A Novel Method to Suppress the Effect of Subdiaphragmatic Activity in 99mTc Myocardial Perfusion SPECT and Evaluation of Its Usefulness Using a Myocardial Phantom.
{"title":"A Novel Method to Suppress the Effect of Subdiaphragmatic Activity in <sup>99m</sup>Tc Myocardial Perfusion SPECT and Evaluation of Its Usefulness Using a Myocardial Phantom.","authors":"Atsushi Komuro, Satomi Teraoka, Yasushi Ishikawa, Masanori Tsuboko, Mika Tanno, Kouichi Ishimori, Kazuo Funaki, Jiro Izumida, Tomiyoshi Saito","doi":"10.17996/anc.22-00154","DOIUrl":null,"url":null,"abstract":"<p><p><i>Background</i>: Smoothing in <sup>99m</sup>Tc myocardial perfusion single-photon emission computed tomography (SPECT) often increases myocardial artifacts due to subdiaphragmatic activity near the heart. To reduce these artifacts, we developed a new process flow, masking on unsmoothed images (MUS), that includes the extraction of the myocardium by masking before smoothing. <i>Methods</i>: This study evaluated the relationships between matrix sizes and distances to the subdiaphragmatic activity using the MUS method compared to conventional methods using a combination of image reconstruction methods (filtered back-projection [FBP] and ordered subset expectation maximization [OSEM]) with or without corrections (attenuation [AC], scatter [SC], and resolution recovery [RR]) using a myocardial phantom. The results were compared for two matrix sizes (pixel sizes) (128×128 [3.3 mm] and 64×64 [6.6 mm]); four subdiaphragmatic activity distances (5, 10, 15, and 20 mm); and three reconstruction methods (FBP without correction; OSEM with RR; and OSEM with AC, SC, and RR). <i>Results</i>: In the conventional method, increasing distance resulted in interference with myocardial perfusion SPECT evaluation however, the artifacts were less apparent when the MUS method was applied. The images converted to 64×64 did not show the same effect as the 128×128 images, even when RR was used. The MUS method was useful for acquisition at 128×128, along with the use of RR in the reconstruction process. <i>Conclusion</i>: MUS mitigated the effects of subdiaphragmatic activity on myocardial perfusion SPECT, particularly combined with 128×128 acquisitions and iterative reconstruction with RR.</p>","PeriodicalId":72228,"journal":{"name":"Annals of nuclear cardiology","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9749759/pdf/8_30.pdf","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Annals of nuclear cardiology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.17996/anc.22-00154","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1
Abstract
Background: Smoothing in 99mTc myocardial perfusion single-photon emission computed tomography (SPECT) often increases myocardial artifacts due to subdiaphragmatic activity near the heart. To reduce these artifacts, we developed a new process flow, masking on unsmoothed images (MUS), that includes the extraction of the myocardium by masking before smoothing. Methods: This study evaluated the relationships between matrix sizes and distances to the subdiaphragmatic activity using the MUS method compared to conventional methods using a combination of image reconstruction methods (filtered back-projection [FBP] and ordered subset expectation maximization [OSEM]) with or without corrections (attenuation [AC], scatter [SC], and resolution recovery [RR]) using a myocardial phantom. The results were compared for two matrix sizes (pixel sizes) (128×128 [3.3 mm] and 64×64 [6.6 mm]); four subdiaphragmatic activity distances (5, 10, 15, and 20 mm); and three reconstruction methods (FBP without correction; OSEM with RR; and OSEM with AC, SC, and RR). Results: In the conventional method, increasing distance resulted in interference with myocardial perfusion SPECT evaluation however, the artifacts were less apparent when the MUS method was applied. The images converted to 64×64 did not show the same effect as the 128×128 images, even when RR was used. The MUS method was useful for acquisition at 128×128, along with the use of RR in the reconstruction process. Conclusion: MUS mitigated the effects of subdiaphragmatic activity on myocardial perfusion SPECT, particularly combined with 128×128 acquisitions and iterative reconstruction with RR.