[Subintimal recanalization. Indications, technique and results]. / Subintimale Rekanalisation. Indikation, Technik und Ergebnisse.

CLINICAL/METHODICAL ISSUE: This article gives an overview of the current importance of so-called subintimal recanalization in the lower extremities. STANDARD RADIOLOGICAL METHODS: The primary technical goal of endovascular interventions in the lower extremities is the endoluminal restoration of blood circulation from the iliac arteries into the feet. METHODICAL INNOVATIONS: If endoluminal recanalization of e.g. high-grade flow-relevant stenoses or chronic total occlusion (CTO) is technically not possible, subintimal recanalization is a promising option and the only remaining minimally invasive alternative. During subintimal recanalization a channel is intentionally generated in the vessel wall (dissection) in order to bypass e. g. a chronic vascular occlusion over as short a distance as possible. PERFORMANCE: The technical success rate for subintimal recanalization of CTO of the lower extremities is 65-100 %. Technical failure occurs in approximately 25 % using the catheter and wire technique and is caused in most cases by difficulties in reaching the true lumen after the subintimal passage (the so-called re-entry). ACHIEVEMENTS: Compared to conventional subintimal recanalization, in recent years so-called re-entry devices have expanded the technical possibilities and depending on the medical experience and training level of the physician, provide an improvement in the technical success rate, a lower complication rate, a reduction of fluoroscopy time and the amount of necessary contrast medium but also result in higher costs. PRACTICAL RECOMMENDATIONS: Subintimal recanalization, whether carried out conventionally with a catheter and wire or using re-entry devices, of high-grade stenoses or CTO in the lower extremities provides a high technical success rate but requires an experienced and trained physician who is capable of operating the elaborate materials and mastering any possible complications.

Sphere-enhanced microwave ablation (sMWA) versus bland microwave ablation (bMWA): technical parameters, specific CT 3D rendering and histopathology.

PURPOSE: This study was designed to compare technical parameters during ablation as well as CT 3D rendering and histopathology of the ablation zone between sphere-enhanced microwave ablation (sMWA) and bland microwave ablation (bMWA). METHODS: In six sheep-livers, 18 microwave ablations were performed with identical system presets (power output: 80 W, ablation time: 120 s). In three sheep, transarterial embolisation (TAE) was performed immediately before microwave ablation using spheres (diameter: 40 ± 10 µm) (sMWA). In the other three sheep, microwave ablation was performed without spheres embolisation (bMWA). Contrast-enhanced CT, sacrifice, and liver harvest followed immediately after microwave ablation. Study goals included technical parameters during ablation (resulting power output, ablation time), geometry of the ablation zone applying specific CT 3D rendering with a software prototype (short axis of the ablation zone, volume of the largest aligned ablation sphere within the ablation zone), and histopathology (hematoxylin-eosin, Masson Goldner and TUNEL). RESULTS: Resulting power output/ablation times were 78.7 ± 1.0 W/120 ± 0.0 s for bMWA and 78.4 ± 1.0 W/120 ± 0.0 s for sMWA (n.s., respectively). Short axis/volume were 23.7 ± 3.7 mm/7.0 ± 2.4 cm(3) for bMWA and 29.1 ± 3.4 mm/11.5 ± 3.9 cm(3) for sMWA (P < 0.01, respectively). Histopathology confirmed the signs of coagulation necrosis as well as early and irreversible cell death for bMWA and sMWA. For sMWA, spheres were detected within, at the rim, and outside of the ablation zone without conspicuous features. CONCLUSIONS: Specific CT 3D rendering identifies a larger ablation zone for sMWA compared with bMWA. The histopathological signs and the detectable amount of cell death are comparable for both groups. When comparing sMWA with bMWA, TAE has no effect on the technical parameters during ablation.