RESUMO
BACKGROUND: 18F-Flurpiridaz is a promising investigational radiotracer for PET myocardial perfusion imaging with favorable properties for quantification of myocardial blood flow (MBF). We sought to validate the incremental diagnostic value of absolute MBF quantification in a large multicenter trial against quantitative coronary angiography. METHODS: We retrospectively analyzed a subset of patients (N = 231) from the first phase 3 flurpiridaz trial (NCT01347710). Dynamic PET data at rest and pharmacologic stress were fit to a previously validated 2-tissue-compartment model. Absolute MBF and myocardial flow reserve (MFR) were compared with coronary artery disease severity quantified by invasive coronary angiography on a per-patient and per-vessel basis. RESULTS: Stress MBF per-vessel accurately identified obstructive disease (c-index 0.79) and progressively declined with increasing stenosis severity (2.35 ± 0.71 in patients without CAD; 1.92 ± 0.49 in non-obstructed territories of CAD patients; and 1.54 ± 0.50 in diseased territories, P < 0.05). MFR similarly declined with increasing stenosis severity (3.03 ± 0.94; 2.69 ± 0.95; and 2.33 ± 0.86, respectively, P < 0.05). In multivariable logistic regression modeling, stress MBF and MFR provided incremental diagnostic value beyond patient characteristics and relative perfusion analysis. CONCLUSIONS: Clinical myocardial blood flow measurement with 18F-flurpiridaz cardiac PET shows promise for routine application.
Assuntos
Doença da Artéria Coronariana/diagnóstico por imagem , Imagem de Perfusão do Miocárdio , Tomografia por Emissão de Pósitrons , Piridazinas , Idoso , Angiografia Coronária , Doença da Artéria Coronariana/fisiopatologia , Feminino , Reserva Fracionada de Fluxo Miocárdico , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Estudos Retrospectivos , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Although N13-ammonia has favorable properties among FDA approved radiotracers, complexity of implementation has limited its use. We describe the initial patient experience of N13-ammonia PET imaging using a compact N13-ammonia production system. METHODS: N13 was produced using the ION-12SC, a 12MeV, 10uA superconducting minimally shielded cyclotron, and reduced to N13-ammonia in an automated multi-use purification unit. Patients were power injected with 9.3 ± 1.1 mCi (344.1 ± 40.7 MBq) of N13-ammonia for rest imaging, and 18.8 ± 0.9 mCi (695.6 ± 33.3 MBq) of N13-ammonia was injected at peak hyperemia for stress testing. Images were interpreted for relative perfusion, left ventricular volumes/function, blood flow quantification, and scored for image quality. RESULTS: In total 97 patients underwent 98 N13-ammonia PET scans (32 rest only/65 rest-stress/1 stress only). Image quality was 91.8% good or excellent. None were poor/non-diagnostic. Study durations were acceptable. Tracer related radiation dosimetry to patients was 0.7 ± 0.1 mSv (rest only), and 2.1 ± 0.1 mSv (rest-stress). CONCLUSION: Clinical N13-ammonia production by the Ionetix ION-12SC delivers high quality myocardial PET perfusion images in a rapid protocol.
Assuntos
Amônia , Doença da Artéria Coronariana/diagnóstico por imagem , Imagem de Perfusão do Miocárdio , Radioisótopos de Nitrogênio , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Idoso , Ciclotrons , Composição de Medicamentos/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , SupercondutividadeRESUMO
BACKGROUND: With appropriate protocols, F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) can visualize myocardial inflammation. Optimal protocols and normative myocardial FDG uptake values are not well-established. METHODS: We evaluated 111 patients referred for inflammation cardiac FDG PET/CT. Patients followed a low-carbohydrate, high-fat diet for 36 hours before imaging and received unfractionated heparin. Glucose and fatty acid metabolism biomarkers were obtained. Mean blood pool and maximum myocardial uptake (SUVmean, SUVmax) were measured, avoiding areas of abnormal FDG uptake or spillover. RESULTS: Adequate suppression of myocardial FDG uptake occurred in 95% of patients (n = 106). Myocardial SUVmax was significantly below background blood pool SUVmean: septal myocardial to blood pool ratio 0.75 (95% CI 0.73-0.77; P < 0.001); lateral myocardial to blood pool ratio 0.70 (95% CI 0.68-0.72; P < 0.001). Glucose, insulin, and C-peptide correlated to blood pool SUVmean (Spearman rs = 0.39, P < 0.01; rs = 0.40, P < 0.01; rs = 0.35, P < 0.01) and myocardial SUVmax (Spearman rs = 0.31, P < 0.01; rs = 0.31, P < 0.01; rs = 0.26, P < 0.01). Fatty acid metabolism biomarkers did not correlate to myocardial SUVmax. CONCLUSIONS: Patients following intensive metabolic preparation have myocardial FDG SUVmax below background SUVmean. Biomarkers of glucose metabolism modestly correlate to FDG uptake.
