Effect of eating on thallium-201 myocardial redistribution after myocardial ischemia

To determine whether eating a high-carbohydrate meal between initial and delayed postexercise thallium-201 (Tl-201) imaging affects detection of Tl-201 redistribution during exercise stress testing, 16 patients with stable angina performed 2 Tl-201 treadmill exercise stress tests within a 14-day interval. Immediately after initial postexercise imaging, patients either drank a commercially available instant breakfast preparation for the intervention test or drank an equivalent volume of water for the control test. Comparable exercise workloads were achieved by exercising patients to the same heart rate for both tests. The order of the 2 (intervention and control) tests were randomized. All patients had at least 1 region of Tl-201 myocardial redistribution on either their eating or control test scans, although only 7 of the 16 had positive treadmill exercise test responses. Forty-six regions showing Tl-201 myocardial redistribution were identified in all 144 regions examined. Significantly more of these regions were identified on control test scans than on eating test scans: 11 of 46 on both test scans, 6 of 46 only on eating test scans and 29 of 46 only on control scans (p less than 0.001). Consistent with results of the quantitative regional analysis, the percentage of Tl-201 clearance over 4 hours in the 46 Tl-201 myocardial redistribution regions was 39 +/- 8% for the eating tests and 29 +/- 8% for control tests (mean +/- standard deviation, p less than 0.003). In 4 patients diagnosis of transient ischemia would have been missed because their 14 Tl-201 myocardial redistribution regions were detected only on the control test scans.(ABSTRACT TRUNCATED AT 250 WORDS)     

Minimal redistribution of thallium-201 representing reversible ischemia after coronary bypass surgery: value of quantitative analysis of exercise thallium-201 SPECT]

We previously reported the value of minimal redistribution (MR) of thallium-201 in analyzing quantitative polar map analysis (QNT) which correlated well with metabolic activity on FDG-PET. To determine whether ischemic areas that have redistribution are truly reversible, we performed stress and 3-hr delayed thallium-201 SPECT imaging and radionuclide ventriculography (RNV) in 41 patients with coronary artery disease before and after coronary bypass surgery (CABG). Redistribution (RD) was categorized into 4 grades: complete RD (CR), incomplete RD (IR), MR and persistent defect (PD). MR was defined as the segment that showed > or = 2SD improvement in more than 1/3 of the area on QNT, but RD was not evident by visual analysis. 1. QNT identified MR in 30 of 56 segments (54%) where PD is noted by visual inspection. 2. The MR segments showed severer wall motion abnormality (wall motion score: 1.83 +/- 1.12) than did the IR or CR segments (0.99 +/- 1.04) (p < 0.01), but the wall motion was well preserved, compared to the PD segments (2.54 +/- 0.90) (p < 0.01). 3. The grade of RD was compared with improvement in regional perfusion and wall motion on RNV after CABG. Improvement in perfusion was observed in 62 of 77 IR or CR segments (81%) and in 17 of 30 MR segments (57%), but in only 3 of 26 PD segments (12%) (p < 0.01). 4. Similarly, improvement in wall motion was observed in 45 of 57 IR or CR segments (79%) and in 22 of 27 MR segments (81%), but in only 5 of 25 PD segments (20%) (p < 0.01). Thus, the MR segments should be considered reversible after CABG. We conclude that QNT of RD should be performed to detect RD which is slight, yet suggestive of viability.     

Silent ischemia: evaluation by exercise and redistribution tomographic thallium-201 myocardial imaging

To compare the amount of myocardium jeopardized during silent ischemia and painful ischemia, 112 consecutive patients undergoing coronary arteriography with ischemia demonstrated by exercise and redistribution tomographic thallium-201 myocardial imaging (SPECT) were divided into two groups: 84 patients without anginal pain (silent ischemia) and 28 with pain (painful ischemia). The SPECT apical, mid and basal ventricular levels of the short-axis view and the apical portion of the long-axis view were divided into 20 segments. The results were 1) 7.4 +/- 4.7 ischemic segments in silent ischemia and 7.6 +/- 3.7 in painful ischemia (p = NS) with 4.7 +/- 3.6 segments in silent ischemia undergoing total redistribution compared with 5.4 +/- 3.4 in painful ischemia (p = NS); 2) no difference in the incidence of single, double or triple vessel disease between silent and painful ischemic groups; 3) similar anatomic distribution of ischemic segments between the two groups; 4) more positive exercise electrocardiographic (ECG) changes in painful ischemia (70%) than in silent ischemia (32%) (p less than 0.001) with equal amounts of ischemia associated with positive and negative exercise ECG findings. Conclusions: 1) Patients with silent and painful ischemia during exercise have similar amounts of ischemic myocardium demonstrated by tomographic thallium-201 imaging and similar extent of angiographically documented coronary artery disease despite the absence of pain and the lower incidence of positive exercise ECG findings in silent ischemia. 2) Positive and negative exercise ECG findings were associated with similar amounts of ischemic myocardium.     

