Novel Applications Of An Injectable Radio-Opaque Hydrogel Tissue Marker For Management Of Thoracic Malignancies

Purpose/Objective(s)Radio-opaque markers (otherwise known as fiducials) are utilized clinically to mark sites of biopsy or resection, which aids with the targeting of adjuvant or definitive local therapy, including surgery and/or radiation therapy. We performed a human cadaveric imaging series using a novel injectable, radio-opaque absorbable hydrogel marker to demonstrate the potential for such a material to be used in the management of thoracic malignancies.Materials/MethodsBaseline CT images were performed on 3 unfixed cadaveric specimens. Hydrogel marker implants were performed in the submucosa of the esophagus, the mediastinum and lung parenchyma by an endoscopic approach. Real-time endobronchial and esophageal ultrasound were utilized to confirm hydrogel placement. Sub-pleural implants in peripheral lung parenchyma were also performed via an anterolateral thoracotomy. Post-implant simulation CT, T2-MRI and cone-beam CT were performed. Gross dissection of the lung parenchyma was used to evaluate localization of the hydrogel.ResultsTransthoracic and endoscopic marker placements were readily achieved. The hydrogel appeared hyperechoic by ultrasound, hyper-enhancing on T2-MRI imaging, and demonstrated radio-opacity of approximately 300 HU in simulation CT and cone-beam CT. Gross dissection of the lung revealed well-localized blebs of hydrogel marker within lung parenchyma.ConclusionsThis cadaveric series demonstrates the excellent visibility of a radio-opaque injectable hydrogel marker in the human thorax by multiple common imaging techniques, and because it forms a well-localized palpable bleb within tissue it can potentially be used to triangulate disease during minimally invasive thoracic surgery. Future in vivo studies are warranted, because radioopaque injectable compounds are promising alternatives to metal fiducials. Purpose/Objective(s)Radio-opaque markers (otherwise known as fiducials) are utilized clinically to mark sites of biopsy or resection, which aids with the targeting of adjuvant or definitive local therapy, including surgery and/or radiation therapy. We performed a human cadaveric imaging series using a novel injectable, radio-opaque absorbable hydrogel marker to demonstrate the potential for such a material to be used in the management of thoracic malignancies. Radio-opaque markers (otherwise known as fiducials) are utilized clinically to mark sites of biopsy or resection, which aids with the targeting of adjuvant or definitive local therapy, including surgery and/or radiation therapy. We performed a human cadaveric imaging series using a novel injectable, radio-opaque absorbable hydrogel marker to demonstrate the potential for such a material to be used in the management of thoracic malignancies. Materials/MethodsBaseline CT images were performed on 3 unfixed cadaveric specimens. Hydrogel marker implants were performed in the submucosa of the esophagus, the mediastinum and lung parenchyma by an endoscopic approach. Real-time endobronchial and esophageal ultrasound were utilized to confirm hydrogel placement. Sub-pleural implants in peripheral lung parenchyma were also performed via an anterolateral thoracotomy. Post-implant simulation CT, T2-MRI and cone-beam CT were performed. Gross dissection of the lung parenchyma was used to evaluate localization of the hydrogel. Baseline CT images were performed on 3 unfixed cadaveric specimens. Hydrogel marker implants were performed in the submucosa of the esophagus, the mediastinum and lung parenchyma by an endoscopic approach. Real-time endobronchial and esophageal ultrasound were utilized to confirm hydrogel placement. Sub-pleural implants in peripheral lung parenchyma were also performed via an anterolateral thoracotomy. Post-implant simulation CT, T2-MRI and cone-beam CT were performed. Gross dissection of the lung parenchyma was used to evaluate localization of the hydrogel. ResultsTransthoracic and endoscopic marker placements were readily achieved. The hydrogel appeared hyperechoic by ultrasound, hyper-enhancing on T2-MRI imaging, and demonstrated radio-opacity of approximately 300 HU in simulation CT and cone-beam CT. Gross dissection of the lung revealed well-localized blebs of hydrogel marker within lung parenchyma. Transthoracic and endoscopic marker placements were readily achieved. The hydrogel appeared hyperechoic by ultrasound, hyper-enhancing on T2-MRI imaging, and demonstrated radio-opacity of approximately 300 HU in simulation CT and cone-beam CT. Gross dissection of the lung revealed well-localized blebs of hydrogel marker within lung parenchyma. ConclusionsThis cadaveric series demonstrates the excellent visibility of a radio-opaque injectable hydrogel marker in the human thorax by multiple common imaging techniques, and because it forms a well-localized palpable bleb within tissue it can potentially be used to triangulate disease during minimally invasive thoracic surgery. Future in vivo studies are warranted, because radioopaque injectable compounds are promising alternatives to metal fiducials. This cadaveric series demonstrates the excellent visibility of a radio-opaque injectable hydrogel marker in the human thorax by multiple common imaging techniques, and because it forms a well-localized palpable bleb within tissue it can potentially be used to triangulate disease during minimally invasive thoracic surgery. Future in vivo studies are warranted, because radioopaque injectable compounds are promising alternatives to metal fiducials.