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1 PET/CT Quantitative Analysis for Small Animal PET/CT INER017(NL940022)

3 1. PET/CT (PET) X (CT) PET CT PET/CT CT PET PET 511 kev (LOR) 3

4 2. Functional PET imaging using targeted molecular probes has become very important in many drug development using small animal models. However, probe uptakes limited to specific targeted areas greatly increase diagnostic difficulty. However, small animal PET/CT scanners have now been recognized as a powerful diagnostic modality. PET/CT scanner provides hardware image fusion capabilities which will make interpretation of PET images much easier due to the anatomical landmarks offered by CT scans. In addition, the CT data can be used to correct PET scans for photon attenuation. The thesis of two-year project is the development of a quantitative imaging system that provides accurate bio-distribution measurement of positron-labeled molecular images for combined 3D PET/CT scanners. The imaging system consists of two major research tasks: (1) automatic CT image segmentation, and (2) accurate estimation of attenuation correction factors for PET imaging. An automatic segmentation algorithm based of fuzzy clustering will be developed for whole-body CT image. After image segmentation, each region of the partitioned CT image, representing one type of material, is then assigned a unique attenuation coefficient of 512 kev photons. The corresponding ACF can be computed via accurately forward projection the 512keV attenuation image. It is anticipated that the newly developed system can provide some quantitative PET image using the co-registered CT image for small animals. 4

PET/CT scanner provides hardware image fusion capabilities which will make interpretation of PET images much easier due to the anatomical landmarks offered by CT scans.

5 3. (microct) (micropet) 511 kev 5

6 4. PET/CT (PET) X (CT) PET CT PET/CT CT PET PET PET/CT 6

7 kev 1 (Cluster Analysis) CT (Homogeneity) 7

8 Centroid Euclidean Distance 2 M Distance x, = x jp µ ip p= µ µ i x j M N N*M M 1 C-Means Clustering ^ µ C C ( x ) ( x µ ) 2 1 if min j i P ωi j 0 otherwise P( ω ) i x j 1 0 8

9 1973 Bezdek Fuzzy K-Means Clustering, FCM P( ω ) i x j FCM Cost Function J fuz = c i n j ( x ) b P ωi j x j µ i b b b b 2 P( ω ) i x j 2 µ x x P( ω ) i x j µ P( ω i x j ) P( ω ) i x j µ µ 1 2 J ( x j µ i) fuz = 0 P( ωi xj) = P( ωi xj) c 1 2 i ( x j µ i) 1 b 1 1 b 1 (4) 9

10 b { P( ωi xj) xj } P( ωi xj) J fuz = 0 µ = µ i n j= 1 i n b j= 1 FCM µ i FCM C 4 P( ω ) N*C P( ω ) i x j i x j N C 5 µ i ( k 1) ( k ) µ µ. = ( k ) µ. FCM k=k [13] FCM x FCM Homogeneous 10

11 FCM FCM In-homogeneity FCM FCM CT CT CT Gaussian Distribution f () x = ( x µ ) 1 2 2σ e 2πσ 2 FCM CT Partial Volume Effect CT PET PET CT Forward Projection LOR CT LOR PET 10 PET CT PET FCM 11

12 Feature Extraction 25 j= 1 ( x j x) 2 S = Standard Deviation CT CT FCM CT CT FCM FCM CT Table 1 CT CT CT CT Soft Tiisue FCM 3 CT 4 12

13 FCM 4 10 FCM FCM 6 CT FCM Fig. 2 FCM FCM 13

14 3*3 FCM 3 Fig. 5 CT FCM CT FCM FCM FCM 3 Hypothesis Testing % 3 Fig. 3(a) CT Fig. 3(b) FCM 14

