Intravenous Dipyridamole Research Articles

Pulmonary thallium-201 uptake following dipyridamole-exercise combination compared with single modality stress testing

Angiographic and clinical determinants of pulmonary uptake of thallium-201 were assessed in a laboratory setting where supine bicycle exercise is used for stress testing in the absence of limiting pharmacologic or physical factors, and where symptom-limited exercise is added to intravenous dipyridamole infusion in other cases. Angiographic correlation was available in 400 patients, including 130 tested with exercise, 94 in whom only handgrip or abbreviated bicycle exercise could be used after dipyridamole, and 176 in whom intravenous dipyridamole was combined with a significant level of exercise. For each test mode, lung/ myocardial ratios on the immediate image were highly correlated (p ≤ 0.001) with a score based on the number of critical coronary artery stenoses, with grading by contrast ventriculography, and with the number of stenosed (≥50%) arteries; relationships (p < 0.05) to history of myocardial infarction and to gender were also present. Multiple regression analysis showed the critical stenosis score and ventricular dysfunction to be the only significant determinants. When dipyridamolebased tests were compared with exercise, curves of receiver-operating characteristics showed a tendency to better diagnostic performance. When dipyridamole is incorporated in stress testing, the value of increased lung uptake as an ancillary diagnostic sign is similar to that established for exercise.

ST-segment depression during dipyridamole infusion, and its clinical, scintigraphic and hemodynamic correlates

The goal of this study was to determine whether dipyridamole-induced ST-segment depression reflects more severe or extensive myocardial hypoperfusion than the absence of this electrocardiographic finding. The clinical, hemodynamic and scintigraphic correlates of ST-segment depression during intravenous dipyridamole infusion were studied in 204 consecutive patients undergoing dipyridamole stress thallium-201 (Tl-201) imaging for evaluation of coronary artery disease. Of 182 patients with a diagnostic baseline electrocardiogram, 28 (15%) developed ST depression after dipyridamole. Patients with ST depression, compared with those without, were older (64 ± 1 vs 60 ± 1 years; p < 0.03) and had a higher frequency of chest pain (57 vs 23%; p < 0.001) and a higher heart rate-blood pressure product (12.7 ± 0.6 vs 11.2 ± 0.2 × 10 3; p < 0.008) after dipyridamole. Patients with ST depression were more likely to have Tl-201 redistribution (64 vs 38%; p < 0.02) and a greater number of redistribution defects (2.3 ± 0.04 vs 0.9 ± 0.1, p < 0.001) than were those without ST depression. By multivariate logistic regression analysis, the most powerful correlate of ST depression was the number of segments having Tl-201 redistribution (p < 0.001). Other independent correlates were presence of chest pain, heart rate at Tl-201 injection, and age. Thus, the determinants of dipyridamole-induced ST-segment depression include the scintigraphic extent of reversible hypoperfusion, as well as indexes of myocardial oxygen demand.

A negative thallium (+/- dipyridamole) stress test excludes significant obstructive epicardial coronary artery disease in hypertensive patients.

The operating characteristics of thallium stress testing for detection of significant epicardial coronary artery disease (CAD) in hypertensive subjects with chest pain or electrocardiographic (ECG) ischemia have not been previously defined. This becomes important because of the high prevalence of both hypertensive heart disease and CAD. Ninety-two hypertensives with a history of typical or atypical chest pain or ECG myocardial ischemia underwent coronary arteriography, 2D-guided echocardiography, and thallium-201 stress testing, combined with intravenous dipyridamole if the rate-pressure product was less than 20,000. Patients with myocardial infarction, prior revascularization procedure, valvular heart disease, and chronic ethanol abuse were excluded. The mean age was 54.8 +/- 9.9 years with 55% blacks and 46% women. Eighteen patients (19.6%) had significant (greater than or equal to 50% luminal diameter narrowing) epicardial CAD at catheterization, of whom 17 had positive thallium scans. Overall, there were 17 true positives, 47 true negatives, 27 false positives, and one false negative resulting in 94.4 +/- 5.4% sensitivity (95% confidence limits [95% CL] 71 to 100%), 63.5 +/- 5.6% specificity (95% CL 51 to 74%), 38.6 +/- 7.3% positive predictive value (95% CL 25 to 54%), 97.9 +/- 2.1% negative predictive value (95% CL 88 to 100%), and 69.6 +/- 4.8% overall accuracy (95% CL 59 to 79%). For hypertensive patients with chest pain or ECG myocardial ischemia, the high sensitivity and negative predictive value and low false negative rate support the role of thallium stress testing +/- dipyridamole as an exclusion test for significant CAD.

