Multiple Perfusion Defects Research Articles

Pulmonary embolism and cerebral venous thrombosis after thoracoscopic surgery for benign pulmonary disease

A-76-year-old woman consulted for open biopsy for a pulmonary mass. Thoracoscopic wedge resection was performed. The lesion was histologically diagnosed as nonspecific inflammation. On the first postoperative day (POD1), the patient lost consciousness transiently. Eleven hours after the first stroke, the patient experienced a second stroke together with hypoxia. Pulmonary perfusion scan on POD2 showed multiple perfusion defects, and the patient was diagnosed with pulmonary embolism (PE). Thrombolitic therapy was started. Neurological symptoms didn't improve, and cerebral angiography on POD3 showed delayed perfusion in superficial veins. The patient was diagnosed with cerebral venous thrombosis (CVT). Thrombolytic and anticoagulant therapy had been continued, and the patient was found to have hemorrhagic cerebral infarction on POD11. After persistent therapy, the patient was discharged on POD120. Although both PE and CVT are rare complications after thoracic surgery, we must consider these complications in patients undergoing thoracic operations including thoracoscopic surgery.

Development of Pulmonary Hypertension in Adults after Ventriculoatrial Shunt Implantation

Background: The insertion of ventriculoatrial (VA) shunts for the treatment of hydrocephalus is thought to be associated with the development of pulmonary hypertension in adults. Objectives: It was the aim of this study to describe the frequency and the clinical spectrum of pulmonary hypertension in adults with VA shunts. Methods: Patients with pulmonary hypertension were retrospectively evaluated from January 1999 to December 2006. Results: Among the 575 patients with pulmonary hypertension, 6 (mean age 42.5 ± 8.3 years) were identified as having received a VA shunt. Mean pulmonary artery pressure for these patients was 53.3 ± 14.9 mm Hg. The interval between shunt placement and the diagnosis of pulmonary hypertension was 9–27 years (median 16.5). While ventilation perfusion scans showed multiple bilateral perfusion defects in all patients, chest CT or pulmonary angiography demonstrated pulmonary thromboembolism in only 2 of the 6 patients. These 2 patients subsequently underwent pulmonary endarterectomy. Another patient required heart-lung transplantation because of severe pulmonary hypertension; lung histology showed prominent eccentric medial hypertrophy and intimal proliferation without evidence of thromboembolism. Contrary to earlier reports, outcomes were generally good, with a 100% survival rate for the first 8 years following diagnosis. Conclusions: Severe pulmonary hypertension can develop in adult patients with VA shunts. Therefore, clinicians should consider pulmonary hypertension as a potential cause for respiratory symptoms in patients who have received VA shunts.

Identifying the Vulnerable Patient with Rupture-Prone Plaque

Atherosclerotic cardiovascular disease is the leading cause of morbidity and mortality in the United States, and the obesity epidemic combined with aging of the population seems destined to increase the burden of this disease. Traditional cardiovascular risk assessment accounts for <50% of the variability in risk in the United States. Therefore, better and more effective identification of persons at high cardiovascular risk is needed. Our understanding of atherosclerosis has shifted from a focal disease whose hallmark is symptoms caused by a severe stenosis to a systemic disease characterized by endothelial dysfunction (ED) and plaque inflammation, with the potential for rupture and thrombosis mainly in those with subcritical stenosis. Under the new paradigm, clinicians require updated strategies to better assess the quality of arterial plaque. Effective tools for primary and secondary prevention of heart attack and stroke include intensive lifestyle modification, blood pressure reduction, and lipid-modifying therapies. These interventions are now understood to decrease plaque inflammation and thereby promote plaque stability. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) appears to be a specific marker of plaque inflammation that may play a direct role in the formation of rupture-prone plaque. In contrast, traditional risk factors, lipid measurement, and most vascular imaging modalities do not directly assess the acute ischemic potential in the arterial wall. Measuring Lp-PLA(2) levels in human serum or plasma is noninvasive and relatively inexpensive. Lp-PLA(2) may provide additional clinically relevant information that shows which patients have a high level of atherosclerotic disease activity as manifested by vascular inflammation, ED, and increased risk for progression toward rupture-prone plaque.

