Talairach Transformation File - Revision history

Jaehyun at 13:33, 5 May 2021

2021-05-05T13:33:29Z

Jaehyun: /* Transforming an AC-PC coordinate */

2018-08-09T19:17:13Z

‎Transforming an AC-PC coordinate

Jaehyun: /* AC-PC to Talairach */

2018-08-09T19:06:17Z

‎AC-PC to Talairach

Jaehyun at 16:49, 9 August 2018

2018-08-09T16:49:30Z

Jaehyun: /* Generate Talairach transformation (.tal) file from BESA MRI coregistration (.sfh) file */

2018-08-09T16:41:52Z

‎Generate Talairach transformation (*.tal) file from BESA MRI coregistration (*.sfh) file

Robert at 17:20, 28 November 2017

2017-11-28T17:20:15Z

Robert at 17:09, 28 November 2017

2017-11-28T17:09:02Z

Robert: Created page with "{{BESAInfobox |title = Module information |module = BESA Research Basic or higher |version = 5.2 or higher }} The tal file contains the transformation parameters from AC-PC c..."

2017-11-28T17:03:56Z

Created page with "{{BESAInfobox |title = Module information |module = BESA Research Basic or higher |version = 5.2 or higher }} The tal file contains the transformation parameters from AC-PC c..."

New page

{{BESAInfobox
|title = Module information
|module = BESA Research Basic or higher
|version = 5.2 or higher
}}

The tal file contains the transformation parameters from AC-PC coordinate system to the Talairach coordinate system.
The following seven points are listed:

#Item 1 AP: Distance from x-z-plane at y==AC to anterior point (AP) along the y axis
#Item 2 PC: Distance from x-z-plane at y==AC to posterior commissure (PC) along the y axis
#Item 3 PP: Distance from x-z-plane at y==AC to posterior point (PP) along the y axis
#Item 4 SP: Distance from x-y-plane at z==AC to superior point (SP) along the z axis
#Item 5 IP: Distance from x-y-plane at z==AC to inferior point (IP) along the z axis
#Item 6 RP: Distance from y-z-plane at x==AC to right point (RP) along the x axis
#Item 7 LP: Distance from y-z-plane at x==AC to left point (LP) along the x axis

Example file content:

<source lang="dos">
66.885850 26.500000 102.697017 68.035304 40.421205 65.232346 64.500000
</source >

Using these points, the transformation is then performed as shown in the figure and example below.

The default values are as such (all distances in mm):

<source lang="dos">
Distance AC to AP 70
Distance AC to PC 23
Distance AC to PP 102
Distance AC to SP 74
Distance AC to IP 42
Distance AC to RP 68
Distance AC to LP 68
</source >

@@ Line 117: / Line 117: @@
 You want to transform an AC-PC coordinate of (-10, -78, -10).
 X value: The coordinate lies in the left compartment. So:
-	X_tal = x * LP_tal / LP =  -10 * 1.054 = -11
+<math> X_{tal} = x \times \frac{{LP}_{tal}}{LP} =  -10 \times 1.054 = -11 </math>
-Y  value: The coordinate lies in the compartment between PC and PP (we use the individual values to decide on the compartment if we transform from the individual AC-PC coordinate system).
+<math> y’ = y – (-PC) = -51.5 </math>
-This means that we first need to subtract the length of the compartment between AC and PC in the individual coordinate system, and then stretch the remaining value in the rear Talairach compartment. At the end, we need to add the length of the compartment between AC_tal and PC_tal (in the Talairach coordinate system) again:
-y’ = y – (-PC) = - 51.5
+<math> Y_{tal} = y’ \times \frac{{PP}_{tal} – {PC}_{tal}}{(PP – PC)} + (-{PC}_{tal}) = -51.5 \times 1.037 + (-23) = -53 – 23 = -76 </math>
 Z-value: The coordinate lies in the bottom compartment. So:
-	Z_tal = z * IP_tal / IP = -10 * 1.040 = -10
+<math> Z_{tal} = z \times \frac{{IP}_{tal}}{IP} = -10 \times 1.040 = -10 </math>
 ==== Generate Talairach transformation (*.tal) file from BESA MRI coregistration (*.sfh) file ====

@@ Line 49: / Line 49: @@
 ==== AC-PC to Talairach ====
-You want to transform the coordinate in AC-PC coordinate system (-38, -15, 12) to the Talairach coordinate system. The .tal file contains the values from the above example:
+You want to transform the coordinate in AC-PC coordinate system (-38, -15, 12) to the Talairach coordinate system. The <code>*.tal</code> file contains the values from the above example:
 <source lang="dos">
@@ Line 100: / Line 100: @@
 (*): For the posterior compartment, the distance between PC and PP is used here.
 X value: The coordinate lies in the left compartment. So:
-	X_tal = x * LP_tal / LP =  -38 * 1.054 = -40
+<math> X_{tal} = x \times \frac{{LP}_{tal}}{LP} = -38 \times 1.054 = -40 </math>
 Y  value: The coordinate lies in the compartment between AC and PC. So:
-	Y_tal = y * PC_tal / PC = -15 * 0.868 = -13
+<math> Y_{tal} = y \times \frac{{PC}_{tal}}{PC} = -15 \times 0.868 = -13 </math>
 Z-value: The coordinate lies in the top compartment. So:
-	Z_tal = z * SP_tal / SP = 12 * 1.088 = 13
+<math> Z_{tal} = z \times \frac{{SP}_{tal}}{SP} = 12 \times 1.088 = 13 </math>
 ==== Transforming an AC-PC coordinate ====

