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Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.1 Corinne GROISELLE  Coded aperture tomography (thesis subject) (thesis subject)  Compton scattering.

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Presentation on theme: "Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.1 Corinne GROISELLE  Coded aperture tomography (thesis subject) (thesis subject)  Compton scattering."— Presentation transcript:

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2 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.1 Corinne GROISELLE  Coded aperture tomography (thesis subject) (thesis subject)  Compton scattering correction  Brain perfusion index determination  Thallium - Mibi wash out

3 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.2 CODED APERTURE TOMOGRAPHY: 3D RECONSTRUCTION BY A ML-EM ALGORITHM USING TWO ORTHOGONAL PROJECTIONS

4 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.3 INTRODUCTION SPECT multiples incidences parallel collimator reconstruction (FBP or iterative) slices perpendicular to the detector Coded aperture tomography an unique incidence multi pinhole mask iterative reconstruction (ML-EM) slices parallel to the detector

5 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.4 ADVANTAGES Spatial resolution improvement Sensibility improvement Tomographic acquisitions possibility: –dynamics –multi spectral acquisitions Attempted advantages of the coded aperture tomography are in relation with the multi pinhole characteristics:

6 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.5 Principle PRINCIPLE OF OUR METHOD Optical instrument –focal distance, f –proximal slice, b –volume of detection detector mask f detector activity b f

7 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.6 OBJECT ACQUISITIO N CODED VIEW 256x256 COMPUTING: decoding iterative reconstruction SLICES PARALLEL TO THE DETECTOR SYNOPTIC

8 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.7 PROTECTIVE MEASURES Patent (n° /12/90) R&D Sopha Medical Vision Intl.

9 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.8 MATERIAL Gamma-camera DST-XL (SMV Intl.) –FOV: 540 x 400 mm² Coded aperture mask –196 pinholes with a 3.1 mm diameter –f = mm –b = mm Volume of detection –w = mm –l = mm –d = mm

10 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.9 MATERIAL  Thyroid phantom  256x256 matrix  2 orthogonal projections

11 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.10 ‚   RL Plexiglas ® 23 mm 2.5 mm 23 mm 2.5 mm 23 mm 2.5 mm 17 mm 8mm Plexiglas ® b RG  ‚  CHARACTERISTICS a d c 8 mm 17 mm 8 mm 12 mm13 mm 10 mm 7 mm Active: A/2 Not active Active: A

12 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.11 METHOD: DECODING Decoding is in relation with: System geometry: focal distance, pinhole Voxels: 4.5 x 4.5 x 4.5 mm 3 Pixels: 2.25 mm for a 256x256 matrix Pixels: 4.52 mm for a 128x128 matrix

13 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.12 METHOD: RECONSTRUCTION ML-EM iterative algorithm (Lange et Carson J. Comput. Assist. Tomogr. Vol. 8, n°2, 1984) OjOj IiIi J I correction

14 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.13 RESULTS: PROJECTIONS 1 st incidence2 nd incidence (orthogonal)

15 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.14 RESULTS: RECONSTRUCTION 29 slices 39 x 29 matrix voxel size: 4.5 mm IBM work station

16 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.15 RESULTS: RECONSTRUCTION

17 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.16 RESULTS: RECONSTRUCTION

18 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.17 SPATIAL RESOLUTION: R x (z) Intrinsic resolution: R I =3.7mm Mask spatial resolution: –pinhole projection size on the detector Detector spatial resolution: Slices spatial resolution: theoretically : mm 5.4 mm

19 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.18 DISCUSSION Position +++ Shape +++ Tomographic effect +++ Resolution x128 quality  256x256 quality  Uniformity – – –

20 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.19 CONCLUSION Acquisition sensibility x10 vs. LEUHR  acquisition time   dose   No rotation or translation  acquisition time   no artifact due to motion (patient or camera)  Tomographic effect +++

21 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.20 PERSPECTIVES Patient acquisition

22 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.21 ADAPTATIVE COMPTON SCATTERING CORRECTION FOR CODED APERTURE

23 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.22 CODED APERTURE TOMOGRAPHY 1 coded projection ML-EM iterative reconstruction algorithm slices parallel to the detector GE 400 AC

24 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.23 GOAL OF OUR STUDY Eliminating Compton scattered photons PH PRETORIUS & al. The Channel Ratio Method of Scatter Correction for Radionucleide Image Quantitation J Nucl Med 1993, 34,

25 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.24 METHOD Energy (keV) Counts percentage F : High energy window E : Low energy window Compton Scatter Primary photons

26 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.25 MATERIAL AND METHOD (1) CALIBRATION 99m Tc point source –acquisitions on air : no scatter –acquisitions with water : scatter correction matrices: G & H

27 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.26 CORRECTION Matrix GMatrix H matrix Gmatrix H 0 Corrected view  corrected view  H update -  water < limite END no yes For different water depths Low energy window counts High energy window counts

28 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.27 MATERIAL AND METHOD (2) Thyroid phantom (~ 500 µCi of 99m Tc) –simples acquisitions –acquisitions with 4 cm of Plexiglas®

29 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.28 CODED APERTURE PROJECTIONS Thyroid phantom - 99m Tc Point source - 99m Tc

30 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.29 ADAPTATION TO THE CODED APERTURE PROJECTIONS Pretorius Region of Interest drawn on the point source view Uniform correction matrices Very high counts rate on the ROI Coded aperture Coded aperture projection is different from the object shape Local correction of each pixel of the view Very high standard deviation

