Optimization of the Diameter of a Radial Irradiation Device for Photodynamic Therapy in the Esophagus

Background and Study Aims: Photodynamic therapy (PDT) is a local therapeutic technique based on the photosensitization of lesions using a dye prior to light-induced tissue destruction. PDT of intraepithelial neoplasia in Barrett’s esophagus, or of early squamous-cell carcinoma of the esophagus, requires light application devices that allow homogeneous and well-defined illumination of the tissue surface. Such devices must be large enough to induce complete unfolding of the esophagus in spite of esophageal motility and elasticity. The aim of this study was therefore to determine the optimal diameter of a cylindrical illumination device for PDT in this organ.
Patients and Methods: The study included nine patients (aged 49-72 years) who underwent panendoscopy. Flexible transparent hollow tubes with diameters ranging from 13 to 19 mm were successively introduced into the esophagus, and the esophageal wall was viewed from the inside through the tube using a flexible small-diameter endoscope. The number of folds was counted. Observations of the upper, middle, and lower thirds of the esophagus were recorded. The radial location of the folds was also recorded, and defined as follows: anterior wall (up), posterior wall (down), side walls (right, left).
Results: No significant difference in the number of folds between the lower and middle parts of the esophagus was noticed. However, the upper third had significantly fewer folds (about 30 %) than the other two parts. For diameters above 17 mm, this difference was less dramatic. The number of such folds was shown to decrease with the increasing diameter of the device.
Conclusions: It appears that 18 mm or more is the optimal diameter for a fixed-geometry cylindrical photodynamic therapy irradiating device for the patient category considered in this study. It was also observed that most folds were located on the side walls of the esophagus.

References

• 1 Hsi R A, Rosenthal D I, Glatstein E. Photodynamic therapy in the treatment of cancer: current state of the art.  Drugs. 1999;  57 725-734
• 2 Henderson B W, Dougherty T J, Peng Q. Photodynamic therapy.  J Natl Cancer Inst. 1998;  90 889-905
• 3 Ell C, Gossner L. Photodynamic therapy.  Recent Results Cancer Res. 2000;  155 175-181
• 4 Gossner L, Stolte M, Sroka R. et al . Photodynamic ablation of high-grade dysplasia and early cancer in Barrett’s esophagus by means of 5-aminolevulinic acid.  Gastroenterology. 1998;  114 448-455
• 5 Wang K K. Current status of photodynamic therapy of Barrett’s esophagus.  Gastrointest Endosc. 1999;  49 S20-23
• 6 van den Bergh H. On the evolution of light delivery systems for photodynamic therapy.  Endoscopy. 1998;  30 392-407
• 7 Dumont J F, Meric B, Sivak M V, Fleischer D. A new method of esophageal dilatation using Savary-Gilliard bougies.  Gastrointest Endosc. 1985;  31 379-382
• 8 Herlin P, Marnay J, Jacob J H. et al . A study of the mechanism of the toluidine blue dye test.  Endoscopy. 1983;  15 4-7
• 9 Radu A, Wagnières G, van den Bergh H, Monnier P. Photodynamic therapy of early squamous cell cancers of the esophagus.  Gastrointest Endosc Clin N Am. 2000;  10 439-460
• 10 Gossner L, May A, Sroka R, Ell C. A new long-range through-the-scope balloon applicator for photodynamic therapy in the esophagus and cardia.  Endoscopy. 1999;  31 370-376
• 11 Panjehpour M, Bergein F, Overholt F, Haydek J M. Light sources and delivery devices for photodynamic therapy in the gastrointestinal tract.  Gastrointest Endosc Clin N Am. 2000;  10 513-532
• 12 Overholt B F, DeNovo R C, Panjehpour M, Petersen M G. A centering balloon for photodynamic therapy of esophageal cancer tested in a canine model.  Gastrointest Endosc. 1993;  39 782-787
• 13 Overholt B F, Panjehpour M, DeNovo R C, Peterson M G. Photodynamic therapy for esophageal cancer: effect of increasing balloon size.  Lasers Surg Med. 1996;  18 248-252
• 14 Bays R, Wagnières G, Robert D. et al . Light dosimetry for photodynamic therapy in the esophagus.  Lasers Surg Med. 1997;  20 290-303
• 15 Beyer W. Systems for light application and dosimetry in photodynamic therapy.  J Photochem Photobiol B. 1996;  36 153-156