Spectroscopic differentiation between normal bronchial and lung cancer tissues by laser-induced fluorescence (LIF) with intravenous injection of hematoporphyrin monomethyl ether (HMME)

Abstract

To study the feasibility of laser-induced fluorescence ( LIF) spectroscopy with intravenous injection of a new agent, hematoporphyrin monomethyl ether (HMME) , in the diagnosis of lung cancer. Fifteen patients with lung cancer were administrated HMME 2. 5 mg/ kg intravenously three hours before lobectomy. Surgical specimens were collected for examination of LIF spectrum. TheLIF spectra of normal bronchial and lung cancer tissues were measured with a detecting system which consists of an YAG laser ( wavelength 355 nm) and an optical multichannel analyzer ( OMA) . The patholog ical examination was performed in each specimen. The fluorescence intensity of the lung cancer tissues ( 31 446±5 017) was much lower than that of the normal bronchial tissues ( 75 430±8 908) ( P < 0. 001) . There was a flat spectrum in the normal bronchial tissues at the wavelength from 580 to 600 nm ( I580nm / I600nm = 1. 081 ±0. 090) , but the cancer tissue spectrum showed a smoothly descending profile ( I580nm/ I600nm = 1. 260±0. 157) . A remarkable characteristic peak ( drug peak) located at the 623. 4 nm±1. 6 nm in the lung cancer spectrum. Using the criterion of I580nm/ I600nm , the sensitivity, specificity, and accuracy of the diagnosis for lung cancer were 80. 0%, 73. 9%, and 76. 7%, respectively , and were 95. 0%, 91. 3% and 93. 0% respectively according to the criterion of the slope of the drug peak. The LIF spectroscopy following intravenous injection of the new photosensitiser HMME can differentiate lung cancer from normal bronchus and can increase the sensitivity, specificity and the accuracy comparing to the laser-induced auto fluorescence in the diagnosis of lung cancer.