Article: Effect of Post-Reconstruction Gaussian Filtering on Image Quality and Myocardial Blood Flow Measurement with N-13 Ammonia PET

Objectives: In order to evaluate the effect of post-reconstruction Gaussian filtering on image quality and myocardial blood flow (MBF) measurement by dynamic N-13 ammonia positron emission tomography (PET), we compared various reconstruction and filtering methods with image characteristics.

Methods: Dynamic PET images of three patients with coronary artery disease (male-female ratio of 2:1; age: 57, 53, and 76 years) were reconstructed, using filtered back projection (FBP) and ordered subset expectation maximization (OSEM) methods. OSEM reconstruction consisted of OSEM_2I, OSEM_4I, and OSEM_6I with 2, 4, and 6 iterations, respectively. The images, reconstructed and filtered by Gaussian filters of 5, 10, and 15 mm, were obtained, as well as non-filtered images. Visual analysis of image quality (IQ) was performed using a 3-grade scoring system by 2 independent readers, blinded to the reconstruction and filtering methods of stress images. Then, signal-to-noise ratio (SNR) was calculated by noise and contrast recovery (CR). Stress and rest MBF and coronary flow reserve (CFR) were obtained for each method. IQ scores, stress and rest MBF, and CFR were compared between the methods, using Chi-square and Kruskal-Wallis tests.

Results: In the visual analysis, IQ was significantly higher by 10 mm Gaussian filtering, compared to other sizes of filter (P<0.001 for both readers). However, no significant difference of IQ was found between FBP and various numbers of iteration in OSEM (P=0.923 and 0.855 for readers 1 and 2, respectively). SNR was significantly higher in 10 mm Gaussian filter. There was a significant difference in stress and rest MBF between several vascular territories. However CFR was not significantly different according to various filtering methods.

Conclusion: Post-reconstruction Gaussian filtering with a filter size of 10 mm significantly enhances the IQ of N-13 ammonia PET-CT, without changing the results of CFR calculation.

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References

1.

Chen G, Branch K, Alessio A, Pham P, Tabibiazar R, Kinahan P . Effect of reconstruction algorithms on myocardial blood flow measurement with 13N-ammonia PET. J Nucl Med. 2007; 48(8):1259-65. PMC: 2586832. DOI: 10.2967/jnumed.106.038232. View

2.

Wang C, Snyder W, Bilbro G, Santago P . Performance evaluation of filtered backprojection reconstruction and iterative reconstruction methods for PET images. Comput Biol Med. 1998; 28(1):13-24; discussion 24-5. DOI: 10.1016/s0010-4825(97)00031-0. View

3.

Razifar P, Sandstrom M, Schnieder H, Langstrom B, Maripuu E, Bengtsson E . Noise correlation in PET, CT, SPECT and PET/CT data evaluated using autocorrelation function: a phantom study on data, reconstructed using FBP and OSEM. BMC Med Imaging. 2005; 5:5. PMC: 1208889. DOI: 10.1186/1471-2342-5-5. View

4.

Boellaard R, van Lingen A, Lammertsma A . Experimental and clinical evaluation of iterative reconstruction (OSEM) in dynamic PET: quantitative characteristics and effects on kinetic modeling. J Nucl Med. 2001; 42(5):808-17. View

5.

Khorsand A, Graf S, Pirich C, Muzik O, Kletter K, Dudczak R . Assessment of myocardial perfusion by dynamic N-13 ammonia PET imaging: comparison of 2 tracer kinetic models. J Nucl Cardiol. 2005; 12(4):410-7. DOI: 10.1016/j.nuclcard.2005.04.002. View