Giuseppe Quero1, Paola Saccomandi1,2, Jung-Myun Kwak1,3, Bernard Dallemagne4, Guido Costamagna1, Jacques Marescaux1,4, Didier Mutter1,4,5, Michele Diana6,7,8. 1. IHU-Strasbourg, Institute of Image-Guided Surgery, Strasbourg, France. 2. Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy. 3. Department of Surgery, Korea University College of Medicine, Seoul, Republic of Korea. 4. IRCAD, Research Institute Against Cancer of the Digestive System, 1, Place de l'Hôpital, 67091, Strasbourg, France. 5. Department of General, Digestive and Endocrine Surgery, University Hospital of Strasbourg, Strasbourg, France. 6. IHU-Strasbourg, Institute of Image-Guided Surgery, Strasbourg, France. michele.diana@ircad.fr. 7. IRCAD, Research Institute Against Cancer of the Digestive System, 1, Place de l'Hôpital, 67091, Strasbourg, France. michele.diana@ircad.fr. 8. Department of General, Digestive and Endocrine Surgery, University Hospital of Strasbourg, Strasbourg, France. michele.diana@ircad.fr.
Abstract
BACKGROUND: Endoscopic submucosal dissection allows for "en bloc" removal of early gastrointestinal neoplasms. However, it is technically demanding and time-consuming. Alternatives could rely on energy-based techniques. We aimed to evaluate a predictive numerical model of thermal damage to preoperatively define optimal laser settings allowing for a controlled ablation down to the submucosa, and the ability of confocal endomicroscopy to provide damage information. MATERIALS AND METHODS: A Nd:YAG laser was applied onto the gastric mucosa of 21 Wistar rats on 10 spots (total 210). Power settings ranging from 0.5 to 2.5W were applied during 1-12 s, with a consequent energy delivery varying from 0.5 to 30 J. Out of the 210 samples, a total of 1050 hematoxilin-eosin stained slides were obtained. To evaluate thermal injury, the ratio between the damage depth (DD) over the mucosa and the submucosa thickness (T) was calculated. Effective and safe ablation was considered for a DD/T ratio ≤ 1 (only mucosal and submucosal damage). Confocal endomicroscopy was performed before and after ablation. A numerical model, using human physical properties, was developed to predict thermal damage. RESULTS: No full-thickness perforations were detected. On histology, the DD/T ratio at 0.5 J was 0.57 ± 0.21, significantly lower when compared to energies ranging from 15 J (a DD/T ratio = 1.2 ± 0.3; p < 0.001) until 30 J (a DD/T ratio = 1.33 ± 0.31; p < 0.001). Safe mucosal and submucosal ablations were achieved applying energy between 4 and 12 J, never impairing the muscularis propria. Confocal endomicroscopy showed a distorted gland architecture. The predicted damage depth demonstrated a significant positive linear correlation with the experimental data (Pearson's r 0.85; 95% CI 0.66-0.94). CONCLUSIONS: Low-power settings achieved effective and safe mucosal and submucosal ablation. The numerical model allowed for an accurate prediction of the ablated layers. Confocal endomicroscopy provided real-time thermal damage visualization. Further studies on larger animal models are required.
BACKGROUND: Endoscopic submucosal dissection allows for "en bloc" removal of early gastrointestinal neoplasms. However, it is technically demanding and time-consuming. Alternatives could rely on energy-based techniques. We aimed to evaluate a predictive numerical model of thermal damage to preoperatively define optimal laser settings allowing for a controlled ablation down to the submucosa, and the ability of confocal endomicroscopy to provide damage information. MATERIALS AND METHODS: A Nd:YAG laser was applied onto the gastric mucosa of 21 Wistar rats on 10 spots (total 210). Power settings ranging from 0.5 to 2.5W were applied during 1-12 s, with a consequent energy delivery varying from 0.5 to 30 J. Out of the 210 samples, a total of 1050 hematoxilin-eosin stained slides were obtained. To evaluate thermal injury, the ratio between the damage depth (DD) over the mucosa and the submucosa thickness (T) was calculated. Effective and safe ablation was considered for a DD/T ratio ≤ 1 (only mucosal and submucosal damage). Confocal endomicroscopy was performed before and after ablation. A numerical model, using human physical properties, was developed to predict thermal damage. RESULTS: No full-thickness perforations were detected. On histology, the DD/T ratio at 0.5 J was 0.57 ± 0.21, significantly lower when compared to energies ranging from 15 J (a DD/T ratio = 1.2 ± 0.3; p < 0.001) until 30 J (a DD/T ratio = 1.33 ± 0.31; p < 0.001). Safe mucosal and submucosal ablations were achieved applying energy between 4 and 12 J, never impairing the muscularis propria. Confocal endomicroscopy showed a distorted gland architecture. The predicted damage depth demonstrated a significant positive linear correlation with the experimental data (Pearson's r 0.85; 95% CI 0.66-0.94). CONCLUSIONS: Low-power settings achieved effective and safe mucosal and submucosal ablation. The numerical model allowed for an accurate prediction of the ablated layers. Confocal endomicroscopy provided real-time thermal damage visualization. Further studies on larger animal models are required.
Entities:
Keywords:
Confocal endomicroscopy; Early gastrointestinal cancer; Laser ablation; Preclinical study; Predictive numerical model
Authors: N Hanaoka; N Uedo; R Ishihara; K Higashino; Y Takeuchi; T Inoue; R Chatani; M Hanafusa; Y Tsujii; H Kanzaki; N Kawada; H Iishi; M Tatsuta; Y Tomita; I Miyashiro; M Yano Journal: Endoscopy Date: 2010-11-30 Impact factor: 10.093
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