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1.11 Hot spot artifacts on myocardial perfusion SPECT images: a retrospective study of potential causes and impact on test specificity
Journal of Nuclear Cardiology V o l u m e 8, N u m b e r
Abstracts
1
1.11
1.9 Intra-patient comparison of 123i-BMIPP assessment in acute myocardial infarction.
$3
T h u r s d a y , M a y 3, 2 0 0 1
and 123i-PHIPA
for viability
A-S Hambye, A Dobbeleir I, H Vanbilloen 2, M Eisenhut 3. Nuclear Medicine
Hot spot artifacts on myocardial perfusion SPECT images: a retrospective study of potential causes and impact on test specificity. F Prigent, M Feuerman, L Pla, R Stevens. Winthrop University Hospital Mineola United States of America
Middelheim Hospital Antwerp Belgium, 1Nuclear Medicine Middelheirn Hospital Antwerp Belgium, 2Radiopharmacy KU Leuven Belgium, 3Radiopharmacy University o f Heidelberg Germany. 123I-BMIPP is a fatty acid analog (FAA) with good intra-cardiac retention, allowing imaging o f fatty acid utilization with SPECT. However, it undergoes some metabolism and backdiffusion. I 123-PHIPA 3-10 ( 13-(4'- 123 I-iodophenyl)3-(p-phenylene)trideeanoic acid) is a new FAA which undergoes only one betaoxidation cycle and almost no other metabolism. Compared to 99mTc-MIBI in patients with myocardial infarction (MI), a mismatch with BMIPP We compared BMIPP and PHIPA imaging to assess viability in patients with recent MI. Dobutamine stress echo (DSE), BMIPP, MIBI and PHIPA SPECT were obtained within 5 days in 5 pts with successfully treated anterior M1. PHIPA was performed before BMIPP in 3. Blood samplings were obtained at TO, 5, 20 and 90 min post-injection. Images were corrected for scatter. Four pts had viability by DSE. All showed a mismatching with FAA lower than MIBI for both FAA. A higher contrast and larger defect size was noted on PHIPA than BMIPP images in all cases. After scatter correction, mean±SD cavity/normal myocardium ratio was 17.3±7.5% for BMIPP and 6.5±6% for PHIPA. At T20 min, blood activity had almost stabilized for BMIPP and was significantly higher than for PHIPA (5.5% ID/1 blood versos 2.5%). For PHIPA, blood activity continued to decrease over time (1.6% ID at 90 min). In conclusion, in recent MI, BMIPP and PHIPA give concordant results with regard to viability assessment. Lower blood pool activity with PHIPA results in better image quality.
Background: During myocardial perfusinn imaging, the presence of prominent tracer activity in the lateral wall, described as "hot spot" (HS) may give the impression of decreased tracer activity in the remaining walls, leading to false (+) interpretation. Little is known on HS etiology and on the impact of this artifact on test specificity. Accordingly, fifty-four consecutive patients (pts) with HS and low (<5%) pre-SPECT likelihood of CAD (LOWLIK) were retrospectively assessed and compared to 93, randomly selected, control (CTL) LOWLIK pts without HS. All pts were studied between 1/1995 and t2/1999. Pts were imaged on one of two single-head SPECT cameras. In our laboratories, Tc-99m perfusion agents are used in >235 lbs males and in females with C or D bra cup size or >220 lbs weight. Tl-201 is used in all others. Results: Comparing HS and CTL pts, HS pts were younger (mean +/SD) (49 +/- 13 Vs 54 +/- 2, p<.02), taller (69 +/- 4 Vs 66 +/- 4", p<.001), more often male (83% VS 49%, p<.001) and had a lower Body Mass Index (BMI) (26 +/- 4 Vs 28 +/- 5, p<.05) than CTL pts. HS pts exercised for a longer duration (9.7 +/- 3 Vs 8.2 +/- 3 min, p<.01), achieved higher heart rates (161 +/- 16 Vs 152 +/- 13 p<.001) and higher peak systolic blood pressure (170 +/- 22 Vs 162 +/- 18, p<.02) than CTL pts. Body weight was