静息201 Tl,201 Tl再分布,Isoket-201 Tl再注射显像评价犬梗死心肌存活力的研究

目的比较201 Tl,201 Tl再分布,Isoket-201 Tl再注射显像评价犬梗死心肌存活力的差异.方法制成9只犬冠状动脉人工结扎模型,随机将9只犬分为三组,进行201 Tl,201 Tl再分布,Isoket-201 Tl再注射显像,并观察其病理学改变.结果Ⅰ、Ⅱ、Ⅲ组犬静息201 Tl显像的放射性分布得分分别为17.1±1.0,18.7±2.1,22.0±2.6;静息 201 Tl再分布显像的放射性分布得分分别为15.3±1.5,17.3±3.5,20.0±1.0;Isoket-201 Tl再注射显像的放射性分布得分分别为12.5±2.5, 14.3±1.2,17.7±2.5.且Isoket-201 Tl再注射显像在检测心肌存活力方面与病理学改变一致性良好.结论 Isoket-201 Tl再注射显像是评价缺血心肌存活力的较准确可靠的方法.     

Reverse and pseudo redistribution of thallium-201 in healed myocardial infarction and normal and negative thallium-201 washout in ischemia due to background oversubtraction

While the interpolative background subtraction used in quantitative planar thallium scanning can significantly overestimate the background overlying the heart, the effects of background oversubtraction on quantitative analysis have not been well defined. A mathematical model that relates myocardial washout determined using interpolative background subtraction to true myocardial washout is presented. The model was validated using phantoms and applied to myocardial and pulmonary thallium kinetic data in 100 patients, 85 with and 15 without coronary artery disease. The model showed that when using interpolative background subtraction, measured washout equals true washout in normally perfused myocardium; however, depending on the relation between myocardial and pulmonary thallium clearance, myocardial washout in ischemic regions and areas of infarction can be substantially over- or underestimated. Based on generally accepted quantitative criteria, this incorrect washout determination can at times lead to misdiagnosis of infarction as ischemia and ischemia as normally perfused tissue. It can also cause both "reverse redistribution" and "pseudo redistribution" of thallium in myocardial infarction in the absence of a physiologic basis.     

Reverse redistribution of thallium-201 detected by SPECT imaging after dipyridamole in angina pectoris

Reverse redistribution refers to a thallium-201 perfusion defect that develops or becomes more evident on delayed imaging compared with the initial image immediately after stress. To determine the diagnostic importance of reverse redistribution after intravenous dipyridamole, thallium-201 single photon emission computed tomography and quantitative coronary arteriography were performed in 90 men with angina pectoris. Of the 250 myocardial segments analyzed, reverse redistribution was present in 17 (7%). Minimal coronary cross-sectional area in proximal vessel segments was less than or equal to 2.0 mm2 more often in regions with transient perfusion abnormalities than in regions with reverse redistribution (66 vs 29%, p less than 0.05). Compared with regions exhibiting transient perfusion abnormalities, regions with reverse redistribution had larger proximal arterial diameters (1.9 +/- 1.1 vs 1.3 +/- 1.1 mm, p less than 0.001) and cross-sectional areas (3.9 +/- 3.1 vs 2.2 +/- 2.6 mm2, p less than 0.001). Coronary artery dimensions and relative stenosis severity did not differ between those regions with normal perfusion and those with reverse redistribution. Reverse redistribution detected by thallium-201 single photon emission computed tomographic imaging after dipyridamole is uncommon, appears to occur as frequently in normal subjects as in patients undergoing coronary arteriography and does not indicate the presence of severe coronary artery disease.     

