prostate probe with spect technique workshop on endoscospic imaging – marseille – 13-01-2011 –...
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Prostate probe with SPECT techniqueWorkshop on endoscospic Imaging – Marseille – 13-01-2011 – F. Garibaldi ISS and INFN Roma1
the medical problem
the proposal
Compton option Collimation techniques SiPM/electronics Multimodality
summary and outlook
1
Compton Camera Applications to Bio-medical Imaging (Mattinata 5-7 September 2002)
Stem cell workshop – Marseille - December 2008
-Topical Symposium on Advanced molecular intraoperative probes assisting surgical interventions - TOF PET workshop
Baia delle Zagare September 2009
next ?
Global incidence of prostate cancer*
<7.4
7.4-13.8
13.8-24.5
24.5-40.7
40.7-124.8
*Age-standardised incidence rates per 100,000 GLOBOCAN 2002
- etherogenous, multifocal, biologically not well understood
-The most common cancer in men, in western countries (97% of all cancers in men) (EJNM (2008),35:1019-1025)
- Primary or recurrent cancer confined in the organ can be curatively treated
-Thus it is important, at primary diagnosis, follow up and recurrence, to obtain accurate assessment of the diesease stage in order to decide the most effective treatment strategy (EJNM (2008),35:1019-1025)
thethe second leading causesecond leading cause of cancer of cancer death death
PSA SENSITIVITY 83%
SPECIFICITY 17%
CTSelective indication : PSA > 10 ng/ml cT3 Gleason score > 7
diagnosisdiagnosis is made from tissue obtained in a is made from tissue obtained in a blind biopsyblind biopsy
Need to consider fundamental changes in the approach to diagnosing prostate cancer
In the future, multimodality imaging approach tailored to each patient
PSADRETRUS
biopsy
prostate specific, not cancer specific (prostatitis, prostatic iperplasia, prostate cancer)
Radionuclides imaging techniques
Patient injected with radioactive drug. Drug localizes according to its metabolic properties.Gamma rays, emitted by radioactive decay, that exit the patient are imaged.
1.CollimatorOnly gammas that are perpendicular to imaging plane reach the detector
2.ScintillatorConverts gammas to visible light3.Photodetector
Convert light to electrical signal
4.Readout ElectronicsAmplify electrical signal and interface to computer5.Computer decoding procedureElaborate signal and gives image output
PETCompton Camera
mechanical collimation
Multi pinhole
Source
Image Plane
1st Detector
2nd DetectorScatteredγ - Rays
Single photon techniques
- simple(r)
- cheape(r)
- extending the radiotracers available
- dual tracer looking at two different biological processes
pros
cons- efficiency- spatial resolution
Compton Prostate Imaging Probe
Internal Compton Probe External Compton Probe
Conventional SPECT Reconstructions
5:1 10:1 15:1 20:1
w / tumor
bkgd
171 and 245 keV, 8.8M events / 40 slices
Spatial resolution ~15mm FWHM
Prostate
Compton Prostate Probe Reconstructions
5:1 10:1 15:1 20:1
w / tumor
bkgd
245 keV only, 1.2 million events, 8mm lesion
Prostate
Spatial resolution ~2mm FWHM
Internal Detector Details
10–12 layers of 1mm thick Si detectors + position and orientation sensor
Exploded View
Assembled Unit
Detector Packaging
Unfolded energy spectrum
“Raw” energy spectrum
Use Tape Automated Bonding (TAB)
(Very thin kapton tape with aluminum traces)
Kapton microcables
Detector
VATA ASIC
Kapton “hybrid” board
Demise of the Compton Prostate Probe
• Decreasing interest in imaging single photon agents
• “Coincidence” PET cameras not reimbursed by HCFA
• Technology ultimately was a bit far off
Source
Image Plane
1st Detector
2nd DetectorScatteredγ - Rays
Single photon Compton camera ( N. Clinthorne. Michigan )
111In-ProstaScint is not a good radiotracer but a new one proposed by M. Pomper looks promising.
Radionuclides Single photon
The single photon endorectal probe provides
2D imaging. We have to try to have 3 D images
( using multipinhole collimation and/or adding
up a SPECT tomograph (spatial resolution would
be dominated by the small probe (see later, the PET
case))
our proposal
-insert scintillator pixels into square holes of the collimator better performances (spatial resolution (?) and sensitivity (thicker
scintillator))
-using diverging collimator better performances (reducing scan time)
-using multipinhole collimation better performances (increasing sensitivity, tomographic
recinstruction)
20% prostate cancer20% prostate cancer
PERIPHERAL ZONERegion postero-lateral70% prostatic parenchyma
TRANSIZION ZONEAround to prostatic urethra25% prostatic parenchyma
CENTRAL ZONEEncircles theEyaculatory ducts 10% prostatic parenchyma
1-5%1-5%Prostate cancerProstate cancer
≥ ≥ 70% prostate cancer70% prostate cancer
CANCER CANCER LOCALIZATIONLOCALIZATION
Radiotracers issue
Radiotracers available for SPECT and PET (from “New agents and Techniques for Imaging prostate cancer” A. Zahreer, S. Y. Cho, M. Pomper”, to be published
on JNM)SPECT: Prostascint, Bombesyn, 99mTechnetium nanocolloid (limphonodes), other coming soon…PET C—11 Choline, F-18-Choline, Ga-68 Dotabomb (Hofmann (Rome workshop)) many others coming… (collaboration with Johns Hopkins for testing in ISS (mice models for prostate available) and/or at JHU)
20
- CITRATE that is present in the normal prostate
-CREATINA that may increase in the phlogosis and all the proliferative processes
- COLINE specific for a neoplastic transformation
M.S. Judenhofer et al. Nature Medicine, Vol. 14 N 4, pg. 439, April 2008
“In conclusion, our results confirm that simultaneous PET and high-field-strength MR imaging with LSO-APD–based PET detectors is feasible without sacrificing the quality of images obtained with either system.”
PET MRI advantages and issues
and fMRI ?
??
Summary and Conclusions
- prostate cancer detection, diagnosis and staging very difficult
- standard imaging systems suffer from VERY low specificity
- better radiotracers + multimodality can be the solution
- single photon techniques are an option because
- simpler and cheaper than PET
- dual tracer
- multimodality with MRI possible
- FDA approved for tests on humans
- better radiotarcers coming soon
- Using also an external SPECT?
- Prospectives: Compton