similar (177+/- 33 Vs 175 +/-36 lbs, p-ns). There was a trend towards more frequent EKG-LVH in the HS Vs CTL pts: 11% VS 3%, p-.075). TI-201 was used in 96% of HS Vs 60% of CTL pts, p<.001. Bra cup size was smaller in HS Vs CTL pts, p<.05. HS frequency was similar with both cameras. By stepwise multivariate analysis, isotope, peak heart rate and LVH were independent predictors ofHS: p - .0006, .024 and .027, respectively. Gender had borderline significance: p=.09. Test accuracy was lower in HS Vs CTL pts: 57% Vs 94% true (-) studies, 30% Vs 1% equivocals and 13% Vs 5% false (+) studies, respectivey, p<.001. Confidence of interpretation was decreased in 31% HS Vs 6% CTL pts, p< .001. Among the 23 non-normal HS studies, the HS pattern was more prominent on stress than on rest images in 22 (96%), leading to "reversible" defects. Conclusions: In LOWLIK pts, TI-201 use, higher peak HR and LVH are associated with HS. The fact that HS is more often associated with TI-201 than Tc-99m may reflect thinner body habitus, hence decreased attenuation in pts selected to receive TI-201; however, a primary isotope factor as a cause of HS cannot be excluded. HS lead to artifactual defects that are mostly reversible and result in decreased test accuracy.
1.10
1.12
Decrease in heart rate variability as a predictor of abnormal scan on adenosine myocardial perfnsion imaging. A Vashist, S Blum, EB Brown Jr, N C Bhalodkar. Division of Cardiology Bronx Lebanon Hospital Center Bronx, N e w York United States of America.
Gender differences in the response to adenosine during myocardial perfusion imaging. L Choudhury, MA Parker, MA Freher, TA Holly. Medicine/Cardiology Northwestern University Medical School Chicago United States of America.
Purpose: To evaluate decrease in heart rate variability as a predictor o f abnormal scans (ABNSC) in adenosine myocardial perfusion imaging (MPI). Methods: We studied 188 consecutive patients, retrospectively, who underwent standard adenosine stress test without exercise with myocardial perfusion imaging (MPl)using Tc 99m sestamibi radioisotope. Heart rate (HR) difference was calculated by substracting resting HR from peak HR and H R % increase was calculated. All patients had both stress and rest SPECT images. Left ventricular ejection fraction (EF) was calculated using Gated SPECT. Findings: The mean age was 60 years (range 27-87) and 135 (72%) were females. O f 188 patients 36% had diabetes, 4% had family history of premature coronary artery disease (CAD), 80% were hypertensive, 11% had a history o f myocardial infarction, 12% were obese, 31% had hypercholesterolemia, 46% were post menopausal and 17% had age/sex predisposition for CAD. We divided the scan results in to two groups: normal scan (NSC) and abnormal scans (ABNSC). N S was present in 142 (75%) while 46 (25 %) patients bad an abnormal scan (ABNSC) defined as presence o f either fixed defects, reversible defects or both. HR increased by 29 beats per minute (bpm) in NSC compared to 19 bpm in ABNSC (p=0.0004). H R % increase was 44% in NSC as opposed to 28% in ABNSC (p-0.0006). Increase in absolute H R as well as HR % increase in females was more (29 bpm vs 20 bpm p=0.0007) and (44% vs 31% p=0.0004) and it was irrespective o f the scan result. Low EF (EF<45%) was present in 47 patients (25%). This group had H R increase and HR % increase o f 20 bpm and 29% compared to an increase of 29 bpm and 44% respectively in patients with normal EF (p=0.002 and p=0.002 respectively). Conclusion: Decrease in HR variability had a significant association with both an abnormal scan and with diminished ejection fraction. Females had a higher H R increase and H R % increase in both NSC and ABNSC group.
