Electromechanical properties of perfusion/metabolism mismatch: comparison of nonfluoroscopic electroanatomic mapping with 18F-FDG PET.

The aim of this study was to compare nonfluoroscopic electroanatomic mapping (NOGA), SPECT perfusion imaging, and PET metabolic imaging for assessment of myocardial viability. In particular, we sought to elucidate differences of electromechanical properties between the perfusion/metabolism mismatch as an indicator of a potentially reversible ischemic injury and the perfusion/metabolism match indicating irreversibly damaged myocardial tissue. METHODS: Twenty-one patients with coronary artery disease underwent NOGA mapping of endocardial unipolar voltage, cardiac 18F-FDG PET of glucose utilization, and resting 201Tl SPECT of myocardial perfusion. RESULTS: Electrical activity was 10.8 +/- 4.6 mV (mean +/- SD) in normal myocardium and was unchanged in hypoperfused segments with maintained glucose metabolism (perfusion/metabolism mismatch), 9.3 +/- 3.4 mV (P = not significant). In contrast, hypoperfused segments with a perfusion/metabolism match and nonviable segments showed significantly lower voltage (6.9 +/- 3.1 mV, P < 0.0001 and 4.1 +/- 1.1 mV, P < 0.0001 vs. normal). In hypoperfused segments, metabolic activity was more closely related to endocardial voltage than was myocardial perfusion (201Tl vs. voltage: r = 0.38, SEE = 3.2, P < 0.001; 18F-FDG PET vs. voltage: r = 0.6, SEE = 2.8, P < 0.0001). CONCLUSION: In hypoperfused myocardium, electrical activity by NOGA mapping is more closely related to PET metabolic activity than to SPECT myocardial perfusion. As NOGA mapping does not differentiate hypoperfused myocardium with enhanced glucose utilization from normal myocardium, results from NOGA mapping need to be correlated with results from perfusion imaging to identify hypoperfused, yet viable, myocardium and to stratify patients for revascularization procedures.     

99m Tc-MIBI心肌显像对冠状动脉病变的定位研究

目的：探讨９９ｍＴｃ－ＭＩＢＩ心肌显像在检出冠心病病变心肌节段和病变血管定位上的价值。方法：对照分析２０例冠心病和５例对照组冠状动脉造影与９９ｍＴｃ－ＭＩＢＩ单光子发射断层显像（ＳＰＥＣＴ）的结果。结果：潘生丁负荷ＳＰＥＣＴ检出冠心病、病变血管和病变心肌节段的敏感性分别为９５．００％、６３．６４％和４３．６８％明显高于静息相的６０．００％、４２．４２％和２７．５９％（Ｐ＜０．０１）。与静息相比较,潘生丁负荷ＳＰＥＣＴ多发现３３．３３％的病变血管和３６．８４％的病变心肌节段。对病变血管的敏感性,ＬＡＤ高于ＲＣＡ和ＬＣＸ;对于病变心肌节段检测敏感性ＲＣＡ支配节段高于ＬＡＤ和ＬＣＸ,特异性均较高。结论：潘生丁ＳＰＥＣＴ能显著提高冠心病的检出,有效估计病变心肌范围和病变冠状动脉     

Myocardial contractile reserve and perfusion defect severity with rest and stress dobutamine (99m)Tc-sestamibi SPECT in canine stunning and subendocardial infarction.

Myocardial contractile reserve and resting perfusion scintigraphy provide independent information to assess myocardial viability. The purpose of this study was to simultaneously evaluate both with (99m)Tc-sestamibi SPECT and low-dose dobutamine in canine stunning and subendocardial infarction (SEMI). METHODS: Eighteen dogs were included in the study: 7 normal, 7 stunned, and 4 with SEMI. Closed-chest stunning and SEMI were produced by angioplasty balloon occlusion of the left anterior descending artery (20 and 90 min, respectively). Subsequent radiolabeled mircospheres confirmed reflow, and (99m)Tc-sestamibi was then administered at rest. Gated SPECT and MRI tagging were performed at rest and during low-dose dobutamine infusion (5 microg/kg/min). SPECT systolic wall thickening index (SWI) and MRI radial strain quantified myocardial contraction. Postmortem 2,3,5-triphenyltetrazolium chloride staining quantified SEMI. RESULTS: Defect severity by SPECT in the anterior wall was mild and was not statistically different for the stunned versus SEMI groups (P = not significant). At rest, anterior wall SPECT SWI was significantly higher in the normal versus stunned groups (21.1 +/- 3.1 vs. 10.1 +/- 9.0; P = 0.0002) and the normal versus SEMI groups (21.1 +/- 3.1 vs. 2.6 +/- 6.0; P = 0.000002). With low-dose dobutamine, SWI increased significantly compared with rest for the stunned group (29.1 +/- 10.4 vs. 10.1 +/- 9.0; P = 0.000007) but did not increase significantly for the SEMI group (11.0 +/- 11.3 vs. 2.6 +/- 6.0; P = 0.09); SWI during low-dose dobutamine infusion for the stunned group was comparable to that for the normal group (29.1 +/- 10.4 vs. 28.2 +/- 7.0; P = 0.80). SWI also showed correlation with MRI radial strain (r = 0.42; P = 0.00015). CONCLUSION: Defect severity for stunned myocardium and SEMI was mild and was not significantly different. Contractile reserve was significantly different in stunned myocardium and SEMI. (99m)Tc-Sestamibi SPECT at rest and with low-dose dobutamine is a promising new technique to simultaneously assess myocardial perfusion and contractile reserve.     