Effect of hyperaemia on thallium-201 redistribution in normal canine myocardium

The specific effect of hyperaemia on thallium redistribution is not known. Therefore we evaluated the effect of initial (group A) and delayed (group B) hyperaemia on thallium kinetics in normal canine myocardium. In group A dogs (n = 14) adenosine was infused into the left circumflex artery (LCx) prior to thallium injection and was continued for either 5, 30 or 120 min after thallium administration. In group B dogs (n = 10) LCx adenosine was begun 10 min post thallium injection and continued for 2 h. Radioactive microspheres were injected simultaneously with thallium and just prior to death in all but the 5 min experiments. The region of the left anterior descending artery (LAD) served as a normal control for each heart. The mean LCx/LAD flow ratio in all group A hearts was 3.81 +/- 1.24 (SD) and the final thallium LCx/LAD ratios averaged 2.29 +/- 0.26, 1.52 +/- 0.27 and 0.93 +/- 0.16 at 5, 30 and 120 min respectively, which represents a significant redistribution of thallium (p less than 0.05). In group B hearts, the mean LCx/LAD flow ratio was 1.06 +/- 0.07 during thallium injection and after LCx adenosine infusion the flow ratio rose to 2.91 +/- 0.75 (p less than 0.001). This resulted in a final thallium LCx/LAD ratio of 0.96 +/- 0.07 which was significantly less than the initial microsphere determined flow ratio (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Early postexercise thallium-201 reinjection after sublingual nitroglycerin augmentation: Effects on detection of myocardial ischemia and/or viability

Background: Thallium-201 (²⁰¹Tl) reinjection after conventional redistribution imaging is a standard procedure, resulting in enhanced ²⁰¹ Tl redistribution which is compatible with viable myocardium. Although this method significantly improves identification of viable myocardium, it increases the investigation time by approximately 1 h. Thus, this technique is suboptimal from the standpoint of patient convenience, since its routine performance may be impractical in a high-volume nuclear medicine laboratory. Hypothesis: This study was undertaken to evaluate the efficacy of an early ²⁰¹Tl reinjection and imaging protocol in combination with sublingual nitroglycerin, to detect myocardial ischemia and/or viability, and to reduce the need for conventional (4 h) redistribution imaging. Materials and Methods: In this study, 62 consecutive coronary patients, referred for the detection of possible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 42 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical chest pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection of 1 m Ci of ²⁰¹Tl were administered, and two further sets of images were acquired 1 h and 4h later. Results: In each set of i mages, a total of496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thallium uptake, 97 (32%) did not change, and 10(3%) showed reverse redistribution on 1 h reinjection imaging (IRI). Of the 97 persistent defects, only 17 (6%) showed fill-in of ²⁰¹ Tl on 4 h redistribution imaging (CRI), while 12 (4%) segments showed reverse redistribution. On the other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis changed from myocardial necrosis to ischemia after analysis ofthe 4h CRI. Conclusion: These results indicate that early postexercise reinjection of ²⁰¹Tl in combination with sublingual nitroglycerin followed by l h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.     

Assessment of thallium-201 redistribution versus glucose uptake as predictors of viability after coronary occlusion and reperfusion

Both 201Tl redistribution and persistent glucose uptake have been proposed as markers of viability after reperfusion. In the present study, they have been compared in the same open-chest canine preparation of occlusion and reperfusion. Ten fasting dogs were subjected to 2 hr of left anterior descending coronary artery occlusion and 4 hr of reperfusion. Myocardial blood flow was determined by a microsphere technique 100 min after occlusion and 3 hr after reperfusion. 201Tl was injected intravenously 20 min before reperfusion. Serial biopsy samples were obtained from ischemic and normal areas. 18F-2-deoxyglucose, a tracer of exogenous glucose uptake, was injected 3 hr after reperfusion. Thirty minutes before the animals were killed, simultaneous blood samples were taken from the femoral artery and the regional coronary veins draining the reperfused and the remote areas. Dogs were killed 4 hr after reperfusion was established. Area at risk was assessed by dye injection in vivo and area of necrosis by triphenyl tetrazolium chloride (TTC) staining, with confirmation by electron microscopy. Immediately after death, endocardial and epicardial samples were taken from regions characterized as risk regions, areas of necrosis, areas of patchy necrosis, and normal areas. These samples were counted in a scintillation well counter. Four hours after reperfusion, in ischemic myocardium (TTC positive) the relative 201Tl gradient between ischemic and normal regions was 26 +/- 13%, whereas in necrotic samples, this gradient was 71 +/- 26%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of thallium-201 imaging in nontransmural ischemia and infarction

