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Medical Applications of Fluorescence Spectroscopy

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Title: Medical Applications of Fluorescence Spectroscopy


1
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.

2
This talk
  • History of the project
  • The fluorescence systems weve used
  • Some work weve done
  • Older examples briefly
  • Recent example in more detail
  • Acknowledgements

3
Detection of tissue fluorescence (why?)
Tissue fluorescence
Fluorescence detection
4
5-aminolaevulinic acid (ALA)
Aminolaevulinic acid (ALA) administered to patient
5
Tissue Fluorescence
AutoFluorescence
PpIX Fluorescence
Photoproducts
6
Fluorescence imaging system
7
Imaging results (In vivo - colon cancer)
8
Point Application
9
A Compact Fluorescence System
10
Monitoring PDT of anal intraepithelial neoplasia
(AIN)
  • Clear decrease in PpIX fluorescence during
    treatment due to photobleaching.
  • Potential for determining appropriate length of
    treatment.

11
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

12
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

13
Photodynamic Therapy
  • PDT now routinely used
  • Mostly involved in topical dermatology
  • Topical PDT increasingly used
  • Other diseases also treated

14
Veterinary PDT
  • Device used at VETSUISSE Faculty, Zurich
  • New Liposomal formulations of m-THPC
    (photosensitizer)
  • Fluorescent measurements to assess
    pharmacokinetics

15
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

16
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

17
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?

18
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.

19
Oral detection
20
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

21
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

22
In-vivo fluorescence measurements (Six patients
and six healthy volunteers)
  • Plot of maximum values of autofluorescence vs
    PpIX fluorescence (dosage 20mg/kg bw))

23
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.

24
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

25
PCA
26
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.

27
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)

28
Future work
  • Correlation study ongoing
  • Hope to show definitive correlation
    optical-histological
  • Just completed PoC project
  • Lifetime measurement
  • MHRA approval for trial

29
Recap
  • History of the project
  • The systems used
  • Some results
  • Future plans

30
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
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