@@ Line 4: / Line 4: @@
 |version = 5.2 or higher
 }}
 The tal file contains the transformation parameters from AC-PC coordinate system to the Talairach coordinate system.
@@ Line 41: / Line 43: @@
 For the posterior compartments (y-axis), it is slightly more complicated because there are two posterior compartments: Between AC and PC, and between PC and PP. Once it is decided which compartment is the correct one, the scaling is done for this compartment only; e.g. if the compartment is between PC and PP:
-First subtract the relevant points from the value, i.e. |y|’ = |y|-PC. Then, scale y’ with (PP_tal-PC_tal)/(PP-PC). Then add PC_tal. Done!
+First subtract the relevant points from the value, i.e. <math>|y|’ = |y|-PC</math>. Then, scale <math>y’</math> with <math>({PP}_{tal}-{PC}_{tal})/(PP-PC)</math>. Then add <math>{PC}_{tal}</math>. Done!
 === Examples ===

@@ Line 132: / Line 132: @@
 ==== Generate Talairach transformation (*.tal) file from BESA MRI coregistration (*.sfh) file ====
-If you want to create a *.tal file from a BESA MRI coregistration *.sfh file to (e.g.) add a custom head-model in BESA Research 6.1, you need the Talairach transformation section in the *.sfh file:
+If you want to create a <code>*.tal</code> file from a BESA MRI coregistration <code>*.sfh</code> file to (e.g.) add a custom head-model in BESA Research 6.1, you need the Talairach transformation section in the <code>*.sfh</code> file:
 <source lang="dos">
@@ Line 145: / Line 145: @@
 </source >
-The values for the *.tal file can be calculated as follows:
+The values for the <code>*.tal</code> file can be calculated as follows:
-* 1st value: AC(x) - AP(x) = 128 – 71 = 57
-* 2nd value: PC(x) – AC(x) = 167 – 128 = 39
+<source lang="text" style="background-color:white">
-* 3rd value: PP(x)  - AC(x) = 240 – 128 = 112
+st value: AC(x) - AP(x) = 128 - 71  = 57
-* 4th value: AC(y) – SP(y) = 128 – 47 = 81
+nd value: PC(x) - AC(x) = 167 - 128 = 39
-* 5th value: IP(y) - AC(y) = 182 – 128 = 54
+rd value: PP(x) - AC(x) = 240 - 128 = 112
-* 6th value: AC(z) – RP(z) = 128 – 59 = 69
+th value: AC(y) - SP(y) = 128 - 47  = 81
-* 7th value: AC(z) – LP(z) = 202 – 128 = 74
+th value: IP(y) - AC(y) = 182 - 128 = 54
 <source lang="dos">
 	39	112	81	54	69	74
 </source >

