Technetium-99m-tetrofosmin imaging with incremental nitroglycerin infusion to detect severely ischaemic but viable myocardium: a comparative study with thallium-201

The aim of this study was to assess the influence of incremental nitroglycerin infusion (NTG+Inf) on the myocardial uptake of 99mTc-tetrofosmin (TF) in order to determine whether nitrates enhance the detection of viable myocardium with TF in patients with coronary artery disease (CAD) and left ventricular dysfunction. Fifty patients (39 males, 11 females; 54 +/- 11 years) with previous myocardial infarction and left ventricular dysfunction, who had been referred for coronary revascularization procedures, were studied. Myocardial single-photon emission tomography (SPET) images were obtained 1 h after injection of 750 MBq TF at baseline and after NTG+Inf, using a 2 day protocol. NTG+Inf was performed starting at 0.4 microg x kg(-1) x min(-1), with equal increments every 5 min up to 2 microg x kg(-1) x min(-1). Within 1 week of the TF study, rest-redistribution (R-RD) 201Tl SPET was performed after the injection of 111 MBq 201Tl. For each study, quantitative analysis was performed in 17 segments. Viability was defined as the presence of tracer uptake of > 50% of the peak activity on baseline studies or reversibility. There was significant correlation between quantitative regional RD 201Tl activity and TF activity after NTG+Inf (r = 0.90, P < 0.001). Of the 131 segments with severely reduced tracer uptake on resting TF images, 34 (26%) were reversible, showing increased tracer uptake after NTG+Inf (from 41%+/-7% to 57%+/-12% of peak activity; P < 0.001). All reversible segments after NTG+Inf had viability criteria on 201Tl studies. There was 95% concordance between TF with NTG+Inf and RD 201Tl imaging with regard to the presence of myocardial viability. We conclude that TF imaging with incremental NTG+Inf improves the detection of ischaemic but viable myocardium, correlating with the viability criteria observed on 201Tl studies. When the advantages of TF imaging are considered, rest TF imaging with NTG+Inf may be a practical diagnostic protocol in patients with CAD and left ventricular dysfunction who are being considered for revascularization.     

Assessment of myocardial viability by resting 201Tl SPECT image

The aim of this study was to assess whether resting 201Tl scintigraphy is superior in detecting viable myocardium than previous conventional methods. We performed not only stress 201Tl SPECT but also resting 201Tl SPECT within one month in 65 patients with coronary artery disease. Resting 201Tl images were quantitatively compared with 4 hour late images of stress study using a polar map. In stress study, redistribution was recognized on 83% (25/30) of non-MI SEGs with perfusion defect in the stress 201Tl image, and on 39% (18/46) of infarcted SEGs. The agreement of resting 201Tl study with 4 hour late images of stress study was shown on 93% (28/30) of non-MI SEGs and on 52% (24/46) of MI SEGs. The increased uptake of 201Tl in resting study, however, was found on 13 (46%) of 28 MI SEGs showing fixed defects in stress study. In stress delayed image with fixed defect, the %Tl uptake of improved SEGs was higher than that of unchanged SEGs (59 +/- 10% vs 48 +/- 11%; p greater than 0.05). There was no viable myocardium which had %Tl uptake less than 40% at stress delayed image. In conclusion, the resting 201Tl imaging will give an important information as for the myocardial viability showing fixed defects, if more than 40% Tl uptake is observed.     