Transient prolonged stunning induced by dipyridamole and shown on 1- and 24-hour poststress 99mTc-MIBI gated SPECT.

We investigated whether poststress gated SPECT, which was believed to show resting wall motion, revealed stunning induced by dipyridamole stress. METHODS: In 62 patients with coronary artery disease (n = 57) or chest pain (n = 5), dipyridamole stress gated 99mTc-hexakis-2-methoxyisobutyl isonitrile (MIBI) SPECT and rest 201Tl SPECT were performed on the first day; 24-h delayed 201Tl SPECT and rest gated 99mTc-MIBI SPECT were performed on the second day. Stress and rest gated 99mTc-MIBI SPECT was performed 1 h after injection. The myocardium was divided into 17 segments, and perfusion was scored on a 4-point scoring system (scores, 0-3 for normal to defect); wall motion during first-day poststress gated and second-day rest gated SPECT was also scored on another 4-point scale (scores, 0-3 for normal to dyskinesia). RESULTS: Thirty-one of 62 patients showed wall motion abnormality that was worse after stress than during resting. Three hundred eight (29%) of the total 1054 segments showed wall motion abnormality on poststress gated SPECT. In 198 of these segments, wall motion abnormality was the same on poststress and rest gated SPECT, and 106 segments showed wall motion that was worse on 1-h poststress than on rest gated SPECT. Perfusion was normal either during rest (n = 113) or after a 24-h delay (n = 18) in 131 segments with the poststress wall motion abnormality. Of these 131 segments, 69 showed the same wall motion abnormality between poststress and resting periods (persistent stunning). However, in 40 segments, abnormal wall motion on 1-h poststress gated SPECT normalized on rest gated SPECT (transient prolonged stunning). The other 20 segments showed improvement of wall motion during rest compared with the poststress period but still showed abnormal wall motion during the resting period (between transient prolonged stunning and persistent stunning). Stress perfusion decrease was more severe in transient prolonged stunning than in persistent stunning. Poststress wall motion abnormality was more severe in persistent stunning. CONCLUSION: Using gated 99mTc-MIBI SPECT, stunned myocardium was found on 1-h poststress SPECT compared with normal resting wall motion found on rest gated SPECT on the next day. We conclude that some myocardial walls did not show true resting wall motion on 1-h poststress gated SPECT; hence, caution is necessary when using wall motion on 1-h poststress gated SPECT to assess resting wall motion.     

Reduction of coronary flow reserve in areas with and without ischemia on stress perfusion imaging in patients with coronary artery disease: A study using oxygen 15-labeled water PET

BACKGROUND: Myocardial perfusion single photon emission computed tomography (SPECT) occasionally fails to detect coronary stenosis in patients with coronary artery disease (CAD). We evaluated coronary flow reserve (CFR) using oxygen 15-labeled water in areas with and without ischemia on technetium 99m tetrofosmin stress perfusion SPECT in patients with angiographically documented CAD. METHODS AND RESULTS: Twenty-seven patients with CAD and eleven age-matched normal subjects were studied. Baseline myocardial blood flow (MBF) and MBF during hyperemia induced by intravenous adenosine triphosphate infusion (0.16 mg. kg(-1). min(-1)) were determined with the use of O-15-labeled water positron emission tomography, and the CFR was calculated. Tc-99m tetrofosmin stress/rest SPECT was performed for comparison. On the basis of the results of coronary angiography and SPECT, coronary segments were divided into 3 types: segments with coronary stenosis and a perfusion abnormality on stress SPECT imaging (group A, n = 16), segments with coronary stenosis without a perfusion abnormality (group B, n = 42), and remote segments with no coronary stenosis or perfusion abnormality (group C, n = 18). Baseline MBF values were similar among the 3 groups. CFR in group A was lower (1.82 +/- 0.54) than in group B (2.22 +/- 0.87, P <.05), in group C (2.92 +/- 1.21, P <.01), and in normal segments (3.86 +/- 1.24, P <.001). CFR in group B was lower than in group C (P <.02) and in normal segments (P <.001). CFR in group C was lower than in normal segments (P <.02). CONCLUSIONS: Areas with a perfusion abnormality on stress SPECT had reduced CFR. In the areas without a perfusion abnormality and with coronary stenosis, lowering of CFR was intermediate between the areas with a perfusion abnormality and remote segments. Moreover, CFR was slightly, but significantly, lower in remote segments in patients with CAD compared with normal segments.     

