CLINICAL MULTICOLOR FLUORESCENCE IMAGING OF MALIGNANT-TUMORS - INITIAL EXPERIENCE

Purpose: The detection of malignant tumours relies on a variety of dia gnostic procedures including X-ray images and, for hollow organs, endo scopy. The purpose of this study was to present a new technique for no n-invasive tumour detection based on tissue fluorescence imaging. Mate rial and Methods: A clinically adapted multi-colour fluorescence syste m was employed in the real-time imaging of malignant rumours of the sk in, breast, head and neck region, and urinary bladder. Tumour detectio n was based on the contrast displayed in fluorescence between normal a nd malignant tissue, related to the selective uptake of tumour-marking agents, such as haematoporphyrin derivative (HPD) and Famine levulini c acid (ALA), and natural chromophore differences between various tiss ues. In order to demarcate basal cell carcinomas of the skin, ALA was applied topically 4-6 h before the fluorescence investigation. For uri nary bladder tumour visualisation (transitional cell carcinoma of diff erent stages including carcinoma in situ), ALA was instilled into the bladder 1-2 h prior to the study. Malignant and premalignant lesions i n the head and neck region were imaged after i.v. injection of HPD (Ph otofrin). Finally, the extent of in situ and invasive carcinomas of th e breast was investigated in surgically excised specimens from patient s that received a low-dose injection of HPD 24 h prior to the study. T he tumour imaging system was coupled to an endoscope. Fluorescence lig ht emission from the tissue surface was induced with 100-ns-long optic al pulses at 390 nm, generated from a frequency-doubled alexandrite la ser. With the use of special image-splitting optics, the tumour fluore scence, intensified in a micro-channel plate, was imaged in 3 selected wavelength bands. These 3 images were processed together to form a ne w optimised-contrast image of the tumour. This image, updated at a rat e of about 3 frames/s, was mixed with a normal colour video image of t he tissue. Results: A clear demarcation from normal surrounding tissue was found during in vivo measurements of superficial bladder carcinom a, basal cell carcinoma of the skin, and leukoplakia with dysplasia of the lip, and in in vitro investigations of resected breast cancer. Co nclusions: The initial clinical experience of using multi-colour fluor escence imaging has shown that the technique has the potential to reve al malignant tumour tissue, including non-invasive early carcinoma and also precancerous tissue. Further investigations are needed to fully develop the method.