Background: Some studies have reported that ST segment depression during adenosine stress testing is associated with isehemic defects on myocardial perfusion imaging (MPI). ST segment depression during exercise is less specific for coronary artery disease in women, but the specificity of adenosineinduced ST segment depression (AD-ST) in women during MPI is unclear. Furthermore, possible gender differences in the symptomatic and hemodynamic responses to adenosine have not been examined. Methods: We reviewed the electrocardiographic, hemodynamic and imaging results of 1,028 patients who had undergone dual isotope single photon emission computed tomography MPI with adenosine. Of these patients, 104 were excluded because of left bundle branch block, paced rhythm or ST segment depression > lmm on the baseline electrocardiogram, leaving 924 for full analysis. Significant ST depression was defined as at least lmm of horizontal or downsloping ST depression from baseline. SPECT images were scored using a 20 segment model, and summed stress, rest and reversibility scores were calculated. Results: The mean age of the patients was 64 ± 14 years, and 49% were female. Women were more likely than men to have chest pain during adenosine infusion (45% vs. 32%, p<0.0001). In addition, peak heart rate and systofic blood pressures were higher in women than in men (92.3 vs. 84.7, p=0.01 and 156.5 vs. 153.0, p=0.03, respectively). Women were more likely than men to have AD-ST (17% vs. 9%, p=0.0001), although reversible perfusion defects were seen less frequently in women than in men with AD-ST (61% vs. 85%, p=0.008). The sensitivity of AD-ST for the detection of ischemia on MPI was low for both sexes, but slightly higher for women (22% vs. 13%, p-0.007). The specificity of AD-ST for the detection ofisehemia on MPI was somewhat lower in women (88% vs. 97%, p-~L0003). For all patients, the summed reversibility score, a measure of the extent and severity of the ischemic defects, was significantly greater in the group with AD-ST (5.4 vs. 2.6, p<0.0001). The prevalence of infarction by MPI was similar in patients with and without ADST (33% in both). Conclusion: During adenosine stress testing, women develop ST segment depression more often than men and are more likely to have chest pain. Although somewhat less specific in women, adenosine-induced ST segment depression is a specific marker of ischemia on myocardial perfusion imaging for both men and women.
T H U R S D A Y
M A Y
Abstracts
1
1.11
1.9 Intra-patient comparison of 123i-BMIPP assessment in acute myocardial infarction.
$3
T h u r s d a y , M a y 3, 2 0 0 1
and 123i-PHIPA
for viability
A-S Hambye, A Dobbeleir I, H Vanbilloen 2, M Eisenhut 3. Nuclear Medicine
Hot spot artifacts on myocardial perfusion SPECT images: a retrospective study of potential causes and impact on test specificity. F Prigent, M Feuerman, L Pla, R Stevens. Winthrop University Hospital Mineola United States of America
Middelheim Hospital Antwerp Belgium, 1Nuclear Medicine Middelheirn Hospital Antwerp Belgium, 2Radiopharmacy KU Leuven Belgium, 3Radiopharmacy University o f Heidelberg Germany. 123I-BMIPP is a fatty acid analog (FAA) with good intra-cardiac retention, allowing imaging o f fatty acid utilization with SPECT. However, it undergoes some metabolism and backdiffusion. I 123-PHIPA 3-10 ( 13-(4'- 123 I-iodophenyl)3-(p-phenylene)trideeanoic acid) is a new FAA which undergoes only one betaoxidation cycle and almost no other metabolism. Compared to 99mTc-MIBI in patients with myocardial infarction (MI), a mismatch with BMIPP We compared BMIPP and PHIPA imaging to assess viability in patients with recent MI. Dobutamine stress echo (DSE), BMIPP, MIBI and PHIPA SPECT were obtained within 5 days in 5 pts with successfully treated anterior M1. PHIPA was performed before BMIPP in 3. Blood samplings were obtained at TO, 5, 20 and 90 min post-injection. Images were corrected for scatter. Four pts had viability by DSE. All showed a mismatching with FAA lower than MIBI for both FAA. A higher contrast and larger defect size was noted on PHIPA than BMIPP images in all cases. After scatter correction, mean±SD cavity/normal myocardium ratio was 17.3±7.5% for BMIPP and 6.5±6% for PHIPA. At T20 min, blood activity had almost stabilized for BMIPP and was significantly higher than for PHIPA (5.5% ID/1 blood versos 2.5%). For PHIPA, blood activity continued to decrease over time (1.6% ID at 90 min). In conclusion, in recent MI, BMIPP and PHIPA give concordant results with regard to viability assessment. Lower blood pool activity with PHIPA results in better image quality.