201Tl与13N-NH3、18F-FDG PET心肌显像判断存活心肌的对比研究

目的　比较再注射2 0 1T1心肌显像与联合应用13 N NH3 及18F 脱氧葡萄糖 (FDG)心肌PET显像判断存活心肌的临床价值。方法　 2 0例心肌梗死患者 ,行2 0 1T1SPECT负荷、再分布、再注射显像及13 N NH3 、18F FDGPET心肌显像。将左室分成 9个节段 ,以视觉评价法对放射性分布进行 4级评分。获得2 0 1T1SPECT再分布、再注射像及18F FDGPET显像的局部心肌摄取率 (%ID)。结果　PET判定为存活心肌的 48个节段中 ,45个节段 (93.8% ) 2 0 1T1再注射像也判定为存活心肌。在2 0 1T1再分布像示放射性分布严重低下的 2 4个节段 ,2 0 1T1再注射像与PET显像判定存活心肌的一致率为 87.5 % ,其中 37.5 %为存活心肌节段 ,5 0 %为无存活心肌节段。 2种显像方法的 %ID无明显差异 ,且呈显著正相关 (r=0 .72 2 )。结论　再注射2 0 1T1心肌显像判断存活心肌的准确性与PET心肌显像相似 ,有较大的临床应用价值。     

Evaluation of myocardial viability following acute myocardial infarctic using201Tl SPECT after thallium-glucose-insulin infusion —Comparison with18F-FDG positron emission tomography—

OBJECTIVE AND METHODS: The aim of this study was to evaluate myocardial viability in patients after acute myocardial infarction (AMI). We compared 201Tl SPECT after 201Tl with GIK (10% glucose 250 ml, insulin 5 U and KCl 10 mEq) infusion (GIK-201Tl) with resting 201Tl and 99mTc-pyrophosphate (PYP) dual SPECT, positron emission computed tomography (PET) using 18F-fluorodeoxyglucose (18F-FDG) in 21 patients with their first AMI, who all underwent successful reperfusion. GIK-201Tl SPECT, 201Tl and 99mTc-PYP dual SPECT were done within 10 days after admission and 18F-FDG-PET was performed at 3 weeks. GIK-201Tl SPECT was obtained after 30 min of GIK-201Tl infusion. 18F-FDG (370 MBq) was injected intravenously after oral glucose (1 g/ kg) loading, and then PET was obtained. PET and SPECT images were divided into 20 segments. Regional tracer uptake was scored using a 4-point scoring system (3 = normal to 0 = defect), and summed to a regional uptake score (RUS). Regional area means the infarcted area in which 99mTc-PYP accumulated. The number of decreased uptake segments (ES) was then determined. The infarcted area was defined as the area of 99mTc-PYP uptake. RESULTS: The ESs for the GIK-201Tl and 18F-FDG-PET images were significantly lower than the number of 99mTc-PYP uptake segments. The RUS for GIK-201Tl was higher than that for resting-201Tl imaging and similar to those for 18F-FDG-PET. CONCLUSIONS: In the detection of myocardial viability following AMI, GIK-201Tl imaging is useful with findings similar to those of 18F-FDG-PET.     

The effect of nitroglycerin on myocardial blood flow in various segments characterized by rest-redistribution thallium SPECT.

The use of nitrates is reported to be effective in viability detection in scintigraphic perfusion imaging. The purpose of the study was to evaluate the effect of nitroglycerin (NTG) on myocardial blood flow (MBF) and coronary vascular resistance (CVR) in various segments characterized by rest-redistribution (201)Tl SPECT. METHODS: Twenty-three patients with coronary artery disease underwent rest-redistribution (201)Tl SPECT and (15)O-labeled water PET at rest and after NTG spray (0.3 mg). In addition, 11 healthy volunteers were also studied using PET. RESULTS: NTG did not change global MBF in the volunteers or in the patients. In segments with normal (201)Tl uptake and in those with a severe irreversible (201)Tl defect, NTG significantly reduced MBF without changing CVR. NTG reduced CVR in segments with a reversible (201)Tl defect (141 +/- 50 to 114 +/- 29 mm Hg/[mL/min/g], P = 0.004) and in those with a mild-to-moderate irreversible (201)Tl defect (165 +/- 64 to 149 +/- 60 mm Hg/[mL/min/g], P = 0.003), while maintaining MBF. CONCLUSION: NTG preferentially reduces CVR in the viable myocardium with ischemia. After NTG, tracer uptake in the ischemic myocardium will be relatively increased compared with that in the nonviable and nonischemic myocardium, leading to improvements in viability detection.     

