Interpretive reproducibility of stress Tc-99m sestamibi tomographic myocardial perfusion imaging.

BACKGROUND: Observer variability has been shown with interpretation of planar thallium-201 images. The interpretive reproducibility of technetium-99m sestamibi tomographic imaging is unknown. This study evaluated the interpretive reproducibility of interpretable Tc-99m sestamibi tomographic images among nuclear cardiologists with a wide range of training and experience. METHODS: Three experienced readers (EX) and 3 less-experienced readers (LEX) interpreted 138 exercise and rest Tc-99m sestamibi tomographic images (101 were abnormal in patients with coronary artery disease [CAD], 37 were normal in patients with <5% likelihood of CAD) twice in random sequence without clinical data. Images of good to excellent quality were randomly selected from a database at 2 nuclear cardiology laboratories. Intraobserver and interobserver agreement for global, left anterior descending (LAD) territory, non-LAD first (normal/abnormal) and second (normal/fixed/reversible) order, and defect extent (normal/single-vessel CAD/multi-vessel CAD) were assessed with percent agreement and Cohen's kappa (kappa) statistic. RESULTS: With regard to intraobserver agreement, first and second order ranged from 87% to 94% and 80% to 90% for global, 82% to 96% and 78% to 95% for LAD, and 88% to 91% and 80% to 90% for non-LAD, respectively. Defect extent ranged from 75% to 90%. There were no differences between EX and LEX for global and non-LAD first and second order, LAD first order, and defect extent. LAD second order was 93% for EX compared with 88% (P = .015) for LEX. With regard to interobserver agreement, first and second order ranged from 73% to 89% and 64% to 85% for global, 73% to 93% and 69% to 91% for LAD, and 76% to 88% and 68% to 84% for non-LAD, respectively. Defect extent ranged from 61% to 82%. Global first and second order ranged from 85% to 87% and 78% to 82% for EX compared with 73% to 84% and 64% to 79% for LEX. LAD first and second order ranged from 89% to 91% and 88% to 89% for EX compared with 73% to 91% and 69% to 70% for LEX. Non-LAD first and second order ranged from 82% to 86% and 76% to 77% for EX compared with 76% to 86% and 68% to 81% for LEX. Defect extent ranged from 69% to 75% for EX compared with 59% to 77% for LEX. CONCLUSIONS: There is moderate to excellent interpretive reproducibility with stress Tc-99m sestamibi SPECT imaging among nuclear cardiologists with a wide range of training and experience.

Clinical value of acute rest technetium-99m tetrofosmin tomographic myocardial perfusion imaging in patients with acute chest pain and nondiagnostic electrocardiograms.

OBJECTIVES: We sought to evaluate the clinical use and cost-analysis of acute rest technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomographic (SPECT) myocardial perfusion imaging in patients with chest pain and a normal electrocardiogram (ECG). BACKGROUND: Current approaches used in emergency departments (EDs) for treating patients presenting with chest pain and a nondiagnostic ECG result in poor resource utilization. METHODS: Three hundred fifty-seven patients presenting to six centers with symptoms suggestive of myocardial ischemia and a nondiagnostic ECG underwent Tc-99m tetrofosmin SPECT during or within 6 h of symptoms. Follow-up evaluation was performed during the hospital period and 30 days after discharge. All entry ECGs, SPECT images and cardiac events were reviewed in blinded manner and were not available to the admitting physicians. RESULTS: By consensus interpretation, 204 images (57%) were normal, and 153 were abnormal (43%). Of 20 patients (6%) with an acute myocardial infarction (MI) during the hospital period, 18 had abnormal images (sensitivity 90%), whereas only 2 had normal images (negative predictive value 99%). Multiple logistic regression analysis demonstrated abnormal SPECT imaging to be the best predictor of MI and significantly better than clinical data. Using a normal SPECT image as a criterion not to admit patients would result in a 57% reduction in hospital admissions, with a mean cost savings per patient of $4,258. CONCLUSIONS: Abnormal rest Tc-99m tetrofosmin SPECT imaging accurately predicts acute MI in patients with symptoms and a nondiagnostic ECG, whereas a normal study is associated with a very low cardiac event rate. The use of acute rest SPECT imaging in the ED can substantially and safely reduce the number of unnecessary hospital admissions.

