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10.18 Simultaneous scatter and attenuation correction in myocardial SPECT
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Abstracts F r i d a y , M a y 4, 2 0 0 1
10.17 Accuracy and reproducibility of four softwares for the left-ventricular function with ECG-gated myocardial perfusion SPECT. T Hignchi, K Nakajima, J Taki, T Yoneyama, N Tonami. Nuclear Medicine Japan/Kanazawa univ. Kauazawa Japan.
Purpose: Myocardial perfusion SPECT using ECG-gating (G-SPECT) allows assessment of left ventficular function. Some different computer soflwares that can automatically assess left ventricular ejection fraction (EF) are currently available with G-SPECT. We validated four different softwares of QGS (Cedars Sinai Medical center), ECToolbox (Emory univ.), 4D-MSPECT(Michigan Univ.), pFAST (Sapporo Medical Univ.) in the same acquisition data. Methods: Twentyfive patients, who had performed both G-SPECT and gated blood-pool study (GBP) within 10 days, were enrolled in this study. The GBP was performed with Tc-99m RBC using 24 frames/cardiac cycle in left anterior oblique projection. Tc-99m-MIBI (740 MBq) was injected at rest, and G-SPECT was performed about 60min later using 360-degree acquisition and by 12 frames/cardiac cycle. We calculated EF using 4 sol'wares in the same G-SPECT acquisition data. We assessed inter- and intra-observer reproducibility, and performed correlation analyses with GBP data using four sottwares. Results: Correlation coefficients of inter- and intra-observer reproducibility for calculating EF were r= 1.00 and 0.99 with QGS, 0.98 and 0.98 with ECToolbox, 0.96 and 0.96 with 4D-MSPECT, 0.85 and 0.88 with pFAST, respectively. Correlation coefficients between EF by GBP and G-SPECT using QGS, ECToolbox, 4D-MSPECT and pFAST were r= 0.89 (y-0.99x+2.7, x= GBP), 0.88 (y=l.03x+3.6, x - GBP), 0.82 (y=0.87x+6.8, x= GBP), and 0.81 (y-0.91x+7.2, x - GBP), respectively. [Conclusion] Although QGS sofiwares showed the best inter- and intra-observer reproducibility, all four software showed good reproducibility and accuracy for calculating EF by GSPECT.
F R I D A Y M A Y 4
10.18 Simultaneous scatter and attenuation correction in myocardial SPECT.
C Pettinato, PL Guidalotti 1, M Marengo, G Guidi, S Civollani, D Pancaldi, S Fanti 1, N Monetti 1, C Bergamini. Health Physics S. Orsola - Malpighi Hospital Bologna Italy, INuclear Medicine S. Orsola - Malpighi Hospital Bologna Italy. Non uniform attenuation and scatter are the physic factors major responsible of image quality degradation in myocardial SPECT. Non uniform attenuation is corrected using a transmission technique implemented in the STEP Protocol of our Marconi Prism 3000. Aim of this work was to develop a scatter correction method compatible with STEP. We have implemented an iterative version of the Convolution-Subtraction technique. ScaRer has been characterized acquiring planar static images of a quasi-point 99mTc source in several positions into an elliptical water phantom, using two sets of collimators (LEHR parallel holes and Cardiofan 65 cm focal length fan beam). Counting profiles sampled from the images have been fitted with a non linear two gaussian model, with a component for primary events and a second for scattered events. A two dimensional stationary convolution filter was selected, using mean values of FWHM of the scattered component and scatter fraction obtained from fitted profiles. We adjusted filter parameters to simulate scatter effects and to allow the evaluation of the scarer component in acquired images. An iterative algorithm has been devised for convolution -- subtraction scatter correction of emission projections before OSEM iterative reconstruction performing attenuation correction. Performances were checked by processing phantom studies (elliptical and Jaszczak phantoms) and 20 patients studies. Results showed that: 1) no artifacts were introduced; 2) iterative convolutionsubtraction converged after two iterations; 3) there was a statistically significant improvement in resolution and contrast in corrected vs. non corrected images in both phantom and patient studies; 4) full reconstruction of a cardiac data set is performed in about 8 minutes. In conclusion, even if this scatter correction technique is stationary, it is easy to implement and routinely applicable; initial results are encouraging and clinical evaluation is presently in development.
