Table 3 Imaging features during follow-up per intervention
|  | Thermal ablation for CRLM | TARE for CRLM | TACE&TARE for HCC | Thermal ablation for renal cancer | Thermal ablation for lung cancer |
|---|---|---|---|---|---|
CT | * increase of ablation zone size * small size difference between metastasis and ablation zone * ablation rim discontinuity or irregular shape | * Choi outperforms RECIST 1.1 for response assessment * arterial perfusion has potential to assess response (reduction in arterial perfusion predicts outcome in liver mets, not HCC) | * residual arterial enhancement (thick, nodular or irregular ring, especially with wash-out) | * early peripheral enhancing rim that sustains after 3 months * focal or nodular enhancement at ablation margin (enhanced > 15 HU at CT * increase in scar volume after 2 months post-ablation | * increase in size of the ablation scar * appearance of nodular, irregular, eccentric solid component in or at the margin of ablation zone * new contrast enhancement > 15 HU |
MRI | * increase of ablation zone size * small size difference between metastasis and ablation zon same as on CT * T2 moderate high signal (focal, eccentric or nodular) at the margin * persistent high signal intensity on high b-value DWI and low ADC * disruption of the interface between ablation zone and liver parenchyma * T1 hyperintensity > 9 months * thickened or irregular peri-ablation zone tissue rim (low T1 & high T2) | * DWI at 4 weeks can predict outcome and potentially can outperform PET-CT * caveat false positives due to inflammation | * same as for CT * DWI and DCE seem promising | * same criteria as for CT * enhancement: >15% increase in signal intensity on MRI is significant) * after cryoablation: interrupted T2 low intensity rim | NA |
PET-CT | * focal, eccentric or rim shaped FDG-uptake after 4-6 months post-ablation | * reduction of ≥50% in SUVmax (FDG-PET-CT) at 4 weeks predicts outcome | NA | NA | * new FDG uptake in the scar > 6 months after ablation |