title: In vivo temporal evolution of ALA-induced normalized fluorescence at different anatomical locations of oral cavity: application to improve cancer diagnostic contrast and potential.
abstract: BACKGROUND
  The focal goal of this study is to identify optimal accumulation periods for ALA-induced PpIX in different healthy anatomical sites of human oral cavity and different types of abnormal mucosa to improve the accuracy of the clinical applications such as photodiagnosis and tissue grading.
  
  
  METHODS
  Laser-induced fluorescence (LIF) emission spectra, with excitation at 404 nm from a diode laser, were recorded with a miniature fiber-optics spectrometer from 13 anatomical sites of oral mucosa in 15 healthy volunteers and 30 suspicious sites in 15 patients after topical application of 0.4% 5-ALA solution for 15 min. The optimal accumulation time in different anatomical sites of healthy subjects and abnormal tissues were determined by studying the temporal variation in normalized fluorescence intensities (NFI) at 635, 685 and 705 nm.
  
  
  CONCLUSIONS
  In masticatory anatomical locations such as (gingival and hard palate) and in lining mucosa (inner lip, soft palate, floor of mouth, transition to floor of mouth, alveolus and ventral tongue) except vermillion border of lip (VBL) of healthy subjects (designated as group I), it was observed that optimum time for maximum accumulation of PpIX is 90 min. In comparison, for lateral side of tongue (LST) and dorsal side of tongue (DST) tissues (designated as group II), maximum accumulation of PpIX was observed in 150 min of ALA application. For diverse grade lesions of group I mucosa in patients, maximum accumulation of PpIX was observed in 90 min, whereas, in group II mucosa the optimum accumulation time was 150 min as in the case of healthy mucosa. Further, between different grades oral mucosa, maximum variation in NFI take place at these optimal time periods.
  
  
  CONCLUSIONS
  The determination of the optimum accumulation time of ALA in oral mucosa based on NFI helps to improve the diagnostic contrast and accuracy of oral cancer diagnosis, and to plan appropriate timing for ensuing PDT.
authors: Biophotonics Laboratory, Centre for Earth Science Studies, Akkulam, Thuruvikkal PO, Trivandrum 695031, Kerala, India. jrmallia@cessind.org
authors: Rupananda Jayachandra
authors: RJ
authors: Mallia
authors: Narayanan
authors: N
authors: Subhash
authors: Paul
authors: P
authors: Sebastian
authors: Rejnish
authors: R
authors: Kumar
authors: Shiny Sara
authors: SS
authors: Thomas
authors: Anitha
authors: A
authors: Mathews
authors: Jayaprakash
authors: J
authors: Madhavan
mesh_terms: D000287:Administration, Topical; D000622:Aminolevulinic Acid / Q000493:pharmacokinetics*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology; D003945:Diagnosis, Oral; D006801:Humans; D009055:Mouth / Q000378:metabolism*; D009059:Mouth Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D009061:Mouth Mucosa / Q000033:anatomy & histology* / Q000473:pathology; D009062:Mouth Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology; D010778:Photochemotherapy; D011524:Protoporphyrins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX