Engineering Better Medicine
New Imaging Methods
D.T. Delpy
Dept of Medical Physics & Bioengineering
UCL
Imaging Modalities
X Ray - Conventional, Tomography
Endoscopy
Magnetic Resonance Imaging - MRI Single
Photon Emission CT -SPECT
Positron Emission Tomography - PET
Ultrasound
Laser Doppler
Optical Coherence Tomography - OCT
NIR Topography, Tomography
Exogenous fluorophores
MID IR
Thermoacoustics
Terahertz
3D X Ray CT of hand
3D X Ray CT of abdomen with
soft tissue rendering
3D visualisation
CT virtual colonoscopy
The endoscopy “pill”
Images obtained when
passing through the bowel
(Given Imaging System)
Conventional MRI system
Open access MRI system
Small Extremity MRI
MRI Brain image
fMRI images of the brain showing
activation changes during 40
minutes of motor learning
MRI movie of the beating heart
Intravascular
imaging with
micro-coils
MRI flow velocity profiling
MR Angiography
Gated MR Image of the heart
Lung imaging with
Hyperpolarised 129Xe
Single headed Gamma camera
PET system
Combined PET & MRI 3D
image of brain
Combined X ray
CT and PET
Ultrasound array transducer and beam steering
Vaginal ultrasound
image of early foetus
3D vaginal ultrasound
image of early foetus
3D Ultrasound imaging of baby
Light penetration distances into the skin with wavelength
Multispectral imaging: 700 - 900 nm range
Photograph & Laser Doppler image of lower legs
Principles of Optical Coherence Tomography
OCT image of the
cornea and pupil
OCT image of the retina
OCT of normal esophagus,
colon and colon carcinoma
Doppler OCT of retinal
blood vessels
Absorption Spectrum of Blood
ULTRAVIOLET
VISIBLE
NEAR INFRARED
Absorption Spectra of Haemoglobin
Molar Extinction
Coefficient
[cm-1[cm-1/M]
Absorption
M-1]
1000000
Hb02
NIR Measurement
Hb
Region
100000
10000
HbO2
1000
Hb
100
200
300
400
500
600
700
Wavelength
[nm]
Wavelength
[nm]
800
900
1000
1100
NIR topography principles
NIR topography system photograph
NIR topographic image of motor cortex activation
NIR Breast Imager (Philips)
Breast Cup
Tumour
Cyst
Tumour 3D
The MONSTIR Project
But near infrared light scatters in tissue.
The (temporal) Impulse
Response Function of
tissue to a pulse of
laser light can be used
to distinguish between
the effects of scatter
and absorption.
~ ns
t
~ ps
t
t
t
Adult Arm Imaging Experiment
Arm Imaging Results (Absolute)
A
A
B
B
Longitudinal
MRI
MRI
ms
ma
Optical Imaging of Luciferase tagged bacteria & tumour cells
Optical imaging of GFP fluorescence
GFP expression monitored
non invasively
Tumour angiogenesis
Mid Infrared (900-1800 cm-1)
Images of
Bone and Single Osteon
top: hydroxyapatite
middle: Protein (amide)
bottom: crystallinity
Thermoacoustic imaging of
kidney with cyst
Contrast depends on absorption
of particular energy type
The “unexplored” parts of the spectrum - Terahertz waves
Terahertz imaging
Just a few imaging topics not mentioned:
X ray: spiral CT, phase imaging
MRI: diffusion, perfusion, oxygenation, CSI, hyperpolarised gas blood
flow
PET: combined CT/PET, MRI/PET
Ultrasound: power doppler, microscopy, bubble contrast (all 3D)
Ultrasound/MRI: Hall effect imaging
Ultrasound/Light/Microwaves: photoacoustic, thermoacoustic imaging
Light: intravascular OCT, OCT spectroscopy, Raman imaging, elastic
scattering spectroscopy, diffusive wave spectroscopy, polarisation
imaging (structural), NIR breast imaging, flow using ICG
etc etc etc
The futures bright:
The futures:
IMAGING
Hopefully not!!
Functional NIRS - Visual Cortex
Functional NIRS - Visual Cortex - Averaged Signal
8
HbO2
Hbvol
Hb
 concentration (mmolar.cm)
6
4
2
0
-2
-4
-10
0
10
20
Time (seconds)
30
40
50
OCT movie of beating tadpole heart
The MONSTIR Imaging System
Reference
PD
VOA
PF
Pulsed
Laser
NDF
S
32 detector
fibre bundles
FC
FS
x32
ATD
Delay
FFM
CFD
PTA
LPF
MCPPMT
PA
x32
x4
32 source
fibres
Control PC
NDF: Neutral Density Filter, S: Shutter, FC: Fibre Coupler, FS: Fibre Switch, VOA: Variable Optical
Attenuator, PF: Polymer Fibre, LPF: Long-Pass Filter, MCP-PMT: Multichannel Plate-Photomultiplier
Tube, PA: Pre-Amplifier, CFD: Constant Fraction Discriminator, PTA: Picosecond Time Analyser,
PD: Photodiode, ATD: Amplifier/Timing Discriminator, FFU: Fast Fan-out Module
Workstation
X Ray CT system
Ultrasound image and Doppler signal from umbilical artery & vein
The MONSTIR Imaging System
BACK
SIDE
FRONT