Reversible renal vasoconstriction in a patient with acute renal failure after exercise

Acute renal failure (ARF) with severe loin pain induced by anaerobic exercise is a rare condition that is accompanied by wedge-shaped contrast enhancement seen on computerized tomographic (CT) scan without evidence of rhabdomyolysis. An 18-year-old Korean male was transferred to our hospital for evaluation of mild azotemia, that developed after anaerobic exercise. The laboratory tests revealed that the serum creatinine was 2.1 mg/dl and the serum uric acid level was 1.6 mg/dl without any elevation of the serum myoglobin or creatine phosphokinase. Under the impression of exercise-induced ARF, we tried to determine the relationship between the occurrence of clinical symptoms, renal dysfunction and the characteristic CT findings by observing those changes prospectively before and after anaerobic exercise. After obtaining a written consent, the patient underwent a strenuous period of anaerobic exercise to induce the clinical symptoms. Before exercise, he was completely asymptomatic; his serum creatinine level was 0.9 mg/dl and CT scan of the kidneys showed no abnormalities. Loin pain developed 2 hours after exercise, and the serum creatinine level increased to 1.2 mg/dl 18 hours after the exercise. CT scan 18 hours after exercise showed multiple perfusion defects, and a 24-hour delayed CT scan showed multiple areas of wedge-shaped enhancement on both kidneys. These changes were completely resolved on the follow-up CT scan obtained 13 days after exercise with the return of a normal serum creatinine level. We conclude that reversible renal vasoconstriction is probably the main pathophysiologic mechanism of acute renal failure induced by anaerobic exercise.

Frequency and severity of myocardial perfusion abnormalities using Tc-99m MIBI SPECT in cardiac syndrome X

BackgroundCardiac syndrome X is defined by a typical angina pectoris with normal or near normal (stenosis <40%) coronary angiogram with or without electrocardiogram (ECG) change or atypical angina pectoris with normal or near normal coronary angiogram plus a positive none-invasive test (exercise tolerance test or myocardial perfusion scan) with or without ECG change. Studies with myocardial perfusion imaging on this syndrome have indicated some abnormal perfusion scan. We evaluated the role of myocardial perfusion imaging (MPI) and also the severity and extent of perfusion abnormality using Tc-99m MIBI Single Photon Emission Computed Tomography (SPECT) in these patients.MethodsThe study group consisted of 36 patients with cardiac syndrome X. The semiquantitative perfusion analysis was performed using exercise Tc-99m MIBI SPECT. The MPI results were analyzed by the number, location and severity of perfusion defects.ResultsAbnormal perfusion defects were detected in 13 (36.10%) cases, while the remaining 23 (63.90%) had normal cardiac imaging. Five of 13 (38.4%) abnormal studies showed multiple perfusion defects. The defects were localized in the apex in 3, apical segments in 4, midventricular segments in 12 and basal segments in 6 cases. Fourteen (56%) of all abnormal segments revealed mild, 7(28%) moderate and 4 (16%) severe reduction of tracer uptake. No fixed defects were identified. The vessel territories were approximately the same in all subjects. The Exercise treadmill test (ETT) was positive in 25(69%) and negative in 11(30%) patients. There was no consistent pattern as related to the extent of MPI defects or exercise test results.ConclusionOur study suggests that multiple perfusion abnormalities with different levels of severity are common in cardiac syndrome X, with more than 30 % of these patients having at least one abnormal perfusion segment. Our findings suggest that in these patients microvascular angina is probably more common than is generally believed.

Noninvasive detection of coronary allograft vasculopathy by myocardial contrast echocardiography

Noninvasive detection of coronary allograft vasculopathy is still challenging. To determine the accuracy of myocardial contrast echocardiography (MCE) in detecting coronary allograft vasculopathy after heart transplantation, we studied 35 asymptomatic patients (30 men, aged 46 +/- 12.7 years) with normal left ventricular function. Patients underwent MCE with continuous contrast (perfluorocarbon-exposed sonicated dextrose albumin) administration. Images were obtained at baseline and during peak dobutamine (up to 40 mg/kg/min) with intermittent harmonic imaging. Areas failing to increase contrast enhancement during peak stress were regarded as abnormal. Coronary artery obstructions greater than 50% at angiography were considered significant. Seven out of 10 patients with coronary artery disease had a positive MCE and one patient with a positive MCE had no angiographically detected disease (sensitivity = 70%, specificity = 96%, accuracy = 88.6%). Agreement between the vascular territory and perfusion defects was good for the left anterior descending coronary artery (kappa = 0.56), but not for other arteries. Although 5 patients had multivessel disease, multiple perfusion defects were detected in only one patient. MCE showed good accuracy in detecting the presence of coronary allograft vasculopathy after heart transplantation; however, it failed to identify the extent of the disease.