Impact of acute propranolol administration on dobutamine-induced myocardial ischemia as evaluated by myocardial perfusion imaging and echocardiography.

Beta-blocker therapy may delay or completely prevent myocardial ischemia during exercise testing, as assessed by ST-segment shifts, myocardial perfusion defects, or echocardiographic wall motion abnormalities. However, the impact of beta-blocker therapy on these end points during dobutamine stress testing has not been well established. The purpose of this study was to determine the impact of propranolol on dobutamine stress testing with ST-segment monitoring, technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) imaging, and echocardiography. In 17 patients with known reversible perfusion defects, dobutamine stress tests with and without propranolol were performed in randomized order and on separate days, following discontinuation of oral beta blockers and calcium antagonists. Propronolol was administered intravenously to a cumulative dose of 8 mg or to a maximum heart rate reduction of 25% and dobutamine was infused in graded doses in 3 minute stages until a standard clinical end point or the maximum dose of 40 microg/kg/min was achieved. The dobutamine stress test after propranolol was associated with a lower maximum heart rate (83 +/- 18 vs 125 +/- 17, p <0.001) and rate pressure product (14,169 +/- 4,248 vs 19,894 +/- 3,985, p <0.001) despite a higher infusion dose. The SPECT myocardial ischemia score was also lower (6.9 +/- 5.8 vs 10.1 +/- 7.1, p = 0.047) and fewer echocardiographic segments were abnormal (3.4 +/- 3.0 vs 4.6 +/- 3.4, p = 0.042). In 4 of 17 patients, reversible perfusion defects and echocardiographic wall motion abnormalities were detected during the control but not during the propranolol test. Thus, during dobutamine stress testing, beta-blocker therapy attenuates, and in some cases eliminates, evidence of myocardial ischemia.

Relation of gender to physician use of test results and to the prognostic value of stress technetium 99m sestamibi myocardial single-photon emission computed tomography scintigraphy.

We analyzed potential gender differences in the use and prognostic value of stress technetium 99m sestamibi tomography, image results, and cardiac event rates over a period of 15 +/- 8 months in 1226 men and 1151 women. Men had more abnormal tomographic images, but referral for catheterization and revascularization similarly increased in relation to the number of defects. Men and women with abnormal images had similar event rates, 19.6% and 18.2%, respectively, although men more often had myocardial infarction or cardiac death (7.6% vs 4.1 %, p < 0.05), whereas women had an increased likelihood of unstable angina or congestive heart failure (11.5% vs 7.6%, p < 0.05). Normal images predicted a low yearly rate of myocardial infarction or death: 1.7% for men and 0.8% for women. Image findings, particularly defect extent, were independent predictors of events in both groups. Thus, after stress Tc-99m sestamibi single-photon emission computed tomography perfusion imaging, there was no gender bias in referral for invasive procedures, and for both men and women image findings were strongly associated with prognostic outcome.

Prognostic importance of scintigraphic left ventricular cavity dilation during intravenous dipyridamole technetium-99m sestamibi myocardial tomographic imaging in predicting coronary events.

Left ventricular (LV) cavity dilation during stress myocardial perfusion imaging has been associated with multivessel disease, and may be an independent prognostic marker in addition to perfusion defects. The present study examines the predictive value for future cardiac events of transient or fixed LV dilation during dipyridamole technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) imaging. The study included 512 consecutive patients who underwent SPECT imaging with Tc-99m sestamibi after dipyridamole infusion. Transient LV dilation was seen in 70 patients (14%) and 74 had fixed cavity dilation (14%); cavity size was normal in 368 patients (72%). Each perfusion scan was classified as normal or abnormal, and if abnormal, defects were categorized as transient or fixed, and as small, medium, or large (depending upon the number of abnormal vascular territories). Events during a mean follow-up of 12.8 +/- 6.8 months were tabulated by direct review of hospital charts and death certificates. The cardiac event rate (cardiac death or nonfatal infarction) was 1.9% in patients with normal cavity size, 11.4% with transient LV dilation, and 13.5% with fixed LV dilation (p < 0.01). Compared with patients with normal cavity size, those with transient LV dilation were more likely to sustain a myocardial infarction (p < 0.01) and those with fixed dilation more frequently suffered cardiac death (p < 0.01) and hospitalization for heart failure (p < 0.01). The group with the highest risk had both a large perfusion defect and cavity dilation. By Cox proportional hazard regression analysis, both transient and fixed LV dilation were strong independent predictors of cardiac events. Transient or fixed LV dilation are commonly seen during dipyridamole Tc-99m sestamibi SPECT imaging (14% incidence for each) and are useful predictors of cardiac events.

