Panjehpour et al., Gastrointestinal Endoscopy Vol. 41 (6), 1995

Spectroscopic diagnosis of esophageal cancer: new classification model, improved measurement system.

- A nitrogen-pumped dye-laser (model LC300C, Laser Photonics, Inc., Orlando, Fla.) was used to deliver 5-ns pulses of excitation light. The dye-laser was tuned at 410 nm.

- Each fluorescence lineshape spectrum was sampled at 15-nm intervals from 430 to 716 nm, excluding 430 nm. This resulted in intensities at 19 wavelengths being used in the statistical analysis.

- The fluorescence lineshapes are clearly different in normal and malignant tissue. The two spectra intersect at about 540 nm. Below 540 nm, the normal tissue fluorescence is stronger than that of malignant tissue. Above 540 nm, the normal tissue
fluorescence is weaker than that of malignant tissue.

- The stepwise discriminate analysis selected only five wavelengths: 490 nm, 580 nm, 670 nm, 685 nm, and 715 nm.

- In this study, the excitation wavelength of 410 nm proved to be suitable for diagnosis of esophageal malignancies. This is in close agreement with data from Richards-Kortum et al. reporting excitation wavelength of 430 + 10 nm for classification of colonic lesions.

(10. Richards-Kortum R, Rava RP, Petras RE, Fitzmaurice M, Sivak M, Feld MS. Spectroscopic diagnosis of colonic dysplasia.
Photochem Photobiol 1991;53:777-86.)

- Schomacker et al. used a nitrogen laser (337 nm) in vivo and in vitro to excite fluorescence of colonic tissue. Using a multivariate linear regression analysis, they distinguished neoplastic tissue from tissue that was not neoplastic with sensitivity and specificity of 80 % and 92 %, respectively.

(3. Schomacker KT, Frisoli JK, Compton CC, et al. Ultraviolet laser-induced fluorescence of colonic tissue: basic biology and diagnostic potential. Lasers Surg Med 1992;12:63~78.)

- Cothren et al. used 370-nm excitation light to examine in vivo fluorescence of colonic tissue. Using a two-dimensional scatter plot of fluorescence intensities at 460 nm versus 680 nm, they defined a straight line representing a decision surface, which minimized the number of misclassified samples. Using this technique, adenomas could be distinguished from nonadenomatous tissue in approximately 97 % of cases.

(4. Cothren RM, Richards-Kortum R, Sivak MV Jr, et al. Gastrointestinal tissue diagnosis by laser-induced fluorescence spectroscopy at endoscopy. Gastrointest Endosc 1990;36:105-11.)