1Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
2Research Center for Molecular and Cellular Imaging, Tehran University of Medical Science, Tehran, Iran
3Radiation Medicine Department, Shahid Beheshti University, Tehran, Iran
4Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Science, Tehran, Iran
Introduction:It is well-recognized that collimator-detector response (CDR) is the main image blurring factor in SPECT. In this research, we compensated the images for CDR in molecular SPECT by using STIR reconstruction framework. Methods: To assess resolution recovery capability of the STIR, a phantom containing five point sources along with a micro Derenzo phantom were investigated. Influence of the lesion size on SPECT quantification was addressed by calculating recovery coefficients (RCs) as well as spill-over ratios (SORs) for reconstructed NEMA image-quality phantom. Impact of the resolution modeling on noise properties was also studied. The RCs were then compared with those of experimentally obtained. In all cases, the images were iteratively reconstructed using an OSEM algorithm with 4 subsets and 32 subiterations. Results: CDR compensation gives rise to a significant drop in tomographic resolution from 2.45 mm to 1.55 mm. RC for hot rods of the NEMA IQ phantom monotonically grows as rod diameter increases, and results in an improvement of the RC up to a factor of 1.24 for the 5-mm rod diameter. PSF modeling also leads to a reduction in SOR from 0.24 to 0.16 averaged for the two cold cylinders. As a consequence of resolution recovery, a 15.5% overshoot near sharp edges imposing Gibbs ringing artifact occurs. In addition, a blobby noise texture is also observed. Furthermore, STIR results are consistent with the experimental ones.
Conclusion: Our findings demonstrate that resolution recovery is required for quantitative molecular SPECT imaging, and CDR compensation by the STIR framework offers superior SPECT image quality.
Zaidi H. Molecular imaging of small animals: instrumentation and applications. 1st ed. New York: Springer;2014.
Kiessling F, Pichler BJ. Small animal imaging. 1st ed. New York: Springer;2011.
Meikle SR, Kench P, Kassiou M, Banati RB. Small animal SPECT and its place in the matrix of molecular imaging technologies. Phys Med Biol. 2005 Nov 21;50(22):R45-61.
Frey EC, Humm JL, Ljungberg M. Accuracy and precision of radioactivity quantification in nuclear medicine images. Semin Nucl Med. 2012 May;42(3):208-18.
Tsui BM, Frey EC, Zhao X, Lalush DS, Johnston RE, McCartney WH. The importance and implementation of accurate 3D compensation methods for quantitative SPECT. Phys Med Biol. 1994 Mar;39(3):509-30.
Shepp LA, Vardi Y. Maximum likelihood reconstruction for emission tomography. IEEE Trans Med Imaging. 1982;1(2):113-22.
Hudson HM, Larkin RS. Accelerated image reconstruction using ordered subsets of projection data. IEEE Trans Med Imaging. 1994;13(4):601-9.
Tsui BMW, Frey EC. Analytic image reconstruction methods in emission computed tomography. In: Zaidi H. Quantitative analysis in nuclear medicine imaging. Singapore: Springer;2006. p. 82-106.
Tsui BMW, Hu HB, Gilland DR, Gullberg GT. Implementation of simultaneous attenuation and detector response correction in SPECT. IEEE Trans Nucl Sci. 1988;35(1):778-83.
Tsui BMW, Zhao XD, Frey EC. Accurate 3D detector response compensation in SPECT using multigrid iterative reconstruction methods. IEEE Nucl Sci Symp Conf Rec. 1995;2:1151-1155.
Wang WT, Tsui BMW, Frey EC, Wessell DE. Comparison of an analytical and an iterative based collimator-detector response compensation method in SPECT. IEEE Nucl Sci Symp Conf Rec. 1998;2:1382-1386.
Bouwens LR, Gifford H, Van de Walle R, King MA, Lemahieu I, Dierckx RA. Resolution recovery for list-mode reconstruction in SPECT. Phys Med Biol. 2001 Aug;46(8):2239-53.
Liu S, Farncombe TH. Collimator-detector response compensation in quantitative SPECT reconstruction. IEEE Nucl Sci Symp Conf Rec. 2007;5:3955-3960.
Chun SY, Fessler JA, Dewaraja YK. Correction for collimator-detector response in SPECT using point spread function template. IEEE Trans Med Imaging. 2013 Feb;32(2):295-305.
Zeraatkar N, Sajedi S, Farahani MH, Arabi H, Sarkar S, Ghafarian P, Rahmim A, Ay MR. Resolution-recovery-embedded image reconstruction for a high-resolution animal SPECT system. Phys Med. 2014 Nov;30(7):774-81.
Moji V, Zeratkar N, Farahani MH, Aghamiri MR, Sajedi S, Teimourian B, Ghafarian P, Sarkar S, Ay MR. Performance evaluation of a newly developed high-resolution, dual-head animal SPECT system based on the NEMA NU1-2007 standard. J Appl Clin Med Phys. 2014 Nov 8;15(6):4936.
Sajedi S, Zeraatkar N, Moji V, Farahani MH, Sarkar S, Arabi H, Teymooriana B, Ghafarian P, Rahmim A, Ay MR. Design and development of a high resolution animal SPECT scanner dedicated for rat and mouse imaging. Nucl Instr Meth Phys Res A. 2014;741:169-76.
Pashazadeh AM, Tanha K, Jafarian-Dehkordi F, Assadi M, Moji V, Zeraatkar N, Ay MR. Experimental evaluation of the performance of HiReSPECT scanner: a high-resolution SPECT system for small-animal imaging. Front Biomed Technol. 2014;1(3):222-227.
Thielemans K, Tsoumpas C, Mustafovic S, Beisel T, Aguiar P, Dikaios N, Jacobson MW. STIR: software for tomographic image reconstruction release 2. Phys Med Biol. 2012 Feb 21;57(4):867-83.
Fuster BM, Falcon C, Tsoumpas C, Livieratos L, Aguiar P, Cot A, Ros D, Thielemans K. Integration of advanced 3D SPECT modeling into the open-source STIR framework. Med Phys. 2013 Sep;40(9):092502.
NEMA Standards Publication NU 4-2008. Performance measurements of small animal positron emission tomographs (PETs). National Electrical Manufacturers Association; 2008.
Rahmim A, Qi J, Sossi V. Resolution modeling in PET imaging: theory, practice, benefits, and pitfalls. Med Phys. 2013 Jun;40(6):064301.
Tong S, Alessio AM, and Thielemans K, Stearns C, Ross S, Kinahan PE. Properties and mitigation of edge artifacts in PSF-based PET reconstruction. IEEE Trans Nucl Sci. 2011;58(5) 2264-2275.
Zeng GL. Gibbs artifact reduction by nonnegativity constraint. J Nucl Med Technol. 2011 Sep;39(3):213-9.
Nuyts J. Unconstrained image reconstruction with resolution modeling does not have a unique solution. Eur J Nucl Med Mol Imaging Phys. 2014;1:98.