To assess the validity of thallium-201 myocardial imaging in the diagnosis of non-transmural ischemia and infarction, the proximal left anterior descending coronary artery was partially occluded for 60 minutes with a balloon-tip catheter in intact anesthetized dogs in a basal state or during atrial pacing. In vivo sclntigrams of myocardium were compared with those obtained in the isolated heart and in the incised ventricle spread flat. None of the animals with partial occlusion wtth or without pacing demonstrated abnormal scintiscans in vivo. Removal of background by isolating the heart increased positive images to 30%; positive images were associated wtth an isotope count ratio between ischemlc and normal muscle of less than 0.67. Removal of superimposed nonischemic muscle in the heart enface increased image detection after pacing to 11 of 15. Since animals with subendocardlal scar failed to demonstrate a “cold area” in vivo, unfavorable geometry as well as extent and degree of ischemia appear to be important Thus, thallium radioactivity in superimposed and adjacent myocardium, as well as background, may limit the detection of nontransmural ischemia and scar.     

Normalization of reverse redistribution of thallium-201 with procainamide pretreatment in Wolff-Parkinson-White syndrome

Stress thallium-201 myocardial perfusion imaging was performed in a patient with Wolff-Parkinson-White syndrome. Reverse redistribution phenomenon was observed in the absence of coronary artery disease. This seems to be the first report of normalization of this phenomenon in association with reversion of accessory pathway to normal atrioventricular conduction after pretreatment with procainamide.     

Reverse redistribution of thallium-201 myocardial single photon emission tomography and contractile reserve

The present study investigated the contractile reserve of myocardium exhibiting reverse redistribution (RRD) of thallium-201 (201Tl) after acute myocardial infarction. Forty patients experiencing their first acute myocardial infarction underwent resting 201Tl single-photon emission computed tomography (SPECT) and low-dose (5-10 microgxkg(-1)xmin(-1)) dobutamine stress echocardiography (DSE) within 4 weeks after the onset of infarction. The left ventricle was divided into 13 segments for analysis. The severity of defects in 201Tl SPECT and the extent of wall motion abnormality in DSE were visually assessed and scored. The sum of each defect score and wall motion score of infarct-related segments were defined as total defect score (TDS) and total wall motion score (TWM), respectively. Quantitative analysis of 201Tl uptake was also performed. Resting 201Tl SPECT revealed RRD in 16 patients (group RRD), fixed defect (FIX) in 23 patients (group FIX), and redistribution in one. There was a significant difference in improvement of TWM between rest and stress in TWM in both the RRD and FIX groups (p<0.0001, each case). The improvement of TWM with dobutamine was significantly greater in RRD than in FIX (1.6+/-1.0 vs 0.6+/-0.7, p=0.001). There was a positive correlation between the magnitude of RRD and improvement of TWM with dobutamine (r=0.48, p=0.002). Myocardium exhibiting RRD on 201Tl SPECT in patients with acute myocardial infarction has greater contractile reserve than that exhibiting a fixed defect.     

Silent versus symptomatic ischemia during a thallium-201 exercise test

One hundred thirty-four patients with redistribution on a thallium-201 exercise test who did not experience angina (group 1) were compared with 134 patients also having redistribution who had angina during the test (group 2). The groups were matched by age, sex, and peak exercise heart rate. Although patients in both groups achieved an equivalent exercise level, patients in group 1 had less frequent (53 vs 71%, p < 0.005) and less severe (0.15 ± 0.13 vs 0.20 ± 0.13 mV, p < 0.005) ischemic ST-segment depression. Group 1 also had less ischemic thallium-201 images in terms of the number of redistributing defects, the severity of the worst redistributing defect, and an ischemic index composite of both extent and severity. Patients in group 1 were less likely to undergo early revascularization (12 vs 29%, p < 0.005), but in the remaining patients the occurrence of adverse cardiac events was similar (21% vs 29%, P = not significant). By multivariate analysis, only the ischemic index correlated with early revascularization in group 1 (p = 0.0017), whereas the percent maximal predicted heart rate correlated best in group 2 (p = 0.0003). In group 1 the ratio of lung/heart thallium-201 uptake correlated best with an outcome of nonfatal myocardial infarction or cardiac death (p = 0.0024); in group 2 the presence of fixed left ventricular dilatation did (p = 0.0022). Thus, patients with exercise-induced thallium-201 redistribution without angina have less ischemia than patients experiencing angina. They are also less likely to undergo early revascularization, but their prognosis is otherwise similar to patients with angina during the test.     

