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Este artigo tem por objetivo analisar os efeitos de sentido decorrentes dos pronunciamentos à imprensa do Presidente da República do Brasil, Jair Messias Bolsonaro, considerando os processos de constituição e circulação de sentidos do discurso autoritário. Foram mobilizados os dispositivos teórico-analíticos formulados por Michel Pêcheux. A análise das sequências discursivas permitiu compreender a filiação do presidente Jair Bolsonaro ao discurso autoritário, além da constituição, formulação e circulação de sentidos na imprensa, que contribuem para reforçar a imagem de autoritarismo.

To describe and validate an artificial intelligence (AI)-driven structured reporting system by direct comparison of automatically generated reports to results from actual clinical reports generated by nuclear cardiology experts. Quantitative parameters extracted from myocardial perfusion imaging (MPI) studies are used by our AI reporting system to generate automatically a guideline-compliant structured report (sR). A new nonparametric approach generates distribution functions of rest and stress, perfusion, and thickening, for each of 17 left ventricle segments that are then transformed to certainty factors (CFs) that a segment is hypoperfused, ischemic. These CFs are then input to our set of heuristic rules used to reach diagnostic findings and impressions propagated into a sR referred as an AI-driven structured report (AIsR). The diagnostic accuracy of the AIsR for detecting coronary artery disease (CAD) and ischemia was tested in 1,000 patients who had undergone rest/stress SPECT MPI. At the high-specificity (SP) level, in a subset of 100 patients, there were no statistical differences in the agreements between the AIsr, and nine experts’ impressions of CAD (P = .33) or ischemia (P = .37). This high-SP level also yielded the highest accuracy across global and regional results in the 1,000 patients. These accuracies were statistically significantly better than the other two levels [sensitivity (SN)/SP tradeoff, high SN] across all comparisons. This AI reporting system automatically generates a structured natural language report with a diagnostic performance comparable to those of experts.

Mental stress-induced myocardial ischemia (MSIMI) is a common phenomenon in patients with coronary artery disease (CAD), but contemporary studies of its prognostic significance and its underlying pathophysiology are limited.We prospectively enrolled patients with confirmed CAD in the Mental Stress Ischemia Prognosis Study (MIPS) between 2011 and 2014. All patients underwent mental stress testing using a standardized public speaking task, and ischemia was detected by Tc-sestamibi myocardial perfusion imaging. Patients also underwent conventional stress testing for myocardial ischemia (CSIMI) using exercise or pharmacological stress testing. Furthermore, digital microvascular flow, endothelial function, arterial stiffness, and blood sample collections were performed before, during, and after mental stress. Two-year adverse clinical outcomes are being assessed.Six-hundred ninety-five patients completed baseline enrollment in the MIPS. Their mean (standard deviation) age was 62.9 (9.1) years, 72% were men, 30% were African American, and 32% had a history myocardial infarction. The prevalence of MSIMI and CSIMI is 16.1% and 34.7%, respectively. A total of 151 patients (22.9%) had only CSIMI, 28 (4.2%) had only MSIMI, and 78 (11.8%) had both MSIMI and CSIMI. Patients with ischemia had a lower ejection fraction and higher prevalence of previous coronary artery bypass grafting compared with those without inducible ischemia (p.050). The prevalence of obstructive CAD was not statistically different between patients with and without MSIMI (p = .426); in contrast, it was higher in patients with CSIMI (p.001).The MIPS data will provide useful information to assess the prognostic significance and underlying mechanisms of MSIMI.

Myocardial perfusion studies suffer from artifacts caused by misalignment of the transmission and emission data due to the influences of voluntary and involuntary patient motion. Regardless of G68e or respiratory‐averaged CT based attenuation correction and good patient cooperation, approximately 21% of perfusion studies exhibit artifacts arising from misalignment that cannot be corrected by manipulating the attenuation acquisition protocol. This misalignment, termed cardiac drift, is caused by slow‐moving abdominal cavity contents that reposition the heart in the thorax and appear as myocardial uptake overlying the left CT lung in fused PET/CT images. This study evaluates three postimaging registration techniques to correct PET/CT misalignment by altering the transmission map to match myocardial uptake. Simulated misalignment studies were performed with a cardiac torso phantom filled with [F18]FDG at 10:1 myocardium/background. An air‐filled saline bag affixed to the medial left lung surface served as a distensible lung. An initial CT acquisition was followed by successive PET acquisitions consisting of small displacements of the cardiac insert into the left lung. Phantom transmission scans were aligned to the myocardial uptake in the emission scans by applying 1) full rigid‐body translations and rotations, 2) rigid‐body restricted to medial / lateral and superior / inferior translation, or 3) an emission‐driven method that adds myocardial tissue to the transmission scan. These methods were also applied to 10 low‐likelihood coronary artery disease (CAD) patients showing signs of cardiac drift. Full rigid‐body registration showed significant over‐correction (p

Ischemia results from an imbalance between myocardial oxygen supply and demand. Ischemia associated with mental stress (MS) has been associated with adverse outcomes in patients with coronary artery diseases (CAD). Higher heart rate (HR) and blood pressure responses to MS are associated with a greater likelihood of MS-induced ischemia. Although multiple genetic loci have been associated with baseline HR, genetic associations for HR responses to MS remain unknown. We aimed to discover the genetic determinants of HR response to MS in a bi-ethnic population. A sample of 499 Caucasian and 271 African American patients with CAD were recruited into the Mental Stress Ischemia Prognosis (MIPS) study. Race was defined using genetic ancestry. Genome-wide SNP data were genotyped using Illumina’s Multi-Ethnic Genotyping (MEG) chip and then imputed to the 1000 Genome Project phase 3 panel. Cardiovascular risk factors, demographic, behavioral, and medication history data were obtained by questionnaires and chart reviews. MS was induced by a public speaking task and the HR response to MS was measured as post-stress HR minus pre-stress HR. We conducted genome-wide association analysis of HR response to MS using multiple linear regression adjusted for age, sex, beta-blocker use, the pre-stress HR and ethnicity. A meta-analysis was performed across the two ethnicities. After multiple-testing correction, no significant associations with HR response to MS were identified among Whites .However, fourteen SNPs located in gene ITGA1 with a mean minor allele frequency of 36.5% (range: 36.3% - 37.1%) were significantly associated with the HR response to MS in Blacks (meta-analysis p-8 ). The minor alleles of all 14 variants were associated with a higher HR response. On average heterozygotic and homozygotic Blacks of the minor allele in any of these SNPs have a 4.558 beat/min (range: 4.514 – 4.659 beat/min) and 9.116 beat/min (range: 9.028 – 9.318 beat/min) increase in HR response to MS, correspondingly. The ITGA1 gene encodes the alpha-1 subunit of integrin receptors. This protein heterodimerizes with the beta-1 subunit to form a cell-surface receptor for collagen and laminin. The heterodimeric receptor is involved in cell-cell adhesion and may play a role in inflammation and fibrosis. Further functional studies to follow up these genetic loci may provide insight into regulatory mechanisms of HR response to mental stress that may be prognostically informative for CAD patients.

Mental stress-induced myocardial ischemia (MSIMI) is associated with increased risk of adverse cardiovascular outcomes, yet the underlying mechanisms are not well understood. We measured the inflammatory response to acute laboratory mental stress in patients with coronary artery disease (CAD) and its association with MSIMI. We hypothesized that patients with MSIMI would have a higher inflammatory response to mental stress in comparison to those without ischemia.Patients with stable CAD underwent 99mTc sestamibi myocardial perfusion imaging during mental stress testing using a public speaking stressor. MSIMI was determined as impaired myocardial perfusion using a 17-segment model. Inflammatory markers including interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), matrix metallopeptidase 9 (MMP-9) and high-sensitivity C reactive protein (hsCRP) were measured at rest and 90 min after mental stress. Results were validated in an independent sample of 228 post-myocardial infarction patients.Of 607 patients analyzed in this study, (mean age 63 ± 9 years, 76% male), 99 (16.3%) developed MSIMI. Mental stress resulted in a significant increase in IL-6, MCP-1, and MMP-9 (all p 0.0001), but not hsCRP. However, the changes in these markers were similar in those with and without MSIMI. Neither resting levels of these biomarkers, nor their changes with mental stress were significantly associated with MSIMI. Results in the replication sample were similar.Mental stress is associated with acute increases in several inflammatory markers. However, neither the baseline inflammatory status nor the magnitude of the inflammatory response to mental stress over 90 min were significantly associated with MSIMI.