Background: During myocardial perfusinn imaging, the presence of prominent tracer activity in the lateral wall, described as "hot spot" (HS) may give the impression of decreased tracer activity in the remaining walls, leading to false (+) interpretation. Little is known on HS etiology and on the impact of this artifact on test specificity. Accordingly, fifty-four consecutive patients (pts) with HS and low (<5%) pre-SPECT likelihood of CAD (LOWLIK) were retrospectively assessed and compared to 93, randomly selected, control (CTL) LOWLIK pts without HS. All pts were studied between 1/1995 and t2/1999. Pts were imaged on one of two single-head SPECT cameras. In our laboratories, Tc-99m perfusion agents are used in >235 lbs males and in females with C or D bra cup size or >220 lbs weight. Tl-201 is used in all others. Results: Comparing HS and CTL pts, HS pts were younger (mean +/SD) (49 +/- 13 Vs 54 +/- 2, p<.02), taller (69 +/- 4 Vs 66 +/- 4", p<.001), more often male (83% VS 49%, p<.001) and had a lower Body Mass Index (BMI) (26 +/- 4 Vs 28 +/- 5, p<.05) than CTL pts. HS pts exercised for a longer duration (9.7 +/- 3 Vs 8.2 +/- 3 min, p<.01), achieved higher heart rates (161 +/- 16 Vs 152 +/- 13 p<.001) and higher peak systolic blood pressure (170 +/- 22 Vs 162 +/- 18, p<.02) than CTL pts. Body weight was similar (177+/- 33 Vs 175 +/-36 lbs, p-ns). There was a trend towards more frequent EKG-LVH in the HS Vs CTL pts: 11% VS 3%, p-.075). TI-201 was used in 96% of HS Vs 60% of CTL pts, p<.001. Bra cup size was smaller in HS Vs CTL pts, p<.05. HS frequency was similar with both cameras. By stepwise multivariate analysis, isotope, peak heart rate and LVH were independent predictors ofHS: p - .0006, .024 and .027, respectively. Gender had borderline significance: p=.09. Test accuracy was lower in HS Vs CTL pts: 57% Vs 94% true (-) studies, 30% Vs 1% equivocals and 13% Vs 5% false (+) studies, respectivey, p<.001. Confidence of interpretation was decreased in 31% HS Vs 6% CTL pts, p< .001. Among the 23 non-normal HS studies, the HS pattern was more prominent on stress than on rest images in 22 (96%), leading to "reversible" defects. Conclusions: In LOWLIK pts, TI-201 use, higher peak HR and LVH are associated with HS. The fact that HS is more often associated with TI-201 than Tc-99m may reflect thinner body habitus, hence decreased attenuation in pts selected to receive TI-201; however, a primary isotope factor as a cause of HS cannot be excluded. HS lead to artifactual defects that are mostly reversible and result in decreased test accuracy.
1.10
1.12
Decrease in heart rate variability as a predictor of abnormal scan on adenosine myocardial perfnsion imaging. A Vashist, S Blum, EB Brown Jr, N C Bhalodkar. Division of Cardiology Bronx Lebanon Hospital Center Bronx, N e w York United States of America.
Gender differences in the response to adenosine during myocardial perfusion imaging. L Choudhury, MA Parker, MA Freher, TA Holly. Medicine/Cardiology Northwestern University Medical School Chicago United States of America.
