Thermometry during coblation and radiofrequency ablation of vertebral metastases: a cadaver study

Abstract

Purpose To evaluate safety of coblation of simulated lytic metastases in human cadaveric vertebral bodies by measuring heat distribution during thermal tissue ablation and comparing it to radiofrequency ablation (RFA). Materials and methods Three devices were compared: a 10 mm single-needle RFA electrode, a 20 mm array RFA electrode and the coblation device. To simulate bone metastases, a spinal tumor model was used stuffing a created lytic cavity with muscle tissue. Measuring of heat distribution was performed during thermal therapy within the vertebral body, in the epidural space and at the ipsilateral neural foramen. Eight vertebral bodies were used for each device. Results Temperatures at heat-sensitive neural structures during coblation were significantly lower than using RFA. Maximum temperatures measured at the end of the procedure at the neural foramen: 46.4°C (±2.51; RFA 10 mm), 52.2°C (±5.62; RFA 20 mm) and 42.5°C (±2.88; coblation). Maximum temperatures in the epidural space: 46.8°C (±4.7; RFA 10 mm), 49.5°C (±6.48; RFA 20 mm) and 42.1°C (±2.5; coblation). Maximum temperatures measured within the vertebral body: 50.6°C (±10.48; RFA 10 mm), 61.9°C (±15.39; RFA 20 mm) and 54. 4°C (±15.77; coblation). Conclusion In addition to RFA, the application of coblation is a safe method to ablate vertebral lesions with regards to heat distribution at heat-sensitive neural spots. The measured temperatures did not harbor danger of thermal damage to the spinal cord or the spinal nerves.

Vertebral Augmentation for Neoplastic Lesions with Posterior Wall Erosion and Epidural Mass

“…25 Cavity creation in the vertebral body was performed with Coblation Wands (Fig 2), as previously reported by other authors, 19,26,27 in 59/70 levels. The decision not to use Coblation was made intraprocedurally when the advancement of the trocar cannulas through the lytic area did not reveal typical softtissue consistency, but rather fluid consistency, such as in markedly necrotic tumors or in some multiple myeloma lesions.…”

Radiofrequenzablation: Temperaturverteilung im angrenzenden Gewebe

“…Daher ist zur Risikominimierung eine gezielte Überwachung der Temperatur während der Ablation notwendig [19]. Da sich die Temperaturverteilung während der Ablation jedoch auch in Abhängigkeit von dem verwendeten Ablationssystem unterscheidet [16], wurden zahlreiche unterschiedliche Verfahren ent-wickelt, um das umliegende Gewebe bei gleichbleibender Effizienz der Ablation zu schützen.…”

“…Sobald die Temperatur des proximalen Temperaturfühlers 50°C erreicht, wird die Energieübertragung gestoppt. Dazu wurden die Thermosonden zuvor unter fluoroskopischer Überwachung nach dem in Grötz et al beschriebenen Vorgehen platziert[16]. Die Platzierung erfolgte ventral epidural mittig, an der medialen Begrenzung des linken Neuroforamens sowie im mittleren Drittel des Wirbelkörpers in Verlängerung der transpedikulären Achse (▶ Abb.…”

Radiofrequency Ablation: Temperature Distribution in Adjacent Tissues

“…During the ablation process, the maximal temperatures in the vertebral body, the neuroforamen and the spinal canal were measured with thermal probes. For this purpose, the thermal probes had been previously positioned under fluoroscopic monitoring, as described by Grötz et al [16]. The probes were positioned centrally, ventrally and epidurally at the medial border of the left foramen and in the midthird of the vertebral body in extension of the transpedicular axis (l " Fig.…”

“…It follows that this risk should be minimised by specific temperature monitoring during ablation [19]. As, however, temperature distribution during ablation also depends on the ablation system used [16], numerous different procedures have been developed to protect the surrounding tissue without altering the efficiency of the ablation. In the study of Buy X et al, three patients with metastases of the vertebral bodies (levels T10 to L3) were treated with RFA.…”