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