The dobutamine stress test with thallium-201 single-photon emission computed tomography and radionuclide angiography: postinfarction study

OBJECTIVES: The purpose of this study was to investigate left ventricular wall motion changes during dobutamine-induced myocardial ischemia. BACKGROUND: Dobutamine is increasingly used as a stress test. It has been assumed that high doses of the drug induce the same changes in contractility as physical exercise. However, some data suggest that ischemic myocardium can respond to dobutamine with an increase in contractility. METHODS: Sixty-three postinfarction patients twice underwent the dobutamine test (up to 40 micrograms/kg per min) within 1 to 2 days. Thallium-201 single-photon emission computed tomography (SPECT) and gated equilibrium radionuclide ventriculography were performed on each patient at rest and with dobutamine. Both global and regional ejection fractions were quantified. Sixty patients underwent coronary cineangiography within 1 week. The presence of redistribution was correlated with global and regional ejection fraction changes and with coronary lesions. RESULTS: Redistribution was present in 45 patients, and no change or a decrease in global or regional ejection fraction was detected in 22. In the entire group of patients global ejection fraction increased from 46 +/- 12% to 56 +/- 14%. The six patients with triple-vessel disease had a flat (-0.2 +/- 5%) ejection fraction response to dobutamine, whereas the remaining patients had an increase of 11 +/- 7% (p = 0.003). The regional ejection fraction of the hypokinetic area increased from 27 +/- 10% to 41 +/- 19%, showing no change or a decrease in 13 patients. The 44 patients with peri-infarct redistribution had a significantly higher increase in regional ejection fraction than those without redistribution (16.4 +/- 10% vs. 4.7 +/- 17%, p = 0.003). In the patients with peri-infarct redistribution, an inverse linear correlation was found between redistribution score and dobutamine-induced regional ejection fraction change (r = -0.44, p = 0.004). CONCLUSIONS: Mild to moderate dobutamine-induced peri-infarct ischemia is compatible with an increase in contractility, whereas severe ischemia induces worsening of wall motion.     

Quantitative digital evaluation of myocardial exercise thallium-201 single-photon emission tomography in post-menopausal women

OBJECTIVE: To determine the respective roles of septal fibrosis, necroinflammatory activity, iron deposition, steatosis, and patterns of nodular and septal remodeling in the collagenization of the perisinusoidal space in livers from patients undergoing transplantation for alcoholic or posthepatitis C cirrhosis and to ascertain whether perisinusoidal collagenization has clinical implications added to those of septal fibrosis. STUDY DESIGN: Sixty-six hepatectomy specimens from patients undergoing liver transplantation for cirrhosis were analyzed. Thirty-two alcoholic and 34 posthepatitis C cirrhoses were included. Picro Sirius-stained slides were examined with polarized light and the amount of perisinusoidal collagenization measured by computerized image analysis. Size distributions of septa and nodules were assessed by mathematical morphology methods. RESULTS: The septal and perisinusoidal fibrosis indices and Knodell and Pugh-Child scores showed significant differences between alcoholic and posthepatitis cirrhoses. Correlation between septal fibrosis and perisinusoidal collagenization was weak, though significant. Both variables correlated significantly with the clinical score. The correlation was negative between septal fibrosis or perisinusoidal collagenization and the Knodell score. CONCLUSION: Perisinusoidal collagenization was not a feature of all cases of cirrhosis, although it was more prominent in alcoholics. For the whole series, it significantly correlated with the clinical score, which increased significantly when high perisinusoidal collagenization was added to high septal fibrosis. No absolute dependence was found between perisinusoidal collagenization and septal fibrosis; percentage of slender fibrous septa and amount of iron deposition were other factors entered in the regression equation.     

