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Impact of patient size on attenuation corrected myocardial perfusion images: Comparison of BITGA and FBP transmission reconstruction
Journal of Nuclear Cardiology Volume 11, Number 4;S21-S38
65.22 IMPACT OF PATIENT SIZE ON ATTENUATION CORRECTED MYOCARDIAL PERFUSION IMAGES: COMPARISON OF BITGA AND FBP TRANSMISSION RECONSTRUCTION JA Case, SJ Cullom, BL Hsu, K Moutray, TM Bateman Cardiovascular Imaging Technologies, Kansas City MO Introduction: Filtered backprojection (FBP) reconstructions for transmission (Tx) data can be used for attenuation correction (AC) in phantom data, however impact on body mass index (BMI) has not been adequately demonstrated. We performed a paired comparison of Tx maps and AC myocardial perfusion images (Em) in patients with clinically relevant range of BMI (20 – 45 kg/m2) processed with the Bayesian Iterative Transmission Gradient Algorithm (BITGA) and FBP. Methods: We examined 50 rest/stress Tc-99m Sestamibi patient studies (5 male and 5 female in five BMI groups: ⬍25, 25–30, 30 –35, 35– 40, ⬎40 kg/m2). with a low-likelihood (⬍5%) of coronary artery disease. Attenuation coefficients were measured in a 5X5 ROI centered in the mediastinum. Uniformity of the Em data was measured as relative uptake in the septal, lateral, anterior, inferior and apical walls. Data Acquisitions: Data was acquired on a Philips Cardio system using VantagePro™ and ExSPECT II™ software using LEHR collimation, 30s/25s (rest/stress) per stop, 64 angles. Results: Tx maps appeared less accurate and less uniform when reconstructed with FBP (see figures). For Em data, BITGA reduced the wall to wall variability from 4.8% (BITGA) to 4.1% (FBP) (p⫽0.02). Furthermore, the number of patients whose septal-lateral wall ratios (SL) differed from unity by more than ten percent was reduced from 12% to 4% (p⬍0.05). Patients with BMI⬎30 were more likely to have a divergent SL (83.3% vs 16.7%). Visual inspection of FBP based images indicate this may be due to poor definition of the lung/heart boundary.
Conclusion: Use of BITGA produced more accurate and uniform TX results for all BMI groups. Also, patients with BMI⬎30, use of FBP Tx maps introduced artifacts that can compromise Em quality. 65.23 DISTRIBUTION OF ISCHEMIA AND FIXED PERFUSION DEFECTS DETECTED IN AN INTERNATIONAL, OBSERVATIONAL, STUDY OF PHARMACOLOGIC STRESS SPECT MYOCARDIAL PERFUSION IMAGING
Abstracts Saturday, October 2, 2004
S27
JE Udelson, RJ Barrett, JR Johnson, C. Menenghetti, R Taillefer, T Ruddy, and R Hachamovitch for the Investigators Tufts-NE Medical Center, Boston, MA; King Pharmaceuticals R&D, Cary, NC; Instituto do Coracao, San Paulo, Brazil; Hotel-Dieu du CHUM, Montreal, Quebec; Univ. Ottawa Heart Inst, Ottawa, Ontario; and USC Medical Center, Los Angeles, CA Objective: To assess the distribution of ischemia and infarct observed across a heterogeneous population of patients enrolled in a study of utilization and outcomes after PS SPECT Imaging. Methods Patients from 8 countries were enrolled, clinically assessed and assigned to an ACC / AHA Pretest Likelihood (LK) for CAD cohort, or the Known CAD cohort. Patients completed a PS-SPECT or Low-Level exercise PS (LEPS) SPECT MPI study. Site investigators assigned summed stress (SSS) rest (SRS), and difference scores (SDS), using the 17-segment (0 – 4 perfusion scale) model. SPECT MPI studies were classified as Normal (SDS ⬍ 2 and SSS ⬍ 3), Abn-No Ischemia (SDS ⬍ 2 and SSS ⱖ3: i.e., fixed defect only), or Abn-Ischemia (SDS ⱖ2 and SSS ⱖ3: i.e., any reversible defect). 5174 patients were enrolled (89 centers) and 4855 (94%) had imaging results scored. Results: Statistically significant differences in rates for Normal, Abn-No Ischemia, and Abn-Ischemia SPECT studies were associated with LK for CAD (Figure 1). The proportion of patients with abn/ischemic scans studies increased with greater pre-test CAD LK. Fixed perfusion defects were apparent in 13–15% of all patients without history of CAD, and in 24% of those patients with Known CAD. A substantial minority of patients with Very Low LK CAD had abn MPI, and a substantial proportion of patients with High LK for CAD had a normal SPECT MPI study. Conclusions: The combination of a clinical assessment for CAD and PS SPECT results are inter-correlated. Further modeling work will be completed to assess patient characteristics contributing to this distribution. Figure 1. Distribution of Normal, Abnormal-No Ischemia, and AbnormalIschemia SPECT MPI studies.
65.24 DESIGN AND RATIONALE FOR AN INTERNATIONAL STUDY OF UTILIZATION AND OUTCOMES FOLLOWING PHARMACOLOGIC STRESS SPECT IMAGING R Hachamovitch, JR Johnson, RJ Barrett, SA Jenkins, J Massaro, and JE Udelson for the Investigators USC Medical Center, Los Angeles, CA; King Pharmaceuticals R&D, Cary, NC; BU School of Public Health, Boston, MA; and Tufts-NE Medical Center, Boston, MA Background: Studies on pharmacologic stress (PS) SPECT Myocardial Perfusion Imaging (SMPI) were completed in a small number of tertiary care academic centers, prior to recent improvements in medical and interventional therapeutics.