Relation between perfusion defects on stress technetium-99m sestamibi SPECT scintigraphy and the location of a subsequent acute myocardial infarction.

Although the presence of perfusion defects on stress myocardial perfusion imaging has been shown to correlate with future cardiac events, including acute myocardial infarction (AMI), it is unknown whether the location of the AMI can be predicted. Therefore, for 25 patients who had an AMI following a stress technetium-99m sestamibi single-photon emission computed tomographic (SPECT) imaging study and whose infarct location could be determined, the territory of infarction was correlated with the location of previous myocardial perfusion defects. A SPECT perfusion defect had been present in 24 patients (96%). The AMI occurred in territories that showed a reversible defect in 14 patients (56%), whereas 3 infarctions (12%) were in territories that revealed a fixed defect, and 8 infarctions (32%) were in territories that had not shown a defect on prior SPECT imaging. Whereas the incidence of infarction in territories with a reversible defect was highest at 14 of 26 (54%), the incidence of infarction in territories with a fixed defect was 3 of 7 (43%), and in territories with no defect was 8 of 42 (19%) (p = 0.011). Neither the time interval between SPECT imaging and infarction, nor the perfusion defect severity, was related to the correlation between perfusion defect and infarct location. Thus, although AMI occurs most often at the site of previous perfusion defects, reversible or fixed, a substantial percentage occur in territories without a perfusion defect. These findings suggest that abnormalities on SPECT perfusion imaging, although they serve as markers of significant coronary disease and increase the likelihood of infarction, do not always predict the exact location of infarction.

Effectiveness of nuclear cardiology training guidelines: a comparison of trainees with experienced readers.

BACKGROUND: To evaluate the effectiveness of published nuclear cardiology training guidelines, the diagnostic accuracy of image interpretation by nuclear cardiology trainees was compared with that of experienced nuclear cardiologists. METHODS AND RESULTS: The accuracy of three experienced nuclear cardiologists and three trainees with level II experience following Society of Nuclear Medicine/American College of Cardiology/American Society of Nuclear Cardiology guidelines in the interpretation of 114 exercise 99mTc-labeled sestamibi single-photon emission computed tomographic imaging studies was evaluated. Studies were selected randomly and included patients with less than 5% likelihood of coronary artery disease, as well as patients with angiographically demonstrated single and multivessel disease. Studies were interpreted by each reader without knowledge of clinical or exercise data. Each reader classified perfusion as normal or abnormal. Accuracy was assessed according to sensitivity, normalcy rate, and predictive accuracy. In addition, the ability of experienced readers and trainees to identify abnormal perfusion in patients with multivessel disease was compared. Trainees had high accuracy, comparable to experienced readers for sensitivity, normalcy rate, and predictive accuracy, as well as the ability to identify abnormal perfusion in patients with multivessel disease. In all categories, experienced interpretors demonstrated a trend toward greater accuracy with less observer variability than did trainees. CONCLUSION: Structured training in nuclear cardiology following Society of Nuclear Medicine/American College of Cardiology/American Society of Nuclear Cardiology guidelines during clinical cardiology fellowship is effective, and trainees possess the skills to interpret myocardial perfusion images accurately. Interpretive skills can be expected to improve further with experience.

