Abstract
PurposeTo evaluate risk factors associated with alterations in venous structures adjacent to an ablation zone after percutaneous irreversible electroporation (IRE) of hepatic malignancies at subacute follow-up (1 to 3 days after IRE) and to describe evolution of these alterations at mid-term follow-up.Materials and Methods43 patients (men/women, 32/11; mean age, 60.3 years) were identified in whom venous structures were located within a perimeter of 1.0 cm of the ablation zone at subacute follow-up after IRE of 84 hepatic lesions (primary/secondary hepatic tumors, 31/53). These vessels were retrospectively evaluated by means of pre-interventional and post-interventional contrast-enhanced magnetic resonance imaging or computed tomography or both. Any vascular changes in flow, patency, and diameter were documented. Correlations between vascular change (yes/no) and characteristics of patients, lesions, and ablation procedures were assessed by generalized linear models.Results191 venous structures were located within a perimeter of 1.0 cm of the ablation zone: 55 (29%) were encased by the ablation zone, 78 (41%) abutted the ablation zone, and 58 (30%) were located between 0.1 and 1.0 cm from the border of the ablation zone. At subacute follow-up, vascular changes were found in 19 of the 191 vessels (9.9%), with partial portal vein thrombosis in 2, complete portal vein thrombosis in 3, and lumen narrowing in 14 of 19. At follow-up of patients with subacute vessel alterations (mean, 5.7 months; range, 0 to 14 months) thrombosis had resolved in 2 of 5 cases; vessel narrowing had completely resolved in 8 of 14 cases, and partly resolved in 1 of 14 cases. The encasement of a vessel by ablation zone (OR = 6.36, p<0.001), ablation zone being adjacent to a portal vein (OR = 8.94, p<0.001), and the usage of more than 3 IRE probes (OR = 3.60, p = 0.035) were independently associated with post-IRE vessel alterations.ConclusionVenous structures located in close proximity to an IRE ablation zone remain largely unaffected by this procedure, and thrombosis is rare.
Highlights
191 venous structures were located within a perimeter of 1.0 cm of the ablation zone: 55 (29%) were encased by the ablation zone, 78 (41%) abutted the ablation zone, and 58 (30%) were located between 0.1 and 1.0 cm from the border of the ablation zone
Venous structures located in close proximity to an Irreversible electroporation (IRE) ablation zone remain largely unaffected by this procedure, and thrombosis is rare
In this review portal vein thromboses/occlusions after hepatic IRE had occurred in 1 case in one study: Kingham et al [15] evaluated safety of IRE ablation of 65 liver tumors being juxtaposed to main hepatic vessels: 25 and 16 tumors were located within a perimeter of 1 cm of a major HV and a major portal pedicle, respectively; only 1 patient had developed post-ablative thrombosis within a portal pedicle
Summary
Thermal ablation of tumors adjacent to major liver vessels remains challenging: on the one hand, because the “heat sink” effect leads to the loss of thermal energy by convection and increases the risk of incomplete ablation [1,2,3], and, on the other hand, because of the risk of vessel damage, especially of the endothelium [4].Irreversible electroporation (IRE) as a non-thermal ablative option seems to overcome those above mentioned limitations of thermal ablation procedures: histopathological animal studies have shown that IRE induces cell death up to a vessel wall without any perivascular sparing [5,6,7] whilst preserving the normal architecture of blood vessels [5, 6, 8, 9]. Mild histopathological changes in adjacent vessel walls as vasculitis and mild endothelial damage have been detected in animal studies [5, 8, 10]. Alterations of vessels adjacent to an IRE ablation zone were detected by means of computed tomography (CT) imaging after IRE on porcine livers [6]. Similar findings have been reported after IRE ablation of 129 tumors in different organs in humans [11]. The objective of this retrospective study was to evaluate risk factors associated with alterations in venous structures adjacent to an ablation zone after IRE of hepatic malignancies in humans at subacute follow-up. The evolution of these changes was evaluated by means of further follow-up imaging
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