• Title/Summary/Keyword: $^{99m}Tc-MIBI$

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Artifactual Perfusion Defects due to the Parameters of Reconstruction Filter in Tc-99m-MIBI Myocardial SPECT Images (Tc-99m-MIBI 심근 SPECT 영상에서 재구성 필터에 의한 인위적 관류결손에 관한 연구)

  • Kwark, Cheol-Eun;Lee, Kyung-Han;Lee, Dong-Soo;Park, Yong-Woo;Chung, June-Key;Lee, Myung-Chul;Seo, Joung-Don;Koh, Chang-Soon
    • The Korean Journal of Nuclear Medicine
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    • v.29 no.1
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    • pp.41-47
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    • 1995

  • Tc-99m-MIBI(Sestamibi) myocardial SPECT along with T1-201 tomographic imaging has demonstrated wide application and high image qualify sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow, The qualitative values of myocardial SPECT with Tc-99m-MIBI as well as the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection(FBP) is the common standard for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it Is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected filter parameters such as cutoff frequencies and order(Butterworth case). The cutoff frequencies basically remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable thresh-old of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Nyquist frequency would reveal severe degradation of radio-active distribution near inferior and/or Inferoseptal myocardium when applying Butterworth or low pass filter.

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Interobserver Reproducibility of Segmental Scoring of $^{99m}Tc$-MIBI Myocardial SPECT ($^{99m}Tc$-MIBI 심근 SPECT의 분절 육안 분석시 판독자간의 일치도)

  • Yeo, Jeong-Seok;Lee, Dong-Soo;Lee, Kyung-Han;Kim, Jong-Ho;Shon, Kyung-Soo;Cho, Sung-Wook;Kwark, Cheol-Eun;Chung, June-Key;Lee, Myung-Chul;Seo, Jeong-Don;Koh, Chang-Soon
    • The Korean Journal of Nuclear Medicine
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    • v.28 no.3
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    • pp.317-325
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    • 1994

  • The accuracy of dipyridamole stress/rest $^{99m}Tc$-MIBI myocardial imaging for detection of ischemia depends on reproducible image interpretation. To evaluate the reproducibility of visual assessment, agreement in interpretation among two independent observers, blind-ed to clinical data, was evaluated in SPECT images of 131 patients (94 males, 38 females; mean age $58{\pm}7yr$) with suspected coronary artery disease who underwent both dipyridamole stress/rest $^{99m}Tc$-MIBI myocardial SPECT and coronary angiography. The left ventricle was divided into twenty-nine segments in stress and rest SPECT images and each segment was visually graded according to a five-point scale (segmental score : 0=normal, 1=equivocal, 2=mild decrease, 3=severe decrease and 4=absent uptake). Overall concordance of segmental scoring between the two observers was 80%. The Pear-son's correlation coefficient (r) of the segmental scores for stress and rest images were 0.67 and 0.65, respectively, while the difference in score between the two images showed a correlation of 0.45 (all p<0.001). Agreement between two observers in final SPECT diagnosis as absence or presence of disease was 93%. The degree of agreement in segmental scoring showed no difference between patients with or without agreement as to the presence of disease. Therefore it appeared that cases with inconcordant diagnosis between the 2 observers were mainly due to a difference in individual threshold for interpretating the significance of a particular decreased uptake area rather than to a difference in perceiving the degree of the hypoactivity Thus, establishment of individual optimum thresholds in visual interpretation of myocardial SPECT may be helpful to improve reproducibility and accuracy of scan diagnosis.

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Transient Prolonged Stunning by Dipyridamole Stress Proved by Post-stress(1 hour) and 24 hour Tc-99m-MIBI Gated SPECT (반복 게이트 심근 Tc-99m-MIBI SPECT로 확인한 디피리다몰 부하에 의한 일과성 심근기절현상)

  • Lee, Dong-Soo;Yoon, Seok-Nam;Lee, Won-Woo;Chung, June-Key;Lee, Myoung-Mook;Lee, Myung-Chul;Koh, Chang-Soon
    • The Korean Journal of Nuclear Medicine
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    • v.31 no.1
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    • pp.57-66
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    • 1997

  • We performed 1st day Tc-99m-sestamibi gated SPECT with dipyridamole/rest T1-201 SPECT and 2nd day 24 hour delay T1-201 SPECT/rest Tc-99m-sestamibi gated SPECT in 27 patients with coronary artery disease(24) or having chest pain(3). Stress and rest Tc-99m-sestamibi gated SPECT was acquired at 60min post-injection. A 4-point scoring system(0 to 3 for normal to absent tracer uptake) for 17 segments was used. Wall motion was scored on another 4 point scale(0 to 3 for normal to dyskinesia) in the 1st day post-stress gated and the 2nd day rest gated SPECT. Post-stress gated SPECT showed wall motion abnormality in 94 segments(20%). Fifty-five segments among these 94 showed the same wall motion between post-stress and rest gated SPECT: i.e. 1-1 23 segments, 2-2: 29 segments, 3-3: 3 segments. Remaining 39 segments(41.5%) showed different wall motion between post- stress and rest Tc-99m-sestamibi gated SPECT. Twenty one segments with wall motion abnormality had normal perfusion(rest : 15 segments, 24 hour delay: 6 segments) at either rest or 24 hour delay. Fifteen among these 21 segments showed persistent post-stress and the 2nd day rest wall motion abnormality(persistent stunning). However, in 6 segments with pro-longed (1 hour after stress) stunning, abnormal wall motion did improve in the 2nd day rest Tc-99m-sestamibi gated SPECT(transient prolonged stunning). These 6 segments had normal perfusion at rest(n=4) or at 24 hour delay(n=2). Post stress wall motions showed significantly higher scores in persistent stunning than in prolonged transient stunning(P value<0.05). It was concluded that we could find stunned myocardium with gated Tc-99m-sestamibi SPECT at either post-stress or rest and that some myocardial walls of post-stress 1 hour gated SPECT did not show truly rest wall motion. So, we should be cautious if we use post-stress Tc-99m-sestamibi wall motion to assess rest wall motion.

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