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neuroimagen:byicv [2015/01/28 11:00]
osotolongo
neuroimagen:byicv [2020/08/04 10:58] (current)
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 </code> </code>
  
-Let's say we want to get the hippocampus volume (HV) correct by ICV. Then we must get Left and Right HV and calculate its medium value. **HV = 0.5*(HVR+HVL)**+Let's say we want to get the hippocampus volume (HV) corrected by ICV. Then we must get Left and Right HV and calculate its medium value. **HV = 0.5*(HVR+HVL)**
  
 Now first step is to fit a straight line for HV //vs// ICV and the ICV mean value (<ICV>). The adjusted HV will be **aHV = HV - b*(ICV-<ICV>)**, with //b// as the regression coefficient of HV //vs// ICV. Now first step is to fit a straight line for HV //vs// ICV and the ICV mean value (<ICV>). The adjusted HV will be **aHV = HV - b*(ICV-<ICV>)**, with //b// as the regression coefficient of HV //vs// ICV.
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 write.csv(x, file="ab255_mri_aHV.csv") write.csv(x, file="ab255_mri_aHV.csv")
 </code> </code>
 +
 +==== For ADNIMERGE package ====
 +
 +{{ :neuroimagen:adni_hippocampus_correction.png?300|}}
 +
 +El paquete ADNIMERGE provee los valores de Hipoocampo (suma de ambos) e ICV. Puede corregirse directamente y dividirse entre 2 para obtener valores similares.
 +
 +<code R>
 +library("ADNIMERGE")
 +a <- lm(adnimerge$Hippocampus~adnimerge$ICV)
 +adnimerge$adj.Hippocampus = 0.5*(adnimerge$Hippocampus - a$coefficients[[2]]*(adnimerge$ICV - mean(adnimerge$ICV, na.rm=T)))
 +</code>
 +
 +Este procedimiento se debera aplicar para realizar la replica de cualquier estudio donde se utilize la semisuma corregida de ambos hipocampos.
neuroimagen/byicv.1422442806.txt.gz ยท Last modified: 2020/08/04 10:47 (external edit)