Comparison of flow capacities of arterial and venous grafts for coronary artery bypass grafting: evaluation with exercise thallium-201 single-photon emission tomography

Stress thallium-201 tomography was performed to compare the flow capacities of arterial and saphenous vein grafts in patients with coronary artery bypass grafting (CABG). One hundred and seven consecutive patients (95 male and 12 female; mean age 58+/-9.1 years) underwent exercise-redistribution 201Tl myocardial single-photon emission tomography 4-5 weeks after CABG. When a reversible perfusion defect was present in the area covered by a patent bypass graft, the flow capacity of the graft was defined as insufficient. Of all 285 grafts, 211 were considered as complete bypass. Reversible perfusion defects were present in 29 (27%) of 108 myocardial areas supplied by patent arterial grafts but in only 5 (5%) of 103 myocardial areas supplied by patent saphenous vein grafts (P<0.0001). In the LAD area reversible defects were observed in 22 of 82 areas covered by arterial grafts, in contrast to only 1 of 29 areas covered by venous grafts (P<0.01); in the RCA area reversible defects were observed in 7 of 17 and 4 of 41 areas respectively (P<0.01). There was no difference between the native coronary artery stenosis bypassed by patent arterial and venous grafts (88%+/-12% vs 86%+/-14% respectively, P=0.27). In conclusion, flow capacities during peak myocardial demand were more frequently insufficient in arterial bypass grafts than in saphenous vein grafts.     

Predicting chemotherapeutic response to small-cell lung cancer of platinum compounds by thallium-201 single-photon emission computerized tomography

Thallium-201 single-photon emission computerized tomography (SPECT) was used to clarify the relationship between 201Tl uptake and the response in chemotherapy to platinum compounds in 21 patients with small-cell lung cancer. 201Tl-SPECT scans were obtained twice: at 15 min (early scan) and 120 min (delayed scan) after an intravenous injection of 111 MBq (3 mCi) of thallium-201 chloride. We obtained the uptake ratio from each scan and calculated the retention index:uptake ratio = region of interest uptake/contralateral normal lung uptake; retention index = (delayed ratio - early ratio)/early ratio. After 201Tl scintigraphy, 12 patients received chemotherapy consisting of platinum compounds and nine were treated with chemoradiation. Among patients receiving only chemotherapy, the retention index correlated with the responses to chemotherapy. In an in vitro study, ouabain, an inhibitor of the Na,K-ATPase pump, reduced sensitivity to cisplatin and inhibited intracellular thallium uptake in the small-cell lung cancer cell line. These studies suggest that 201Tl-SPECT is a useful indicator of response to chemotherapy with platinum compounds in small-cell lung cancer, and that Na,K-ATPase is commonly involved in transporting both thallium and platinum compounds into cancer cells.     

Utility of stress single-photon emission computed tomography (SPECT) perfusion imaging in predicting outcome after coronary artery bypass grafting

Previous studies have examined the predictors of outcome in medically treated patients with coronary artery disease (CAD). There is limited information on predictors of outcome after coronary artery bypass grafting (CABG). This study examined the predictors of outcome of 255 patients with CAD, at a mean time of 5 years after CABG for angina pectoris. The 255 patients underwent coronary angiography and stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging after CABG. During a mean follow-up of 41 +/- 28 months after stress testing, there were 34 hard events (24 cardiac deaths and 10 nonfatal myocardial infarctions). The hemodynamics during stress testing, and age and gender were not predictors of events. The SPECT variables of multivessel perfusion abnormality, perfusion deficit size, and increased lung thallium uptake were predictors of death and total events by uni- and multivariate survival analysis. There were 14 events in 45 patients (31%) with multivessel abnormality and increased lung thallium uptake, 14 events in 101 patients (14%) with either multivessel abnormality or increased lung uptake, and 6 events in 109 patients (6%) with neither of these 2 variables (p = 0.0001). The annual mortality and total event rates were 7.5% and 9.5% with both variables, 3.4% and 4.3% with either variable, and 0.6% and 1.7% with neither of the variables (p = 0.01). Thus, stress SPECT perfusion imaging is useful to stratify patients after CABG into low, intermediate, and high risk groups for future cardiac events.     