15 FCM a b c d Fig. 3(d) CT FCM FCM 15

16 Fig. 3(c) FCM FCM (a) (b) Figure 4. (a) INER microct images, (b) Segmentation results. Fig 4 INER micropet PET/CT 16

17 6. CT FCM FCM FCM Hierarchical CT PET 17

18 7. 1. Raghu Krishnapuram and James M. Keller. A possibilistic approach to clustering. IEEE Transactions on Fuzzy Systems, Vol. 1, pp , 1993; 2. M. Xu, P. D. Cutler, and W.K. Luk. Adaptive, segmented attenuation correction for whole-body PET imaging. IEEE Transactions on Nuclear Science, Vol. 43, pp , S R Cherry et al, MicroPET: A high resolution PET scanner for imaging small animals, IEEE Trans. Nucl. Sci., 44, , PE Kinahan, DW Townsend, T Beyer, D Sashin, Attenuation correction for a combined 3D PET/CT scanner, Med Phys., Vol. 25, No. 10, pp , Thomas Beyer, David W. Townsend and Tony Brun, et al. A Combined PET/CT Scanner for Clinical Oncology. The Journal of Nuclear Medicine, Vol. 41: , S R Cherry and S S Gambhir, Use of positron emission tomography in animal research, ILAR J, , S S Gambhir et al, Imaging transgene expression with radionuclide imaging technologies, Neoplasia , Richard O. Duda, Peter E. Hart and David G. Stork. Pattern Classification. Wiley-Interscience, , H Zaidi, M Diaz-Gomez1, A Boudraa and D O Slosman. Fuzzy clustering-based segmented attenuation correction in whole-body PET imaging. Physics in Medical Biology, Vol. 47, , Heiko Schoder, Yusuf E. Erdi, Steven M. Larson and Henry W. D. Yeung. PET/CT: a new imaging technology in nuclear medicine. European Journal of Nuclear Medicine and Molecular Imaging Vol. 40, pp , Paul E. Kinahan, Bruce H. Hasegawa, and Thomas Beyer. X-Ray-Based Attenuation Correction for Positron Emission Tomography/Computed Tomography Scanners. Seminars in Nuclear Medicine 2003; XXXIII: S Cherry, In vivo molecular and genomic imaging: new challenges for imaging physics, Phys. Med. Biol., Vol. 49, No. 3, pp. R13-R48, AM Alessio, PE Kinahan, PM Cheng, H Vesselle, JS Karp, PET/CT scanner instrumentation, challenges, and solutions, Radiol Clin North Am., Vol. 42, No. 6, pp , David W. Townsend, Jonathan P.J. Carney, Jeffrey T. Yap and Nathan C. Hall. PET/CT Today and Tomorrow. The Journal of Nuclear Medicine, Vol. 45, pp. 4S-14S, Vibhu Kapoor, Barry M. McCook and Frank S. Torok. An Introduction to PET/CT Imaging. RadioGraphics, Vol. 24, pp , Patrick L Chow, Fernando R Rannou and Arion F Chatziioannou. Attenuation correction for small animal PET tomographs. Physics of Medical Biology Vol. 50, pp ,

1-336, 1996. 3. S R Cherry et al, MicroPET: A high resolution PET scanner for imaging small animals, IEEE Trans. Nucl. Sci., 44

物理学报 Acta Phys. Sin. Vol. 62, No. 14 (2013) 147802 叠 [4]. PET 设备最重要的部件就是探测器环, 探测备重建图像具有减少数据插值的优势. 器环的性能直接影响 PET 的成像能力. 探头与探头之间得到的符合直线叫做投影线. 所有的投影线在

物理学报 Acta Phys. Sin. Vol. 62, No. 14 (2013) 147802 叠 [4]. PET 设备最重要的部件就是探测器环, 探测备重建图像具有减少数据插值的优势. 器环的性能直接影响 PET 的成像能力. 探头与探头之间得到的符合直线叫做投影线. 所有的投影线在数据插值对正电子发射断层成像设备的图像重建影响的研究 * 杨昆刘新新李晓苇 ( 河北大学物理学院, 保定 071000 ) ( 2013 年 1 月 30 日收到 ; 2013 年 4 月 9 日收到修改稿 ) 正电子发射断层扫描 (positron emission computed tomography,