Quantification of limited augmentation of myocardial (99m)Tc-tetrofosmin uptake at exercise in stable coronary artery disease

We evaluated the diagnostic accuracy of a new method for quantitative analysis of myocardial perfusion at exercise using (99m)Tc-tetrofosmin tomographic imaging. (99m)Tc-tetrofosmin imaging of an exercise-rest sequence was performed in 30 patients with coronary artery disease (CAD) and eight age-matched control subjects. The exercise-induced myocardial count increase was calculated as the relative value (per cent increase ratio, %IR) to that at rest by correcting for physical decay for (99m)Tc and injected doses and by a subtraction technique. Exercise and rest (99m)Tc-tetrofosmin images were assessed visually and quantitatively using the per cent peak count and %IR of the myocardial count at exercise. Segments with significant coronary stenosis (diameter stenosis=75% or more) showed a significantly lower %IR than did those without significant coronary stenosis in the CAD patients (37+/-19% vs 63+/-21%, P<0.05). The diagnostic efficacy of visual analysis for detecting coronary stenosis was as follows: sensitivity, 58.1% and specificity, 81.4%. When %IR=37% was used for detecting significant coronary stenosis, sensitivity and specificity increased to 74.2% and 93.2%, respectively. Furthermore, the quantitative analysis significantly (P=0.04) improved the overall diagnostic accuracy from 73.3% to 86.7% compared to that of visual assessment. Thus, augmentation of myocardial (99m)Tc-tetrofosmin uptake at exercise is blunted in the myocardium with significant coronary stenosis. The calculation of myocardial count increase at exercise relative to that at rest can improve the diagnostic value of (99m)Tc-tetrofosmin SPECT imaging and may contribute to more accurate quantification of myocardial ischaemia and impaired tracer uptake in coronary artery disease.     

门控~（99m）Tc－MIBI心肌断层显像诊断多支冠状动脉病变和心肌缺血

目的：评价门控心肌显像诊断冠心病（ＣＡＤ）的临床意义。方法：对３２例ＣＡＤ患者的９９ｍＴｃ—甲氧基异丁基异腈（ＭＩＢＩ）门控。非门控心肌断层显像和冠状动脉造影进行了比较，以及对４０例ＣＡＤ患者的门控与常规潘生丁─静息心肌断层显像也作了比较。结果：１．门控与非门控显像法诊断ＣＡＤ的灵敏度和特异性无差别，但前者对检测病变冠状动脉和诊断多支冠状动脉病变性ＣＡＤ的灵敏度高于后者，而特异性无差别。２．射血分数（ＥＦ）值显著影响非门控图像的病变显示。３．与非门控显像比较，门控显像能观察到更多的再分布节段和较少的无再分布节段。静息门控心肌显像除发现较多的灌注异常外，还观察到了许多单纯收缩功能受损节段。后者虽然可判断８４％的灌注再分布节段，但特异性不高。结论：门控心肌断层显像对诊断ＣＡＤ无优势，但对诊断ＥＦ值较高的或多支冠状动脉病变性ＣＡＤ、检测病变冠状动脉和心肌缺血有一定价值。     

Nitrate administration increases blood flow in dysfunctional but viable myocardium, leading to improved assessment of myocardial viability: A PET study.

SPECT with 99mTc-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasodilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. METHODS: 13N-Ammonia PET was used to quantitatively assess blood flow, and 18F-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent 13N-ammonia PET at rest and after nitrate administration. RESULTS: A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P < 0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. CONCLUSION: 13N-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability.     

Post-stress end-systolic left ventricular dilation: a marker of endocardial post-ischemic stunning