Impairment of regional fatty acid uptake in relation to wall motion and thallium-201 uptake in ischaemic but viable myocardium: Assessment with iodine-123-labelled beta-methyl-branched fatty acid

In coronary artery disease, discrepancy in the uptake of thallium-201 and of methyl-branched fatty acid at rest has been described. The purpose of this study was to evaluate iodine-123 labelled beta-methylbranched fatty acid (BMIPP) myocardial uptake and wall motion at rest in segments with stress-induced ischaemia identified by stress²⁰¹Tl tomography in patients with chronic coronary artery disease.¹²³I-BMIPP myocardial tomography was performed at rest and was compared with the findings of exercise-reinjection²⁰¹Tl tomography in 45 patients with chronic coronary artery disease. Regional wall motion was evaluated by contrast left ventriculography in 36 patients. Among 237 segments with reversible²⁰¹Tl defects, equally decreased uptake on both reinjection²⁰¹Tl and BMIPP images was observed in 93 (39%), more severely decreased uptake of BMIPP in 118 (50%) and more severely decreased uptake of reinjection²⁰¹Tl in 26 (11%). On the other hand, among 90 segments with non-reversible²⁰¹Tl defects, each pattern was observed in 71 (79%), 6 (7%) and 13 (14%) segments, respectively. When comparing the ischaemic segments with and without more severely reduced uptake of BMIPP than of reinjection²⁰¹Tl, wall motion was impaired to a greater extent in the segments with more severely reduced uptake of BMIPP than of reinjection²⁰¹Tl [severe hypo- or dyskinesis was present in 64 (70%) of 91 segments and in 24 (22%) of 110 segments, respectively,P<0.005]. In patients with chronic coronary artery disease, resting fatty acid uptake was frequently more reduced than reinjection²⁰¹Tl in the segments with stress-induced ischaemia, while in most of the fixed perfusion defects BMIPP and reinjection²⁰¹Tl uptake decreased concordantly. In ischaemic myocardium, wall motion was impaired to a greater extent in those segments which showed more severely reduced uptake of BMIPP than of reinjection²⁰¹Tl. In ischaemic but viable myocardium, discordant BMIPP uptake less than reinjection²⁰¹Tl uptake may indicate metabolic alterations and wall motion abnormality at rest independent of perfusion abnormalities. In conclusion, the combination of resting BMIPP and stress-reinjection²⁰¹Tl imaging may provide information on metabolic alterations and wall motion abnormality at rest independent of perfusion abnormalities.     

The diagnostic value of Tc-99m PYP, Tl-201 dual isotope SPECT to predict the viability of damaged myocardium in the acute phase of myocardial infarction--comparison with stress, delayed, and reinjected Tl-201 SPECT]

To assess the diagnostic value of Tc-99m PYP, Tl-201 dual isotope SPECT for the evaluation of myocardial viability, segmental comparison between dual isotope SPECT and exercise, delayed, and reinjected Tl study were performed with 18 AMI patients. Among 72 damaged myocardial segments, 48 segments (67%) were judged as viable by chronic phase Tl studies. The segments with severely reduced Tl uptake by dual SPECT showed significantly lower prevalence of viable myocardium than the segments with reduced and normal Tl uptake (p less than 0.001). The segments with PYP accumulation localized to the subendocardium represented the favorable outcome compared with the transmural accumulation (p less than 0.001). And overlap segments show better prognosis than the segments without overlap (p less than 0.05). Most importantly, we can get better predictive accuracy of myocardial scar by dual isotope SPECT than the judgement by Tl or PYP SPECT alone (83.3% vs 77.8%, 68.1%). Thus, we conclude that Tc-99m PYP, Tl-201 dual isotope SPECT is useful to assess the severity of myocardial damage in the acute phase of myocardial infarction.     