Long‐term prognostic value of a normal dipyridamole thallium‐201 perfusion scan

In a 4-year period, 84 patients who were referred for a dipyridamole thallium-201 stress test to rule out significant coronary artery disease had normal scans. A dipyridamole study was recommended instead of exercise because of arthritis, severe obesity, peripheral vascular disease, pulmonary disease, other chronic illnesses, or combinations of these problems. All patients had three-view (i.e., anterior, shallow left anterior oblique, and steep left anterior oblique) planar thallium-201 imaging 10 minutes and 3.5 hours after administration of 0.6 mg/kg of intravenous dipyridamole. The patients were followed for 42 +/- 13 (range 1-58) months to document the cardiac event rate. Of the 84 patients with normal results, 14 died during the follow-up period from noncardiac causes. Three other patients died 29-51 months after the test due to an acute myocardial infarction, a probable acute myocardial infarction, and sudden cardiac death, respectively. Of the survivors, 5 suffered an acute myocardial infarction 28-50 months after the dipyridamole thallium scan and 1 had coronary artery bypass grafting due to increasing angina pectoris 58 months after the scan (overall cardiac event rate of 0.4% per year). Of the remaining 61 patients, 39 (64%) were asymptomatic, 20 (33%) had the same symptoms they had at the time of testing without significant deterioration, while 2 patients (3%) had deterioration of their chest pains but no cardiac complication. Thus, in this group of patients, a normal dipyridamole thallium-201 perfusion scan predicted a good cardiovascular outcome for at least 24 months following the test.

Accuracy and safety of technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile (Sestamibi) myocardial scintigraphy with high dose dipyridamole test in patients with effort angina pectoris: A multicenter study

Clinical and physiologic evidence indicates that maximal coronary vasodilation is not achieved in a large number of patients with use of the standard dose of dipyridamole (0.56 mg/kg body weight over 4 min). The feasibility, safety and accuracy of technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile (Sestamibi) scintigraphy associated with intravenous high dose dipyridamole (0.56 mg/kg over 4 min followed 4 min later by an additional 0.28 mg/kg over 2 min) were evaluated in a multicenter study. Planar myocardial perfusion images were obtained at rest and after dipyridamole in 101 patients with effort chest pain and no prior myocardial infarction. High dose dipyridamole (62 patients) was used when typical chest pain or electrocardiographic (ECG) signs of ischemia, or both, did not occur during or after the standard dose (39 patients). With high dose dipyridamole, 34 patients had pain (18 patients) or ECG signs of ischemia (ST depression ≥2 mm) (8 patients), or both (8 patients), whereas the other 28 patients had Sestamibi injection in the absence of symptoms or ECG changes.All patients underwent coronary angiography: 81 had significant coronary artery disease (≥50% reduction of lumen diameter) (affecting one vessel in 38, two vessels in 19 and three vessels in 24 patients) and 20 patients had normal coronary arteries. The overall sensitivity, specificity and predictive accuracy of Sestamibi scintigraphy were 81%, 90% and 83%, respectively. No significant hypotension, ventricular arrhythmias or other serious adverse reactions occurred in any of the patients tested with the high dose dipyridamole; minor side effects occurred in 52% and 57% of patients at standard and high dose dipyridamole, respectively, and were well tolerated in all.In conclusion, Sestamibi scintigraphy associated with high dose dipyridamole is an accurate method of evaluating suspected ischemic heart disease in patients; it did not result in an increased number of side effects as compared with those associated with the standard dose protocol.