Journal of Nuclear Cardiology January/February 2001
10.19 Early myocardial BMIPP uptake is enhanced relative to perfusion in a canine model of reperfused, viable myocardium.
K Takehaua, M Ruiz, LM Riou, T lwasaka 1, DD Watson, GA Belier, DK Glover. Internal Medicine/Cardiology University of Virginia Charlottesville, VA United States of America, lMedicine/Cardiovascular Division Kansai Medical Unive;sity Osaka Japan. Background: 123I-betamethyliodophenylpentadecanoic acid (BMIPP) is used clinically to assess myocardial fatty acid metabolism. In many of these studies, a "mismatch" pattern with normal perfusion and reduced BMIPP uptake has been observed 5-7 days following reperfusion of severe ischemia. To better understand this phenomenon, we sought to compare the uptake pattern of BMIPP with TI-201 in the early stage aider reperfusion. Methods: Accordingly, 10 open-chest dogs underwent total lefi anterior descending coronary occlusion for 30 minutes followed by either flail (Group 1, n-5) or partial reperfusion with a severe residual stenosis which reduced resting flow by -50% (Group 2, n=5). Sixty minutes after reflow, when net lactate production had ceased, TI-201 and BMIPP were injected and 10 minutes later the dogs were killed. Myocardial T1-201 and BM1PP activities were quantified by gamma-well counting. Myocardial segments were grouped according to flow during the occlusion into ischemie (flow < 0.3 rnl/min/g) and normal (flow >= 0.3 ml/min/g) zones. Results: In both groups, transmural TI-201 uptake in the ischemic zone (Groupl:0.72±0.02; Group 2:0.67i0.02) was identical to injection flow (Groupl:0.76±0.03; Group 2:0.63±0.04), indicating substantial preservation of myocardial viability. Interestingly, ischemic zone BMIPP uptake (Group 1:0.87±0.08; Group 2:0.79a-0.04) was significantly higher than both TI-201 and injection flow (p<0.01) whereas normal zone segments had similar uptake of both tracers (Groups l&2:0.99a_0.01 vs. 0.98±0.01). Conclusion: Unlike the mismatch pattern observed clinically, these data show that early after reperfusion, fatty acid uptake in viable myocardium may actually be enhanced relative to perfusion and T1-201 uptake. For viability assessment early after reflow, in the presence of a residual infarct-vessel stenosis, BMIPP imaging may be more sensitive than T1-201.
10.20 Use of zoom in detection of ischaemic heart disease. D Victoria, E Alexanderson, H Chaya, O Villarreal, I Martinez, T Bustamante, D Bialostozky. Cardiologia Nuclear INCICH Mexico DF Mexico.
There is controversy regarding the use of zoom in the evaluation of ischemic territories in patients with known left ventricular hypertrophy. The increased wall thickness may cause an underestimation of the true ischemic area. Objective: We are to evaluate the utility of zoom in patients with myocardial hypertrophy. Methods: The acquisition was performed (180°, 35 seconds by stop, 32 stops, mould 64 x 64), using one single head Siemens Orbiter camera with colimator LEAP using Tc 99m sestamibi in one day rest-stress protocol, with two acquisitions, zoom = 1.0 and with zoom = 1.2. Perfusion data were read using 20 SPECT segments analysis and each segment was scored using a 5 points scoring system (0 = normal, 4 = absent Uptake). GATED was obtained during stress. The images were reconstructed using a 5 order Butterworth filter with a Nyquist frequency of 0.5. The ejection fraction (EF) was calculated with and without zoom automatically by the QGS system. Results: We analyzed the results from 28 patients, of which 16 had coronariography. We compared the results from the coronariography with the Zoom images. All 4 patients with a normal curonariography had normal zoom perfusion images. Of the 12 patients with some degree of stenosis, 10 had a perfusion defect with zoom of which only 6 were noticed without zoom. The sensitivity and specificity was calculated at 88% and 100% respectively with zoom compared to 50% and 100% without zoom. The EF without zoom was overestimated in comparison to zoom by 20%. Conclusions: The employment of zoom in gated-SPECT images can be helpful in the detection of perfusion abnormalities in patients with left ventricular hypertrophy.