Usefulness of resting thallium-201 delayed imaging for detecting myocardial viability in patients with previous myocardial infarction

To test the feasibility of resting thallium-201 (²⁰¹Tl) initial and delayed scintigraphy for detecting the area of viable myocardium, we performed single photon emission computed tomography (SPECT) in 57 patients with previous myocardial infarction (MI). All had received coronary arteriography (CAG) and left ventriculography (LVG). Initial and delayed myocardial imagings were carried out 10 min and 2 hours, respectively, after the injection of²⁰¹Tl at rest. Redistribution was judged by visual interpretation and/or the circumferential profile curve, and found in the infarcted or its adjacent area in 40 of the 57 cases (70.2%). A negative washout (net increase of²⁰¹Tl uptake in delayed image) was detected in 17 of these 40 cases. In 10 of the 57 patients, both exercise and rest-injected²⁰¹Tl myocardial images were obtained at exercise and rest, and compared visually. The areas of abnormal perfusion were smaller in the resting delayed images than those seen after exercise in 9 of the 10 cases, and were equal in one case. Thus, resting²⁰¹Tl delayed myocardial scintigraphy appears to reduce the underestimation of the size of the viable myocardium by the usual²⁰¹Tl images obtained after exercise or by single initial images obtained at rest in patients with previous MI.     

Comparative accuracy of various Tl-201 reinjection imaging protocols to detect myocardial viability

The conventional exercise-3 hours-redistribution thallium-201 [²⁰¹Tl] imaging protocol has been recognized to be suboptimal for reliable detection of myocardial viability. Although²⁰¹Tl restreinjection after exercise has improved detection of viable myocardium, it is still underestimated in some patients. The present study was designed to compare detection of viable myocardium in five separate imaging steps: step 1: initial-exercise imaging, step 2: delayed-exercise imaging, step 3: Tl-201 reinjection imaging after delayed-exercise imaging, step 4: separate day rest-reinjection imaging, and step 5: separate day delayed-rest imaging. The study group consisted of 22 patients scheduled for coronary revascularization (either percutaneous transluminal coronary angioplasty or coronary bypass surgery). Pre- and postintervention echocardiographic wall motion and thickness served as independent markers of myocardial viability. Results: Accuracy in identifying myocardial viability gradually improved incrementally from²⁰¹Tl imaging step 1 to step 5. The positive predictive value, negative predictive value and overall accuracy were best for the separate day delayed-rest study (step 5) at 90%, 33% and 78%, respectively. Myocardial segments had fixed defects on separate day delayed-rest²⁰¹Tl imaging (step 5), but nevertheless echocardiographic evidence of myocardial viability indicated less severe defects than segments judged non viable by echocardiography (p = 0.021). The overall accuracy of separate day delayed-rest imaging (step 5) in predicting viability improved to 88% when segments with moderate or mild defects were considered viable. In conclusion, the most reliable predictor of myocardial viability with²⁰¹Tl imaging is defect severity on separate day delayed-rest images.     

Acute myocardial infarction: myocardial viability assessment in patients early thereafter comparison of contrast-enhanced MR imaging with resting (201)Tl SPECT. Single photon emission computed tomography

PURPOSE: To compare contrast material-enhanced magnetic resonance (MR) imaging with resting thallium 201 ((201)Tl) single photon emission computed tomography (SPECT) for predicting myocardial viability in patients early after acute myocardial infarction. MATERIALS AND METHODS: Inversion-recovery contrast-enhanced MR images and resting (201)Tl SPECT images were obtained in 22 patients after acute myocardial infarction. The (201)Tl SPECT images were obtained 4.3 days +/- 0.2 (standard error) after the onset of myocardial infarction. Contrast-enhanced MR imaging was performed 7.9 days +/- 1.6 after (201)Tl SPECT. Transmural extent of hyperenhancement on contrast-enhanced MR images and regional (201)Tl activity were quantitatively analyzed with a 12-segment model. Regional wall thickening on follow-up cine MR images obtained 67 days +/- 17 after contrast-enhanced MR imaging was used as an index for myocardial viability. Statistical analyses were performed with the chi(2) and two-tailed Student t tests. RESULTS: Both contrast-enhanced MR and resting (201)Tl SPECT images showed significant correlations with regional wall thickening on follow-up cine MR images. The sensitivity, specificity, and accuracy of contrast-enhanced MR imaging in the prediction of viable myocardium were significantly higher than those of resting (201)Tl SPECT (98.0% vs 90.3%, P <.01; 75.0% vs 54.4%, P <.05; and 92.0% vs 81.1%, P <.001, respectively). CONCLUSION: Delayed contrast-enhanced MR imaging can help predict myocardial viability as seen on follow-up cine MR images after acute myocardial infarction, with significantly improved sensitivity, specificity, and accuracy in comparison with those of resting (201)Tl SPECT.     