Mental stress-induced myocardial ischemia (MSIMI) in patients with coronary artery disease (CAD) is associated with adverse cardiovascular outcomes. We aim to assess hemodynamic, neuro-hormonal, endothelial, vasomotor and vascular predictors of MSIMI.We subjected 660 patients with stable CAD to 99mTc sestamibi myocardial perfusion imaging at rest, with mental (speech task) and with conventional (exercise/pharmacological) stress. Endothelium-dependent flow-mediated dilation (FMD), microvascular reactivity [reactive hyperemia index (RHI)] and arterial stiffness [pulse wave velocity (PWV)] were measured at rest and 30-min after mental stress. The digital microvascular vasomotor response during mental stress was assessed using peripheral arterial tonometry (PAT). A total of 106(16.1%) patients had MSIMI. Mental stress was accompanied by significant increases in rate-pressure-product (heart rate x systolic blood pressure; RPP), epinephrine levels and PWV, and significant decreases in FMD and PAT ratio denoting microvascular constriction. In comparison to those with no MSIMI, patients with MSIMI had higher hemodynamic and digital vasoconstrictive responses (p0.05 for both), but did not differ in epinephrine, endothelial or macrovascular responses. Only presence of ischemia during conventional stress (OR of 7.1, 95%CI of 4.2, 11.9), high hemodynamic response (OR for RPP response≥vsROC cutoff of 1.8, 95%CI of 1.1, 2.8), and high digital vasoconstriction (OR for PAT ratiovs≥ROC cutoff of 2.1, 95%CI of 1.3, 3.3) were independent predictors of MSIMI.Ischemia during conventional stress testing and hemodynamic and vasoconstrictive responses to mental stress can help predict subjects with CAD at greater risk of developing MSIMI.

We set out to develop normal databases and prospectively validate abnormality criteria for a low-dose Tc-99m tetrofosmin myocardial perfusion SPECT protocol using the 530c CZT camera. All patients received 6 mCi rest/20 mCi stress doses of Tc-99m tetrofosmin. Rest and stress images were obtained over 7-9 and 5-7 minutes according to the chest size. Low-dose CT of the chest was obtained on a standalone CT scanner. Forty patients with very low likelihood (LLK) of coronary artery disease (CAD) were used to define the normal count distributions. The abnormality criteria were prospectively validated in 55 patients who had coronary angiography and in 40 patients with LLK of CAD. The results for quantitative non-attenuation-corrected (AC) and AC analysis and visual analysis were as follows: sensitivity of 79%, 85%, and 92% (P = NS) and specificity of 44%, 75%, and 56% (P = NS), respectively. The normalcy rates for quantitative non-AC and AC analyses and visual analysis were 95%, 98%, and 98% (P = NS). We have developed non-AC and AC normal databases for low-dose rest/stress Tc-99m tetrofosmin myocardial perfusion SPECT protocol using the 530c CZT camera. The per-patient diagnostic performance of quantitative analyses is not significantly different from visual analysis by an experienced reader.

The accuracy of zero coronary calcium score as a filter in patients with chest pain has been demonstrated at the emergency room and outpatient clinics, populations with low prevalence of coronary artery disease (CAD).To test the gatekeeping role of zero calcium score in patients with chest pain admitted to the coronary care unit (CCU), where the pretest probability of CAD is higher than that of other populations.Patients underwent computed tomography for calcium scoring, and obstructive CAD was defined by a minimum 70% stenosis on invasive angiography.In 146 patients studied, the prevalence of CAD was 41%. A zero calcium score was present in 35% of the patients. The sensitivity and specificity of zero calcium score yielded a negative likelihood ratio of 0.16. After logistic regression adjustment for pretest probability, zero calcium score was independently associated with lower odds of CAD (OR = 0.12, 95%CI = 0.04-0.36), increasing the area under the ROC curve of the clinical model from 0.76 to 0.82 (p = 0.006). Zero calcium score provided a net reclassification improvement of 0.20 (p = 0.0018) over the clinical model when using a pretest probability threshold of 10% for discharging without further testing. In patients with pretest probability50%, zero calcium score had a negative predictive value of 95% (95%CI = 83%-99%), with a number needed to test of 2.1 for obtaining one additional discharge.Zero calcium score substantially reduces the pretest probability of obstructive CAD in patients admitted to the CCU with acute chest pain. (Arq Bras Cardiol. 2017; [online].ahead print, PP.0-0).A acurácia do escore de cálcio coronário zero como um filtro nos pacientes com dor torácica aguda tem sido demonstrada na sala de emergência e nos ambulatórios, populações com baixa prevalência de doença arterial coronariana (DAC).Testar o papel do escore de cálcio zero como filtro nos pacientes com dor torácica admitidos numa unidade coronariana intensiva (UCI), na qual a probabilidade pré-teste de DAC é maior do que em outras populações.Pacientes foram submetidos a tomografia computadorizada para quantificar o escore de cálcio, DAC obstrutiva foi definida por uma estenose mínima de 70% na cineangiocoronariografia invasiva. Um escore clínico para estimar a probabilidade pré-teste de DAC obstrutiva foi criado em amostra de 370 pacientes, usado para definir subgrupos na definição de valores preditivos negativos do escore zero.Em 146 pacientes estudados, a prevalência de DAC foi 41% e o escore de cálcio zero foi demonstrado em 35% deles. A sensibilidade e a especificidade para escore de cálcio zero resultaram numa razão de verossimilhança negativa de 0,16. Após ajuste com um escore clínico com a regressão logística para a probabilidade pré-teste, o escore de cálcio zero foi preditor independente associado a baixa probabilidade de DAC (OR = 0,12, IC95% = 0,04-0,36), aumentando a área abaixo da curva ROC do modelo clínico de 0,76 para 0,82 (p = 0,006). Considerando a probabilidade de DAC10% como ponto de corte para alta precoce, o escore de cálcio aumentou a proporção de pacientes para alta precoce de 8,2% para 25% (NRI = 0,20; p = 0,0018). O escore de cálcio zero apresentou valor preditivo negativo de 90%. Em pacientes com probabilidade pré-teste50%, o valor preditivo negativo foi 95% (IC95% = 83%-99%).O escore de cálcio zero reduz substancialmente a probabilidade pré-teste de DAC obstrutiva em pacientes internados em UCI com dor torácica aguda. (Arq Bras Cardiol. 2017; [online].ahead print, PP.0-0).

Background Emerging data suggest that young women with coronary heart disease ( CHD ) are disproportionally vulnerable to the adverse cardiovascular effects of psychological stress. We hypothesized that younger, but not older, women with stable CHD are more likely than their male peers to develop mental stress‐induced myocardial ischemia ( MSIMI ). Methods and Results We studied 686 patients (191 women) with stable coronary heart disease ( CHD ). Patients underwent 99m Tc‐sestamibi myocardial perfusion imaging at rest and with both mental (speech task) and conventional (exercise/pharmacological) stress testing. We compared quantitative (by automated software) and visual parameters of inducible ischemia between women and men and assessed age as an effect modifier. Women had a more‐adverse psychosocial profile than men whereas there were few differences in medical history and CHD risk factors. Both quantitative and visual indicators of ischemia with mental stress were disproportionally larger in younger women. For each 10 years of decreasing age, the total reversibility severity score with mental stress was 9.6 incremental points higher (interaction, P MSIMI was 82.6% higher (interaction, P =0.004) in women than in men. Incidence of MSIMI in women ≤50 years was almost 4‐fold higher than in men of similar age and older patients. These results persisted when adjusting for sociodemographic and medical risk factors, psychosocial factors, and medications. There were no significant sex differences in inducible ischemia with conventional stress. Conclusions Young women with stable CHD are susceptible to MSIMI , which could play a role in the prognosis of this group.