Intravenous Dipyridamole: Use in Thallous Chloride TL 201 Stress Imaging

An intravenous form of dipyridamole has been approved for cardiac stress testing with thallous chloride Tl 201 (201Tl) imaging. The procedure provides an alternative method for stress testing of patients who cannot perform strenuous physical exercise because of physical limitations or those in the immediate postinfarction period. Dipyridamole simulates the physiologic effects of physical exercise by increasing adenosine concentrations, which in turn increases coronary blood flow. Dipyridamole maximizes the differences in uptake of radioactive thallium in myocardial regions supplied by normal coronary arteries and those distal to stenosed arteries where blood flow is reduced. The sensitivity and specificity of dipyridamole-201Tl stress imaging for the detection of coronary disease are comparable to those of traditional exercise-201Tl stress testing. The intravenous dipyridamole usually is well tolerated, and the majority of adverse effects can be reversed with the administration of aminophylline.

Comparison of coronary vasodilation with intravenous dipyridamole and adenosine

Although both intravenous dipyridamole and adenosine have been used to produce coronary valuation during cardiac imaging, the relative potency of the commonly administered doses of these agents has not been evaluated, Accordingly, the coronary and systemic hemodynamic effects of intravenous adenosine (140 μg/kg per min) and intravenous dipyridamole (0,56 mg/kg over 4 min) were compared with a maximally dilating dose of intracoronary papaverine in 15 patiente. Coronary blood flow responses were assessed using a Doppler catheter in a nonstenotic coronary artery. The protocol was discontinued in two patients because of transient asymptomatic atriaventricular (AV) block during adenosine infusion.The mean heart rate increased more with adenosine (11 ± 9 beats/min) and dipyridamole (11 ± 7 beats/min) than with papaverine (4 ± 3 beats/min, p < 0.05 vs. adenosine and papaverine). The mean arterial pressure decreased less with dipyridamole (−20 ± 3 mm Hg) and papaverine (−9 ± 4 mm Hg) than with adenosine (t-16 ± 5 mm Hg, p < 0.01 vs. dipyridamole and papaverine). The peak/rest coronary blood flow velocity ratio was greater with papaverine (3.9 ± 1.1) than with adenosine (3.4 ± 1.2, p ≤ 0.05 vs. papaverine) or dipyridamole (3.1 ± 1.2, p < 0.01 vs. papaverine). A larger decrease in coronary resistance as measured by the coronary vascular resistance index occurred with papaverine (0.25 ± 0.06) and adenosine (0.26 ± 0.09) than with dipyridamole (0.31 ± 0.10, p < 0.01 vs. papaverine, p < 0.05 vs. adenosine). The maximal coronary blood flow velocity was reached more quickly after the start of adenosine infusion (55 ±34 s) than after the start of dipyridamole infusion (287 ± 101 s, p < 0.0001). The proximal coronary artery diameter was unchanged during dipyridamole or adenosine infusion. Thus, the vasodilator potency of adenosine was greater than that of dipyridamole when changes in coronary resistance were considered, though increases in flow were similar with the two agents. The rapid onset of action of adenosine compared with that of dipyridamole may allow a reduction in the duration or diagnostic studies. The incidence of AV block during adenosine infusion requires evaluation in larger studies.

Evaluation of dipyridamole-Doppler echocardiography for detection of myocardial ischemia and coronary artery disease

Doppler assessment of left ventricular filling and ejection during dipyridamole stress may supplement wall motion analysis for detection of myocardial ischemia and coronary artery disease (CAD). Thirty-four patients taking no cardioactive therapy were studied using intravenous dipyridamole (0.6 mg/kg) during 2-dimensional and pulsed Doppler echocardiography. Twelve patients had normal coronary arteries (group 1) and the remainder, who had significant CAD, were divided into groups 2 (n = 11) and 3 (n = 11). Only subjects in group 2 developed myocardial ischemia manifest as reversible regional asynergy and ST-segment depression. Heart rate increased (16 ± 9 beats/min, p < 0.01) and mean blood pressure decreased (-5 ± 8 mm Hg, p = not significant) uniformly across groups. Exaggerated hyperkinesia of normally contracting wall segments was the common response to dipyridamole infusion in patients with CAD. The respective mean percent changes in peak early diastolic velocity, peak atrial velocity, their ratio and ejection peak velocity, and mean acceleration for groups 1 (20, 42, −13, 20 and 23%), 2 (22, 32, −2, 10 and 14%) and 3 (23, 33, −6, 16 and 18%) were similar. Comparisons between normal patients and those with CAD and between groups 2 and 3 revealed no significant differences in the effect of dipyridamole on any variable. However, a decrease in both peak velocity and mean acceleration of left ventricular ejection was seen in 3 of 4 group 2 patients who developed severe ischemia. Dipyridamole-Doppler echocardiography is insensitive for detection of CAD and appears unable to identify myocardial ischemia unless this is severe. Hemodynamic changes and compensatory wall motion induced by dipyridamole may explain these findings.