Reverse redistribution on exercise-redistribution (201)Tl SPECT in chronic ischemic dysfunction: predictive of functional outcome after revascularization?

This study analyzed the incidence and clinical significance of reverse redistribution (RR) on stress-redistribution (201)Tl SPECT studies in patients with poor left ventricular function and tested the hypothesis that the RR phenomenon could be caused by artifacts. METHODS: Seventy-three consecutive patients with chronic coronary artery disease and left ventricular dysfunction (ejection fraction, 36% +/- 12%) who underwent exercise-redistribution-reinjection (201)Tl SPECT before myocardial revascularization were included. Recovery of left ventricular systolic function was assessed with 2-dimensional echocardiography performed before and 5.5 +/- 2.5 mo after revascularization. RR was determined visually and confirmed quantitatively as a > or = 10% decrease in (201)Tl uptake on the circumferential profiles. The left ventricle was divided in 16 segments for (201)Tl uptake and wall motion analyses. RESULTS: RR was present in 39 of 1,168 segments (3.3%) and in 18 of 73 patients (25%). Before revascularization, regional wall motion was normal in 26 of 39 RR segments (67%), hypokinetic in 7 of 39 (18%), and akinetic in 6 of 39 (15%). Eight percent of all dysfunctional segments (13/167) of RR patients presented RR. After revascularization, 60 of 167 dysfunctional segments (36%) improved function by > or = 1 grade, among which 8 (13%) displayed RR on (201)Tl SPECT before revascularization. Segments with RR improved function more frequently than those without RR (62% vs. 34%; P = 0.05). Using a threshold for segmental (201)Tl uptake of >54%, the accuracy of (201)Tl reinjection to detect functional improvement in RR segments after revascularization was 77% (10/13). Artifactually induced RR was also excluded in all but 1 case because no increased activity of the pixel used for normalization could be found on redistribution images relative to that of the stress images. CONCLUSION: These data suggest that in patients with chronic left ventricular ischemic dysfunction, RR on exercise-redistribution (201)Tl SPECT is not an artifact and occurs rarely in normally functioning and in dysfunctional myocardium. In the latter, RR is frequently associated with myocardial viability as shown by functional recovery after revascularization. However, the presence or absence of RR in dysfunctional segments seems to be of little clinical relevance.     

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.     

Low-dose dobutamine electrocardiograph-gated myocardial SPECT for identifying viable myocardium: comparison with dobutamine stress echocardiography and PET.