65.22 IMPACT OF PATIENT SIZE ON ATTENUATION CORRECTED MYOCARDIAL PERFUSION IMAGES: COMPARISON OF BITGA AND FBP TRANSMISSION RECONSTRUCTION JA Case, SJ Cullom, BL Hsu, K Moutray, TM Bateman Cardiovascular Imaging Technologies, Kansas City MO Introduction: Filtered backprojection (FBP) reconstructions for transmission (Tx) data can be used for attenuation correction (AC) in phantom data, however impact on body mass index (BMI) has not been adequately demonstrated. We performed a paired comparison of Tx maps and AC myocardial perfusion images (Em) in patients with clinically relevant range of BMI (20 – 45 kg/m2) processed with the Bayesian Iterative Transmission Gradient Algorithm (BITGA) and FBP. Methods: We examined 50 rest/stress Tc-99m Sestamibi patient studies (5 male and 5 female in five BMI groups: ⬍25, 25–30, 30 –35, 35– 40, ⬎40 kg/m2). with a low-likelihood (⬍5%) of coronary artery disease. Attenuation coefficients were measured in a 5X5 ROI centered in the mediastinum. Uniformity of the Em data was measured as relative uptake in the septal, lateral, anterior, inferior and apical walls. Data Acquisitions: Data was acquired on a Philips Cardio system using VantagePro™ and ExSPECT II™ software using LEHR collimation, 30s/25s (rest/stress) per stop, 64 angles. Results: Tx maps appeared less accurate and less uniform when reconstructed with FBP (see figures). For Em data, BITGA reduced the wall to wall variability from 4.8% (BITGA) to 4.1% (FBP) (p⫽0.02). Furthermore, the number of patients whose septal-lateral wall ratios (SL) differed from unity by more than ten percent was reduced from 12% to 4% (p⬍0.05). Patients with BMI⬎30 were more likely to have a divergent SL (83.3% vs 16.7%). Visual inspection of FBP based images indicate this may be due to poor definition of the lung/heart boundary.
Conclusion: Use of BITGA produced more accurate and uniform TX results for all BMI groups. Also, patients with BMI⬎30, use of FBP Tx maps introduced artifacts that can compromise Em quality. 65.23 DISTRIBUTION OF ISCHEMIA AND FIXED PERFUSION DEFECTS DETECTED IN AN INTERNATIONAL, OBSERVATIONAL, STUDY OF PHARMACOLOGIC STRESS SPECT MYOCARDIAL PERFUSION IMAGING
Abstracts Saturday, October 2, 2004
S27
JE Udelson, RJ Barrett, JR Johnson, C. Menenghetti, R Taillefer, T Ruddy, and R Hachamovitch for the Investigators Tufts-NE Medical Center, Boston, MA; King Pharmaceuticals R&D, Cary, NC; Instituto do Coracao, San Paulo, Brazil; Hotel-Dieu du CHUM, Montreal, Quebec; Univ. Ottawa Heart Inst, Ottawa, Ontario; and USC Medical Center, Los Angeles, CA Objective: To assess the distribution of ischemia and infarct observed across a heterogeneous population of patients enrolled in a study of utilization and outcomes after PS SPECT Imaging. Methods Patients from 8 countries were enrolled, clinically assessed and assigned to an ACC / AHA Pretest Likelihood (LK) for CAD cohort, or the Known CAD cohort. Patients completed a PS-SPECT or Low-Level exercise PS (LEPS) SPECT MPI study. Site investigators assigned summed stress (SSS) rest (SRS), and difference scores (SDS), using the 17-segment (0 – 4 perfusion scale) model. SPECT MPI studies were classified as Normal (SDS ⬍ 2 and SSS ⬍ 3), Abn-No Ischemia (SDS ⬍ 2 and SSS ⱖ3: i.e., fixed defect only), or Abn-Ischemia (SDS ⱖ2 and SSS ⱖ3: i.e., any reversible defect). 5174 patients were enrolled (89 centers) and 4855 (94%) had imaging results scored. Results: Statistically significant differences in rates for Normal, Abn-No Ischemia, and Abn-Ischemia SPECT studies were associated with LK for CAD (Figure 1). The proportion of patients with abn/ischemic scans studies increased with greater pre-test CAD LK. Fixed perfusion defects were apparent in 13–15% of all patients without history of CAD, and in 24% of those patients with Known CAD. A substantial minority of patients with Very Low LK CAD had abn MPI, and a substantial proportion of patients with High LK for CAD had a normal SPECT MPI study. Conclusions: The combination of a clinical assessment for CAD and PS SPECT results are inter-correlated. Further modeling work will be completed to assess patient characteristics contributing to this distribution. Figure 1. Distribution of Normal, Abnormal-No Ischemia, and AbnormalIschemia SPECT MPI studies.
65.24 DESIGN AND RATIONALE FOR AN INTERNATIONAL STUDY OF UTILIZATION AND OUTCOMES FOLLOWING PHARMACOLOGIC STRESS SPECT IMAGING R Hachamovitch, JR Johnson, RJ Barrett, SA Jenkins, J Massaro, and JE Udelson for the Investigators USC Medical Center, Los Angeles, CA; King Pharmaceuticals R&D, Cary, NC; BU School of Public Health, Boston, MA; and Tufts-NE Medical Center, Boston, MA Background: Studies on pharmacologic stress (PS) SPECT Myocardial Perfusion Imaging (SMPI) were completed in a small number of tertiary care academic centers, prior to recent improvements in medical and interventional therapeutics.