OBJECTIVES: This study sought to investigate whether patients with mental stress–induced myocardial ischemia will have high resting and post–mental stress high-sensitivity cardiac troponin I (hs-cTnI). BACKGROUND: Hs-cTnI is a marker of myocardial necrosis, and its elevated levels are associated with adverse outcomes. Hs-cTnI levels may increase with exercise in patients with coronary artery disease. Mental stress–induced myocardial ischemia is also linked to adverse outcomes. METHODS: In this study, 587 patients with stable coronary artery disease underwent technetium Tc 99m sestamibi–single-photon emission tomography myocardial perfusion imaging during mental stress testing using a public speaking task and during conventional (pharmacologic/exercise) stress testing as a control condition. Ischemia was defined as new/worsening impairment in myocardial perfusion using a 17-segment model. RESULTS: The median hs-cTnI resting level was 4.3 (interquartile range [IQR]: 2.9 to 7.3) pg/ml. Overall, 16% and 34.8% of patients developed myocardial ischemia during mental and conventional stress, respectively. Compared with those without ischemia, median resting hs-cTnI levels were higher in patients who developed ischemia either during mental stress (5.9 [IQR: 3.9 to 8.3] vs. 4.1 [IQR: 2.7 to 7.0] pg/ml; p < 0.001) or during conventional stress (5.4 [IQR: 3.9 to 9.3] vs. 3.9 [IQR: 2.5 to 6.5] pg/ml; p < 0.001). Patients with high hs-cTnI (cutoff of 4.6 pg/ml for men and 3.9 pg/ml for women) had greater odds of developing mental (odds ratio [OR]: 2.4; 95% confidence interval [CI]: 1.5 to 3.9; p < 0.001) and conventional (OR: 2.4; 95% CI: 1.7 to 3.4; p < 0.001) stress-induced ischemia. Although there was a significant increase in 45-min post–treadmill exercise hs-cTnI levels in those who developed ischemia, there was no significant increase after mental or pharmacological stress test. CONCLUSIONS: In patients with coronary artery disease, myocardial ischemia during either mental stress or conventional stress is associated with higher resting levels of hs-cTnI. This suggests that hs-cTnI elevation is an indicator of chronic ischemic burden experienced during everyday life. Whether elevated hs-cTnI levels are an indicator of adverse prognosis beyond inducible ischemia or whether it is amenable to intervention requires further investigation.

Introduction: Synchronized contraction of left ventricle (LV) is necessary for normal cardiac pump function. Delayed activation of LV segments, known as “dyssynchrony,” can result in systolic and diastolic function deterioration and clinical heart failure. The autonomic nervous system regulates LV conduction and is influenced by psychological stress. We used mental stress testing to examine the effects of psychological stress on LV dyssynchrony and assess whether patients who develop mental stress-induced myocardial ischemia (MSI), a condition associated with doubling of risk for mortality and cardiovascular events, have greater LV dyssynchrony at baseline and/or during stress as compared to MSI negative subjects. We compared results with a control condition of conventional physical (exercise/ pharmacological) stress. Methods: 660 patients with CAD underwent 99mTc[[Unable to Display Character: ‐]]sestamibi myocardial perfusion imaging at rest and following both mental and physical stress. Dyssynchrony parameters, measured using the Emory Cardiac Toolbox software, included phase standard deviation (SD) and phase bandwidth; higher levels indicate higher desynchronized contraction. Ischemia with both conditions was blindly assessed by 2 independent readers, with consensus reading for any discordance. The Gensini score was calculated from angiographic data to assess CAD burden. Dyssynchrony data at baseline and during mental/physical stress were log-transformed for analyses. Results: Mean age was 63 years (SD: 9), 180 (27%) were females and 432 (66%) were whites. Overall, 108 (16%) subjects developed mental stress ischemia (MSI+), while 232 (35%) developed physical stress ischemia (PSI+). After adjusting for age, sex, race, traditional CAD risk factors, indicators of CAD burden, history of heart failure, and LV ejection fraction, at baseline MSI+ subjects compared with MSI- had 11% higher phase SD (95% CI: 1% to 19%), and 11% higher phase bandwidth (95% CI: 3% to 20%). PSI+ subjects compared with PSI- had a more modest and non-significant increase in phase SD (mean increase of 4%, 95% CI: -3% to 12%) and phase bandwidth (4%, 95% CI: -3% to 11%). The associations of MSI with baseline dyssynchrony was independent of PSI status. A similar association was noted between MSI and dyssyncrony during mental stress. Among the covariates, male sex (P=0.01), smoking (P=0.02), Gensini score (P=0.01), history of MI (P Conclusion: MSI is associated with greater LV dyssynchrony at rest and during stress. Baseline LV dyssynchrony may be a marker of susceptibility to stress-induced ischemia possibly due to recurrent or chronic subclinical ischemia during daily life. LV dyssynchrony may be a potential mechanism for adverse cardiac events in patients with MSI.

We have previously reported normal values for LV mechanical synchrony from post-stress exercise (99m)Tc SPECT studies; the goal of this study was to develop normal values for mechanical synchrony from pharmacologic stress and rest (82)Rb PET studies and compare these values to a population of LBBB patients.The normal population consisted of 40 patients with a low likelihood of coronary artery disease. The LBBB population consisted of 23 patients with ECG evidence of LBBB. All patients were imaged with pharmacologic stress and processed using SyncTool™ (Emory Cardiac Toolbox™). Means and standard deviations were calculated for the stress and rest phase parameters. Normal male and female phase standard deviation were 15.0 ± 7.0 and 13.2 ± 7.7, respectively, for stress (P = NS), and 22.7 ± 13.2 and 16.6 ± 14.3 for rest (P = NS). Normal male and female histogram bandwidth were 38.1 ± 13.3 and 32.0 ± 13.5, respectively, for stress (P = NS) and 50.8 ± 18.7 and 44.4 ± 44.9 for rest (P = NS). ROC analysis yielded a sensitivity/specificity as high as 80%/90% for males, and 92%/75% for females (P = NS).Normal values for LV mechanical synchrony have been developed for (82)Rb pharmacologic stress and rest PET studies; furthermore, the stress pharmacologic values do not differ significantly from our previously reported exercise post-stress SPECT normal values. Finally, ROC analysis confirmed that these normal values were able to differentiate normal and LBBB populations.

Objective We set out to determine whether a coronary artery calcium (CAC) score of zero on computed tomography (CT) would predict a normal myocardial perfusion positron emission tomography (PET) in a population mostly at intermediate pretest likelihood of coronary artery disease (CAD). Methods We enrolled 206 outpatients (36% men, mean age 60±13years) referred for Rb-82 myocardial perfusion PET/CT for suspected CAD. CAC scoring was performed by the Agatston method. The PET images were scored on a 5-point scale using a 17-segment left ventricular model. A summed stress score ≥2 was considered abnormal. Multivariable logistic regression analysis was used to test the independent predictive value of a CAC score of zero to exclude inducible myocardial ischemia. Results Ninety-nine of 206 patients (48%) had a CAC score of zero and of these only 1 had inducible ischemia on PET. This yielded a negative predictive value of 99% (95% CI 95%–100%). CAC score of zero was the strongest independent predictor of a normal myocardial perfusion PET (OR=0.05; 95% CI=0.006–0.38; p =0.004). Conclusion In a population of predominately intermediate likelihood of CAD, a CAC score of zero excludes inducible ischemia on myocardial perfusion PET.

There are a number of imaging tests that are used in the setting of acute myocardial infarction and acute coronary syndrome. Each has their strengths and limitations. Experts from the European Society of Cardiac Radiology and the North American Society for Cardiovascular Imaging together with other prominent imagers reviewed the literature. It is clear that there is a definite role for imaging in these patients. While comparative accuracy, convenience and cost have largely guided test decisions in the past, the introduction of newer tests is being held to a higher standard which compares patient outcomes. Multicenter randomized comparative effectiveness trials with outcome measures are required.