Assessment of myocardial viability by dobutamine echocardiography, positron emission tomography and thallium-201 SPECT: correlation with histopathology in explanted hearts

OBJECTIVES: We examined the relationship among viability assessment by dobutamine echocardiography (DE), positron emission tomography (PET) and thallium-201 single-photon emission computed tomography (TI-SPECT) to the degree of fibrosis. BACKGROUND: DE, PET and TI-SPECT have been shown to be sensitive in identifying viability of asynergic myocardium. However, PET and TI-SPECT indicated viability in a significant percentage of segments without dobutamine response or functional improvement after revascularization. METHODS: Twelve patients with coronary artery disease and severely reduced left ventricular function (EF 14.5+/-5.2%) were studied with DE prior to cardiac transplantation: 5 had additional PET and 7 had TI-SPECT studies. Results of the three techniques were compared to histologic findings of the explanted hearts. RESULTS: Segments with >75% viable myocytes by histology were determined to be viable in 78%, 89% and 87% by DE, PET and TI-SPECT; those with 50-75% viable myocytes in 71%, 50% and 87%, respectively. Segments with 25-50% viable myocytes showed response to dobutamine in only 15%, but were viable in 60% by PET and 82% by TI-SPECT. Segments with <25% viable myocytes responded to dobutamine in 19%; however, PET and TI-SPECT demonstrated viability in 33% and 38%, respectively. Discrepant segments without dobutamine response but viability by PET and SPECT had significantly more viable myocytes by pathology than did those classified in agreement to be nonviable but had significantly less viable myocytes than those classified in agreement to be viable (p < .001). CONCLUSIONS: These findings suggest that contractile reserve as evidenced by a positive dobutamine response requires at least 50% viable myocytes in a given segment whereas scintigraphic methods also identify segments with less viable myocytes. Thus, the methods may provide complementary information: Nuclear techniques appear to be highly sensitive for the detection of myocardial viability, and negative tests make it highly unlikely that a significant number of viable myocytes are present in a given segment. Conversely, dobutamine echo may be particularly useful for predicting recovery of systolic function after revascularization.     

Myocardial perfusion reserve studied by single-photon emission-computed tomography with thallium-201 and a drug stress test with adenosine triphosphate in patients with cardiovascular risk factors

INTRODUCTION AND OBJECTIVE: Recent studies have suggested that the evaluation of coronary reserve is a sensitive method in the early detection of vascular alterations before plaques exist, and certainly before clinical detection of atherosclerotic lesions. Single-photon emission-computed tomography (SPECT) with thallium-201 (201Tl) provides a noninvasive tool for evaluating myocardial perfusion reserve. The objective of this study was to measure the myocardial perfusion reserve in two groups of subjects, some with and some without cardiovascular risk factors and in a group of patients with coronary artery disease. METHODS: Seventy-four subjects, divided into three groups, were recruited to assess regional and global myocardial perfusion reserve. The control group consisted of 11 asymptomatic individuals without cardiovascular risk factors. The second group was composed of 49 patients with one or more risk factors. Finally, the third group included 14 patients with coronary artery disease. 201Tl-SPECT at rest and after pharmacological stress with a 7 minute adenosine triphosphate (ATP) infusion (140 micrograms/kg/min) was performed in all patients. ATP minus rest value subtraction was applied in order to obtain the stress data. Relative myocardial perfusion reserve indices were calculated as the ratio between stress and rest values. RESULTS: Global and regional myocardial perfusion reserves of the vascular territories were significantly lower in patients with cardiovascular risk factors than in control subjects (Global: 1.48 +/- 0.19 vs 1.81 +/- 0.08, LAD: 1.52 +/- 0.21 vs 1.85 +/- 0.09, CX: 1.45 +/- 0.2 vs 1.79 +/- 0.86, RCA: 1.47 +/- 0.2 vs 1.79 +/- 0.86) and higher than in patients with coronary artery disease (Global: 1.48 +/- 0.19 vs 1.31 +/- 0.14, LAD: 1.52 +/- 0.21 vs 1.35 +/- 0.15, CX: 1.45 +/- 0.2 vs 1.2 +/- 0.24). Univariate linear regression analysis in a group of 40 patients with high risk lipid profiles revealed a significant negative correlation between myocardial perfusion reserve and total cholesterol (r = -0.35; p = 0.01), LDL-cholesterol (r = -0.38; p = 0.036) and LDL/HDL ratio (r = -0.39; p = 0.029). CONCLUSION: Determination of myocardial perfusion reserve with 201Tl-SPECT allows the detection of abnormal vasodilatory response to intravenous ATP in patients with cardiovascular risk factors. These patients have higher reserves than patients with coronary disease, which might suggest an early phase of atherosclerosis.     