Comparison of rubidium-82 positron emission tomography and thallium-201 SPECT imaging for detection of coronary artery disease

The diagnostic performance of rubidium-82 (Rb-82) positron emission tomography (PET) and thallium-201 (TI-201) single-photon emission-computed tomography (SPECT) for detecting coronary artery disease was investigated in 81 patients (52 men, 29 women). PET studies using 60 mCi of Rb-82 were performed at baseline and after intravenous infusion of 0.56 mg/kg dipyridamole in conjunction with handgrip stress. TI-201 SPECT was performed after dipyridamole-handgrip stress and, in a subset of patients, after treadmill exercise. Sensitivity, specificity and overall diagnostic accuracy were assessed using both visually and quantitatively interpreted coronary angiograms. The overall sensitivity, specificity and accuracy of PET for detection of coronary artery disease (>50% diameter stenosis) were 84,88 and 85%, respectively. In comparison, the performance of SPECT revealed a sensitivity of 84%, specificity of 53% (p < 0.05 vs PET) and accuracy of 79%. Similar results were obtained using either visual or quantitative angiographic criteria for severity of coronary artery disease. In 43 patients without prior myocardial infarction, the sensitivity for detection of disease was 71 and 73%, respectively, similar for both PET and SPECT. There was no significant difference in diagnostic performance between imaging modalities when 2 different modes of stress (exercise treadmill vs intravenous dipyridamole plus handgrip) were used with SPECT imaging. Thus, Rb-82 PET provides improved specificity compared with TI-201 SPECT for identifying coronary artery disease, most likely due to the higher photon energy of Rb-82 and attenuation correction provided by PET. However, post-test referral cannot be entirely excluded as a potential explanation for the lower specificity of TI-201 SPECT.

Dipyridamole thallium imaging

Dipyridamole cardiac imaging is a useful alternative to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole has been approved recently for clinical use. Oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow in excess of the increase in myocardial oxygen consumption and cardiac output. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg and the optimal oral dose is 300-375 mg, although higher doses may be necessary in some patients. The sensitivity and specificity of dipyridamole-thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole-thallium imaging has also been useful in identifying high-risk patients undergoing major elective vascular surgery. The relative merits of dipyridamole imaging versus exercise testing after acute myocardial infarction require further studies.

Perioperative and long-term prognostic value of intravenous dipyridamole thallium scintigraphy in patients with peripheral vascular disease: Younis LT, Aguirre F, Byers S, et al. Am Heart J 1990; 119: 1287-92

Perioperative and long-term prognostic value of intravenous dipyridamole thallium scintigraphy in patients with peripheral vascular disease: Younis LT, Aguirre F, Byers S, et al. Am Heart J 1990; 119: 1287-92

Noninvasive quantification of regional myocardial blood flow in coronary artery disease with oxygen-15-labeled carbon dioxide inhalation and positron emission tomography.

Oxygen-15-labeled water is a diffusible, metabolically inert myocardial blood flow tracer with a short half-life (2 minutes) that can be used quantitatively with positron emission tomography (PET). The purpose of this study was to validate a new technique to quantify myocardial blood flow (MBF) in animals and to assess its application in patients. The technique involves the administration of 15O-labeled carbon dioxide (C15O2) and rapid dynamic scanning. Arterial and myocardial time activity curves were fitted to a single tissue compartment tracer kinetic model to estimate MBF in each myocardial region. Validation studies consisted of 52 simultaneous measurements of MBF with PET and gamma-labeled microspheres in nine closed-chest dogs over a flow range of 0.5-6.1 ml/g/min. A good correlation between the two methods was obtained (y = 0.36 + 1.0x, r = 0.91). Human studies consisted of 11 normal volunteers and eight patients with chronic stable angina and single-vessel disease, before and after intravenous dipyridamole infusion. In the normal group, MBF was homogeneous throughout the left ventricle both at rest and after administration of dipyridamole (0.88 +/- 0.08 ml/g/min and 3.52 +/- 1.12 ml/g/min, respectively; p less than or equal to 0.001). In patients, resting MBF was similar in the distribution of the normal and stenotic arteries (1.03 +/- 0.23 and 0.93 +/- 0.21 ml/g/min, respectively). After dipyridamole infusion, MBF in normally perfused areas increased to 2.86 +/- 0.83 ml/g/min, whereas in the regions supplied by stenotic arteries it increased to only 1.32 +/- 0.27 ml/g/min (p less than or equal to 0.001). PET with C15O2 inhalation provides an accurate noninvasive quantitative method for measuring regional myocardial blood flow in patients.