31 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.30 RESULTS: THYROID PHANTOM Reference view 140 keV ± 10% Corrected slice by the adaptive Pretorius method

32 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.31 RESULTS: THYROID PHANTOM + 4 cm PLEXIGLAS® Reference view 140 keV ± 10% Corrected slice by the adaptive Pretorius method

33 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.32 CONCLUSION Contrast enhancement Resolution improvement Simple and fast method

34 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.33 IMPROVEMENT IN MEASURING 99m Tc-ECD BRAIN PERFUSION INDEX BY TEMPORAL ANALYSIS

35 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.34 INTRODUCTION Brain perfusion imagery –cerebral blood flow Nuclear Medicine Imagery –Radioactivity detected in counts/min. but not as a flow (ml/min.) Interest of an absolute brain perfusion index for clinical studies

36 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.35 REFERENCE Matsuda & al. –Eur J Nucl Med 1992, 19, 195:200 : A Quantitative Approach to Technetium-99m HexaMethyl- Propylene Amine Oxime –Eur J Nucl Med 1995, 22, 633:637 : A Quantitative Approach to 99m-Ethyl Cysteinate Dimer : A Comparison with Technetium-99m HexaMethyl- Propylene Amine Oxime

37 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.36 MATSUDA’S METHOD Dynamic study –Brain angioscintigraphy Aorta activity –Region of interest on the aortic arch Brain activity –Regions of interest on brain hemispheres Brain perfusion index –Ratio of cumulated counts in aorta and brain ROIs

38 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.37 DISADVANTAGES OF MATSUDA’S METHOD Aortic arch Very low counts rate ROI manually drawn

39 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.38 GOAL OF OUR STUDY Improvement of ROI drawing to make this method not observer dependant

40 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C patients & 4 observers Head position : OM orthogonal to the detector Bolus injection of 800 MBq of 99mTc-ECD Brain angioscintigraphy –150 views at 1-second interval –anterior and posterior view MATERIAL AND METHOD

41 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.40 DATA POST-PROCESSING (1) Factorial Analysis with 3 main components on the cardiac first past frames –entry of the bolus in the right atrium –pulmonary transit phase –passage of the tracer into the aorta

42 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.41 DATA POST- PROCESSING (2) First Harmonic Fourier Analysis on the obtained curves Low-pass filter Isocontour algorithm to draw the aortic arch outline Phase Amplitude

43 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.42 DATA POST-PROCESSING (3) Sum of the posterior frames Low-pass filter Line on the OM Mask to highlight the brain image ROIs of each hemisphere are hand-drawn

44 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.43 DATA POST-PROCESSING (4) Brain perfusion index Time/activity curves BPI = 100. k u. ROI aorta size ROI brain size B(t) A(t) A(  ) d   t  kuku A0A0 B0B0 A0A0 B0B0 1 - aorta 2 - brain

45 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.44 RESULTS

46 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.45 CONCLUSION ROI accuracy +++ Reproducibility +++ User friendly-method +++

47 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.46 PERSPECTIVES Automatically brain ROIs outlines draw Observer independent method

48 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.47 FUNCTIONAL IMAGERY OF BRONCHIAL TUMOR RESISTANCE Groiselle C., Moretti J.-L., Michel A., Safi N.

49 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.48 INTRODUCTION Thallium 201 ( 201 Tl) and Sestamibi Tc-99m (MIBI) are tumors tracers Intra-tumors concentration is dependent on perfusion MIBI is recognized by PgP and MRP Proteins incite wash-out Groiselle C., Moretti J.-L., Michel A., Safi N.

50 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.49 GOAL OF THIS STUDY Finding bronchial carcinoma with two tracers and planar & dynamic views so as to determine wash-out Groiselle C., Moretti J.-L., Michel A., Safi N.

51 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.50 MATERIAL AND METHOD Patients : 15 males (60 ± 7 years) Groiselle C., Moretti J.-L., Michel A., Safi N.

52 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.51 ACQUISITION t 0 –bolus injection of 110 MBq of 201 Tl in the brachial vein on opposite side from the tumor –dynamic acquisition : 18 frames at 2-minutes interval –2 energy windows : 71 keV ± 10% & 140 keV ± 10% t min. –bolus injection of 700 MBq of MIBI t min. –planar acquisition Groiselle C., Moretti J.-L., Michel A., Safi N.

53 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.52 POST-PROCESSING Shifting of views (angiography and planar acq.) Correction of radioactive decay of planar acq. Correction of 99m Tc scattering on 201 Tl ROI draw to outline the tumor Subtraction of dynamic views from planar acq. ROI counts Groiselle C., Moretti J.-L., Michel A., Safi N.

54 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.53 RESULTS Groiselle C., Moretti J.-L., Michel A., Safi N. THp: extracted from Tl dynamic acquisition MIp: extracted from MIBI dynamic acquisition MIt: MIBI planar acquisition Diffp: early subtraction frame Difft: late subtraction frame

55 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.54 RESULTS Groiselle C., Moretti J.-L., Michel A., Safi N. THp: extracted from Tl dynamic acquisition MIp: extracted from MIBI dynamic acquisition MIt: MIBI planar acquisition Diffp: early subtraction frame Difft: late subtraction frame

56 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.55 CONCLUSION We can detect chemotherapy resistant tumors on thallium-MIBI functional images Groiselle C., Moretti J.-L., Michel A., Safi N.

57 Groiselle C., Rocchisani J.-M., Moretti J.-L., Paré C.56 Service Central de Biophysique et de Médecine Nucléaire Hôpital Avicenne - 125, rue de Stalingrad Bobigny cedex


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