Paget-Schroetter Syndrome and Pulmonary Thromboembolism: Clinical Follow-up Over 5 years

A scaffold constructor lost consciousness at work, leading to emergency admission to our hospital. He had noted gradual worsening of exertional dyspnea over the previous 1 month. Chest radiography showed localized oligemia and enlarged hilar vessels. Pulmonary perfusion scintigraphy confirmed the existence of multiple perfusion defects, so a diagnosis of pulmonary thromboembolism was made. Upper and lower limb venography disclosed interruption of the right subclavian vein (so-called Paget-Schroetter syndrome). However, there was no difference in appearance between the right and left upper extremities. Five years after starting anticoagulant therapy, his symptoms have resolved, but serial perfusion scintigraphy and upper extremity venography revealed the persistence of abnormalities. In patients with pulmonary thromboembolism, lifestyle factors (especially heavy manual labor) should be considered and the possibility of subclavian vein thrombosis should be kept in mind.

Prognostic value of quantitative stress myocardial perfusion imaging in unstable angina patients with negative cardiac enzymes and no new ischemic ECG changes

Limited data are available on the value of quantitative stress myocardial perfusion imaging (MPI) in patients with unstable angina. In this report we sought to study the long-term prognostic value of quantitative stress MPI in patients hospitalized with unstable angina with no new ischemic electrocardiographic changes and negative cardiac enzymes. The study population consisted of 136 patients who were hospitalized at the Methodist Hospital, Houston, Tex, with unstable angina and subsequently underwent MPI before discharge. Cox proportional hazards (regression) analysis was performed to identify clinical and MPI predictors of hard cardiac events (death or nonfatal myocardial infarction). During a mean follow-up of 31 +/- 17 months, 20 patients (15%) sustained either cardiac death (n = 12) or nonfatal myocardial infarction (n = 8). The significant multivariate predictors of cardiac events were the total perfusion defect size ( P = .002), the presence of reversible perfusion defects ( P = .01), and the presence of multiple perfusion defects ( P = .03). The perfusion defect size was significantly larger in patients with events than in those without events (21% +/- 20% vs 12% +/- 14%, P = .002). Kaplan-Meier analysis showed that cardiac events were much more likely to develop in patients with defects involving 15% or more of the left ventricle than in those with defects involving less than 15% of the left ventricle ( P = .003). In patients hospitalized with unstable angina with no new ischemic electrocardiographic changes and negative cardiac enzymes, quantitative stress MPI provides powerful prognostic information that can be used in the risk stratification of these patients.

Descriptive patterns of severe chronic pulmonary hypertension by chest radiography

To find chest roentgenographic (CXR) features to help differentiate two representative diseases with severe chronic pulmonary hypertension (PH). Thirty-six consecutive patients with chronic thromboembolic PH (CTEPH), 38 with primary PH (PPH), and 37 with left heart disease and PH. CXRs were reviewed about 6 features (left 2nd arc protrusion, right descending pulmonary artery diameter (rPAD), cardiothoracic ratio (CTR), right 2nd arc width, avascular area and pleural abnormality). Hemodynamic data and the degree of tricuspid regurgitation (TR) on echocardiography were compared with CXR findings. The diagnostic pattern of CTEPH was the presence of one of two findings, an avascular area or marked rPAD (>20mm) together with pleuritic change. The diagnostic pattern of PPH was one of the two features; without pleuritic abnormality, marked left 2nd arc protrusion (>10mm) or moderate left 2nd arc protrusion (5-10mm) with marked rPAD (<20mm). The sensitivity for the diagnosis of CTEPH among the three diseases was 78% and specificity was 92%. The sensitivity for the diagnosis of PPH was 45% and specificity was 88%. CTR and right 2nd arc width were related to the degree of TR in CTEPH and PPH. Characteristic roentgenographic findings can help differentiate two frequent diseases associated with chronic pulmonary hypertension and reflect the severity of disease.