Pharmacologic Stress Imaging

Pharmacologic stress imaging has increasingly been employed as an alternative to exercise imaging for detection of coronary artery disease and risk stratification particularly in patients who are unable to perform adequate exercise. Sensitivity and specificity of thallium 201 scintigraphy using intravenous dipyridamole infusion as a stress for coronary artery disease detection average 85% and 91%, respectively. Dipyridamole imaging is also useful for differentiating between ischemia and scar and identifying patients who have an increased risk for subsequent cardiac events. Dipyridamole imaging is particularly useful for preoperative risk stratification in patients undergoing surgery for peripheral vascular or aortic disease. Dipyridamole imaging is also useful for identifying residual myocardial ischemia after myocardial infarction and detecting restenosis after coronary angioplasty. Adverse side effects of dipyridamole are promptly reversed by aminophylline. Dipyridamole stress can also be employed in association with echocardiography for detection of ischemia-induced regional wall motion abnormalities.

Comparative side effect profile and safety of intravenous adenosine versus dipyridamole radionuclide imaging

Comparative side effect profile and safety of intravenous adenosine versus dipyridamole radionuclide imaging

Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study.

Thallium imaging of the heart using dipyridamole-induced coronary arteriolar vasodilation has proven to be an effective means of detecting significant coronary stenosis. However, intravenous dipyridamole has not yet been made available for general use. We therefore examined the feasibility of substituting amyl nitrite inhalation as an arteriolar vasodilator prior to thallium imaging. Seventeen patients, all of whom had catheterization-proven coronary stenosis, inhaled amyl nitrite for 2-5 min. Thallium was injected after 45-60 s of inhalation. Completion of inhalation was followed immediately by planar imaging. Of 6 patients who inhaled amyl nitrite for at least 4 min, 5 had moderate or severe image defects on immediate scans which completely resolved on delayed scans. Only 3 of 11 who inhaled amyl nitrite for 2 min or less prior to scanning had similarly positive tests. Overall sensitivity for significant stenosis was 8 of 17 (47%). Inhalation was well tolerated with only one episode of angina and hypotension. We conclude that amyl nitrite inhalation for at least 4 min may offer an effective and readily available alternative to intravenous dipyridamole for vasodilator imaging of the heart.

Dipyridamole perfusion scintigraphy: The experience with its application in one hundred seventy patients with known or suspected unstable angina

We evaluated the safety, accuracy, and potential clinical utility of intravenous dipyridamole perfusion scintigraphy with thallium-201 in 170 patients, 78 with suspected and 92 with known unstable angina. All had coronary angiography. Noncardiac side effects (26%), induced chest discomfort (44%), and ST segment changes (12%) were similar in the two groups. No significant arrhythmias occurred. Two patients had prolonged chest pain, both withextensive reversible image abnormalities and associated creatinine kinase-MB release. Both had elective bypass surgery. Twenty-eight patients had normal coronary arteries, and 35 had single-vessel disease. Scintigraphic per patients sensitivity and specificity were 91% and 79% with a per vessel sensitivity of 74% and a per vessel specificity of 78% without between-group differences. During a brief follow-up period, 62 patients with image abnormalities had coronary revascularization, and there were seven deaths without intergroup differences. In a similar patient group that did not have angiography, scintigraphic defects were less frequent and less extensive, revascularization was not performed, and subsequent deaths occurred less often. Dipyridamole perfusion scintigraphy is an accurate alternative to exercise testing in the evaluation of patients with unstable angina pectoris. Although not without risk, the method appears relatively safe and should be considered as a guide to diagnosis, and probably to prognosis and management.

