# MRI and CT Fusion in Stereotactic Electroencephalography: A Literature Review
## 3 Results
### Methods of Image Fusion  
Image fusion is a technique that composes an image with better information from multiple inputs, which has two steps: registration and merging. The first step transforms all input images into a common standard to represent the same object or phenomena, while the second step merges all aligned images [30]. The article was organized taking the image registration and image merging separately.  
\begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Paper** & **Method** & **Image Source** & **Validation** & **Software Platform** \\ \hline
[15] & Rigid image registration & Retrospective Image Registration Evaluation (RIRE) & Target Registration Error (TRE) & Elastik ITK \\ \hline
[16] & Rigid Image registration & 2D slices from the RIRE & Rotation and translation error & MATLAB \\ \hline
[17] & Rigid image registration & Image from ten patients with pharmacoresistant epilepsy & Error in the localization of electrodes measured in mm & ITK \\ \hline
[18] & Non-rigid image registration & Image from five patients with pharmacoresistant epilepsy & Error in the localization of electrodes measured in mm & BrainLab \\ \hline
[19] & Rigid image registration & Image from 20 datasets of Deep Brain Stimulation (DBS) studies & Target area registration error & C++ \\ \hline
[20] & Rigid image registration & CT and MRI images from seven patients with epilepsy. & Error in the localization of electrodes measured in mm & MATLAB SPM \\ \hline
[21] & Rigid image registration & Image from five patients with pharmacoresistant epilepsy & Euclidean distance between the location estimated procedure and determined by visual inspection & MATLAB SPM \\ \hline
[22] & Automatic method to evaluate and quantify the multi-modal image registration accuracy & Porcine skull dataset and RIRE & Electrode localization accuracy measured in mm & MATLAB \\ \hline
[23] & Quantify the registration accuracy in SESE, from pre-implantation MRI and psi-implantation CT & Image from 14 patients with pharmacoresistant epilepsy & Error in the localization of electrodes measured in mm & FSL \\ \hline
[24] & Multi-modal image fusion & Two image datasets of CT and MRI & Peak-Signal-to-Noise-Ratio (PSNR), Mean-Squared Error (MSE), and Entropy (EN) & N/A \\ \hline
[25] & Multi-modal image fusion & Nine pairs of MRI and CT images, from patients with severe cardiovascular accident & Mutual Information (MI), Standard Deviation (STD), Universal Image Quality Index (UIQI), and Spatial Frequency (SF) & MATLAB \\ \hline
[26] & Multi-modal image fusion using Pulse-Coupled Neural Network (PCNN) & five pairs of MRI and CT images & MI, ST, SID, EN, and Structural Similarity Index (SSIM) & MATLAB \\ \hline
[27] & Multi-modal image fusion using WT and neuro-fuzzy & Two pairs of MRI and CT images & EN, MI, and fusion factor & N/A \\ \hline
[28] & Metric mutual image fusion using DisGuider Filter (GF) & 14 pairs of MRI and CT images & STD, average gradient, and edge strength & N/A \\ \hline
[29] & Multi-modal image fusion using Non-Subsampled Shearlet Transform (NSST) & 10 pairs of medical grayscale images and 4 pairs of medical color images & EN, STD, MI, SSIM, and edge strength & MATLAB \\ \hline \hline \end{tabular}
\end{table}
Table 2: The fifteen original research articles selected.