Several studies have shown the accuracy of gated single photon emission computed tomography (SPECT) using thallium-201 and technetium tracers in the assessment of myocardial perfusion and function. Gated SPECT has been successfully utilized to detect post-stress left ventricular ejection fraction (LVEF) reduction resulting from post-ischemic stunning in patients with coronary obstruction. The aim of this study was to evaluate whether the post-stress LVEF impairment could be related to the post-stress end-systolic ventricular dilation resulting from post-ischemic endocardial stunning. Two hundred and eighty-two consecutive patients were studied by conventional diagnostic 2 day stress/rest gated SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual-headed SPECT camera. One hundred and forty-seven of these patients (52%) showed reversible perfusion defects, 69 (24%) permanent defects and the remaining 66 (24%) had normal perfusion. One hundred and thirty-eight of these patients had a history of myocardial infarction (MI) and 19% underwent coronary angiography without an intervening cardiac event. Perfusion was analysed on ungated images using 20 segments scored on a five-point scale (0, normal; 4, no uptake), while wall thickening (WT) was assessed visually on stress/rest end-systolic images using a four-point score (0, normal; 3, absence of WT). LVEF and volumes were calculated using an automatic algorithm. The post-stress and rest ratios were determined for both end-diastolic (EDV) and end-systolic (ESV) volume. Normal values for all these parameters were obtained using data from 149 patients with a low likelihood (<5%) of coronary artery disease (CAD). In 50 of the 147 (34%) of patients with reversible perfusion defects, post-stress LVEF was >5% lower than rest values (stunned group), while the remaining 97 patients did not show a significant LVEF change (group 2A). The percentage of patients who developed exercise-induced angina, the percentage of patients who underwent coronary angiography and the segmental summed perfusion and WT scores were significantly higher in the stunned group compared with group 2A. Only ESV increased significantly post-stress, and this increase occurred only in stunned patients. Both EDV and ESV ratios were significantly higher in the stunned group compared with normal controls (P=0.008 and P<0.000001, respectively) and with the subgroup 2A (P=0.011 and P<10(-12), respectively). The ESV stress/rest ratio correlated significantly with the summed WT difference score by univariate analysis in stunned patients. It can be concluded that the post-stress ESV dilation, obtained by stress/rest gated SPECT, seems to be due to endocardial post-ischemic stunning. The stunned patients showed more severe clinical, angiographic, perfusion and function parameters.     

Resting “solar polar” map pattern and reduced apical flow reserve: Characteristics of apical hypertrophic cardiomyopathy on SPECT myocardial perfusion imaging

BACKGROUND: Patients with apical hypertrophic cardiomyopathy (ACM) are often referred for myocardial perfusion single photon emission computed tomography (SPECT) as a result of marked T-wave inversion and chest pain syndromes. Stress perfusion defects have been reported in ACM, but the characteristic SPECT pattern as well as the typical findings on volume-weighted polar maps has not been described. METHODS AND RESULTS: Dual-isotope rest (thallium 201) and exercise or adenosine stress (technetium 99m tetrofosmin) myocardial perfusion SPECT was performed in 11 patients with ACM, including 8 with either normal coronary arteriography (n = 5) or a low pretest probability of coronary artery disease (CAD) (n = 3), and 14 control patients with concentric left ventricular hypertrophy. An 8-pixel-diameter circular region of interest was used to quantitatively compare apical and septal counts on CEqual volume-weighted polar maps. A characteristic "Solar Polar" map pattern resulting from the increased apical counts was present in each ACM patient at rest, with a mean apical-septal ratio of 1.39 +/- 0.17 (range, 1.23-1.62, P <.01 vs concentric left ventricular hypertrophy group). With stress, there was a significant decrease in the apical-septal ratio (0.96 +/- 0.18, P <.001 vs rest) in the ACM subgroup without CAD. CONCLUSION: Patients with ACM demonstrate a newly described "Solar Polar" map pattern at rest, as well as relative apical ischemia on the stress images even in the absence of CAD.     

Assessment of lung perfusion impairment in patients with pulmonary artery-occlusive and chronic obstructive pulmonary diseases with noncontrast electrocardiogram-gated fast-spin-echo perfusion MR imaging

PURPOSE: To evaluate the ability of noncontrast electrocardiogram (ECG)-gated fast-spin-echo (FSE) perfusion MR images for defining regional lung perfusion impairment, as compared with technetium (Tc)-99m macroaggregated albumin (MAA) single-photon emission computed tomography (SPECT) images. MATERIALS AND METHODS: After acquisition of ECG-gated multiphase FSE MR images during cardiac cycles at selected lung levels in nine healthy volunteers, 11 patients with pulmonary artery-occlusive diseases, and 15 patients with chronic obstructive pulmonary diseases (COPD), the subtracted perfusion-weighted (PW) MR images were obtained from the two-phase images of the minimum lung signal intensity (SI) during systole and the maximum SI during diastole, and were compared with SPECT images. RESULTS: ECG-gated PW images showed uniform but posture-dependent perfusion gradient in normal lungs and visualized the various sizes of perfusion defects in affected lungs. These defect sites were nearly consistent with those on SPECT images, with a significant correlation for the affected-to-unaffected perfusion contrast (r = 0.753; P < 0.0001). These MR images revealed that the pulmonary arterial blood flow in the affected areas of COPD was relatively preserved as compared with pulmonary artery-occlusive diseases, and also showed significant decrease in blood flow, even in the areas with homogeneous perfusion on SPECT images in patients with focal pulmonary emphysema. CONCLUSION: This noninvasive MR technique allows qualitative and quantitative assessment of lung perfusion, and may better characterize regional perfusion impairment in pulmonary artery-occlusive diseases and COPD.     