Neuropsychological correlates of single photon emission computed tomography (SPECT) in Alzheimer's disease.

Examined associations between regional cortical perfusion on SPECT scans and cognitive test performance in 15 patients (mean age 67.1 yrs) with probable Alzheimer's disease (AD) of mild to moderate severity. The degree and extent of decreased perfusion of SPECT scans was associated with severity of AD and neuropsychological test scores correlated with findings of lateralized perfusion deficits on SPECT scans. Perfusion deficits on SPECT scans were also associated with estimates of global changes in intellectual functioning. Instruments included the Wechsler Adult Intelligence Scale—Revised (WAIS—R), the Mini-Mental State Examination, the Aphasia Screening Test, and the Trail Making Test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tc-99m-HMPAO single photon emission computed tomography (SPECT) as an ancillary test in the diagnosis of brain death

Lipomatosis has not previously been reported in minor salivary glands. Its occurrence in the parotid gland is well recognized. We present the first reported case of lipomatosis of the minor salivary glands in the nasal cavity. We also review the tumours of the minor salivary glands, lipomas and lipomatosis of the parotid, and the few reported cases of lipomas of the sinonasal tract.     

Early diagnosis of herpes simplex virus encephalitis by single photon emission computed tomography (SPECT) in patients with normal MRI

Since treatment of herpes simplex virus encephalitis (HSVE) is most effective when started early, a sensitive and specific method for early diagnosis would be of great benefit. MRI and CT are commonly used for this purpose. In this study, we presented two patients who had serologically confirmed HSVE and had normal CT and MRI, but were diagnosed as having HSVE by means of SPECT in the early stage. Case 1 was a 56-year-old man who suddenly developed alexia. On admission, physical and neurological examination were unremarkable except for alexia, agraphia, acalculia, and left-right disorientation. Brain CT, MRI, and cerebral angiography were all normal. However, SPECT showed hyperaccumulation of 99m Tc-HM-PAO in the right temporal-occipital area. On the 5th hospital day, he became comatose. CSF study revealed marked pleocytosis. Even then, MRI including Gd-enhanced study was normal while SPECT continued to show hyperaccumulation. Detection of herpes simplex virus DNA in CSF by polymerase chain reaction was negative. Anti-HSV antibody titer in CSF and serum confirmed intrathecal production of the antibody on the 14th hospital day. Abnormal accumulation of tracer in SPECT returned to normal on the 31st day when he was alert but still had a mild Gerstman syndrome. Case 2 was a 61-year-old man with disturbance of consciousness, mental dysfunction, and generalized convulsion. He was diagnosed as having HSVE by means of CSF pleocytosis, detection of HSV DNA in CSF by polymerase chain reaction, and presence of anti-HSV antibody in the CSF. CT and MRI again revealed no abnormality while SPECT clearly showed hyperaccumulation in the left temporal lobe in an early stage. Hyperaccumulation of lipophilic tracer on SPECT study, especially in the temporal lobes, has been reported in the early stage of HSVE by previous investigators. Unlike MRI or enhanced CT, the increased tracer accumulation in SPECT does not reflect disruption of the blood-brain-barrier or inflammatory edema, but reflects hyperperfusion or some other HSVE related abnormality which is currently unknown. From these observations, we suggest that local hyperperfusion occurs before local inflammation, and that SPECT is the most useful scanning method for early diagnosis of HSVE when this disease is clinically suspected.     

