Stretching the boundaries of conventional thought: Larry Golub and the tetracycline story

In vivo optical coherence tomography for the diagnosis of oral malignancy

BACKGROUND AND OBJECTIVE

Oral cancer results in 10,000 U.S. deaths annually. Improved highly sensitive diagnostics allowing early detection of oral cancer would benefit patient survival and quality of life. Objective was to investigate in vivo non-invasive optical coherence tomography (OCT) techniques for imaging and diagnosing neoplasia-related epithelial, sub-epithelial changes throughout carcinogenesis.

STUDY DESIGN/MATERIALS AND METHODS

In the standard hamster cheek pouch model for oral carcinogenesis (n = 36), in vivo OCT was used to image epithelial and sub-epithelial change. OCT- and histopathology-based diagnoses on a scale of 0 (healthy) to 6 (squamous cell carcinoma, SCC) were performed at all stages throughout carcinogenesis by two blinded investigators.

RESULTS

Epithelial, sub-epithelial structures were clearly discernible using OCT. OCT diagnosis agreed with the histopathological gold standard in 80% of readings.

CONCLUSION

In vivo OCT demonstrates excellent potential as a diagnostic tool in the oral cavity.

In vivo multiphoton fluorescence imaging: a novel approach to oral malignancy

BACKGROUND AND OBJECTIVE

Current techniques for oral diagnosis require surgical biopsy of lesions, and may fail to detect early malignant change. Non-invasive, sensitive tools providing early detection of oral cancer and a better understanding of malignant change are needed. These studies evaluated in vivo multiphoton excited fluorescence (MPM) techniques to (1) map epithelial and subepithelial changes through out oral carcinogenesis and (2) serve as an effective diagnostic modality.

STUDY DESIGN/MATERIALS AND METHODS

In the hamster model (n = 70), epithelial and subepithelial change was imaged in vivo throughout carcinogenesis. MPM- and histopathology-based diagnoses on a scale of 0 (healthy)-6 (squamous cell carcinoma [s.c.c.]) were scored by two pre-standardized investigators.

RESULTS

Collagen matrix and fibers, cellular infiltrates, blood vessels, and microtumors were clearly visible. MPM agreed with the histopathology for 88.6% of diagnoses.

CONCLUSIONS

In vivo MPM images provide (1) high resolution information on specific components of the carcinogenesis process (2) an excellent basis for oral diagnostics.

Acceleration of ALA-induced PpIX fluorescence development in the oral mucosa

BACKGROUND AND OBJECTIVES

The development of 5-aminolevulinic acid (ALA)-induced tissue fluorescence is optimal 2-4 hours after ALA application. Goal of this work was to develop a means of accelerating oral topical ALA-induced tissue fluorescence.

STUDY DESIGN/MATERIALS AND METHODS

In 300 hamsters, DMBA (9,10 dimethyl-1,2-benzanthracene) cheek pouch carcinogenesis produced dysplasia in 3-5 weeks. Topical application of 20% ALA in Eucerin was followed by localized ultrasound treatment (1, 3.3 MHz) in 150 animals. In 75 animals, ALA was applied in an Oral Pluronic Lecithin Organogel (OPLO-an absorption enhancer) vehicle. Seventy-five animals received only topical ALA in Eucerin. Hamsters were sacrificed and cryosections underwent fluorescence measurements, histological evaluation, 20-180 minutes after ALA application. One-way ANOVA detected independent effects of pathology on laser-induced fluorescence (LIF). Two-way ANOVA tested for independent effect of pathology and of OPLO, ultrasound, and interaction effects.

RESULTS

Ultrasound significantly (P < 0.05) accelerated tissue fluorescence development.

CONCLUSIONS

Low-frequency ultrasound can accelerate ALA-induced fluorescence development.

Detection and diagnosis of oral cancer by light-induced fluorescence

BACKGROUND AND OBJECTIVE

New techniques for non-invasive early detection and diagnosis of oral dysplasia and carcinoma are required. Our objective was to determine in the hamster cheek pouch model whether differentiation between the healthy tissue and the different stages of oral premalignancy and malignancy is possible using laser-induced fluorescence after tissue exposure to 5-Aminolevulinic acid (ALA).

STUDY DESIGN/MATERIALS AND METHODS

DMBA carcinogenesis was applied to one cheek pouch in 18 hamsters for 0-20 weeks. Prior to sacrifice, 20% ALA was applied to the cheek tissues. Excised cheek tissues were cryosectioned and imaged using fluorescence microscopy with excitation at 405 nm, detection at 635 nm. After fluorescence measurement, H&E staining and histopathological evaluation were performed.

RESULTS

Fluorescence intensity was significantly lower in healthy tissue than in pathological tissues. Significantly higher intensities and more "fluorescence hot spots" occurred in severe dysplasia and carcinoma than in healthy tissue, hyperkeratosis, mild and moderate dysplasia.

CONCLUSIONS

Light-induced fluorescence after ALA exposure can differentiate between the different stages of premalignancy and malignancy. Its ability to differentiate between healthy tissue and early pathology is particularly interesting