Value of thallium-201 reinjection after delayed SPECT imaging for predicting reversible ischemia after coronary artery bypass grafting

The reinjection of a small dose (40 MBq) of thallium-201 after stress and delayed imaging often shows new redistribution in the regions with persistent defect. To assess whether these segments may represent reversible ischemia, reinjection thallium-201 single-photon emission computed tomography (SPECT) was performed after stress and 3-hour delayed imaging in 24 patients before coronary artery bypass grafting (CABG). The left ventricular myocardium was divided into 5 myocardial segments and regional wall motion was scored on a scale from 0 (normal) to 4 (dyskinesia). Thallium-201 findings were compared with improvement in regional perfusion and wall motion 1 to 2 months after CABG. The reinjection imaging identified new redistribution in 15 of 32 persistent defects (47%) on the 3-hour delayed images. In the study of stress and delayed SPECT imaging, the improvement in perfusion was observed in 34 of 43 segments (79%) exhibiting redistribution and 15 of 32 (47%) segments without redistribution (p less than 0.01). The reinjection SPECT identified new redistribution in 12 of the 15 improved segments that were not detected on the delayed images. Similarly, the improvement in wall motion was observed in 23 of 31 segments (74%) exhibiting redistribution and 14 of 30 segments (47%) without redistribution on the delayed images (p less than 0.05). The reinjection identified new redistribution in 10 of the 14 improved segments that were undetected on the delayed images. The predictive values for improvement in perfusion and wall motion by the reinjection imaging were significantly higher (92 and 89%) than those by the delayed imaging (69 and 62%, respectively, p less than 0.05 each).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of ischemia on thallium-201 clearance from the myocardium

To determine the effect of ischemia on myocardial clearance of thallium-201 (201Tl), we studied 12 dogs with ischemia produced after the injection of Tl. Tl was given I.V. 10 minutes before left anterior descending (LAD) coronary artery ligation. 85Sr-microspheres (MS) were administered 5 minutes later, and control biopsies were obtained from the myocardium. The LAD was tied and repeat biopsies obtained from the ischemic zone (IZ) and normal zone (NZ) 15 minures and 2 hours later. 46Sc-MS were given just before the final giopsy. Tl activity in the IZ was not significantly different from that in the NZ either before LAD occlusion or 15 minutes and 2 hours later. Tl clearance at the end of 2 hours was not significantly different (27 +/- 5% vs 28 +/- 5%, IZ vs NZ respectively) between the two zones. The half-time of Tl clearance from both the IZ and NZ was calculated at 4.5 hours (consistent with previously reported normal values). This occurred despite a decrease in regional myocardial blood flow to 24 +/- 6% of control (P less than 0.01) in the IZ and an increase to 47 +/- 14% of control (P less than 0.01) in the NZ during the study. We conclude that myocardial ischemia does not alter the normal rate of Tl clearance from the myocardium.     

High prevalence of the thallium-201 reverse redistribution phenomenon in patients with syndrome X