Independent prognostic value of intravenous dipyridamole with technetium-99m sestamibi tomographic imaging in predicting cardiac events and cardiac-related hospital admissions.

OBJECTIVES: This study sought to establish the prognostic value of intravenous dipyridamole technetium-99m (Tc-99m) sestamibi single-photon emission computed tomographic (SPECT) myocardial perfusion imaging. BACKGROUND: Optimal management of patients with coronary artery disease involves strategies designed to reduce the risk of myocardial infarction and cardiac death. The role of myocardial perfusion imaging using newer clinical techniques to determine risk and possible benefit from therapy has not been evaluated. METHODS: Myocardial imaging results were classified as normal or abnormal (fixed or reversible defects; small, moderate or large). Follow-up evaluation of all patients included the occurrence of cardiac death or nonfatal myocardial infarction and other cardiac-related hospital admissions. RESULTS: During a mean (+/- SD) follow-up period of 12.8 +/- 6.8 months in 512 patients, 25 had a cardiac event. Patients with abnormal perfusion had significantly more cardiac events than those with normal perfusion (22 vs. 3, p < 0.01). Patients with reversible defects had the highest event rates (8.6%), and those with normal study results had a very low event rate (1.4%). Large defects were strongly associated with more cardiac events and hospital admissions than either normal scan results or abnormal results showing small defects. CONCLUSIONS: Patients with normal study results or a small defect after intravenous dipyridamole Tc-99m sestamibi SPECT imaging had an excellent short-term prognosis. Those with abnormal results (reversible or large defect) had an increased risk of subsequent cardiac death, nonfatal myocardial infarction and other cardiac-related hospital admissions.

Comparison of dobutamine and exercise using technetium-99m sestamibi imaging for the evaluation of coronary artery disease.

Studies using dobutamine thallium-201 myocardial perfusion imaging have suggested a high sensitivity and specificity for the detection of coronary artery disease. However, few data are available comparing dobutamine with exercise stress for the detection and localization of perfusion defects. This study compared the effects of dobutamine and exercise stress using technetium-99m sestamibi single-photon emission computed tomographic imaging in the same patients in a prospective crossover trial. Twenty-four patients with a high likelihood of coronary artery disease underwent tomographic myocardial imaging at rest, after symptom-limited treadmill exercise, and after intravenous dobutamine (maximum 30 micrograms/kg/min). Tomograms of the left ventricle were divided into 20 segments and were interpreted without knowledge of patient identity or stress protocol. Dobutamine was well tolerated by all patients. Segment-by-segment concordance between exercise and dobutamine images was highly significant (kappa = 0.56, p < 0.0001). Global first-order agreement (normal vs abnormal) between exercise and dobutamine studies was 96% (kappa = 0.65, p = 0.02); global second-order agreement (normal vs fixed vs ischemic defect) was 88% (kappa = 0.45, p = 0.02). Regional first- and second-order agreement were 96 and 93%, respectively (p < 0.001 for both). Twenty patients underwent coronary angiography. Comparisons between exercise and angiography and between dobutamine and angiography were similar for both global agreement (95 vs 100%, p = NS) and regional agreement (77 vs 72%, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of exercise, dipyridamole, and adenosine by use of technetium 99m sestamibi tomographic imaging.

BACKGROUND: Pharmacologic stress has been shown in animal studies to induce high degrees of myocardial hyperemia. At these levels of myocardial blood flow, the myocardial uptake of technetium 99m sestamibi may plateau and may affect the diagnostic accuracy. This study compared the effects of myocardial hyperemia induced by exercise, dipyridamole, and adenosine on 99mTc sestamibi tomographic imaging in normal subjects and patients with ischemic coronary artery disease. METHODS AND RESULTS: Twenty subjects (group I, 10 normal subjects; group II, 10 patients with known coronary artery disease) underwent 99mTc sestamibi tomographic imaging after rest, exercise, dipyridamole infusion, and adenosine infusions on separate occasions. Total and background-corrected myocardial counts of the resulting images were calculated. Visual and computer-generated quantitative myocardial perfusion defect analysis was performed in subjects in group II. For subjects in both groups I and II, there were no significant differences in the background-corrected myocardial counts obtained with exercise, dipyridamole, and adenosine stress. There were no significant differences in the myocardial perfusion defects obtained after the three different modes of stress, including percentage defect size, stress deficit percentage, percentage of ischemia, count deficit index, and defect nadir. CONCLUSIONS: The myocardial uptake of 99mTc sestamibi in normal subjects and patients with coronary artery disease is comparable after exercise, dipyridamole, and adenosine stress. In addition, the defect sizes and intensities with 99mTc sestamibi after all forms of stress were equivalent. Thus 99mTc sestamibi, in combination with either adenosine or dipyridamole infusions, provides imaging data equivalent to those with exercise and may be considered an alternative in patients unable to undergo adequate exercise.