Diagnosis of right ventricular infarction by overlap images of simultaneous dual emission computed tomography using technetium-99m pyrophosphate and thallium-201

The validity of dual energy single-photon emission computed tomography (SPECT) with technetium-99m pyrophosphate (Tc-99m PPi) and thallium-201 for the diagnosis of right ventricular (RV) infarction, and the clinical features of RV infarction, were investigated in 190 patients with acute myocardial infarction. Diagnosis of RV infarction was performed by Tc-99m PPi accumulation in the RV myocardium on thallium-201 and Tc-99m PPi over-lay images at the dual SPECT with simultaneous imaging taken 2 to 9 days after the onset of myocardial infarction. Thirty RV infarctions were found among the 190 patients with left ventricular infarction (15.8%): 29 (97%) in association with the inferior and 1 (3%) with the lateral infarction. Tc-99m PPi accumulation was mostly observed in the posterior wall of the right ventricle. A total occlusion or a severe stenosis of the right coronary artery was demonstrated angiographically in 92% of the patients with RV infarction. The prevalence of RV infarctions was significantly lower in patients who achieved successful early reperfusion than in those who did not (26.7 vs 68.4%, respectively, p < 0.01). However, a successful early reperfusion therapy could not significantly decrease the rate of RV involvement in patients without significant collateral flow (p < 0.01). Thus, dual isotope SPECT with Tc-99m PPi and thallium-201 can be used as a reliable method for the diagnosis of RV infarction.     

Enhanced accuracy of defect detection by myocardial single-photon emission computed tomography with attenuation correction with gadolinium 153 line sources: evaluation with a cardiac phantom

Moral imagination has been described by Murdoch as 'a way of seeing'. The focus of concern here is the influence of belief upon moral imagination and those attitudes that are needed if moral imagination is to be developed. The perspective adopted endorses a Humean recognition of the potent influence of personal experience upon those beliefs that are held, and therefore upon how we see the world. Kantian commitment to the power of the will, and to the ability of individuals to choose who they wish to be, allows room for optimism, a view which is supported by the findings of Liaschenko.     

Underestimation of extent and severity of coronary artery disease by dipyridamole stress thallium-201 single-photon emission computed tomographic myocardial perfusion imaging in patients taking antianginal drugs

OBJECTIVES: This study evaluated the diagnostic value of dipyridamole plus low level treadmill exercise (dipyridamole stress) thallium-201 single-photon emission computed tomography (SPECT) in patients taking antianginal drugs. BACKGROUND: Dipyridamole stress is the major substitute for maximal exercise in patients referred for myocardial perfusion imaging. Although antianginal drugs are commonly suspended before exercise, dipyridamole stress is usually performed without discontinuing these drugs. METHODS: Twenty-six patients underwent two dipyridamole perfusion studies: the first without (SPECT-1) and the second with (SPECT-2) antianginal treatment. Twenty-one patients (81%) received calcium antagonists, 19 (73%) received nitrates, and 8 (31%) received beta-blockers. Eighteen of the patients underwent coronary angiography. Data are presented as the mean value +/- SD. RESULTS: Visual scoring yielded significantly larger and more severe reversible perfusion defects for SPECT-1 than for SPECT-2. Quantitative analysis showed larger perfusion defects on stress images of SPECT-1 in the left anterior descending coronary artery (LAD) (25 +/- 21% vs. 17 +/- 15%, p = 0.003), left circumflex coronary artery (LCx) (56 +/- 35% vs. 48 +/- 36%, p = 0.03) and right coronary artery (RCA) (36 +/- 27% vs. 25 +/- 24%, p = 0.008) territories. Individual vessel sensitivities in the LAD, LCx and RCA territories were 93%, 79% and 100% for SPECT-1 and 64%, 50% and 70% for SPECT-2, respectively. These differences were highly significant for the LAD (p = 0.004) and LCx (p = 0.00004) territories. The overall individual vessel sensitivity of SPECT-1 was significantly higher than that of SPECT-2 (92% vs. 62%, p = 0.000003). Specificity was not significantly different in SPECT-1 compared with SPECT-2 (80% and 93%, p = 0.33). CONCLUSIONS: Continued use of antianginal drugs before dipyridamole plus low level treadmill exercise thallium-201 SPECT may reduce the extent and severity of myocardial perfusion defects, resulting in underestimation of coronary artery disease.     

