairach</span>0062 <span class="comment">%</span>0063 <span class="comment">% An alternative is to use some sort of transformation that</span>0064 <span class="comment">% may differ for different brain areas. One method might be</span>0065 <span class="comment">% to do an automated non-linear match of the MNI to the</span>0066 <span class="comment">% Talairach brain. For example, you could apply an SPM or</span>0067 <span class="comment">% AIR warping algorithm. However, there are two problems</span>0068 <span class="comment">% here. First, as we stated above, we do not have an MRI</span>0069 <span class="comment">% image of the brain in the Talairach atlas, which was a</span>0070 <span class="comment">% post-mortem specimen. Second, the automated non-linear</span>0071 <span class="comment">% transforms produce quite complex equations relating the</span>0072 <span class="comment">% two sets of coordinates.</span>0073 <span class="comment">%</span>0074 <span class="comment">% An alternative is to apply something like the transform</span>0075 <span class="comment">% that Talairach and Tournoux designed; here different</span>0076 <span class="comment">% linear transforms are applied to different brain regions.</span>0077 <span class="comment">% This is the approach I describe below.</span>0078 <span class="comment">%</span>0079 <span class="comment">% To get a good match for both the temporal lobes and the</span>0080 <span class="comment">% top of the brain, I used different zooms, in the Z (down/up)</span>0081 <span class="comment">% direction, for the brain above the level of the AC/PC line,</span>0082 <span class="comment">% and the brain below. The algorithm was:</span>0083 <span class="comment">%</span>0084 <span class="comment">% I assumed that the AC was in the correct position in the MNI</span>0085 <span class="comment">% brain, and therefore that no translations were necessary;</span>0086 <span class="comment">% Assumed that the MNI brain was in the correct orientation in</span>0087 <span class="comment">% terms of rotation around the Y axis (roll) and the Z axis (yaw);</span>0088 <span class="comment">% Using the SPM99b display tool, I compared the MNI brain to the</span>0089 <span class="comment">% images in the Talairach atlas;</span>0090 <span class="comment">%</span>0091 <span class="comment">% Compared to the atlas, the MNI brain seemed tipped backwards,</span>0092 <span class="comment">% so that the cerebellar / cerebral cortex line in the sagittal</span>0093 <span class="comment">% view, at the AC, was too low. Similarly, the bottom of the</span>0094 <span class="comment">% anterior part of the corpus collosum seemed too high. I</span>0095 <span class="comment">% therefore applied a small (0.05 radian) pitch correction to</span>0096 <span class="comment">% the MNI brain;</span>0097 <span class="comment">%</span>0098 <span class="comment">% Matching the top of the MNI brain to the top of the brain in</span>0099 <span class="comment">% the atlas, required a zoom of 0.92 in Z. Similarly a Y zoom</span>0100 <span class="comment">% of 0.97 was required as a best compromise in matching the front</span>0101 <span class="comment">% and back of the MNI brain to the atlas. The left / right match</span>0102 <span class="comment">% required a 0.99 zoom in X;</span>0103 <span class="comment">%</span>0104 <span class="comment">% The transform above provided a good match for the brain superior</span>0105 <span class="comment">% to the AC/PC line, but a poor match below, with the temporal lobes</span>0106 <span class="comment">% extending further downwards in the MNI brain than in the atlas. I</span>0107 <span class="comment">% therefore derived a transform for the brain below the AC/PC line,</span>0108 <span class="comment">% that was the same as the transform above, except with a Z zoom of</span>0109 <span class="comment">% 0.84;</span>0110 <span class="comment">%</span>0111 <span class="comment">% This algorithm gave me the following transformations:</span>0112 <span class="comment">%</span>0113 <span class="comment">% Above the AC (Z >= 0):</span>0114 <span class="comment">%</span>0115 <span class="comment">% X'= 0.9900X</span>0116 <span class="comment">%</span>0117 <span class="comment">% Y'= 0.9688Y +0.0460Z</span>0118 <span class="comment">%</span>0119 <span class="comment">% Z'= -0.0485Y +0.9189Z</span>0120 <span class="comment">%</span>0121 <span class="comment">%</span>0122 <span class="comment">% Below the AC (Z < 0):</span>0123 <span class="comment">%</span>0124 <span class="comment">% X'= 0.9900X</span>0125 <span class="comment">%</span>0126 <span class="comment">% Y'= 0.9688Y +0.0420Z</span>0127 <span class="comment">%</span>0128 <span class="comment">% Z'= -0.0485Y +0.8390Z</span>0129 <span class="comment">%</span>0130 <span class="comment">%</span>0131 <span class="comment">% The matlab function mni2tal.m implements these transforms.</span>0132 <span class="comment">% It returns estimated Talairach coordinates, from the</span>0133 <span class="comment">% transformations above, for given points in the MNI brain.</span>0134 <span class="comment">% To use it, save as mni2tal.m somewhere on your matlab path.</span>0135 <span class="comment">%</span>0136 <span class="comment">% So, taking our example point in the MNI brain, X = 10mm, Y = 12mm, Z = 14mm:</span>0137 <span class="comment">%</span>0138 <span class="comment">% With the mni2tal.m function above on your path, you could</span>0139 <span class="comment">% type the following at the matlab prompt:</span>0140 <span class="comment">%</span>0141 <span class="comment">%</span>0142 <span class="comment">% mni2tal([10 12 14])</span>0143 <span class="comment">%</span>0144 <span class="comment">% Which would give the following output (see above):</span>0145 <span class="comment">%</span>0146 <span class="comment">%</span>0147 <span class="comment">% ans =</span>0148 <span class="comment">%</span>0149 <span class="comment">% 9.9000 12.2692 12.2821</span>0150 <span class="comment">%</span>0151 <span class="comment">%</span>0152 <span class="comment">% which is, again, an estimate of the equivalent X, Y and Z</span>0153 <span class="comment">% coordinates in the Talairach brain.</span>0154 <span class="comment">%</span>0155 <span class="comment">% The inverse function, tal2mni.m, gives MNI coordinates for</span>0156 <span class="comment">% given Talairach coordinates, using the same algorithm.</span>0157 <span class="comment">%</span>0158 <span class="comment">% We could of course do a more complex transform to attempt</span>0159 <span class="comment">% to make a closer match between the two brains. The approach</span>0160 <span class="comment">% above is only intended to be preliminary. It does have the</span>0161 <span class="comment">% advantage that it is very simple, and therefore the distortions</span>0162 <span class="comment">% involved are easy to visualise, and unlikely to have dramatic</span>0163 <span class="comment">% unexpected effects.</span>0164 <span class="comment">%</span>0165 <span class="comment">% Incidentally, if you use the above transform, and you want to</span>0166 <span class="comment">% cite it, I suggest that you cite this web address. The transform</span>0167 <span class="comment">% is also mentioned briefly in the following papers: Duncan, J.,</span>0168 <span class="comment">% Seitz, R.J., Kolodny, J., Bor, D., Herzog, H., Ahmed, A., Newell, F.N.,</span>0169 <span class="comment">% Emslie, H. "A neural basis for General Intelligence", Science (21 July</span>0170 <span class="comment">% 2000), 289 (5478), 457-460; Calder, A.J., Lawrence, A.D. and</span>0171 <span class="comment">% Young,A.W. "Neuropsychology of Fear and Loathing" Nature Reviews</span>0172 <span class="comment">% Neuroscience (2001), Vol.2 No.5 352-363</span>0173 <span class="comment">%</span></pre></div><hr><address>Generated on Fri 21-May-2004 12:38:21 by <strong><a href="http://www.artefact.tk/software/matlab/m2html/">m2html</a></strong> © 2003</address></body></html>⌨️ 快捷键说明
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