| Ultrasound |
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● Susceptible to interference from gas and bone ● Blind areas in liver ultrasound; target tumors on the top of the diaphragm, adjacent to gastrointestinal tract, and under the ribs are not well visualized ● Relatively low resolution; some lesions are isoechoic; difficult to visualize small lesions, especially in patients with cirrhotic nodules ● The outline of applicators is only partially displayed; sub-electrodes of expandable electrodes are sometimes poorly visualized ● The tiny bubbles generated during ablation may interfere with ultrasound imaging |
| Computerized Tomography |
● Almost no blind area; can clearly display air-containing tissues such as lungs, the gastrointestinal tract and bones ● Can clearly show the outline of the “ice ball” produced by cryoablation, thereby helping to determine the boundary of cryoablation ● The outline of applicators is fully displayed; sub-electrodes of expandable electrodes are well visualized |
● Soft tissue exhibits relatively low resolution under a plain CT scan; some target tumors are iso-density under a plain CT scan; small target tumors are often poorly visualized; sometimes needs to be combined with TACE lipiodol marking ● X-ray ionizing radiation ● No real-time guidance; only horizontal scanning can be performed; large applicator artifacts, which may cover target tumors Postoperative ablative margin is poorly displayed, thus the positional relationship between targets tumor and ablation zones cannot be clearly shown |
| Magnetic Resonance Imaging |
● Soft tissue exhibits high resolution; no bone and gas artifacts; small target tumors can be clearly displayed ● No X-ray ionizing radiation ● Can be combined with diffusion-weighted imaging (DWI) or MRI contrast agents to visualize target tumors that are not visible under normal circumstances ● Blood vessels can be clearly displayed without a contrast agent, so as to clarify the anatomical relationships between target tumors and the surrounding blood vessels ● Imaging can be performed in any orientation and on any plane; can evaluate the curative effect immediately after ablation; It is a temperature-sensitive imaging technique, which can monitor the thermal coagulation zone |
● Fewer devices dedicated to MRI-guided ablation ● Relatively complicated operation; closed MRI cannot be used for real-time guidance; ablation treatment takes a long time ● Some MRI-compatible applicators have large artifacts, which can cover target tumors ● Not applicable for patients with pacemakers and metal implants |