Incremental value of assessment of regional wall motion for detection of multivessel coronary artery disease in exercise (201)Tl gated myocardial perfusion imaging.

Assessment of reversible perfusion defects in exercise (201)Tl perfusion SPECT has low sensitivity and high specificity for detection of multivessel coronary artery disease (CAD). The goal of this study was to evaluate whether worsening of left ventricular regional wall motion assessed by an automated algorithm in exercise (201)Tl electrocardiography-gated SPECT had incremental diagnostic value over perfusion data for detection of multivessel CAD. METHODS: Two hundred one patients underwent exercise (201)Tl gated SPECT. Software that automatically analyzes left ventricular function was used to assess exercise and rest regional wall motion. Regional wall motion on initial images was compared with that on rest images, that is, delayed images for patients without reinjection images and reinjection images for patients with reinjection images. The left ventricle was divided into 9 segments, with individual segments assigned to 3 coronary territories. Worsening of wall motion was defined as worsening in any segment on initial images compared with rest images. RESULTS: Of 73 patients with multivessel CAD, 20 (27.4%) had reversible perfusion defects in multiple coronary territories, 26 (35.6%) exhibited worsening of regional wall motion in multiple territories, and 37 (50.7%) had reversible perfusion defects or worsening of regional wall motion in multiple territories. The sensitivity of the combination of reversible perfusion defect and worsening of regional wall motion was significantly higher than that of reversible perfusion defect alone for detection of multivessel CAD (50.7% vs. 27.4%, P < 0.05). The specificity of the combination of reversible perfusion defect and worsening of regional wall motion for detecting multivessel CAD did not differ from that of reversible perfusion defect alone and that of worsening of regional wall motion alone (94.5% vs. 99.2% and 97.7%, respectively, P = not statistically significant). CONCLUSION: Combined assessment of worsening of left ventricular regional wall motion by exercise and perfusion data in exercise (201)Tl gated myocardial SPECT was more sensitive, with acceptable specificity, than was assessment with perfusion data alone for detection of multivessel CAD.     

Cardiac tomography with 99mTc-tetrofosmin after nitrate administration in patients with ischemic cardiopathy and left ventricular dysfunction

PURPOSE: To investigate the role of technetium-99m (99mTc) tetrofosmin single-photon emission Computed Tomography (SPECT) associated with nitrate administration in the detection of hypoperfused but still viable myocardium in patients with chronic coronary artery disease and left ventricular (LV) dysfunction. MATERIAL AND METHODS: Twenty-two patients (mean age 54 +/- 11 years) with coronary artery disease, previous myocardial infarction and LV dysfunction (LV ejection fraction 38 +/- 13%) were examined. On different days all patients underwent 99mTc tetrofosmin (740 MBq) SPECT under control conditions at rest and after sublingual nitroglycerin administration (10 mg). Regional tetrofosmin activity was quantitatively measured in 22 myocardial segments per patient. In each segment, tracer uptake was expressed as a percentage of the region with the peak activity. RESULTS: Under control conditions, 267 myocardial segments (55%) showed normal tetrofosmin uptake (> 70% of peak activity), 107 segments (22%) showed a moderate reduction (51-70%) and 110 segments (23%) a severe reduction (< or = 50%) in tracer uptake. Among the 110 segments with a severe reduction in tetrofosmin uptake, 20 (18%) showed increased tracer uptake > or = 10% of after nitrate administration (from 44 +/- 5% to 58 +/- 3%, p < 0.0001). The remaining 90 (82%) segments with a severe reduction in tetrofosmin uptake did not show any change after nitroglycerin administration (from 38 +/- 9% to 39 +/- 8%, p = ns). CONCLUSIONS: In patients with chronic coronary artery disease and LV dysfunction, tetrofosmin cardiac SPECT associated with sublingual nitrate administration allows the detection of severely hypoperfused but still viable myocardium.     