Prediction of functional recovery and prognosis in patients with acute myocardial infarction by 123I-BMIPP and 201Tl myocardial single photon emission computed tomography: a multicenter trial

123I-BMIPP [15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid] was developed for metabolic imaging with SPECT. A multicenter collaborative study was conducted on a large patient series to determine whether 123I-BMIPP and 201Tl myocardial SPECT are of use in predicting the prognosis and ventricular function after acute myocardial infarction (AMI). Patients with uncomplicated first AMI underwent resting 123I-BMIPP and 201Tl myocardial SPECT in the subacute phase after the onset of AMI. Of these, 167 patients who had been followed up for an average of 22 months were retrospectively reviewed to predict serious cardiac events and recurrent ischemia. In addition, the association between changes in radionuclide parameters and recurrent ischemia was investigated in Subgroup A (58 patients) who had repeated SPECT in the chronic phase. Furthermore, prediction of the ejection fraction (EF) was investigated in Subgroup B (94 patients) and Subgroup C (76 patients) in whom left ventriculography was performed at the time of discharge and 90 days or more after the onset, respectively. The prognosis was generally favorable, with 4 cases of cardiac death (2%), 3 of heart failure (2%), 4 of nonfatal reMI (2%), and 25 of recurrent ischemia (15%). The results of Cox multivariate regression analysis revealed a high probability of serious cardiac events in patients who were elderly (p = 0.04), who had 90% or more residual stenosis of the infarct-related artery (p = 0.09), and who had a high BMIPP defect score (p = 0.17). There was a high probability of recurrent ischemia in elderly patients (p = 0.10) who had multi-vessel disease (p = 0.03), but no association was found with radionuclide parameters in the subacute phase. In Subgroup A, however, the probability of recurrent ischemia tended to be high in patients with a large mismatch scorebetween 123I-BMIPP and 201Tl in the subacute to chronic phase. An important observation was that the extent of BMIPP defect was more strongly correlated with EF at the time of discharge and 90 days or more after the onset than the extent of Tl defect (r = -0.60 vs. r = -0.47, and r = -0.53 vs. r = -0.43, respectively). In addition, multiple regression analysis showed that parameters related to the BMIPP defect were also better predictive factors of EF both at the time of discharge and 90 days or more after the onset. In conclusion, resting 123I-BMIPP and 201Tl myocardial SPECT performed in the subacute phase of AMI were shown to be useful in predicting prognosis and ventricular function for patient management.     

Attenuation-corrected 99mTc-tetrofosmin single-photon emission computed tomography in the detection of viable myocardium: comparison with positron emission tomography using 18F-fluorodeoxyglucose

OBJECTIVES: The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (99mTc)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). BACKGROUND: The role of 99mTc-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images. METHODS: Twenty-four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting 99mTc-tetrofosmin SPECT and FDG PET imaging. Both AC and non-attenuation-corrected (NC) SPECT images were generated. RESULTS: Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between 99mTc-tetrofosmin and FDG on the patient basis increased from 79.8%+/-14.0% (mean+/-SD) on the NC images to 90.8%+/-10.6% on the AC images (p=0.002). The percentage of 99mTc-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8%+/-15.2% on the NC images to 9.7%+/-12.6% on the AC images (p=0.01). Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior-septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region. CONCLUSIONS: The results indicate that AC 99mTc-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior-septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction.     

Evaluation of the cardiac and pulmonary uptake of Thallium 201 in subject with suspected ischemic heart disease examined by single-photon emission tomography with Thallium 201, at rest and after exertion

Counts in selected lung and heart ROI were taken in 10 thallium-201 stress SPECT. They were tested for diseased or welfare status of the patient. Eighteen parameters from scintigraphies and from stress test for each patient were placed in a file and tested for correlation in a minicomputer. Lung/heart ratio was found to be not indicative of disease while it is a sign of thallium distribution in the body. Numerical evaluation of scintigraphies was however found to be a sign of disease.     