To compare the diagnostic accuracy of Rb-82 myocardial perfusion three-dimensional (3D) PET with and without prompt-gamma compensation (PGC).Retrospective, single center study of 76 patients who had rest and adenosine stress Rb-82 myocardial perfusion 3D PET. All studies were acquired using a Siemens Biograph-40 PET/CT scanner and were reconstructed with and without PGC. Fifty-seven patients (mean age 63 +/- 11 years, 26 men) had coronary angiography within 40 days of Rb-82 imaging. Nineteen patients (mean age 43 +/- 7 years, 10 men) had low likelihood of coronary artery disease (CAD). All PET images were scored by consensus of two blinded readers on a standard 5-point scale using a 17-segment left ventricular model. A normal PET test was defined as a summed stress score of less than four. Obstructive CAD at coronary angiography was used as the gold-standard and was defined as luminal stenosesor =50% in one or more major coronary arteries. The prevalence of obstructive disease at coronary angiography was 68% (39/57). The mean summed stress score was 12 +/- 12 for PGC images and was 18 +/- 14 for non-PGC images. Sensitivity and specificity for obstructive CAD were 90% (95% CI 88-99) and 72% (95% CI 52-93) for PGC images and 95% (95% CI 88-100) and 22% (95% CI 3-41) for non-PGC images.PGC in Rb-82 3D PET improves the specificity for obstructive CAD at coronary angiography with no significant loss in sensitivity.

Objective To compare the diagnostic performance of a new dedicated ultrafast solid-state cardiac camera (Discovery NM 530c [DNM]) with standard dual detector cameras (S-SPECT) in myocardial perfusion imaging. The primary goal was a per-patient analysis of diagnostic performance of the DNM using S-SPECT as the reference standard. Methods and results In total, 168 patients underwent one-day Tc-99m tetrofosmin rest/stress myocardial perfusion SPECT. DNM and S-SPECT images were obtained with the same injected doses. The DNM camera uses an array of cadmium zinc telluride pixilated detectors and a multipinhole collimator simultaneously imaging all cardiac views with no moving parts. Rest and stress acquisition times were 4 and 2 minutes for DNM and 14 and 12 minutes for S-SPECT. Two blinded readers independently interpreted all scans on a patient level and on a vascular territory level using a standard five-point scale. Interobserver differences were resolved by a third observer. Agreement between DNM and S-SPECT for presence or absence of myocardial perfusion defects on a per-patient analysis was 91.9% and 92.5%, respectively. Correlation coefficients of rest and stress left ventricular ejection fractions were 0.87 (P

PET/CT perfusion studies suffer from artifacts caused by misalignment of transmission and emission data due to contractile cardiac and respiratory motion. This study investigates whether substantial differences exist between two respiration-averaging approaches for attenuation correction (AC): low-pitch helical (HCT) and time-averaged CT (ACT). Fifty-four consecutive patients received paired HCT (0.45 pitch, 120 kVp, 76 mA, 24 × 1.2 mm collimated slice width, 1 s gantry rotation time, 4.93 mGy CTDI) and ACT (sequence mode: 6.1 s acq./bed, 80 kVp, 13 mA, 24 × 1.2 mm collimated slice width, 5.53 mGy CTDI) AC scans under free-breathing prior to Rb-82 rest/adenosine stress. Mismatch between the emission and paired transmission data was compared by calculating the volume of myocardial uptake overlying the left CTlung field. Data were then reconstructed with the CT AC scans and normalized to injected dose and bodyweight. Paired rest and paired stress PETimages were reoriented identically along the short axis and sampled into a 17-segment polar map for comparison. The ratio of HCT-PET and ACT-PET polar maps at rest and stress was calculated and grouped by segment for all patients. 95% confidence intervals were calculated to compare changes in the polar map ratios between the two AC methods. No significant difference was observed between the HCT and ACT overlying volume in the rest or stress emission data. 68% of the patients presented visual respiratory artifacts in the HCT images compared to 32% in the ACT. That 23% of the ACT images presented with photon starvation artifacts and increasing BMI was a significant indicator for the occurrence of photon starvation in the ACT AC scans ( p 0.001 ) . The ratio of the reconstructedPET polar segment data showed good agreement between AC methods with 95% confidence intervals ranging from 0.92 to 1.07 in the rest data and 0.93 to 1.07 in the stress data segments. Bias, calculated by averaging the polar segment ratios, showed 1% higher values in the ACT-PET rest reconstructions compared to the HCT-PET rest reconstructions and no measurable bias in the stress reconstructions. This study shows good agreement and negligible bias between low-pitch HCT and ACT protocols for attenuation correction of cardiac PET data.

Background Integrated positron emission tomography/computed tomography (PET/CT) is increasingly being utilized for myocardial perfusion imaging (MPI). However, there is a potential for increased imaging artifact compared with standard PET due to the different temporal resolution of PET and CT. We reviewed the diagnostic accuracy of adenosine stress Rb myocardial perfusion PET/CT to detect obstructive coronary artery disease (CAD) on invasive angiography at our institution. Methods and results Seventy-five patients were included, 23 (13 men, mean age 55.8+/-11.8 years) with low likelihood of CAD and 52 (28 men, mean age 67.1+/-11.4 years) with intermediate to high pretest probability of disease. Coronary angiography was performed only in the latter 52 patients on average within 17 days of the MPI study. The test characteristics of PET/CT MPI were assessed using a threshold of >or=50 and >or=70% stenosis in one or more major coronary artery on invasive angiography. Dedicated software was used for registration, processing, and interpretation. Consensus interpretation of the tomographic PET slices using a 4-point scale (1=definitely normal, 2=probably normal, 3=probably abnormal, 4=definitely abnormal) was done by two readers blinded to clinical information. Results All MPI studies in the 23 low likelihood patients were normal. In the remaining 52 patients using a stenosis severity>or=50%, global sensitivity and specificity, negative and positive predictive value for detection of CAD were 86, 100, 57, and 100%. Using a stenosis severity>or=70%, these values changed to 90, 83, 71, and 87%. Conclusion Adenosine stress Rb MPI using PET/CT with manual registration demonstrates diagnostic accuracy comparable with that of traditional PET MPI.

The introduction of positron emission/computed tomography (PET/CT) systems coupled with multidetector CT arrays has greatly increased the amount of clinical information in myocardial perfusion studies. The CT acquisition serves the dual role of providing high spatial anatomical detail and attenuation correction for PET. However, the differences between the interaction of respiratory and cardiac cycles in the CT and PET acquisitions presents a challenge when using the CT to determine PET attenuation correction. Three CT attenuation correction protocols were tested for their ability to produce accurate emission images: gated, a step mode acquisition covering the diastolic heart phase; normal, a high-pitch helical CT; and slow, a low-pitch, low-temporal-resolution helical CT. The amount of cardiac tissue in the emission image that overlaid lung tissue in the transmission image was used as the measure of mismatch between acquisitions. Phantom studies simulating misalignment of the heart between the transmission and emission sequences were used to correlate the amount of mismatch with the artificial defect changes in the emission image. Consecutive patients were studied prospectively with either paired gated (diastolic phase, 120 kVp, 280 mA, 2.6 s) and slow CT (0.562:1 pitch, 120 kVp, Auto-mA, 16 s) or paired normal (0.938:1 pitch, 120 kVp, Auto-mA,more » 4.8 s) and slow CT protocols, prior to a Rb-82 perfusion study. To determine the amount of mismatch, the transmission and emission images were converted to binary representations of attenuating tissue and cardiac tissue and overlaid using their native registration. The number of cardiac tissue pixels from the emission image present in the CT lung field yielded the magnitude of misalignment represented in terms of volume, of where a small volume indicates better registration. Acquiring a slow CT improved registration between the transmission and emission acquisitions compared to the gated and normal CT protocols. The volume of PET cardiac tissue in the CT lung field was significantly lower (p