Postnephrectomy pseudoaneurysm with arteriovenous fistula.

Sonography detected a paraaortic pulsatile tubular mass in a patient 10 years after "stump" nephrectomy, which was subsequently confirmed as a renal artery-renal vein fistula by computed tomography, angiography, and laparotomy.

The role of magnetic resonance imaging in giant cell tumor of bone.

In six cases of giant cell tumor the magnetic resonance (MR) images obtained with various pulse sequences and field strengths were compared to the corresponding computed tomography (CT) scans and plain roentgenograms. MRI was superior to CT and plain films in demonstrating areas of tissue inhomogeneity within the tumor as well as soft tissue extension. CT was superior in demonstrating cortical thinning. Multiplanar imaging capability and visualization of articular cartilage may demonstrate intra-articular tumor spread. The characteristic MRI findings with short TR/TE (T1-weighting) and long TR/TE (T2-weighting) are described. We also describe one case where serial MR scans were used to assess response to therapy.

Magnetic resonance imaging of papillary renal cell carcinoma.

The authors report magnetic resonance (MR) studies in a case of papillary renal cell carcinoma. The preoperative ultrasound and computed tomographic scans suggested either a hemorrhagic cyst or a carcinoma, but the angiogram demonstrated avascularity. The magnetic resonance scan was more consistent with carcinoma than complicated cyst. We report the MR findings with pathologic correlation.

Systemic hypertension associated with coronary artery bypass surgery. Predisposing factors, hemodynamic characteristics, humoral profile, and treatment.

Systemic hypertension occurs in more than one third of patients having coronary artery bypass graft (CABG) operations. This report describes our studies in 100 consecutive patients undergoing CABG. We found that certain preoperative clinical, angiographic, and biochemical factors predispose to the development of perioperative hypertension. These included a well-documented history of hypertension, an elevated blood pressure the day prior to operation, greater than 50 percent obstruction of the left main coronary artery, and increased levels of dopamine beta hydroxylase (DBH). The hemodynamic pattern of perioperative hypertension was that of an increased systemic vascular resistance which was associated with increased levels of plasma catecholamines and plasma renin activity (PRA). Nitroprusside was shown to be effective in managing CABG hypertension, although other, more specific therapy may be preferable.

Physiologic observations of the heart six months after ischemic normothermic cardioplegia.

The late effects of normothermic ischemic cardioplegia were studied in four experimental groups of dogs subjected to intervals of aortic cross-clamping during cardiopulmonary bypass. Groups which had zero, 20, 30, or 40 minutes of aortic cross-clamping, respectively, were studied 6 months later for cardiac performance and morphology. The immediate operative mortality rate of animals subjected to 40 minutes of ischemia was 65 percent, compared to 22 percent in controls. There were no late deaths in any group Compliance, histology, biochemical determination of deoxyribonucleic acid: ribonucleic acid, and Vmax determinations after cross-clamping revealed no differences between the experimental groups. Open chest isovolumetric contraction curves showed decreased experimental groups. Open chest isovolumetric contraction curves showed decreased function in the 40 minute ischemia group at the extreme levels of cardiac stress. These results suggest that under the conditions of this study normothermic cardiac ischemia of greater than 30 minutes in duration results in a high initial mortality rate (65 percent) and leads to compromise of cardiac function under stress in the late postoperative period.