# Application of Image Fusion in Diagnosis and Treatment of Liver Cancer
## 5 Clinical Applications of Image Fusion in Liver Cancer Diagnosis and Treatment
### CT/MRI
#### 5.2.2 Surgical Operation Assistance  
Image fusion is a valuable tool for planning treatment strategies and examining pathological changes. The CT portal vein image is automatically registered with Gd-EOB-DTPA-enhanced MRI images using Mitrokbatch software prior to the operation. The CT-MRI fusion image provides detailed lesion information, in turn, improving diagnostic accuracy [176; 177]. At the same time, three-dimensional models and virtual surgical images based on CT/MRI fusion image reconstruction are applied to guide the key surgical procedures. Combined with indocyanine green molecular fluorescence images, CT/MRI image fusion efficiently defines tumor boundaries and identifies hidden microscopic lesions, leading to improved surgical precision. In addition, fusion imaging is particularly useful for lesions for which anatomical images are difficult to obtain from various angles with conventional techniques, such as anatomically complex hilar lesions. Based on tumor location in combination with the distance between the tumor and intrahepatic vasculature and spatial positional relationship, the optimal virtual resection plane can be determined. Additionally, fusion imaging may be effective for therapeutic evaluation. Posttreatment changes can be easily clarified by creating a fused image prior to treatment. Moreover, since 3D images can be obtained without difficulty, we may be able to successfully simulate surgical treatment in the future. Fusion imaging further allows patients to visually understand the disease process.  
Intraoperative bleeding is a critical aspect of liver surgery, and an important factor affecting the success of surgery and the postoperative recovery of patients [178]. Enhanced preoperative CT/MRI fusion imaging can assist surgeons to better understand information related to intrahepatic vascular alignment, portal vein alignment variation, location of main hepatic vein branches and spatial distance from the tumor lesions. Thus, identification of important vessels and anatomical markers surrounding the lesion can be improved by the assessment of enhanced CT/MRI image fusions before the operation, which is vital in reducing intraoperative bleeding and operation times and accelerating postoperative recovery. [PERSON] et al. [179] conducted a series of clinical studies to evaluate the efficiency of contrast-enhanced CT/MRI image fusion technology in hepatectomy for different anatomical locations. Data from their study suggest that most preoperative surgical planning schemes based on image fusion are similar to the actual operative procedure conducted following the exploration of the liver. Therefore, routine preoperative contrast-enhanced CT/MRI image fusion could provide a valuable guide for planning surgical procedures, leading to the improvement of surgical treatment outcomes.  
For the fusion of CT and MRI in real clinical applications, the common methods are Arithmetic combination [177], the PCA-wavelet transformation-based method [47; 48; 49; 53; 54; 56; 117] and the Pyramid method [58; 59]. Here, we show one real clinical example for the assessment of the cryoablation margin using MRI-CT fusion imaging in hepatic malignancies [180]. From their study, it is shown that MRI-CT fusion imaging was achieved successfully in 46 (97.9%) of 47 lesions, and was useful for evaluating the Minimal ablative margin (MAM) of cryoablation in hepatic malignancies. An example of the fused MRI-CT images from [PERSON] et al. [180] using Arithmetic combination is shown in Figure 4.