Evaluation of myocardial viability with technetium-99m hexakis-2-methoxyisobutyl isonitrile and iodine-123 phenylpentadecanoic acid and single photon emission tomography

The detection of viable myocardium in infarcted regions, i.e. hibernating myocardium, is a major goal in clinical cardiology today. We applied combined planar and single photon emission tomography (SPET) to the non-invasive estimation of the left ventricular ejection fraction (LVEF), myocardial blood flow and free fatty acid uptake in the heart. Of the 31 patients with coronary artery disease, 25 (81%) had had a previous myocardial infarction. All patients had at least one persistent perfusion defect on the stress-rest technetium-99m hexakis-2-methoxyisobutyl isonitrile (Sestamibi) study, and the results revealed 57/124 (46%) persistent perfusion defects. As a part of the perfusion study, the LVEF was measured at rest using the first-pass ^99mTc-Sestamibi injection, and the mean LVEF was 47% ±9% (mean ± 1 standard deviation). Iodine-123 phenylpentadecanoic acid (¹²³I-pPPA) imaging at rest was performed within 2 weeks from the perfusion study. Then 6-mm transaxial, sagittal and coronal slices of the perfusion and ¹²³I-pPPA studies were reconstructed. The bull's eye displays of the coronal slices were visually surveyed and divided into 4 quadrants: anterior, lateral, posterior and septal. The following image score was used: 0 = fixed defect, 1 = partial uptake and 2 =normal uptake. Moreover an index of metabolic reserve (MR) was calculated by dividing the bull's eye of the ¹²³I-pPPA study by the bull's eye of resting ^99mTc-Sestamibi, and its maximum value was normalized to 100%. Fourteen segments (25%) had a normal ¹²³I-pPPA uptake with a MR value of 96% ±8%. Twenty-two segments (39%) had a partial ¹²³I-pPPA uptake with a MR of 74% ±20%, whereas 21 segments (36%) had no ¹²³I-pPPA uptake and a very low MR of 36%±34%. There was a highly significant correlation (r =0.70) between LVEF and MR. These findings suggest that it is possible to identify viable myocardium by measuring contractile function (first-pass, multiple-gated ^99mTc-Sestamibi) and myocardial perfusion (stress-rest ^99mTc-Sestamibi) and by combining these parameters with myocardial fatty acid uptake (1231-pPPA) studies. Correspondence to: IT Kuikka     

The effects of solid food in prevention of intestinal activity in Tc-99m tetrofosmin myocardial perfusion scintigraphy

BACKGROUND: The aim of this study was to investigate the effect of a standardized meal on intestinal activity in technetium 99m tetrofosmin myocardial perfusion scintigraphy. METHODS AND RESULTS: The study population consisted of 60 patients (42 men and 18 women; mean age, 56 +/- 8 years) referred for myocardial perfusion imaging. All patients underwent same-day exercise-rest Tc-99m tetrofosmin single photon emission computed tomography (SPECT) imaging. All patients were given 200 mL of milk 15 minutes after the injection for the exercise SPECT study and just after the injection for the first rest SPECT study. None of the patients ate or drank between the exercise and the first rest SPECT studies. After the first rest SPECT study, 30 patients (meal group) were given a standardized meal of solid food and liquid to increase the volume of the stomach, and a second rest SPECT image was obtained 30 minutes after the end of the first rest SPECT study. In 30 patients (control group) a second rest SPECT image was obtained 30 minutes after the end of the first rest SPECT study, but this group did not eat or drink in this interval. The effect of the meal on intestinal activity was evaluated both visually and quantitatively. Frequency of intestinal activity was assessed visually on SPECT images. Inferior myocardial wall and abdominal activity adjacent to the myocardium was quantitatively assessed on 3 different planar projections in the rest studies, and the mean inferior wall-to-abdomen count ratio was calculated. In the meal group, inferior wall-to-abdomen count ratios in the first and second rest studies were 1.48 +/- 0.3 and 2.09 +/- 0.4, respectively (P <.0001), and in the control group, 1.41 +/- 0.2 and 1.40 +/- 0.2 (P >.05), respectively. The frequency of intestinal activity was 63% (n = 19) in the first rest SPECT study and 10% (n = 3) in the second study in the meal group (P <.0001); it was 66% (n = 20) in the first rest SPECT study and 76% (n = 23) in the second study in the control group (P >.05). CONCLSUIONS: Our results indicate that filling of the stomach with a meal of solid food and liquid before rest acquisition may provide a high target-to-nontarget ratio. This simple modification may reduce the frequency of intestinal activity of Tc-99m-labeled radiopharmaceuticals in myocardial perfusion imaging.     