Effects of dipyridamole and aminophylline on hemodynamics, regional myocardial blood flow and thallium-201 washout in the setting of a critical coronary stenosis

Experiments were performed to characterize the interaction of intravenous dipyridamole and aminophylline on thailium-201 transport kinetics, regional myocardial blood flow and systemic hemodynamics in the presence of a critical coronary artery stenosis. In 12 dogs with a critical left anterior descending coronary artery stenosis, arterial pressure decreased from a mean value (±SEM) of 107 ± 6 to 94 ± 3 mm Hg (p < 0.05) and distal left anterior descending artery pressure decreased from 70 ± 7 to 55 ± 4 mm Hg (p < 0.05) after intravenous administration of dipyridamole (0.25 mg/kg body weight). In the left anterior descending perfusion zone, the endocardial/epicardial flow ratio decreased from 0.70 to 0.36 and the intrinsic thallium washout rate was significantly prolonged. Intravenous aminophylline (5 mg/kg) reversed the dipyridamole-induced systemic hypotension and transmural coronary steal and restored the thallium washout rate to baseline values. In six other dogs, aminophylline alone resulted in no alterations in systemic and coronary hemodynamics or regional myocardial blood flow. As expected, dipyridamole-induced vasodilation and coronary steal were prevented by aminophylline pretreatment.These data show that in a canine model of partial coronary stenosis, systemic hypotension, adverse regional flow effects (coronary steal) and prolonged thallium-201 washout consequent to intravenously administered dipyridamole are promptly reversed by intravenous aminophylline administration. Aminophylline alone had no significant hemodynaniic and coronary flow effects. This study provides further insight into the altered thallium kinetics occurring as a consequence of dipyridamole-induced vasodilation and suggests that the prompt reversal of symptoms and signs of ischemia with aminophylline in patients receiving intravenous dipyridamole for clinical imaging studies probably reflects the reversal of transmural coronary steal.

Assessment of post-infarction jeopardized myocardium by vasodilation—thallium-201 tomography: impact on risk stratification

For the purpose of risk stratification 80 consecutive patients (mean age 58 +/- 7 years) with a chest pain syndrome after documented myocardial infarction underwent tomographic vasodilation-redistribution thallium-201 perfusion imaging, using 0.56 mg kg-1 intravenous dipyridamole. Tomograms were analysed for size and location of reversible and fixed perfusion defects and correlated to angiographic characteristics, left ventricular ejection fraction and wall motion, collateral status and 1-year prognosis, as measured by cardiac events within 12 months. No serious side-effects were noted with the diagnostic use of intravenous dipyridamole. According to the perfusion pattern three subgroups of post-infarction patients were identified: (1) by ischaemia at a distance with redistribution in non-infarct related territories (n = 48); (2) by peri-infarctional ischaemia with redistribution in the territory of the 'infarct artery' (n = 9); and (3) by exclusively fixed defects without redistribution (n = 23). Ischaemia at a distance was associated with a larger reversible defect than peri-infarctional ischaemia (P less than 0.05) and the pattern without redistribution (P less than 0.005); the fixed defect size, however, was similar in all three subgroups. In addition, the severity of coronary artery disease (Gensini score and number of diseased vessels) and the degree of collateralization was higher in the presence of a redistribution pattern (P less than 0.05), although no significant differences in global and regional function were noted as a function of thallium-201 redistribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Safety and Diagnostic Value of Intravenous Dipyridamole Thallium Scintigraphy in Patients with Suspected Coronary Artery Disease

Thallium-201 myocardial perfusion imaging (Tl-201 MPI) performed in patients after maximum exercise is widely used to evaluate patients with suspected coronary artery disease (CAD). Intravenous dip...

Intravenous Dipyridamole Thallium-201 SPECT Imaging Methodology, Applications, and Interpretations

Dipyridamole TI-201 imaging is an ideal alternative to exercise TI-201 scintigraphy in patients who are unwilling or unable to perform maximum exercise stress. The use of intravenous dipyridamole, alone or in combination with exercise, has not been approved for clinical practice by the Food and Drug Administration. Once approval is granted, the test will become a widely used and important component of the cardiac work-up. The indications, methodology, side effects, and utility of dipyridamole cardiac imaging in the clinical setting are discussed and a variety of examples presented.