Efficacy of an Esophageal Spacer for Spine Radiosurgery: First Experience

Abstract

This is the first study to investigate the use of an esophageal hydrogel spacer in spine stereotactic radiosurgery. The tolerability and the dose reduction to the esophagus are predicted to reduce the incidence of high-grade toxicities, which in turn can permit dose escalation to optimize tumor control.

Figure 1

Representative axial and sagittal T2-weighted magnetic resonance imaging views acquired at diagnosis (A) and after spacer insertion (B,C) showing displacement of the esophagus away from the paraspinal tumor. Abbreviations: OAR = organs at risk.

Figure 2

The spacer was placed via video-assisted thoracic surgery (A). Intrathoracic view after dissection of the esophagus from the spine and chordoma (B). The hydrogel was injected around the esophagus and polymerized to form a solid gel between the tumor and esophagus.

Figure 3

Representative axial (A), coronal (B), and sagittal (C) sections from the postspacer computed tomography simulation scan and treatment plan demonstrate comprehensive coverage of the target volume and steep dose falloff. Dose-volume histograms illustrate esophageal dose sparing after versus before spacer placement (D). The spacer reduced the volume of the esophagus that initially overlapped with the high-dose region. All target volume constraints were achieved. Abbreviations: PTV = planning target volume.

Figure 4

Representative axial T2-weighted magnetic resonance imaging views acquired after spacer placement (A) and 2 years after radiation therapy with completely absorbed spacer (B).