The identification of severely dysfunctional but viable myocardium is of particular importance for the selection of patients with depressed left ventricular function who will benefit from coronary revascularization. Assessment of inotropic reserve with dobutamine has recently been used for this purpose. This study compared the accuracy of low-dose dobutamine stress gated myocardial SPECT (DS SPECT) with the accuracy of dobutamine stress echocardiography (DSE) and resting perfusion SPECT for the identification of viable myocardium in patients with previous myocardial infarction. METHODS: Resting and low-dose dobutamine (7.5 microg/kg/min) gated (99m)Tc-tetrofosmin SPECT and echocardiography and resting (18)F-FDG PET were prospectively studied in 23 patients with previous myocardial infarction and severely depressed regional function. Twenty-one of them were successfully studied with each technique. The left ventricular wall was divided into 14 segments to assess wall motion using a 5-point scale. PET viability was defined as FDG uptake >/= 50% of the maximum uptake in a region with normal wall motion. For DS SPECT and DSE studies, viable myocardium was defined as hypokinetic areas with > or = 1 point improvement in wall motion. For resting perfusion SPECT, viable myocardium was defined as hypokinetic areas with a relative uptake > or = 50% of the maximum uptake. RESULTS: Of a total of 294 segments, 55 had severe resting dyskinesis. Thirty-four segments were identified as viable on FDG PET, and 21 segments were identified as nonviable. Eleven segments were inadequately visualized with DSE, including 5 segments in the apex. Sensitivities (78% vs. 76%) and specificities (94% vs. 100%) were similar for DSE and DS SPECT, with a concordance of 86% (kappa = 0.72). DS SPECT and perfusion SPECT did not significantly differ with respect to sensitivities (76% vs. 85%, respectively). However, specificity was significantly higher for DS SPECT than for perfusion SPECT (100% vs. 52%, respectively, P < 0.05). CONCLUSION: This study indicated that DS SPECT correlates well with DSE in the assessment of viability. In addition, gated SPECT can evaluate regional wall motion, even in areas inadequately assessed by echocardiography. DS SPECT may also provide additional information for identifying viable myocardium, which is often overestimated by routine perfusion scans.     

Influence of increased 201Tl lung uptake on the myocardial viability of the patients with dilated cardiomyopathy under congestive heart failure]

Influence of increased 201Tl lung uptake on the myocardial viability was studied in 15 patients with dilated cardiomyopathy under congestive heart failure. Rest and 4 hours delayed 201Tl SPECT were obtained. At the same time anterior planar images were collected. In 10 patients of 15 patients 201Tl lung heart ratio in SPECT (LHR) was larger than that in planar images. Maximal 201Tl lung uptake was noted at the lower left lung adjacent to the heart. In the delayed images 201Tl lung uptake diminished. In 10 patients the value of LHR in the delayed images was less than 0.5. By comparing initial images with delayed images it was proved to be difficult to determine the myocardial margin adjacent to the increased 201Tl lung uptake. In 2 patients lateral defects were concealed by the increased 201Tl lung uptake. In the remaining patients lateral wall was similar to the hypertrophic myocardium. The effect of scatter due to the increased 201Tl lung uptake was noted in the neighboring myocardium. In most cases %201Tl uptake in the septum was relatively depressed by increased %201Tl uptake in the lateral wall. In the delayed images pseudo-redistribution was noted in the septum. Mean value of differences in %201Tl uptake between initial and delayed images was 8 (2-15)%. It was concluded that in case of increased 201Tl lung uptake SPECT could not accurately estimate myocardial viability by initial images and delayed images were necessary for precise estimation.     

123I-BMIPP心肌断层显像对劳力性心绞痛的诊断价值

目的 探讨安静时＾１２３Ｉ－β甲基碘苯脂十五烷酸（ＢＭＩＰＰ）心肌断层显像（简称＾１２３Ｉ－ＢＭＩＰＰ ＳＰＥＣＴ）对劳力性心绞痛的诊断价值,并与运动负荷＾２０１Ｔｌ心肌断层显像对比分析,方法 对３２例劳力性心绞痛患者及１２例健康对照者进行＾２０１Ｔｌ ＳＰＥＣＴ检查;将左室划分为９个节段,采用４级评分法对各节段放射性分布进行半定量评价（ＤＳ）。结果 心绞痛组＾２０１Ｔｌ ＳＰＥＣＴ表现为放射性分     

Diagnostic accuracy of supine and prone thallium-201 stress myocardial perfusion single-photon emission computed tomography to detect coronary artery disease in inferior wall of left ventricle