← Older revision		Revision as of 17:20, 28 November 2017
Line 42:		Line 42:
	For the posterior compartments (y-axis), it is slightly more complicated because there are two posterior compartments: Between AC and PC, and between PC and PP. Once it is decided which compartment is the correct one, the scaling is done for this compartment only; e.g. if the compartment is between PC and PP:		For the posterior compartments (y-axis), it is slightly more complicated because there are two posterior compartments: Between AC and PC, and between PC and PP. Once it is decided which compartment is the correct one, the scaling is done for this compartment only; e.g. if the compartment is between PC and PP:
	First subtract the relevant points from the value, i.e. \|y\|’ = \|y\|-PC. Then, scale y’ with (PP_tal-PC_tal)/(PP-PC). Then add PC_tal. Done!		First subtract the relevant points from the value, i.e. \|y\|’ = \|y\|-PC. Then, scale y’ with (PP_tal-PC_tal)/(PP-PC). Then add PC_tal. Done!
		+
		+	=== Examples ===
		+
		+	==== AC-PC to Talairach ====
		+
		+	You want to transform the coordinate in AC-PC coordinate system (-38, -15, 12) to the Talairach coordinate system. The .tal file contains the values from the above example:
		+
		+	<source lang="dos">
		+	66.885850 26.500000 102.697017 68.035304 40.421205 65.232346 64.500000
		+	</source >
		+
		+	This means that the distances have the following relationships:
		+
		+	{\| class="wikitable"
		+	! style="font-weight: bold;" \| Point
		+	! style="font-weight: bold;" \| Individual value
		+	! style="font-weight: bold;" \| Talairach standard
		+	! style="font-weight: bold;" \| Ratio in compartment
		+	\|-
		+	\| AP
		+	\| 66.9
		+	\| 70
		+	\| 1.046
		+	\|-
		+	\| PC
		+	\| 26.5
		+	\| 23
		+	\| 0.868
		+	\|-
		+	\| PP
		+	\| 102.7
		+	\| 102
		+	\| 1.037(*)
		+	\|-
		+	\| SP
		+	\| 68.0
		+	\| 74
		+	\| 1.088
		+	\|-
		+	\| IP
		+	\| 40.4
		+	\| 42
		+	\| 1.040
		+	\|-
		+	\| RP
		+	\| 65.2
		+	\| 68
		+	\| 1.043
		+	\|-
		+	\| LP
		+	\| 64.5
		+	\| 68
		+	\| 1.054
		+	\|}
		+
		+	(*): For the posterior compartment, the distance between PC and PP is used here.
		+
		+	X value: The coordinate lies in the left compartment. So:
		+
		+	X_tal = x * LP_tal / LP = -38 * 1.054 = -40
		+
		+	Y value: The coordinate lies in the compartment between AC and PC. So:
		+
		+	Y_tal = y * PC_tal / PC = -15 * 0.868 = -13
		+
		+	Z-value: The coordinate lies in the top compartment. So:
		+
		+	Z_tal = z * SP_tal / SP = 12 * 1.088 = 13
		+
		+	==== Transforming an AC-PC coordinate ====
		+
		+	You want to transform an AC-PC coordinate of (-10, -78, -10).
		+
		+	X value: The coordinate lies in the left compartment. So:
		+
		+	X_tal = x * LP_tal / LP = -10 * 1.054 = -11
		+
		+	Y value: The coordinate lies in the compartment between PC and PP (we use the individual values to decide on the compartment if we transform from the individual AC-PC coordinate system).
		+	This means that we first need to subtract the length of the compartment between AC and PC in the individual coordinate system, and then stretch the remaining value in the rear Talairach compartment. At the end, we need to add the length of the compartment between AC_tal and PC_tal (in the Talairach coordinate system) again:
		+
		+	y’ = y – (-PC) = - 51.5
		+
		+	Y_tal = y’ * (PP_tal – PC_tal) / (PP – PC) +(-PC_tal) = -51.5 * 1.037 + (-23) = -53 – 23 = -76
		+
		+	Z-value: The coordinate lies in the bottom compartment. So:
		+
		+	Z_tal = z * IP_tal / IP = -10 * 1.040 = -10
		+
		+	==== Generate Talairach transformation (.tal) file from BESA MRI coregistration (.sfh) file ====
		+
		+	If you want to create a .tal file from a BESA MRI coregistration .sfh file to (e.g.) add a custom head-model in BESA Research 6.1, you need the Talairach transformation section in the *.sfh file:
		+
		+	<source lang="dos">
		+	AC: 128 128 128
		+	PC: 167 128 128
		+	AP: 71 124 125
		+	PP: 240 130 143
		+	SP: 150 47 128
		+	IP: 210 182 122
		+	RP: 166 128 59
		+	LP: 170 128 202
		+	</source >
		+
		+	The values for the *.tal file can be calculated as follows:
		+	* 1st value: AC(x) - AP(x) = 128 – 71 = 57
		+	* 2nd value: PC(x) – AC(x) = 167 – 128 = 39
		+	* 3rd value: PP(x) - AC(x) = 240 – 128 = 112
		+	* 4th value: AC(y) – SP(y) = 128 – 47 = 81
		+	* 5th value: IP(y) - AC(y) = 182 – 128 = 54
		+	* 6th value: AC(z) – RP(z) = 128 – 59 = 69
		+	* 7th value: AC(z) – LP(z) = 202 – 128 = 74
		+
		+	The content of the *.tal file is then:
		+	<source lang="dos">
		+	57 39 112 81 54 69 74
		+	</source >

@@ Line 2: / Line 2: @@
 |title = Module information
 |module = BESA Research Basic or higher
-|version = 5.2 or higher
+|version = BESA Research 5.2 or higher
 }}

← Older revision		Revision as of 17:09, 28 November 2017
Line 35:		Line 35:
	Distance AC to LP 68		Distance AC to LP 68
	</source >		</source >
		+
		+	[[File:Talairach values.png\|600px]]
		+
		+	Example of how to apply Talairach values. The principle is followed in all three directions (x, y, z). First the compartment is identified (e.g. for z axis, superior to AC, or inferior to AC). Then the coordinate is scaled with the Talairach value divided by the real value.
		+
		+	For the posterior compartments (y-axis), it is slightly more complicated because there are two posterior compartments: Between AC and PC, and between PC and PP. Once it is decided which compartment is the correct one, the scaling is done for this compartment only; e.g. if the compartment is between PC and PP:
		+	First subtract the relevant points from the value, i.e. \|y\|’ = \|y\|-PC. Then, scale y’ with (PP_tal-PC_tal)/(PP-PC). Then add PC_tal. Done!