Abstracts F r i d a y , M a y 4, 2 0 0 1
10.17 Accuracy and reproducibility of four softwares for the left-ventricular function with ECG-gated myocardial perfusion SPECT. T Hignchi, K Nakajima, J Taki, T Yoneyama, N Tonami. Nuclear Medicine Japan/Kanazawa univ. Kauazawa Japan.
Purpose: Myocardial perfusion SPECT using ECG-gating (G-SPECT) allows assessment of left ventficular function. Some different computer soflwares that can automatically assess left ventricular ejection fraction (EF) are currently available with G-SPECT. We validated four different softwares of QGS (Cedars Sinai Medical center), ECToolbox (Emory univ.), 4D-MSPECT(Michigan Univ.), pFAST (Sapporo Medical Univ.) in the same acquisition data. Methods: Twentyfive patients, who had performed both G-SPECT and gated blood-pool study (GBP) within 10 days, were enrolled in this study. The GBP was performed with Tc-99m RBC using 24 frames/cardiac cycle in left anterior oblique projection. Tc-99m-MIBI (740 MBq) was injected at rest, and G-SPECT was performed about 60min later using 360-degree acquisition and by 12 frames/cardiac cycle. We calculated EF using 4 sol'wares in the same G-SPECT acquisition data. We assessed inter- and intra-observer reproducibility, and performed correlation analyses with GBP data using four sottwares. Results: Correlation coefficients of inter- and intra-observer reproducibility for calculating EF were r= 1.00 and 0.99 with QGS, 0.98 and 0.98 with ECToolbox, 0.96 and 0.96 with 4D-MSPECT, 0.85 and 0.88 with pFAST, respectively. Correlation coefficients between EF by GBP and G-SPECT using QGS, ECToolbox, 4D-MSPECT and pFAST were r= 0.89 (y-0.99x+2.7, x= GBP), 0.88 (y=l.03x+3.6, x - GBP), 0.82 (y=0.87x+6.8, x= GBP), and 0.81 (y-0.91x+7.2, x - GBP), respectively. [Conclusion] Although QGS sofiwares showed the best inter- and intra-observer reproducibility, all four software showed good reproducibility and accuracy for calculating EF by GSPECT.
F R I D A Y M A Y 4
10.18 Simultaneous scatter and attenuation correction in myocardial SPECT.
C Pettinato, PL Guidalotti 1, M Marengo, G Guidi, S Civollani, D Pancaldi, S Fanti 1, N Monetti 1, C Bergamini. Health Physics S. Orsola - Malpighi Hospital Bologna Italy, INuclear Medicine S. Orsola - Malpighi Hospital Bologna Italy. Non uniform attenuation and scatter are the physic factors major responsible of image quality degradation in myocardial SPECT. Non uniform attenuation is corrected using a transmission technique implemented in the STEP Protocol of our Marconi Prism 3000. Aim of this work was to develop a scatter correction method compatible with STEP. We have implemented an iterative version of the Convolution-Subtraction technique. ScaRer has been characterized acquiring planar static images of a quasi-point 99mTc source in several positions into an elliptical water phantom, using two sets of collimators (LEHR parallel holes and Cardiofan 65 cm focal length fan beam). Counting profiles sampled from the images have been fitted with a non linear two gaussian model, with a component for primary events and a second for scattered events. A two dimensional stationary convolution filter was selected, using mean values of FWHM of the scattered component and scatter fraction obtained from fitted profiles. We adjusted filter parameters to simulate scatter effects and to allow the evaluation of the scarer component in acquired images. An iterative algorithm has been devised for convolution -- subtraction scatter correction of emission projections before OSEM iterative reconstruction performing attenuation correction. Performances were checked by processing phantom studies (elliptical and Jaszczak phantoms) and 20 patients studies. Results showed that: 1) no artifacts were introduced; 2) iterative convolutionsubtraction converged after two iterations; 3) there was a statistically significant improvement in resolution and contrast in corrected vs. non corrected images in both phantom and patient studies; 4) full reconstruction of a cardiac data set is performed in about 8 minutes. In conclusion, even if this scatter correction technique is stationary, it is easy to implement and routinely applicable; initial results are encouraging and clinical evaluation is presently in development.