~(99)Tc~m-NOET门控心肌灌注SPECT评价冠心病的价值

目的 评价~(99)Tc~m-双(N-乙氧基,N-乙基-二硫代氨基甲酸酯)氮化锝(~(99)Tc~m-NOET)静息门控断层心肌灌注显像对冠心病患者的诊断价值.方法 疑诊为冠心病的45例患者注射925 MBq~(99)Tc~m-NOET后1h用SPECT行静息门控心肌灌注显像,获得舒张未期容积(EDV)、收缩未期容积(ESV)、左室射血分数(LVEF)等心功能参数和舒张末期容积灌注、局部射血分数、局部室壁活动和室壁增厚度4个靶心图.所有患者在1周内行冠状动脉造影,将冠状动脉狭窄≥50%定为病变血管.根据冠状动脉造影结果将其分为心肌梗死组、心肌缺血组和对照组三组.结果 ~(99)Tc~m-NOET静息门控SPECT诊断冠心病的灵敏度和特异度分别为68.42%和83.33%.心肌梗死组的心功能参数[EDV=(129.32±9.14)ml,ESV=(80.97±9.49)ml,LVEF=(40.15±3.28)%]与对照组[EDV=(80.91±3.12)ml,ESV=(30.12±1.79)ml,LVEF=(63.51±1.04)%]相比,统计学差异有显著性(EDV:F=22.103,ESV:F=32.277,LVEF:F=42.604,均为P＜0.01),心肌缺血组的心功能参数[(EDV=(70.83±3.46)ml,ESV=(25.13±2.85)ml,LVEF=(65.55±2.62)%]与对照组相比,统计学差异无显著性意义.心肌梗死组左室心肌共分为460个节段,其中209个节段局部灌注、局部射血分数、局部室壁活动和室壁增厚度4个靶心图均异常.局部灌注异常的节段共328个节段.伴有局部射血分数、局部室壁活动和室壁增厚度异常分别有250个、240个和276个节段.局部灌注异常的节段与局部射血分数、局部室壁活动和室壁增厚度异常的节段不完全匹配.结论 ~(99)Tc~m-NOET静息门控心肌灌注显像对冠心病的诊断有较大临床应用价值,所获得的整体心室功能参数在心肌梗死的评价中有优越性,但对心肌缺血的诊断价值不大.心肌梗死中存在有不少的局部灌注与心肌室壁功能异常节段的不匹配,对心肌存活的评价有帮助.     

Restoration of myocardial blood flow following percutaneous coronary balloon dilatation and stent implantation: assessment with qualitative and quantitative contrast-enhanced magnetic resonance imaging

AIM: To examine the serial use of magnetic resonance imaging (MRI) to evaluate regional myocardial perfusion changes following percutaneous coronary angioplasty and stent implantation (PTCA). MATERIALS AND METHODS: Six patients with single vessel coronary artery disease (CAD) underwent contrast-enhanced first pass MRI immediately prior to (visit A) and within 7 days after (visit B) PTCA. Three sequential short axis slices were obtained after gadodiamide (Gd) bolus (0.025 mmol/kg(-1)) at rest and during adenosine. Each short axis was divided radially into eight regions of interest (ROIs). ROIs were anatomically assigned to a coronary artery territory (CAT). Stress and rest qualitative and quantitative (unidirectional extraction fraction constant (K(i)); index of myocardial perfusion reserve (MPRI) = stressK(i) / restK(i)) perfusion parameters were determined for ROI supplied by remote and stenosed/stented vessels for each visit. RESULTS: In stented ROIs the number of ROIs demonstrating normal perfusion, as opposed to reversible perfusion deficits, increased. Qualitative perfusion assessment in remote CATs was unchanged. MPRI in stenotic CATs was lower than in remote CATs at visit A (P < 0.001). Following PTCA, MPRI increased in stented CATs (P < 0.001) but was unchanged in remote CATs. CONCLUSION: Restoration of myocardial perfusion following PTCA can be delineated with qualitative and quantitative perfusion MRI. Although at present the investigation is technically complex and not perfectly sensitive or specific, MRI has the potential to be a valuable tool for patient follow-up and evaluation of revascularization strategy efficacy.     

Detection of regional myocardial perfusion deficit using rest and stress perfusion MRI: a feasibility study

OBJECTIVE: Providing high temporal and spatial resolution, perfusion MRI is an attractive alternative to traditional radionuclide methods like SPECT and PET. Although first-pass perfusion MRI examinations have gained increasing attention during the past years, this technique still exhibits relatively low signal-to-noise ratio and cardiac coverage. Previous studies have suggested that refocused gradient sequence technology (e.g., true fast imaging with steady-state precession [FISP]) should improve perfusion MRI examinations. The aim of this study was to assess myocardial perfusion deficits in patients with proven coronary artery disease using a saturation recovery true FISP perfusion sequence. SUBJECTS AND METHODS: Rest and stress perfusion MRI studies were performed in 22 patients with coronary artery disease at 1.5 T using a multislice saturation recovery true FISP sequence after the bolus injection of 0.025 mmol/kg of body weight of gadopentetate dimeglumine. The myocardium of each slice was divided into 12 radial segments with subdivision into subendocardial and subepicardial subregions. Myocardial perfusion was assessed semiquantitatively and independently for each subregion. The standard of reference for myocardial perfusion was SPECT. Delayed enhancement images were acquired after the injection of 0.15 mmol/kg of body weight of gadopentetate dimeglumine. RESULTS: Sensitivity and specificity of perfusion MRI examinations for the detection of perfusion deficits were 81% and 89%, respectively, for the semiquantitative perfusion parameter upslope and 78% and 86% for the parameter peak signal intensity. More specifically, rest perfusion examinations were able to detect areas of infarction, whereas stress examinations increased the perfusion differences between normal and ischemic myocardial areas. Excellent correlation was observed between rest perfusion and late enhancement findings (r = 0.90). CONCLUSION: In patients with single-vessel coronary artery disease, perfusion deficits can reliably be detected using a saturation recovery true FISP sequence. Semiquantitative perfusion parameters upslope and peak signal intensity yielded similar results.     