Cardiac resynchronization therapy (CRT) is approved for the treatment of patients with advanced systolic heart failure and evidence of dyssynchrony on electrocardiograms. However, a significant percentage of patients do not demonstrate improvement with CRT. Echocardiographic techniques have been used for more accurate determination of dyssynchrony. Single photon emission computed tomography (SPECT) myocardial perfusion imaging has not previously been used to evaluate cardiac dyssynchrony. The objective of this study is to evaluate mechanical dyssynchrony as described by phase analysis of gated SPECT images in patients with left ventricular dysfunction, conduction delays, and ventricular paced rhythms.A novel count-based method is used to extract regional systolic wall thickening amplitude and phase from gated SPECT images. Five indices describing the phase dispersion of the onset of mechanical contraction are determined: peak phase, phase SD, bandwidth, skewness, and kurtosis. These indices were determined in consecutive patients with left ventricular dysfunction (n = 120), left bundle branch block (n = 33), right bundle branch block (n = 19), and ventricular paced rhythms (n = 23) and were compared with normal control subjects (n = 157). Phase SD, bandwidth, skewness, and kurtosis were significantly different between patients with left ventricular dysfunction, left bundle branch block, right bundle branch block, and ventricular paced rhythms and normal control subjects (all P.001) Peak phase was significantly different between patients with right ventricular paced rhythms and normal control subjects (P = .001).A novel SPECT technique for describing left ventricular mechanical dyssynchrony has been developed and may prove useful in the evaluation of patients for CRT.

Os modelos de Regressão Linear Multivariada apesar de serem pouco utilizados são muito úteis pois, dentre outras vantagens, permitem a construçãoo de modelos considerando estruturas de correlação entre medidas tomadas na mesma ou em distintas unidades amostrais. Neste trabalho apresentamos os métodos de estimação dos parâmetros, medidas para análise de diagnóstico, procedimentos de seleção de variáveis e uma aplicação dessa técnica de modelagem em um conjunto de dados reais. Multivariate Linear Regression Models are not frequently used although they are very useful. Working with this kind of model, it is possible to analyse correlated response variables jointly. In this dissertation, we dedicate initially to describe the inferencial methods in Multivariate Linear Regression models. Further, we describe some measures of diagnostics and methods of variable selection in this model. Finally, some of the describe procedures are applied in a real data set.

Ischemic heart disease (IHD) is the leading cause of death in women. Women present with coronary artery disease later in life than men, with greater number of risk factors and higher rate of angina. Women have higher mortality compared with age-matched men despite having less anatomical coronary artery disease. Distinct pathophysiologies are thought to account for sex-related differences in the presentation and prognosis of IHD. More women than men have chest pain secondary to coronary reactivity, microvascular dysfunction, and plaque erosion with distal microembolization. Sex-related factors such as lower exercise capacity, less specific ST-segment electrocardiographic changes, smaller left ventricular size, and breast attenuation can complicate the diagnosis of IHD in women. These sex-specific factors should be considered before determining the appropriate test to be performed in a woman with suspected IHD. Technological advances in nuclear cardiology including attenuation correction and coronary flow reserve measurement by PET hold promise in optimizing the diagnosis and risk stratification of women with IHD.

Mental stress-induced (MSIMI) or physical stress-induced (PSIMI) myocardial ischemia portends a worse prognosis in patients with coronary artery disease (CAD). Vitamin D insufficiency is associated with adverse cardiovascular outcomes, but its relationship to myocardial ischemia remains unclear. We hypothesized that vitamin D insufficiency will be associated with a higher prevalence of myocardial ischemia in patients with CAD.In 255 patients with stable CAD, myocardial perfusion imaging was performed to assess ischemia in response to mental and physical stress protocols. Vitamin D insufficiency was defined as serum 25-hydroxyvitamin D [25(OH)D] levels below 30 ng/ml, collected on the day of stress testing.Mean (standard deviation) 25(OH)D level was 30.8 (12.8) ng/ml, and 139 (55%) patients had vitamin D insufficiency. MSIMI occurred in 30 (12%) patients and PSIMI in 67 (27%). Individuals with MSIMI had significantly lower levels of 25(OH)D as compared with those without MSIMI (24.0 [8.6] versus 31.7 [12.9], p = .002). The prevalence of MSIMI was higher in those with as compared with those without vitamin D insufficiency (17% versus 6%, p = .009). Moreover, low 25(OH)D levels remained independently associated with MSIMI after adjusting for potential confounders. Conversely, 25(OH)D levels were similar between those with or without PSIMI (29.8 [13.0] versus 31.4 [12.7], p = .37), as was the prevalence of PSIMI in those with or without vitamin D insufficiency (29% versus 24%, p = .42).Vitamin D insufficiency is associated with a higher prevalence of MSIMI but not PSIMI among stable patients with CAD. Whether this association serves as a potential mechanism linking low vitamin D status to adverse cardiovascular outcomes warrants further investigation.

We hypothesized that zero calcium score (ZCS) would predict normal myocardial perfusion SPECT in patients with end stage renal disease (ESRD) undergoing evaluation for renal transplant. We enrolled 354 consecutive patients (65% men, mean age 52 ± 11 years) without known coronary artery disease

OBJETIVO: Comparar a letalidade hospitalar (LH) de homens e mulheres submetidos a angioplastia transluminal coronária primária (ATCP) como estratégia de reperfusão no infarto agudo do miocárdio (IAM). MÉTODOS: Estudo de coorte retrospectivo baseado em informações de prontuários médicos de pacientes hospitalizados devido a IAM em hospital de referência para doença coronária, utilizando preferencialmente a ATCP como técnica de reperfusão miocárdica precoce. Foram incluídos 83 pacientes, 35 (42%) mulheres e 48 (58%) homens, que preencheram critérios para reperfusão miocárdica precoce. RESULTADOS: A média de idade das mulheres foi superior a dos homens (66±10 vs 58±11 anos; p

Background Mental stress–induced myocardial ischemia ( MSIMI ) is associated with adverse prognosis in patients with coronary artery disease ( CAD ), yet the mechanisms underlying this phenomenon remain unclear. We hypothesized that compared with exercise/pharmacological stress–induced myocardial ischemia ( PSIMI ) that is secondary to the atherosclerotic burden of CAD , MSIMI is primarily due to vasomotor changes. Methods and Results Patients with angiographically documented CAD underwent 99m Tc‐sestamibi myocardial perfusion imaging at rest and following both mental and physical stress testing, performed on separate days. The severity and extent of CAD were quantified using the Gensini and Sullivan scores. Peripheral arterial tonometry (Itamar Inc) was used to assess the digital microvascular tone during mental stress as a ratio of pulse wave amplitude during speech compared with baseline. Measurements were made in a discovery sample (n=225) and verified in a replication sample (n=159). In the pooled (n=384) sample, CAD severity and extent scores were not significantly different between those with and without MSIMI , whereas they were greater in those with compared with those without PSIMI ( P peripheral arterial tonometry ratio was lower in those with compared with those without MSIMI (0.55±0.36 versus 0.76±0.52, P =0.009). In a multivariable analysis, the peripheral arterial tonometry ratio was the only independent predictor of MSIMI ( P =0.009), whereas angiographic severity and extent of CAD independently predicted PSIMI . Conclusions The degree of digital microvascular constriction, and not the angiographic burden of CAD , is associated with MSIMI . Varying causes of MSIMI compared with PSIMI may require different therapeutic interventions that require further study.

Myocardial perfusion imaging (MPI) using nuclear cardiology techniques has been widely applied in clinical practice because of its well-documented value in the diagnosis and prognosis of coronary artery disease. Industry has developed innovative designs for dedicated cardiac SPECT cameras that constrain the entire detector area to imaging just the heart. New software that recovers image resolution and limits image noise has also been implemented. These SPECT innovations are resulting in shortened study times or reduced radiation doses to patients, promoting easier scheduling, higher patient satisfaction, and, importantly, higher image quality. This article describes these cardiocentric SPECT software and hardware innovations, which provide a strong foundation for the continued success of myocardial perfusion SPECT.

Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-10Bitstream added on 2014-06-13T19:46:38Z : No. of bitstreams: 1 silva_fe_dr_guara.pdf: 4813239 bytes, checksum: 7b1a8a775c16ce46ca6ecfe04355f872 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Companhia Siderurgica de Tubarao Somente com a melhoria do processo de produção e a com a utilização consciente da energia por parte da população é que se conseguirá atingir êxito de acordo com os objetivos referentes ao seu uso racional. Para isso, faz-se necessário que professores sejam orientados a tratar os conhecimentos sobre energia a partir da ótica científica e tecnológica em suas aulas. Estudos apontam que utilizar recursos didáticos que possibilitem a contextualização do conteúdo transmitido com o uso de exemplos do cotidiano é a forma eficiente de se promover conhecimento. Indo mais além, é possível delinear uma mudança de comportamento que promova uma postura pró-eficiência energética. Neste sentido, a presente tese tem como objetivo pesquisar, desenvolver e testar uma proposta de intervenção educacional no tratamento da temática “Educação em Energia e Eficiência Energética” para professores do Ensino Fundamental. Em se tratando de métodos de abordagem, os procedimentos utilizados basearam-se em técnicas referenciadas na pesquisa-ação, que possibilitaram ao pesquisador intervir e testar possíveis soluções para o problema. Uma série de atividades foram desenvolvidas, incluindo uma formação complementar de professores, elaboração de materiais didáticos e formas de intervenção e conscientização de alunos, todas elas norteadas segundo critérios da metodologia da Aprendizagem Baseada em Projetos. Estas ações foram pautadas na conscientização do grupo estudado sobre os problemas atuais que a sociedade está enfrentando e a urgente necessidade de se praticar o uso racional de energia. O resultado final mostrou que é viável realizar uma ampla campanha de divulgação sistematizada sobre o tema no Ensino Básico, despertar o interesse de professores e alunos e, ainda, atingir metas de redução de consumo em longo prazo It is certainly true that only through the improvement of the production process and the conscious use by the population will make it possible to achieve goals concerning the rational use of energy. It is necessary that teachers are instructed to deal with knowledge about energy from the scientific and technological point of view along their lessons. Studies point that using instructional resources that make the knowledge contextualization possible by including examples of daily life is an efficient form of transmitting knowledge. Furthermore, it is possible to outline the behavior change that promotes a proactive stance on energy efficiency. In this sense, this thesis goal is to research, develop and test an educational intervention proposal in the thematic treatment of Energy Education and Energy Efficiency for teachers of elementary school. When it comes to methods of approach, the procedures used were based on techniques referenced in action research that enable the researcher to intervene and to test possible solutions for the problem. A series of activities were developed, including complementary training of teachers, elaboration of didactic materials, forms of assistance and awareness of students, and all of them were oriented according to the Problem-Based Learning. These actions were based on the awareness of the studied group about the current problems that modern society is experiencing and the urgent need to practice the rational use of energy. The final result showed that it is feasible to conduct a broad campaign of systematized disclosure on the topic to arouse the interest of teachers and students and still achieve aims of consumption reduction in the long term

Left ventricular dyssynchrony is an adverse consequence of ST-elevation myocardial infarction (STEMI) and bears an unfavorable prognosis. Mechanical dyssynchrony as measured by phase analysis from gated single photon emission computed tomography (GSPECT) correlates well with other imaging methods of assessing dyssynchrony but has not been studied in STEMI. We hypothesized that systolic dyssynchrony as measured by GSPECT would correlate with adverse remodeling after STEMI. In 28 subjects suffering STEMI, GSPECT with technetium-99m sestamibi was performed immediately after presentation (day 5) and remotely (6 months). Parameters of left ventricular dyssynchrony (QRS width, histogram bandwidth (HBW) and phase standard deviation (PSD)) were measured from GSPECT using the Emory Cardiac Toolbox. Left ventricular volumes, ejection fraction (LVEF) and infarct size were also assessed. After successful primary percutaneous coronary intervention to the infarct-related artery, subjects had an LVEF of 46.4% ± 11% and a resting perfusion defect of 27.4% ± 16% at baseline. Baseline QRS width was normal (91.5 ± 17.5 ms). Subjects with STEMI had dyssynchrony compared with a cohort of 22 normal subjects (age 57.2 ± 10.6 years

In a subanalysis of the CORE64 (Coronary Evaluation Using Multi-Detector Spiral Computed Tomography Angiography Using 64 Detectors) study, Gottlieb et al. ([1][1]) evaluated whether absent coronary artery calcium (CAC) could exclude obstructive coronary stenosis in patients referred for conventional

Background The objective of the study was to determine whether the effects of infarct-related artery (IRA) infusion of autologous bone marrow–derived CD34 + cells after ST elevation myocardial infarction (STEMI) are dependent on the dose (quantity and mobility) of the cells infused. Beneficial effects of IRA infusion of mononuclear cells after STEMI have been inconsistent, possibly because of differences in timing, cell type, quantity, and mobility of infused cells. Methods Patients were randomized to bone marrow harvest (n = 16) or control (n = 15). At a median of 8.3 days after coronary stenting for STEMI, CD34 + cells were infused via the IRA at 3 dose levels (5, 10, and 15 × 10 6 ) in cohorts of 5 patients each. Baseline and follow-up imaging and ex vivo CD34 + cell mobility were performed. Results Cell harvest and infusion were safe. Quantitative rest hypoperfusion score measured by single-photon emission computed tomography improved at 6 months in the ≥10 million cohorts compared with controls (−256 vs +14, P = .02). There was a trend toward improved ejection fraction at 6 months (+4.5%) in the ≥10 million cohorts compared with no change in the controls and 5 million cohort (+0.7%). Improved perfusion and infarct size reduction correlated with the quantity and mobility of the infused CD34 + cells. Conclusions The effects of CD34 + cell IRA infusion during the repair phase after STEMI are dose dependent and, at a threshold dose of 10 million CD34 + cells, associated with a significant improvement in perfusion that may limit deterioration in cardiac function (IRA infusion of CD34 + cells in patients with acute myocardial infarction [AMR-01] NCT00313339).

PET/CT perfusion studies suffer from artifacts caused by misalignment of transmission and emission data due to contractile cardiac and respiratory motion. This study investigates whether substantial differences exist between two respiration-averaging approaches for attenuation correction (AC): low-pitch helical (HCT) and time-averaged CT (ACT). Fifty-four consecutive patients received paired HCT (0.45 pitch, 120 kVp, 76 mA, 24 x 1.2 mm collimated slice width, 1 s gantry rotation time, 4.93 mGy CTDI) and ACT (sequence mode: 6.1 s acq/bed, 80 kVp, 13 mA, 24 x 1.2 mm collimated slice width, 5.53 mGy CTDI) AC scans under free-breathing prior to Rb-82 rest/adenosine stress. Mismatch between the emission and paired transmission data was compared by calculating the volume of myocardial uptake overlying the left CT lung field. Data were then reconstructed with the CT AC scans and normalized to injected dose and bodyweight. Paired rest and paired stress PET images were reoriented identically along the short axis and sampled into a 17-segment polar map for comparison. The ratio of HCT-PET and ACT-PET polar maps at rest and stress was calculated and grouped by segment for all patients. 95% confidence intervals were calculated to compare changes in the polar map ratios between the two AC methods. No significant difference was observed between the HCT and ACT overlying volume in the rest or stress emission data. 68% of the patients presented visual respiratory artifacts in the HCT images compared to 32% in the ACT. That 23% of the ACT images presented with photon starvation artifacts and increasing BMI was a significant indicator for the occurrence of photon starvation in the ACT AC scans (p0.001). The ratio of the reconstructed PET polar segment data showed good agreement between AC methods with 95% confidence intervals ranging from 0.92 to 1.07 in the rest data and 0.93 to 1.07 in the stress data segments. Bias, calculated by averaging the polar segment ratios, showed 1% higher values in the ACT-PET rest reconstructions compared to the HCT-PET rest reconstructions and no measurable bias in the stress reconstructions. This study shows good agreement and negligible bias between low-pitch HCT and ACT protocols for attenuation correction of cardiac PET data.