Analysis of referral patterns, predictive accuracy, and impact on patient management of myocardial perfusion imaging in a new nuclear cardiology laboratory

Background. Most of the published data on myocardial perfusion imaging (MPI) come from large tertiary-referral medical centers with extensive experience in cardiac imaging as well as a large volume of procedures. Whether the results of MPI remain as reliable in new nuclear cardiology laboratories with smaller volumes of procedures is unknown. The purpose of this study was to analyze the referral patterns, predictive accuracy, and impact of MPI on clinical practice in a newly opened nuclear cardiology laboratory. Methods and Results. We performed a prospective study on all patients referred for MPI at our nuclear cardiology laboratory during its first year of operation. Patients were followed up for 3 months after the MPI study to determine whether they underwent coronary angiography. The study population consisted of 334 patients. Their mean age was 56 ± 10 years, and 80% were men. Of the patients, 30% were asymptomatic, 29% had angina, and only 6% had recent acute myocardial infarction or unstable angina. Fifty-one patients (fifteen percent) were subsequently referred for coronary angiography. The positive and negative predictive values of MPI were 91% and 86%, respectively. The presence of reversible perfusion defects ( P = .02) and the presence of multiple perfusion defects ( P = .01) on MPI were the most important determinants of subsequent referral to coronary angiography. Conclusions. MPI stress testing retains its high diagnostic accuracy in a new nuclear cardiology laboratory with a relatively small volume of procedures. Furthermore, MPI findings in this population had a strong impact on the clinical practice of the referring physicians in terms of subsequent referral to coronary angiography. (J Nucl Cardiol 2003;10:148-53)

Pulmonary Takayasu’s Arteritis Masquerading as Acute Pulmonary Embolism

Pulmonary involvement may sometimes be the initial presentation of Takayasu's arteritis (TA). Since the signs and symptoms of pulmonary TA may be subtle and may not be easily distinguishable from other pulmonary diseases, one has to maintain a high index of suspicion. Cases of pulmonary TA mimicking chronic thromboembolism have been reported. We describe a patient with TA whose initial presentation mimicked acute pulmonary embolism. The patient presented with a 3-day history of cough and shortness of breath and had multiple bilateral perfusion defects on ventilation-perfusion scan, typical of acute pulmonary embolism. However, the constellation of clinical features, elevated erythrocyte sedimentation rate and the angiographic appearance helped us establish the correct diagnosis of pulmonary Takayasu's arteritis. At a 6-year follow-up, the patient had no worsening of pulmonary symptoms but presented with postural dizziness with angiographic evidence of carotid and innominate artery stenosis; she underwent arterial bypass grafting. In young women presenting with a clinical picture of acute pulmonary embolism without the previous history (or risk factors) of thromboembolism, pulmonary TA must be considered in the differential diagnosis.

Dobutamine-atropine stress echocardiography and dipyridamole sestamibi scintigraphy for the detection of coronary artery disease: limitations and concordance

OBJECTIVESWe sought to compare dobutamine-atropine stress echocardiography (DASE) and dipyridamole Technetium 99-m (Tc-99m) sestamibi single photon emission computed tomography (SPECT) scintigraphy (DMIBI) for detecting coronary artery disease (CAD).BACKGROUNDBoth DASE and DMIBI are effective for evaluating patients for CAD, but their concordance and limitations have not been directly compared.METHODSTo investigate these aims, patients underwent multistage DASE, DMIBI and coronary angiography within three months. Dobutamine-atropine stress echocardiography and stress-rest DMIBI were performed according to standard techniques and analyzed for their accuracy in predicting the extent of CAD. Segments were assigned to vascular territories according to standard models. Angiography was performed using the Judkin’s technique.RESULTSThe 183 patients (mean age: 60 ± 11 years, including 50 women) consisted of 64 patients with no coronary disease and 61 with single-, 40 with two- and 18 with three-vessel coronary disease. Dobutamine-atropine stress echocardiography and DMIBI were similarly sensitive (87%, 104/119 and 80%, 95/119, respectively) for the detection of CAD, but DASE was more specific (91%, 58/64 vs. 73%, 47/64, p < 0.01). Sensitivity was similar for the detection of CAD in patients with single-vessel disease (84%, 51/61 vs. 74%, 45/61, respectively) and multivessel disease (91%, 53/58 vs. 86%, 50/58, respectively). Multiple wall motion abnormalities and perfusion defects were similarly sensitive for multivessel disease (72%, 42/58 vs. 66%, 38/53, respectively), but, again, DASE was more specific than DMIBI (95%, 119/125 vs. 76%, 95/125, respectively, p < 0.01). Dobutamine-atropine stress echocardiography and DMIBI were moderately concordant for the detection and extent of CAD (Kappa 0.47, p < 0.0001) but were only fairly (Kappa 0.35, p < 0.001) concordant for the type of abnormalities (normal, fixed, ischemia or mixed).CONCLUSIONSDobutamine-atropine stress echocardiography and DMIBI were comparable tests for the detection of CAD. Both were very sensitive for the detection of CAD and moderately sensitive for the extent of disease. The only advantage of DASE was greater specificity, especially for multivessel disease. Dobutamine-atropine stress echocardiography may be advantageous in patients with lower probabilities of CAD.

