Medical Applications of Fluorescence Spectroscopy

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Medical Applications of Fluorescence Spectroscopy

• Martin ODwyer and Miles Padgett
• Optics Group at
• Department of Physics and Astronomy
• University of Glasgow
• In collaboration with the Department of
  Photobiology, Ninewells Hospital, Dundee, and the
  Maxillofacial Department, the Royal Infirmary,
  Glasgow.

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This talk

• History of the project
• The fluorescence systems weve used
• Some work weve done
• Older examples briefly
• Recent example in more detail
• Acknowledgements

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Detection of tissue fluorescence (why?)
Tissue fluorescence
Fluorescence detection
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5-aminolaevulinic acid (ALA)
Aminolaevulinic acid (ALA) administered to patient
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Tissue Fluorescence
AutoFluorescence
PpIX Fluorescence
Photoproducts
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Fluorescence imaging system
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Imaging results (In vivo - colon cancer)
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Point Application
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A Compact Fluorescence System
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Monitoring PDT of anal intraepithelial neoplasia
(AIN)

• Clear decrease in PpIX fluorescence during
  treatment due to photobleaching.
• Potential for determining appropriate length of
  treatment.

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Finished System

• Distinguishes between normal and cancerous
  fluorescence.
• Compact, portable, robust and user-friendly
  system.
• Fibre-coupled for endoscopic use.
• Low cost and easily maintained

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Some Applications

• Monitoring PDT of anal intraepithelial neoplasia
• Endoscopic detection of gastrointestinal (GI)
  cancers
• Characterisation of new formulations in-vivo
• In-vitro study of new drug combinations
• Optimise procedures
• Study effects of modifying treatment

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Photodynamic Therapy

• PDT now routinely used
• Mostly involved in topical dermatology
• Topical PDT increasingly used
• Other diseases also treated

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Veterinary PDT

• Device used at VETSUISSE Faculty, Zurich
• New Liposomal formulations of m-THPC
  (photosensitizer)
• Fluorescent measurements to assess
  pharmacokinetics

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New Formulations

• New liposomal formulation of the well-known
  photosensitizer Foscan (mTHPC, Temoporfin)
• In-vivo measurements in cats with spontaneousely
  occuring squamous cell carcinoma
• Concentration 1.5 mg Temoporfin/ml Fospeg
• Drug dosage 0.15 mg/kg 10 J/cm2

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A Patient/VolunteerFeline squamous cell carcinoma

• 17 year old neutered tom
• A - Before treatment
• B - 3 weeks after, central necrosis of the tumour
• C - 15 weeks after, complete destruction of
  tumour

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Biopsy

• False negative rates   
• Inadequacies of sampling
• Inadequacies of slide preparation
• Processing problems - 90 of all slides are
  normal easy to miss the comparatively rare
  abnormal slide.
• Unnecessary costly procedures
• Inability to detect the earliest signs 
• Optical techniques may be as effective?

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Endoscopic inspection of Oral/Oesophageal cancers

• Ratio of autofluorescence and PpIX fluorescence
  peaks allows normal and pre-cancerous tissue to
  be clearly distinguished.
• Potential for use in early detection of GI
  cancers.

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Oral detection
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Why

• Rising UK incidence of oral cancer especially in
  Scotland
• Early diagnosis is difficult
• Hence Poor Prognosis
• A Tool to aid the early diagnosis of cancer would
  be useful
• Pilot study to explore a fluorescence technique
  to identify suspicious tissue

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Procedure

• Fluorescence spectra were recorded from all
  regions at 30min, 60min and 90min after mouthwash
• PpIX fluorescence levels were greater at 60 and
  90mins than at 30min (as expected)
• 12 standard points were looked at after 90mins

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In-vivo fluorescence measurements (Six patients
and six healthy volunteers)

• Plot of maximum values of autofluorescence vs
  PpIX fluorescence (dosage 20mg/kg bw))

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In-vivo fluorescence measurements (Six patients
and six healthy volunteers)

• Patient 1 mild and severe dysplasia..
• Patient 2 Well differentiated squamous cell
  carcinoma with marked lichenoid reaction.
• Patient 3 Ulceration, severe dysplasia adjacent
  to biopsy site. Moderate dysplasia extending to
  excision margin.
• Patient 4 Severe dysplasia and hyperkeratosis.
  The reading from FEMS was carried out after
  excision of the lesion.
• Patient 5 chronic inflammation with reactive
  epithelial changes, diagnosed as chronic
  hyperplastic candidiasis.
• Patient 6 Squamous carcinoma that had been
  resected from the right floor of mouth. PDD
  carried out at 3 months subsequently.

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PCA

• Data reduction technique
• Determine covariance between dimensions of data
  set
• Principle components are eigenvectors of
  covariance matrix
• Eigenvector with the highest eigenvalue contains
  the most information about the original data set
• Attractive way of processing large amounts of
  data

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PCA
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Endoscopic inspection of Oral/Oesophageal cancers

• Barretts Oesophagus Patients
• Glasgow has the highest incidence in the UK
• Royal Infirmary
• ALA administered orally (dosage 20mg/kg bw).
• Fluorescence spectra measured during routine
  endoscopy from various tissue types.

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Oral/Oesophageal parallel measurements

• Optical measurement at same point at biopsy
• Hope to show definitive correlation
  optical-histological
• Want to know how progressed cancer is
• Prompt early biopsy
• Help triage urgency of biopsy
• Indicate Site to biopsy (if large lesion)

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Future work

• Correlation study ongoing
• Hope to show definitive correlation
  optical-histological
• Just completed PoC project
• Lifetime measurement
• MHRA approval for trial

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Recap

• History of the project
• The systems used
• Some results
• Future plans

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Thanks to

• Miles Padgett
• Graham Ogden, Stuart McLaren, Carol Goodman
• Julia Buchholtz
• Jacqueline Hewett Valerie Nadeau
• EPSRC, Scottish Enterprise, Royal Society of
  Edinburgh
• Jo-Etienne Abela, Robert Stuart