An increasing number of nuclear cardiology labo-ratories, including ours, image all of their myocardialperfusion SPECT patients using attenuation correction(AC). When compared to non-AC, AC studies generateimages with increased linearity between tracer uptakeand reconstructed counts yielding increased perfusiondefect contrast.

OBJECTIVES This study was performed to determine the prognostic performance of quantitative PET tools in the stratification of patients with ischemic cardiomyopathy undergoing myocardial viability assessment. METHODS We applied four different quantitative tools to 104 consecutive patients with coronary artery disease and previous myocardial infarction who had undergone rest Rb/gated F-fluorodeoxyglucose (FDG) PET, to assess myocardial viability for potential revascularization. One of these tools was based on the FDG study alone and the other three tools assessed the extent of match/mismatch defects using FDG in comparison with a perfusion reference database. The four quantitative tools used in this research to define viability were (i) FDG alone, which calculates the percentage of left ventricular myocardium (LVM) that is above the 50% of the maximum LVM FDG counts, (ii) low flow match/mismatch, which determines the area with a 5% increase in normalized FDG counts in relation to defined resting perfusion defects as compared with a reference database, (iii) all regions match/mismatch, which computes the area with a 10% increase in normalized FDG counts in relation to the left ventricle resting perfusion distribution, and (iv) percentage max FDG match/mismatch, which defines the area with FDG uptake greater than 60% of the maximum LVM FDG counts within defined perfusion defects as determined by the reference database. The primary endpoint for this analysis was cardiac death. RESULTS During the follow-up period (22+/-14 months), 19 patients (18%) died; in 17 of these the cause of death was cardiac. Using univariate analysis, none of the methods were predictive of cardiac death. Receiver operating characteristic analysis defined the optimal thresholds for the extent of myocardial viability for the four tools in the prediction of cardiac death: FDG alone=20%, low flow match/mismatch=15%, all regions match/mismatch=35%, and percentage max FDG match/mismatch=20%. A censored survival analysis using a Kaplan-Meier method showed a statistically significant difference between patients with cardiac death and those with no cardiac death using only the low flow match/mismatch (hazard ratio=0.29, P=0.01) and percentage max FDG match/mismatch criteria (hazard ratio=0.23, P=0.005) tools. CONCLUSION The low flow match/mismatch and percentage max FDG match/mismatch quantitative PET tools are useful for prognostic stratification of patients with ischemic cardiomyopathy undergoing myocardial viability assessment.

We evaluated the incremental diagnostic value of fusion images of coronary computed tomography angiography (CTA) and myocardial perfusion imaging (MPI) over MPI alone or MPI and CTA side-by-side to identify obstructive coronary artery disease (CAD > 50% stenosis) using invasive coronary angiography (ICA) as the gold standard. 50 subjects (36 men; 56 ± 11 years old) underwent rest-stress MPI and CTA within 12-26 days of each other. CTAs were performed with multi-detector CT-scanners (31 on 64-slice; and 19 on 16-slice). 37 patients underwent ICA while 13 subjects did not because of low (

Background The use of Rb positron emission tomography (PET) for the diagnosis of coronary artery disease (CAD) has increased in recent years but the role of some of the traditional parameters used in SPECT for the diagnosis of CAD, such as transient ischaemic dilation index (TID) of the left ventricle, have not been validated in PET studies. Methods and results We studied 95 patients who had undergone rest/pharmacological stress Rb PET scans. Thirty of these patients (18 female and 12 male) who had less than 5% likelihood of CAD (LLK) based on sequential Bayesian analysis, were used to determine the normal limits of TID index in this protocol. The remaining 65 patients (33 female and 32 male) underwent coronary angiography within 15 days of the cardiac PET scan. This second group of patients was used to validate the TID normal limits determined in the first group. In LLK patients mean TID index was 1.01+/-0.07 and there were no significant differences between genders. The TID index upper normal limit was 1.15 and was calculated as mean+2 SD. Using this cut-off point, TID index had high specificity and PPV in the diagnosis of single vessel CAD (100% and 100% respectively) and multiple vessel CAD (93% and 85%, respectively). Conclusion Our results indicate that elevated TID index is a specific, although not sensitive marker of single and multiple vessel CAD in pharmacologically stressed Rb PET myocardial perfusion studies.

The introduction of positron emission/computed tomography (PET/CT) systems coupled with multidetector CT arrays has greatly increased the amount of clinical information in myocardial perfusion studies. The CT acquisition serves the dual role of providing high spatial anatomical detail and attenuation correction for PET. However, the differences between the interaction of respiratory and cardiac cycles in the CT and PET acquisitions presents a challenge when using the CT to determine PET attenuation correction. Three CT attenuation correction protocols were tested for their ability to produce accurate emission images: gated, a step mode acquisition covering the diastolic heart phase; normal, a high-pitch helical CT; and slow, a low-pitch, low-temporal-resolution helical CT. The amount of cardiac tissue in the emission image that overlaid lung tissue in the transmission image was used as the measure of mismatch between acquisitions. Phantom studies simulating misalignment of the heart between the transmission and emission sequences were used to correlate the amount of mismatch with the artificial defect changes in the emission image. Consecutive patients were studied prospectively with either paired gated (diastolic phase, 120 kVp, 280 mA, 2.6 s) and slow CT (0.562:1 pitch, 120 kVp, Auto-mA, 16 s) or paired normal (0.938:1 pitch, 120 kVp, Auto-mA, 4.8 s) and slow CT protocols, prior to a Rb-82 perfusion study. To determine the amount of mismatch, the transmission and emission images were converted to binary representations of attenuating tissue and cardiac tissue and overlaid using their native registration. The number of cardiac tissue pixels from the emission image present in the CT lung field yielded the magnitude of misalignment represented in terms of volume, of where a small volume indicates better registration. Acquiring a slow CT improved registration between the transmission and emission acquisitions compared to the gated and normal CT protocols. The volume of PET cardiac tissue in the CT lung field was significantly lower (p0.03) for the slow CT protocol in both the rest and stress emission studies. Phantom studies showed that an overlaying volume greater than 2.6 mL would produce significant artificial defects as determined by a quantitative software package that employs a normal database. The percentage of patient studies with overlaying volume greater than 2.6 mL was reduced from 71% with the normal CT protocol to 28% with the slow CT protocol. The remaining 28% exhibited artifacts consistent with heart drift and patient motion that could not be corrected by adjusting the CT acquisition protocol. The low pitch of the slow CT protocol provided the best match to the emission study and is recommended for attenuation correction in cardiac PET/CT studies. Further reduction in artifacts arising from cardiac drift is required and warrants an image registration solution.

We investigated the ability of coronary artery calcium (CAC) to predict a normal adenosine stress rubidium-82 (Rb-82) myocardial perfusion positron emission tomography (PET) in patients admitted to the chest pain unit. Eighty-four consecutive patients (33 men; mean age 62 +/- 14.8 years) with low to intermediate likelihood of coronary artery disease were included. A single noncontrast computed tomogram under shallow breathing was obtained for attenuation correction and to assess the presence of CAC. This was followed by a rest and adenosine stress dynamic Rb-82 emission PET. Computed tomography and PET images were interpreted independently. There was a high prevalence of risk factors (80% hypertension, 30% diabetes, 38% hypercholesterolemia, 13% smoking); prior coronary revascularization and myocardial infarction were present in 21% and 15% of the patients, respectively. The absence of CAC was associated with a normal adenosine stress Rb-82 myocardial perfusion PET in 34 of 34 patients, yielding a negative predictive value of 100%. The presence of CAC (50 of 84) was associated with a higher incidence of myocardial perfusion defects (13 of 50), yielding a positive predictive value of 26%. Sensitivity was 100% (13 of 13) and specificity was 48% (34 of 71). In conclusion, the absence of CAC is predictive of a normal adenosine stress Rb-82 myocardial perfusion PET in patients admitted to the chest pain unit. If these results are confirmed, myocardial perfusion imaging probably can be safely avoided in chest pain patients with negative CAC with low to intermediate pretest likelihood of disease. This approach may decrease overall radiation exposure and hospital time and prove to be cost effective.