OBJECTIVE: Prone thallium-201 ((201)Tl) myocardial perfusion single-photon emission computed tomography (SPECT) reduces false-positive rates when evaluating inferior wall abnormalities by minimizing diaphragmatic attenuation. The present study investigates the diagnostic validity of prone (201)Tl stress myocardial perfusion SPECT for detecting coronary artery disease in the inferior wall of the left ventricle in Japanese patients. METHODS: Of the 104 consecutive patients who underwent (201)Tl stress myocardial perfusion SPECT to diagnose coronary artery disease, we evaluated 46 who underwent image acquisition in both the supine and prone positions, and coronary angiography within 3 months thereafter. Images were acquired in the routine supine position immediately following (201)Tl (111 MBq) injection and 4 h following early acquisition. Images were acquired in the prone position only during the early phase following supine acquisition. We evaluated the SPECT images of the inferior half segments of the left ventricle using a five-point defect scoring system. According to the coronary angiographic findings, we investigated the diagnostic accuracy of stress-rest supine, stress supine, stress prone, and combined supine-prone images. Reduced uptake in the stress supine image of the combined images was considered as attenuation when uptake was normal in the prone image. RESULTS: The sensitivity of the stress-rest supine, stress supine, stress prone, and stress-combined supine-prone images was 77%, 86%, 55%, and 55%, and the specificity was 71%, 54%, 79%, and 83%, respectively. Diagnostic accuracy was the highest in stress-rest supine images. CONCLUSIONS: Prone images tended to improve the specificity of detecting coronary artery disease in the inferior wall, but not diagnostic accuracy compared with stress-rest supine images because of decreased sensitivity.     

Assessment of myocardial viability in patients with myocardial infarction using twenty-four hour thallium-201 late redistribution imaging

BACKGROUND: Rest thallium-201 (201Tl) myocardial perfusion imaging has been widely used for evaluation of myocardial ischemia/viability after myocardial infarction, but the ideal timing for imaging after injection to maximally estimate viability is not well established. METHODS: Thirty-six patients with myocardial infarction underwent the initial, 3 h, and 24 h redistribution imaging after intravenous injection of 148-185 MBq 201Tl. The initial and 3 h images, the initial and 24 h images, and the 3 and 24 h images were compared double-blinded. RESULTS: Out of the 184 abnormal segments based on the initial imaging, 56 (30%) segments improved by at least 1 grade on the 3 h imaging while 78 (42%) segments improved by at least 1 grade on the 24 h imaging. The 24 h late imaging detected more viable myocardium than the 3 h imaging did, with a significant difference (chi2= 5.680, p = 0.017). There were 158 abnormal segments on the 3 h imaging, with average 28% (44) segments improved by at least 1 grade on the 24 h imaging. There were 128 initial abnormal segments with no improvement on the 3 h imaging. Out of these segments, the 24 h late redistribution imaging detected additional redistribution in 26 segments, taking up 20%. CONCLUSIONS: Twenty-four hour late 201Tl imaging will demonstrated additional redistribution in patients who have incompletely reversible defects on early redistribution imaging at 3h.     

缺血心肌动物模型PET和SPECT显像及组织学对比研究

目的评估^201TI SPECT及^18F-脱氧葡萄糖（FDG）PET显像对模型猪心肌活力的鉴别。方法健康家猪12头，其中10头于冠状动脉左旋支起始处放置Ameriod环，饲养28d形成慢性心肌缺血动物模型（另2头作正常对照），行^201TI SPECT心肌灌注显像和^18F—FDG PET心肌代谢显像并与HE染色病理学改变进行比较。结果81个心肌节段中，^18F—FDG心肌显像示心肌有活力的节段为73个（90．1％），明显高于^201TI心肌显像所示的62个（76．5％），差异有显著性（P〈0．05）。HE染色结果示有心肌活力的节段为74个（91．3％），与^18F—FDG心肌显像所示结果差异无显著性（P〉0．05）。结论^18F—FDGPET心肌显像检测心肌活力的准确性明显高于^201TI SPECT心肌显像。     