Case of Pulmonary Embolism

A65-year-old man was admitted with a pulmonary embolism. He complained of progressive exertional dyspnea followed by thrombophlebitis of his left lower limb for several weeks before admission. Venography showed multiple thrombi in the varicose left small saphenous vein. A pulmonary perfusion scintigram revealed multiple perfusion defects in both lungs; the ventilation scintigram was normal. The patient was placed on heparin 20 000 …

A Case of Pulmonary Thromboembolism due to Congenital Antithrombin III Deficiency

We report a case of congenital and familial antithrombin III deficiency developing massive pulmonary thromboembolism. A 44-year-old man was admitted to our hospital because of sudden chest pain and severe dyspnea. Five years ago, he was operated due to a mesenteric vein thrombosis of unknown cause. On admission, radioisotopic venogram showed deep vein thrombosis and lung scintigram showed multiple segmental perfusion defects. His plasma antithrombin III level was 10.5 mg/dL which was less than 50% of normal and those of a son and two daughters were also decreased. After treatment with tissue plasminogen activator, heparin and coumadin, his symptom and lung scintigram were significantly improved. As far as we reviewed, there were very rare reports with congenital antithrombin III deficiency presenting as pulmonary thromboembolism in Korea.

A Case of Acute Respiratory Distress Syndrome with Pulmonary Embolism induced by Injection of Silicone at Vaginal Wall

Silicone fluid(polydimethylsiloxane) is widely used in breast augmentation and other cosmetic procedures because of little incidence of complications and low mortality rate. However, local reaction following silicone injections can be occurred sometimes leading to serious complications. Especially, illicit silicone injections have resulted in severe reactions within the pulmonary area, and some have resulted in acute respiratory distress syndrome subsequently. We experienced a case of acute respiratory distress syndrome induced by subcutaneous injections of silicone at vaginal wall. The patients was 39-year-old, previously healthy woman who had complained of dyspnea related to silicone injection at vaginal wall. Chest X-ray and chest CT scan show diffuse air consolidation with ground glass opacities and perfusion lung scan revealed likelihood of pulmonary embolism as showing multiple perfusion defects. We report a case of acute respiratory distress syndrome occured after silicone injection with review of literature.

Pulmonary Manifestations of Fat Embolism on Thin-section CT: A Case Report

We report thin-section Ct findings of pulmonary fat embolism confirmend by dlincal features and microscopic examination of cells obtained by bronchoalveolar lavage. Initial thin-section CT showed extensive air space consolidation and multiple ill-defined nodular densities in both lungs. A perfusion scan showed multiple small perfusion defects in the peripheral portion of both lungs.

Postpulmonary Embolism Pericarditis: A Case Report and Review of the Literature

Pericarditis developing as a sequela of pulmonary embolism has been rarely described. A 44‐year‐old male presented with acute dyspnea and pleuritic pain; V/Q scan showed multiple perfusion defects, and he was treated with heparin. Three days later retrosternal pain was accompanied by a pericardial friction rub. There was a rapid response to systemic corticosteroid therapy; anticoagulation was continued. Steroids were discontinued after four weeks, and anticoagulation (warfarin) was continued. Two months later he presented with clinical features of pulmonary embolus and new perfusion defects on scan. He was treated with heparin and warfarin; three weeks later clinical features of pericarditis recurred, and he was again treated successfully with four weeks′ oral prednisone. Three months later pericarditis recurred without signs of pulmonary embolism; computed tomography scan showed thickening of the pericardium. The patient was asymptomatic for five months on indomethacin. A literature search showed 11 cases of pericarditis associated with emboli, all responding promptly to steroids. Continuation of anticoagulation does not appear to increase the risk (or magnitude) of hemorrhagic pericardial effusion.