The use of myocardial perfusion (82)Rb PET/CT studies continues to increase but its accuracy using database quantification methods for the diagnosis of coronary artery disease (CAD) has not been established.A sex-independent normal database and criteria for abnormality for rest-stress (82)Rb PET/CT myocardial perfusion imaging were developed and validated by evaluation of 281 patients (136 females: mean age +/- SD, 63.3 +/- 13.3 y; 145 males: mean age +/- SD, 63.9 +/- 12.8 y) who underwent a rest-adenosine stress (82)Rb PET/CT study. These patients were divided into 3 groups: (a) healthy group: 30 patients, with5% likelihood of CAD (low likelihood [LLK]) based on sequential Bayesian analysis; these patients were used to generate the normal distribution; (b) pilot group: 174 patients; these patients were used to determine the optimal criteria for detecting and localizing the perfusion abnormality; and (c) validation group: 76 patients (23 with LLK of CAD and 53 who underwent coronary angiography; these patients were used for prospective validation.Of the 53 patients who underwent coronary angiography, 8 had50% stenosis and 45 patients had at least one stenosisor =50% in one major artery. Fifteen patients had single-vessel disease, 17 had double-vessel disease, and 13 had triple-vessel disease. The prospective validation shows a normalcy rate of 78% (18/23) for global CAD. The analyses by individual arteries show a normalcy rate of 96% (22/23) for the left anterior descending coronary artery, 96% for the left circumflex coronary artery (22/23), and 100% for the right coronary artery (23/23). The overall sensitivity for detection of CAD (or =50% stenosis) was 93% (42/45). The overall specificity for detection of the absence of CAD (or =50% stenosis) was 75% (6/8). Also, the positive predictive value for global CAD was 95% (42/44), the negative predictive value was 67% (6/9), and the accuracy was 91% (48/53).The quantitative (82)Rb PET/CT database created and validated in this study is highly accurate for the detection and localization of CAD. Physicians should consider using the quantitative output of these algorithms as decision support tools to aid with image interpretation.

The 24-hour creatinine clearance is the standard clinical technique for measuring kidney function; however, this measurement is cumbersome and inconvenient for patients. We hypothesized that a camera-based technetium-99m mercaptoacetyltriglycine (MAG3) clearance obtained simultaneously with a standard MAG3 scan would correlate well with the 24-hour creatinine clearance and could serve as a simple marker of kidney function.Data were obtained from a retrospective analysis of 28 patients with varying degrees of kidney dysfunction and 85 subjects evaluated for kidney donation. The MAG3 clearance was calculated using a camera-based technique without blood or urine sampling. The creatinine clearance was measured using the plasma creatinine and a 24-hour urine collection. The MAG3 and creatinine clearances were corrected for body surface area, and clearance values in healthy subjects and patients were compared using the paired Student's t test. The linear association between the MAG3 and creatinine clearances was expressed by Pearson's correlation coefficient.The mean MAG3 clearance in the potential kidney donors was 321 +/- 95 mL/min/1.73 m2 (95% CI, 171-546 mL/min/1.73 m2), significantly higher than the mean creatinine clearance of 152 +/- 51 mL/min/1.73 m2 (79-278 mL/min/1.73 m2, p0.001). The mean MAG3 clearance in patients was 153 +/- 70 mL/min/1.73 m2 (32-316 mL/min/1.73 m2) and was also significantly higher than the mean creatinine clearance of 74 +/- 36 mL/min/1.73 m2 (21-138 mL/min/1.73 m2, p0.001). The ratio of the mean creatinine clearance to the mean MAG3 clearance was essentially the same for volunteers and patients, 0.47 and 0.48, respectively. The Pearson's correlation between the MAG3 and creatinine clearances was 0.80 (0.72-0.86).The camera-based 99mTc-MAG3 clearance correlates well with the 24-hour creatinine clearance and can provide a simple and convenient index of kidney function.

To compare computed tomography (CT) with positron emission tomography-CT (PET-CT) scans with respect to anorectal tumor volumes, correlation in overlap, and influence on radiation treatment fields and patient care.From March to November 2003, 20 patients with rectal cancer and 3 patients with anal cancer were treated with preoperative or definitive chemoradiation, respectively. Computed tomography simulation data generated a CT gross tumor volume (CT-GTV) and CT planning target volume (CT-PTV) and (18)F-fluoro-2-deoxy-glucose PET (FDG-PET) created a PET-GTV and PET-PTV. The PET-CT and CT images were fused using manual coregistration. Patients were treated with three-dimensional conformal therapy to traditional doses. The PET, CT, and overlap volumes (OVs) were measured in cubic centimeters.Mean PET-GTV was smaller than the mean CT-GTV (91.7 vs. 99.6 cm(3)). The mean OV was 46.7%. As tumor volume increased, PET and CT OV correlated significantly (p0.001). In 17% of patients PET-CT altered the PTV, and in 26% it changed the radiation treatment plan. For 25% of patients with rectal cancer, PET detected distant metastases and changed overall management. Ten rectal cancer patients underwent surgery. When the pretreatment PET standardized uptake value was10 and the posttreatment PET standardized uptake value was6, 100% achieved pathologic downstaging (p = 0.047).Variation in volume was significant, with 17% and 26% of patients requiring a change in treatment fields and patient management, respectively. Positron emission tomography can change the management for anorectal tumors by early detection of metastatic disease or disease outside standard radiation fields.

Transient ischemic dilation (TID) has been established as an important independent marker of severe and extensive coronary artery disease (CAD) in myocardial perfusion imaging (MPI). The accuracy of the TID index is dependent on a well-determined threshold (normal limits) between normal and abnormal values for each study protocol. To date, the effects of neither gender nor attenuation correction (AC) on TID normal limits have been established. Thus, the objectives of this study were to determine if AC processing changes the normal value of the TID index and if there were gender-related differences in the TID index of normal patients who had undergone rest/exercise-stress technetium-99m sestamibi MPI.Seventy-five patients (33 women, 42 men; mean age, 57.7 +/- 11.7 y and 55.9 +/- 10.0 y, respectively) with less than a 5% likelihood of CAD, who had undergone low-dose rest/high-dose exercise-stress Tc-99m sestamibi MPI, were studied. All studies were acquired using simultaneous emission/transmission scans and were corrected for attenuation, scatter, and resolution effects using the ExSPECT II method. Both the AC and non-AC studies were analyzed using the Emory Cardiac Toolbox (ECTb; Syntermed, Inc, Atlanta, Ga) quantitative software. The TID index was calculated automatically as the ratio of stress mean left ventricular volumes to rest mean left ventricular volumes by ECTb. Patients were grouped by gender and the TID indices from AC and non-AC studies were compared. Linear regressions of the TID index and body mass index were analyzed to exclude differences in body size between male and female patients as a confounding factor in gender-related differences in TID. The TID index upper normal limits were calculated as the mean value plus 2 standard deviations (SDs). AC processing did not change the TID index significantly whether the genders were combined or separated (AC TID = 0.97 +/- 0.14 vs non-AC TID = 0.98 +/- 0.12 for all patients). Female patients showed higher mean TID indices than male patients in both AC (1.01 +/- 0.15 vs 0.95 +/- 0.12) and non-AC studies (1.00 +/- 0.15 vs. 0.97 +/- 0.10), but this difference was statistically significant only in AC studies (p = .03). TID indices remained constant across the range of body mass index studied. The TID index upper normal limit was 1.31 for female and 1.18 for male patients.TID normal values for rest/exercise-stress Tc-99m sestamibi MPI are gender-dependent and not affected by AC processing. Thus, diagnosticians should take into account these gender-related differences, as compared with the traditional value generated from mostly male populations, to ensure both men and women have the same overall accuracy of using the TID index in the diagnosis and prognosis of CAD.