Journal of Nuclear Cardiology January/February 2001
10.19 Early myocardial BMIPP uptake is enhanced relative to perfusion in a canine model of reperfused, viable myocardium.
K Takehaua, M Ruiz, LM Riou, T lwasaka 1, DD Watson, GA Belier, DK Glover. Internal Medicine/Cardiology University of Virginia Charlottesville, VA United States of America, lMedicine/Cardiovascular Division Kansai Medical Unive;sity Osaka Japan. Background: 123I-betamethyliodophenylpentadecanoic acid (BMIPP) is used clinically to assess myocardial fatty acid metabolism. In many of these studies, a "mismatch" pattern with normal perfusion and reduced BMIPP uptake has been observed 5-7 days following reperfusion of severe ischemia. To better understand this phenomenon, we sought to compare the uptake pattern of BMIPP with TI-201 in the early stage aider reperfusion. Methods: Accordingly, 10 open-chest dogs underwent total lefi anterior descending coronary occlusion for 30 minutes followed by either flail (Group 1, n-5) or partial reperfusion with a severe residual stenosis which reduced resting flow by -50% (Group 2, n=5). Sixty minutes after reflow, when net lactate production had ceased, TI-201 and BMIPP were injected and 10 minutes later the dogs were killed. Myocardial T1-201 and BM1PP activities were quantified by gamma-well counting. Myocardial segments were grouped according to flow during the occlusion into ischemie (flow < 0.3 rnl/min/g) and normal (flow >= 0.3 ml/min/g) zones. Results: In both groups, transmural TI-201 uptake in the ischemic zone (Groupl:0.72±0.02; Group 2:0.67i0.02) was identical to injection flow (Groupl:0.76±0.03; Group 2:0.63±0.04), indicating substantial preservation of myocardial viability. Interestingly, ischemic zone BMIPP uptake (Group 1:0.87±0.08; Group 2:0.79a-0.04) was significantly higher than both TI-201 and injection flow (p<0.01) whereas normal zone segments had similar uptake of both tracers (Groups l&2:0.99a_0.01 vs. 0.98±0.01). Conclusion: Unlike the mismatch pattern observed clinically, these data show that early after reperfusion, fatty acid uptake in viable myocardium may actually be enhanced relative to perfusion and T1-201 uptake. For viability assessment early after reflow, in the presence of a residual infarct-vessel stenosis, BMIPP imaging may be more sensitive than T1-201.
10.20 Use of zoom in detection of ischaemic heart disease. D Victoria, E Alexanderson, H Chaya, O Villarreal, I Martinez, T Bustamante, D Bialostozky. Cardiologia Nuclear INCICH Mexico DF Mexico.
There is controversy regarding the use of zoom in the evaluation of ischemic territories in patients with known left ventricular hypertrophy. The increased wall thickness may cause an underestimation of the true ischemic area. Objective: We are to evaluate the utility of zoom in patients with myocardial hypertrophy. Methods: The acquisition was performed (180°, 35 seconds by stop, 32 stops, mould 64 x 64), using one single head Siemens Orbiter camera with colimator LEAP using Tc 99m sestamibi in one day rest-stress protocol, with two acquisitions, zoom = 1.0 and with zoom = 1.2. Perfusion data were read using 20 SPECT segments analysis and each segment was scored using a 5 points scoring system (0 = normal, 4 = absent Uptake). GATED was obtained during stress. The images were reconstructed using a 5 order Butterworth filter with a Nyquist frequency of 0.5. The ejection fraction (EF) was calculated with and without zoom automatically by the QGS system. Results: We analyzed the results from 28 patients, of which 16 had coronariography. We compared the results from the coronariography with the Zoom images. All 4 patients with a normal curonariography had normal zoom perfusion images. Of the 12 patients with some degree of stenosis, 10 had a perfusion defect with zoom of which only 6 were noticed without zoom. The sensitivity and specificity was calculated at 88% and 100% respectively with zoom compared to 50% and 100% without zoom. The EF without zoom was overestimated in comparison to zoom by 20%. Conclusions: The employment of zoom in gated-SPECT images can be helpful in the detection of perfusion abnormalities in patients with left ventricular hypertrophy.