Re: Adjunctive hydrodissection of the bare area of liver during percutaneous thermal ablation of sub-cardiac hepatic tumours

Abstract

We read with significant attention and intrigue the article by Garnon et al. [1] recently published in abdominal radiology evaluating the use of hydrodissection of the bare area of the liver as a protective mechanism during the intervention of the sub-cardiac hepatic tumors via percutaneous thermal ablation (PTA). We want to provide several comments. First, we would like to commend the authors for their study, which successfully demonstrates the efficacy and technical feasibility of the hydrodissection technique used to target the liver’s bare area. This study serves to provide evidence supporting an innovative approach used to assist in targeting tumors near locations of higher safety concern [1]. Hydrodissection is a technique gaining prominence for its use in thermal protection at high-risk locations to minimize the risk of damage to non-target organs before undergoing microwave ablation (MWA); however, these supplementary measures include their own risks and complications. Consequently, MWA without using hydrodissection has been studied and demonstrated to be safe and effective even in challenging locations [2, 3]. We strongly believe that performing MWA of hepatic lesions near the heart, ≤ 5 mm, can be routinely executed without the added use of hydrodissection. The authors of this study found a 100% technical success rate of hydrodissection; however, additional studies of MWA without ancillary methods have shown equivalent technical success rates in these difficult areas [3]. Therefore, our intent is not to question the feasibility of hydrodissection but to limit this intervention when the result may be of little clinical benefit to the patient. It is mentioned in this study that serious complications can be seen with PTA in high-risk areas without thermo-protection [1]. However, we believe these risks to be infrequent enough not to surpass the risks associated with hydrodissection. Recent literature has shown major complications to be extremely rare in PTA alone, and minor complications often require no additional intervention [2, 3]. Understandably, much of this literature involves smaller sample sizes and a retrospective nature, so more studies need to be performed to evaluate the complications and long-term safety. The point was also made that operator caution in high-risk areas near the heart can lead to undertreatment of the targeted lesion and higher local tumor progression rates. However, studies have seen no significant difference in tumor recurrence, and instances of incomplete response have been attributable to the larger size of the tumor, irrespective of location [3]. Furthermore, since procedural induced arrhythmias are noted to resolve after cessation of ablation [4], arrhythmias should not be a significant factor in operator caution. These high-risk areas will continue to have operator-dependent degrees of success and complications. The comfort level of the performing interventional radiologist can indeed play a role in the need for hydrodissection. Aside from these circumstances, we feel the need to question the routine implication of this technique prior to PTA. In conclusion, the use of PTA for hepatic lesions in close proximity, ≤ 5 mm, to the heart has demonstrated comparable safety and efficacy with or without the use of adjunctive measures such as hydrodissection.