Myocardial viability assessment with gated SPECT Tc-99m tetrofosmin % wall thickening: Comparison with F-18 FDG-PET

OBJECT: This study was designed to assess the value of gated SPECT Tc-99m-tetrofosmin (TF) wall thickening (WT) in addition to TF exercise (Ex)/rest myocardial SPECT, in comparison with F-18 fluorodeoxyglucose (FDG)-PET. METHODS: The study population consisted of 33 patients with old myocardial infarction (27 men and 6 women; mean age, 62 +/- 8 years old). All patients underwent Ex/rest TF SPECT and glucose loading FDG-PET. Polar map images of Ex/rest TF were generated and divided into 24 segments for further analysis. We classified LV segments according to the exercise-rest perfusion scintigraphy. LV segments with less than 70% of the maximum TF activity on the exercise image were defined as stress-induced defects. Among these, the segments whose TF activity increased by 10% from exercise to rest images or exceeded 70% of the maximum uptake were defined as reversible (viable) defects. The remaining defects on the rest image were irreversible (non-viable) defect segments, and were considered for viability study on the basis of %WT. %WT was calculated according to the standard method: [(counts ES - counts ED)/counts ED] x 100. A viable segment on gated SPECT was defined as a segment whose %WT exceeded the lower limit of the normal value (mean - SD). PET viability was defined as FDG uptake exceeding 50% of the maximum count. RESULTS: Among the 792 segments evaluated in the 33 patients studied, there were 689 PET viable segments. Of the 689 segments analyzed, 198 (29%) were identified as having defects on Ex images. Among these defects, 55 (8%) were reversible or partially reversible, as evidenced by rest images, and 143 (21%) were irreversible. Of the irreversible segments on Ex/rest images, 106 (15%) demonstrated no apparent WT by gated TF SPECT, whereas 37 (6%) segments with irreversible defects did have apparent WT. Overall, the sensitivity of Ex/rest TF perfusion imaging was 79%. Sensitivity was improved from 79% to 85% by combining %WT and perfusion data, but specificity was reduced from 70% to 56%. CONCLUSION: %WT evaluated from gated TF imaging enhanced myocardial viability assessment in comparison with FDG-PET.     

Prediction of post-revascularization functional recovery of asynergic myocardium using quantitative thallium-201 rest-redistribution tomography: has the reverse redistribution pattern an independent significance?

The significance of reverse redistribution on rest-redistribution thallium-201 myocardial scintigraphy is unclear. Previous studies suggested that reverse redistribution segments with normal resting activity include viable myocardium, whilst resting defects with further worsening correspond to scar. We evaluated whether reverse redistribution has an independent significance for the prediction of post-revascularization recovery, particularly as compared with the quantification of redistribution activity. We studied 26 coronary artery disease patients with left ventricular dysfunction, who underwent ²⁰¹Tl rest-redistribution single-photon emission tomography (SPET) and echocardiography before revascularization. Viability was defined by the detection of wall motion improvement on follow-up echocardiography. ²⁰¹Tl activity was considered normal if ≥80%, moderately reduced if <80% but ≥50%, and severely decreased if <50%. Reverse redistribution was defined as a defect in redistribution images with ≥10% decrease in relative ²⁰¹Tl activity compared with the resting value. Reverse redistribution was detected in 33 segments (10%). Baseline dysfunction was equally observed in the reverse redistribution and in the non-reverse redistribution segments (64% vs 56%, P=0.40) and the rate of asynergic segments with post-revascularization recovery was not different between the two groups (33% vs 54%, P=0.11). The rate of functional recovery in redistribution defects without reverse redistribution was 53% in moderate and 30% in severe defects; the corresponding values for the reverse redistribution segments were 50% and 27% (all non-significant versus non-reverse redistribution segments). For the prediction of post-revascularization recovery in asynergic segments, the detection of reverse redistribution on rest-redistribution ²⁰¹Tl SPET does not add any information to the quantitative analysis of redistribution activity. Received 19 November 1997 and in revised form 20 February 1998