## 3 Imaging in the Follow-Up of Treated HCC  
### Considerations on the MRI Scanning Protocol in HCC Follow-Up  
Although each imaging center is free to use a protocol that makes the best use of their MRI machine and equipment, and is most useful for image interpretation, during the last years the LI-RADS recommendations have become standard and are widely applied [112; 113; 114]. Briefly, the guideline requires T1 in- and out-of-phase images, T2 with or without fat suppression, and 3D thin (less than 5 mm slice thickness) multiphase T1 contrast-enhanced imaging (with unenhanced, late arterial, and portal venous phase) using either gadobenate dimeglumine or gadoxetate disodium with appropriate delayed or transitional and hepatobiliary phases (at approximately 20 min after contrast injection) [12]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ablative Method** & **BCLC Stage** & **Advantages** & **Limitations** & **Histological (maging) Result** & **Overall Survival at 5 Years** \\ \hline \hline \multicolumn{6}{c}{_Thermal abative methods_} \\ \hline RFA & 0-A & Better control for larger nodules & Not recommended for superficial or near-hil lesions & Coagulation necrosis (H-iso T1, hT2) & 40–68\% \\  & & & Heat sink effect & & \\ \hline MWA & 0-A & Higher ablation & Ablation volume may be difficult to estimate More complications in larger nodules & Coagulation necrosis (H-iso T1, hT2) & 50–60\% \\ \hline LA & 0-A & Better control for larger nodules & Relatively small zone of ablation, requiring multiple fibers to achieve sufficient volume & Coagulation necrosis (H-iso T1, hT2) & 15–34\% \\  & & & & volume & \\ \hline HIFU & 0-A & Minimal heat sink effect & Possible damage to adjacent structures & Coagulation necrosis (H-iso T1, hT2) & 15–60\% \\  & & Less invasive & Longer procedure time & & \\ \hline CA & 0-A & Less painful & Cryoshock syndrome is a possible complication & Coagulation necrosis (H-iso T1, hT2) & 23–59\% \\  & & & & \\ \hline \multicolumn{6}{c}{_Non-thermal abative methods_} \\ \hline PEI & 0-A & Simple, cheap, accessible & Risk of local progression Difficulty to obtain safety margins & Coagulation necrosis (H-iso T1, hT2) & up to 4\% \\ \hline IRE & 0-A & No heat sink effect & Possible technical difficulty in needle positioning & Coagulation necrosis (H-iso T1, hT2) & 14–56\% \\  & & & near-hilum lesions & Cardiac gating is required & \\ \hline cTACE & 0-B & Combination of local chemotherapy and tumor & Vascular or biliary complications may occur & Lougatactic necrosis (H- and hT1, H- and hT2) & 24–54\% \\  & & & & Difficult in anatomical proximal variants & \\ \hline DEB-TACE & 0-B & Superior chemotherapeutic effect & Postembolization syndrome may occur & Coagulation and liquefactive necrosis (H- and hT1, H- and hT2) & \\  & & & & \\ DEB-TACE & 0-B & Fewer adverse effects & Poor response in hypovascular nodules & (H- and hT1, H- and hT2) & 33–61\% \\  & & & & chromat therapeutic drugs & \\ \hline TARE & 0-B & Increased radiation dose with curative effect & Radiation-related hepatitis & Coagulation necrosis (H-iso T1, hT2) & up to 40\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Overview of the minimally invasive treatments for HCC [46; 47; 63; 73; 100; 101; 102; 103; 104; 105; 106; 107; 108; 109; 110; 111]. Regarding the choice of contrast agent, some authors showed that gadoxetate disodium has superior sensitivity in the diagnosis of HCC, while other studies cite similar lesion-to-liver contrast ratios, therefore yielding similar diagnostic powers [115; 116; 117; 118]. Within LI-RADS, it is also suggested that diffusion-weighted imaging (DWI), subtraction imaging, and multiplanar acquisition are considered as optional images. Increasing the flip angle of the late 3D T1 fat saturated images may increase the contrast between the liver parenchyma and the tumoral lesion [119]. DWI brings a well-recognized advantage in the positive and differential diagnosis of tumors.