Invasive and Noninvasive Diagnosis of Pulmonary Embolism: Preliminary Results of the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA-PED)

It is maintained that pulmonary angiography is required for confirmation or exclusion of pulmonary embolism in the majority of patients suspected of having pulmonary embolism. The aim of this study was to reappraise the role of perfusion scan in conjunction with clinical assessment in the diagnosis of pulmonary embolism and to identify subsets of patients in whom angiography is strictly required for definitive diagnosis. At the time of referral, each of 252 consecutive patients was assigned a clinical probability of pulmonary embolism (very likely, possible, unlikely). Perfusion scan was subsequently obtained and assigned to one of the following categories: (1) normal; (2) near normal; (3) single or multiple wedge-shaped perfusion defects compatible with pulmonary embolism (PE+); (4) perfusion defects other than wedge-shaped not compatible with pulmonary embolism (PE–). By protocol, angiography had to be obtained in all patients with abnormal scan (PE+ and PE–). The protocol was completed in 176 patients (107 with normal/near normal and 69 with abnormal scan in whom a definitive diagnosis was reached). The overall rate of correct clinical classification was 86%. Sensitivity and specificity of PE+ perfusion scan were 89 and 92%, respectively. Pulmonary embolism was present in all 37 patients with very likely or possible clinical presentation and PE+ scan (positive predictive value 100%) and in 2 of 17 cases with low likelihood of pulmonary embolism and PE– scan (negative predictive value of 88%). These preliminary results indicate that pulmonary embolism can be diagnosed noninvasively in the majority of cases and that angiography is strictly required only for a minority of patients (21% in this study) in whom clinical and perfusion scan assessment are discordant. It is maintained that pulmonary angiography is required for confirmation or exclusion of pulmonary embolism in the majority of patients suspected of having pulmonary embolism. The aim of this study was to reappraise the role of perfusion scan in conjunction with clinical assessment in the diagnosis of pulmonary embolism and to identify subsets of patients in whom angiography is strictly required for definitive diagnosis. At the time of referral, each of 252 consecutive patients was assigned a clinical probability of pulmonary embolism (very likely, possible, unlikely). Perfusion scan was subsequently obtained and assigned to one of the following categories: (1) normal; (2) near normal; (3) single or multiple wedge-shaped perfusion defects compatible with pulmonary embolism (PE+); (4) perfusion defects other than wedge-shaped not compatible with pulmonary embolism (PE–). By protocol, angiography had to be obtained in all patients with abnormal scan (PE+ and PE–). The protocol was completed in 176 patients (107 with normal/near normal and 69 with abnormal scan in whom a definitive diagnosis was reached). The overall rate of correct clinical classification was 86%. Sensitivity and specificity of PE+ perfusion scan were 89 and 92%, respectively. Pulmonary embolism was present in all 37 patients with very likely or possible clinical presentation and PE+ scan (positive predictive value 100%) and in 2 of 17 cases with low likelihood of pulmonary embolism and PE– scan (negative predictive value of 88%). These preliminary results indicate that pulmonary embolism can be diagnosed noninvasively in the majority of cases and that angiography is strictly required only for a minority of patients (21% in this study) in whom clinical and perfusion scan assessment are discordant.

Posterior ischemia during an attack of transient global amnesia.

The popular concept that cerebral ischemia causes transient global amnesia has been difficult to prove by cerebral blood flow studies during attacks because the transient global amnesia attacks are so short. We performed single-photon emission computed tomography (SPECT) of the brain and neuropsychological assessment in a 37-year-old woman during a 10-hour attack and twice thereafter. A neuropsychological evaluation 3 hours after the onset of transient global amnesia revealed severe impairment of recent memory and verbal fluency, both of which returned to normal 2 and 28 days later, respectively. A 99mTc-labeled hexamethylpropyleneamine oxime SPECT of the brain performed 6 hours after the onset showed multiple perfusion defects in both occipital lobes, the medial left temporal lobe, and the left thalamus. A second brain SPECT performed 3 days later showed perfusion defects in only the occipital regions. A third brain SPECT performed 28 days later was normal. The patient's brain computed tomographic scan, electroencephalogram, duplex ultrasound of the carotid artery, and echocardiogram were normal. The perfusion defects revealed by the brain SPECT during the transient global amnesia attack indicated ischemia in the territory of the posterior cerebral arteries, which partially resolved in 3 days and completely resolved by 28 days.

Is dipyridamole-thallium imaging preferable to submaximal exercise thallium testing for risk stratification after thrombolysis?

We describe a patient who underwent thrombolysis for acute inferior wall myocardial infarction with only a small ischemic area on the submaximal exercise thallium test but multiple severe perfusion defects on dipyridamole-thallium imaging