A comparative regional analysis of coronary atherosclerosis and calcium score on multislice CT versus myocardial perfusion on SPECT.

For the noninvasive evaluation of coronary artery disease (CAD), both multislice CT and gated SPECT are available. How these 2 modalities relate, however, is yet unclear. The purpose of this study was to perform a head-to-head comparison of the results of multislice CT and gated SPECT on a regional basis (per vessel distribution territory) in patients with known or suspected CAD. METHODS: One hundred forty patients underwent both multislice CT for coronary calcium scoring and coronary angiography and gated SPECT for myocardial perfusion imaging. The coronary calcium score was determined for each coronary artery. Coronary arteries on multislice CT angiography were classified as having no CAD, insignificant stenosis (<50% luminal narrowing), significant stenosis, or total or subtotal occlusion (>/=90% luminal narrowing). Gated SPECT findings were classified as normal or abnormal (reversible or fixed defects) and were allocated to the territory of one of the various coronary arteries. RESULTS: In coronary arteries with a calcium score of 10 or less, the corresponding myocardial perfusion was normal in 87% (n = 194/224). In coronary arteries with extensive calcifications (score > 400), the percentage of vascular territories with normal myocardial perfusion was lower, 54% (n = 13/24). Similarly, in most of the normal coronary arteries on multislice CT angiography, the corresponding myocardial perfusion was normal on SPECT (156/175, or 89%). In contrast, the percentage of normal SPECT findings was significantly lower in coronary arteries with obstructive lesions (59%) or with total or subtotal occlusions (8%) (P < 0.01). Nonetheless, only 48% of vascular territories with normal perfusion corresponded to normal coronary arteries on multislice CT angiography, whereas insignificant and significant stenoses were present in, respectively, 40% and 12% of corresponding coronary arteries. CONCLUSION: Although a relationship exists between the severity of CAD on multislice CT and myocardial perfusion abnormalities on SPECT, analysis on a regional basis showed only moderate agreement between observed atherosclerosis and abnormal perfusion. Accordingly, multislice CT and gated SPECT provide complementary rather than overlapping information, and further studies should address how these 2 modalities can be integrated to optimize patient management.     

Irbesartan has a masking effect on dipyridamole stress induced myocardial perfusion defects

BACKGROUND AND AIM: The angiotensin II type 1 (AT1) receptor antagonist irbesartan is used for the treatment of hypertension, but its anti-ischaemic effect is not yet known. Our aim was to assess the effect of irbesartan administration on the diagnostic yield of 99mTc sestamibi single photon emission computed tomography (SPECT) in patients with coronary artery disease (CAD) after dipyridamole stress. METHODS: Our study group consisted of 13 patients (11 men and two women; mean age, 53.3 +/- 10.6 years; body mass index, 26.9 +/- 3.3 kg x m(-2)) with angiographically documented CAD. All patients underwent SmTc sestamibi SPECT studies at rest, before (STRESS-1) and 2 weeks after irbesartan (150 mg daily) administration (STRESS-2) at dipyridamole stress. The extent and severity of defects were analysed by using visual and quantitative 99mTc sestamibi SPECT. RESULTS: The mean summed stress score was significantly higher during the STRESS-1 study than the STRESS-2 study (13.2 +/- 7.4 vs. 11 +/- 7.4, P=0.003). The mean size of perfusion defects at stress was significantly larger for the STRESS-1 group than the STRESS-2 group (17.8% +/- 2.85% vs. 15.3% +/- 2.95%, P=0.01). CONCLUSION: Our study showed that the AT1 receptor blocker irbesartan reduces the extent and severity of 99mTc sestamibi perfusion defects after dipyridamole stress in patients with CAD. Irbesartan may alter coronary blood flow reserve. The continued use of irbesartan before stress myocardial perfusion SPECT has a masking effect on stress induced myocardial perfusion defects. For this reason AT1 receptor blockers must be stopped before stress myocardial perfusion scintigraphic examinations.