Purpose: To evaluate decrease in heart rate variability as a predictor o f abnormal scans (ABNSC) in adenosine myocardial perfusion imaging (MPI). Methods: We studied 188 consecutive patients, retrospectively, who underwent standard adenosine stress test without exercise with myocardial perfusion imaging (MPl)using Tc 99m sestamibi radioisotope. Heart rate (HR) difference was calculated by substracting resting HR from peak HR and H R % increase was calculated. All patients had both stress and rest SPECT images. Left ventricular ejection fraction (EF) was calculated using Gated SPECT. Findings: The mean age was 60 years (range 27-87) and 135 (72%) were females. O f 188 patients 36% had diabetes, 4% had family history of premature coronary artery disease (CAD), 80% were hypertensive, 11% had a history o f myocardial infarction, 12% were obese, 31% had hypercholesterolemia, 46% were post menopausal and 17% had age/sex predisposition for CAD. We divided the scan results in to two groups: normal scan (NSC) and abnormal scans (ABNSC). N S was present in 142 (75%) while 46 (25 %) patients bad an abnormal scan (ABNSC) defined as presence o f either fixed defects, reversible defects or both. HR increased by 29 beats per minute (bpm) in NSC compared to 19 bpm in ABNSC (p=0.0004). H R % increase was 44% in NSC as opposed to 28% in ABNSC (p-0.0006). Increase in absolute H R as well as HR % increase in females was more (29 bpm vs 20 bpm p=0.0007) and (44% vs 31% p=0.0004) and it was irrespective o f the scan result. Low EF (EF<45%) was present in 47 patients (25%). This group had H R increase and HR % increase o f 20 bpm and 29% compared to an increase of 29 bpm and 44% respectively in patients with normal EF (p=0.002 and p=0.002 respectively). Conclusion: Decrease in HR variability had a significant association with both an abnormal scan and with diminished ejection fraction. Females had a higher H R increase and H R % increase in both NSC and ABNSC group.
Background: Some studies have reported that ST segment depression during adenosine stress testing is associated with isehemic defects on myocardial perfusion imaging (MPI). ST segment depression during exercise is less specific for coronary artery disease in women, but the specificity of adenosineinduced ST segment depression (AD-ST) in women during MPI is unclear. Furthermore, possible gender differences in the symptomatic and hemodynamic responses to adenosine have not been examined. Methods: We reviewed the electrocardiographic, hemodynamic and imaging results of 1,028 patients who had undergone dual isotope single photon emission computed tomography MPI with adenosine. Of these patients, 104 were excluded because of left bundle branch block, paced rhythm or ST segment depression > lmm on the baseline electrocardiogram, leaving 924 for full analysis. Significant ST depression was defined as at least lmm of horizontal or downsloping ST depression from baseline. SPECT images were scored using a 20 segment model, and summed stress, rest and reversibility scores were calculated. Results: The mean age of the patients was 64 ± 14 years, and 49% were female. Women were more likely than men to have chest pain during adenosine infusion (45% vs. 32%, p<0.0001). In addition, peak heart rate and systofic blood pressures were higher in women than in men (92.3 vs. 84.7, p=0.01 and 156.5 vs. 153.0, p=0.03, respectively). Women were more likely than men to have AD-ST (17% vs. 9%, p=0.0001), although reversible perfusion defects were seen less frequently in women than in men with AD-ST (61% vs. 85%, p=0.008). The sensitivity of AD-ST for the detection of ischemia on MPI was low for both sexes, but slightly higher for women (22% vs. 13%, p-0.007). The specificity of AD-ST for the detection ofisehemia on MPI was somewhat lower in women (88% vs. 97%, p-~L0003). For all patients, the summed reversibility score, a measure of the extent and severity of the ischemic defects, was significantly greater in the group with AD-ST (5.4 vs. 2.6, p<0.0001). The prevalence of infarction by MPI was similar in patients with and without ADST (33% in both). Conclusion: During adenosine stress testing, women develop ST segment depression more often than men and are more likely to have chest pain. Although somewhat less specific in women, adenosine-induced ST segment depression is a specific marker of ischemia on myocardial perfusion imaging for both men and women.
T H U R S D A Y
M A Y