OBJECTIVE: To evaluate the stress-redistribution myocardial perfusion patternin patients with angina, positive exercise test and angiographicallysmooth coronary arteries (syndrome X). DESIGN: Prospective study. PATIENTS AND METHODS: Twenty-five consecutive patients (seven males, mean age 54 ±8 years) with typical angina, positive exercise test, normalcoronary arteries and no inducible spasm, underwent stress-redistributionthallium- 201 myocardial perfusion scintigraphy. Thirty-twoconsecutive patients (14 males, mean age 49 ± 7 years)with atypical chest pain and negative exercise test, undergoingstress redistribution thallium scan, served as controls. RESUITS: Exercise was discontinued for angina and/or ST segment depressionafter 12 ± 3 min. Thallium stress images revealed 40hypoperfused segments in 27 patients (77%); after 4 h, 16 ofthese segments had completely normalized, 10 remained unchanged,six exhibited partial reperfusion and eight worsened. Twenty-fourpatients (69%) exhibited thallium reverse redistribution in33 segments. Thirty-four patients (97%) had at least one hypoperfusedsegment in one of the two scintigraphic phases. Of the 24 patientswith reverse redistribution, eight also underwent stress-rest99mTc-MIBI SPECT: six exhibited reduced tracer uptake that waspresent at rest, but not on stress images, in the same segmentsshowing thallium reverse redistribution. Thallium stress imagesrevealed four hypoperfused segments in three controls (9%) atredistribution, one segment normalized, two remained unchangedand one exhibited partial reperfusion. Additionally, there werefour new underperfused segments appearing on redistributionin four patients (13%). Overall, there were seven controls (22%)with at least one hypoperfused myocardial segment in one ofthe two scintigraphic phases. CONCLUSIONS: Our study confirms that perfusion abnormalities are presentin most syndrome X patients. Additionally, the data show thatreverse redistribution (a perfusion defect that develops orbecomes more evident on delayed imaging) is a common findingin these patients. The mechanisms of the phenomenon remain obscure:we suggest that it is due to inhomogeneous perfusion, and thehyperaemic response induced by exercise masks resting underperfusionof certain areas. (Eur Heart J 1996; 17: 1482–1487)     

Rest and redistribution thallium-201 myocardial scintigraphy to predict improvement in left ventricular function after coronary arterial bypass grafting

To examine the value of rest and redistribution thallium-201 imaging in predicting improvement in left ventricular (LV) ejection fraction (EF) after coronary artery bypass grafting (CABG), 26 patients with coronary artery disease (CAD) and abnormal LV function were studied. Nineteen patients had pathologic Q waves preoperatively. Rest and redistribution thallium-201 images and radionuclide ventriculograms were obtained before and after CABG, and the thallium scintigrams were evaluated both quantitatively and qualitatively. The patients were divided according to the preoperative thallium scintigrams into 2 groups: Group I (16 patients) had either normal resting thallium-201 images or reversible resting perfusion defects, and Group II (10 patients) had fixed resting perfusion defects. The resting EF was < 50% preoperatively in all patients. Fourteen patients (54%) showed improvement in EF postoperatively. Three patients (2 in Group I and 1 in Group II) showed new postoperative perfusion defects, and none of the 3 showed improvement in LV function. Of the remaining 14 patients in Group I, 12 (86%) showed improvement in LV function, compared with 2 of 9 patients in Group II (p < 0.01). Improvement in LV function was observed in 8 of the 19 patients (42%) with abnormal Q waves. Nitroglycerin intervention radionuclide ventriculograms were obtained in 20 patients before CABG. Of the 6 patients who showed improvement in LV function with nitroglycerin, 4 also showed improvement postoperatively. Postoperative improvement in LV function was also observed in 6 of the 14 patients who did not improve with nitroglycerin.Thus, rest and redistribution thallium imaging is useful in identifying patients whose LV function will improve after CABG. Normal rest thallium-201 images or reversible resting defects correctly identified 12 of 14 patients (86%) who showed improvement in LV function postoperatively. Nitroglycerin-intervention ventriculography and abnormal Q waves were less useful in this differentiation.     

Dipyridamole thallium-201 myocardial scintigraphy in coronary diagnosis; a comparison of methods with thallium-201 myocardial scintigraphy after ergometer stress

Two scintigraphic methods, resting dipyridamole and exercise thallium-201 myocardial perfusion imaging, to detect and localize coronary artery stenosis were compared in 32 patients suffering from coronary artery disease. The sensitivity of detecting a greater than 50% coronary stenosis was 94% for exercise thallium-201 perfusion imaging and 88% for dipyridamole thallium-201 perfusion imaging. The overall sensitivity and specificity of localizing a greater than 50% coronary stenosis by the two methods were also not significantly different. The results of the two scintigraphic methods were independent of the severity of coronary artery disease. Dipyridamole thallium-201 myocardial perfusion imaging provides a useful and safe alternative test for detecting and localizing coronary artery stenosis in patients unable to perform maximal exercise.