Single photon emission computed tomography (SPECT) in a patient with bilateral temporal seizures: correlation between ictal EEG and postictal/ictal SPECT

We report a patient with bilateral independent temporal lobe seizures in whom two [99mTc]HMPAO single photon emission computed tomograph (SPECT) scans were performed during two different seizures. In the first periictal SPECT, [99mTc]HMPAO was injected in the interval between two closely spaced seizures (one localized in the left temporal lobe and the other in the right temporal lobe). SPECT images showed hypoperfusion in the left lateral temporal lobe, hyperperfusion of the left mesial temporal region, and pronounced hyperperfusion in the right anterior temporal lobe. These results suggest both a postictal left temporal SPECT pattern and an ictal right temporal pattern. In the second periictal SPECT, [99mTc]HMPAO was injected immediately after a right temporal lobe seizure and showed right lateral temporal lobe hypoperfusion and right mesial hyperperfusion, suggesting a postictal right temporal SPECT pattern. Interpretation of the periictal SPECT should take into account EEG changes at the time or in the minutes immediately after injection of [99mTc]HMPAO.     

Assessment of myocardial viability: Dobutamine echocardiography and thallium-201 single-photon emission computed tomographic imaging predict the postoperative improvement of left ventricular function after bypass surgery

The aim of this study was to evaluate the usefulness of dobutamine echocardiography and quantitative thallium-201 single photon emission computed tomography myocardial scintigraphy with reinjection in the detection of viable myocardium in patients with coronary artery disease and reduced left ventricular function, which will improve after aortocoronary bypass surgery. Forty-eight patients (47 men, aged 61 +/- 6 years) with angiographically documented reduced left ventricular function (ejection fraction 35 +/- 14, 63% with chronic transmural myocardial infarction) were examined by dobutamine two-dimensional echocardiography (before and during low dosage), 201Tl, and gated radionuclide ventriculography before and 3 +/- 2 months after aortocoronary bypass surgery. Four of 55 areas classified viable before operation were revascularized inadequately and discarded. Global left ventricular ejection fraction at rest rose from 35% +/- 14% before operation to 40% +/- 13% (p < 0.05) after operation. Stress-induced perfusion defects involved 40% +/- 19% of the left ventricle circumference after stress and showed a significant reduction of size to 23% +/- 14% (p < 0.01) at rest, 4 hours later, and after reinjection. This value fell to 16% +/- 12% (p < 0.05) 3 months after aortocoronary bypass surgery. We conclude that both dobutamine echocardiography (sensitivity 95%, specificity 80%, positive predictive value 87%, negative predictive value 88%) and 201Tl studies (sensitivity 87%, specificity 98%, positive predictive value 97%, negative predictive value 93%) are suitable and comparable accurate methods for predicting improvement in systolic function 3 months after revascularization in a selected population with a high prevalence of viable but hypokinetic or akinetic myocardium.     

Accuracy of single-photon emission computed tomography myocardial perfusion imaging in patients with stents in native coronary arteries

Strategies to noninvasively evaluate patients after coronary stenting have not been evaluated. To determine the accuracy of single-photon emission computed tomography (SPECT) myocardial perfusion imaging in patients after coronary stenting, 209 patients who had undergone stenting followed by late stress SPECT myocardial perfusion imaging were evaluated. Quantitative coronary angiography was performed in 33 patients following SPECT imaging. SPECT restenosis was defined as a reversible or fixed defect within the stented vascular territory. Angiographic restenosis was examined using 2 definitions: total area narrowing > or =50% or > or =70% of the stent site or stented artery. The SPECT and angiographic findings were concordant in 22 of 33 stented vascular territories using the 50% definition of restenosis and in 29 of 33 stented territories using the 70% definition. Use of the 70% definition of restenosis resulted in improved accuracy of SPECT to detect a significant stenosis in the stented artery. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SPECT were 95%, 73%, 88%, 89%, and 88% respectively. In patients with positive SPECT scans, the most significant stenosis in the stented artery was outside the stent site in 50% of cases. SPECT imaging appears to be accurate to predict significant stenosis in the stented artery, although the most severe stenosis is frequently distant from the stent site.