Assuntos
Fluordesoxiglucose F18 , Glucose/metabolismo , Coração/diagnóstico por imagem , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Idoso , Biomarcadores/metabolismo , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Inflamação , Masculino , Pessoa de Meia-Idade , Miocárdio/metabolismo , Peptídeos/química , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Estudos RetrospectivosRESUMO
BACKGROUND: Clinical use of myocardial blood flow (MBF) and flow reserve (MFR) is increasing. Motion correction is necessary to obtain accurate results but can introduce variability when performed manually. We sought to reduce that variability with an automated motion-correction algorithm. METHODS: A blinded randomized controlled trial of two technologists was performed on the motion correction of 100 dynamic 82Rb patient studies comparing manual motion correction with manual review and adjustment of automated motion correction. Inter-rater variability between technologists for MBF and MFR was the primary outcome with comparison made by analysis of the limits of agreement. Processing time was the secondary outcome. RESULTS: Limits of agreements between the two technologists decreased significantly for both MBF and MFR, going from [- 0.22, 0.22] mL/min/g and [- 0.31, 0.36] to [- 0.12, 0.15] mL/min/g and [- 0.15, 0.18], respectively (both P < .002). In addition, the average time spent on motion correcting decreased by 1 min per study from 5:21 to 4:21 min (P = .001). CONCLUSIONS: In this randomized controlled trial, the use of automated motion correction significantly decreased inter-user variability and reduced processing time.
Assuntos
Circulação Coronária/fisiologia , Imagem de Perfusão do Miocárdio/métodos , Radioisótopos de Rubídio , Adulto , Idoso , Feminino , Reserva Fracionada de Fluxo Miocárdico/fisiologia , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Patient motion can lead to misalignment of left ventricular (LV) volumes-of-interest (VOIs) and subsequently inaccurate quantification of myocardial blood flow (MBF) and flow reserve (MFR) from dynamic PET myocardial perfusion images. We aimed to develop an image-based 3D-automated motion-correction algorithm that corrects the full dynamic sequence for translational motion, especially in the early blood phase frames (~ first minute) where the injected tracer activity is transitioning from the blood pool to the myocardium and where conventional image registration algorithms have had limited success. METHODS: We studied 225 consecutive patients who underwent dynamic rest/stress rubidium-82 chloride (82Rb) PET imaging. Dynamic image series consisting of 30 frames were reconstructed with frame durations ranging from 5 to 80 seconds. An automated algorithm localized the RV and LV blood pools in space and time and then registered each frame to a tissue reference image volume using normalized gradient fields with a modification of a signed distance function. The computed shifts and their global and regional flow estimates were compared to those of reference shifts that were assessed by three physician readers. RESULTS: The automated motion-correction shifts were within 5 mm of the manual motion-correction shifts across the entire sequence. The automated and manual motion-correction global MBF values had excellent linear agreement (R = 0.99, y = 0.97x + 0.06). Uncorrected flows outside of the limits of agreement with the manual motion-corrected flows were brought into agreement in 90% of the cases for global MBF and in 87% of the cases for global MFR. The limits of agreement for stress MBF were also reduced twofold globally and by fourfold in the RCA territory. CONCLUSIONS: An image-based, automated motion-correction algorithm for dynamic PET across the entire dynamic sequence using normalized gradient fields matched the results of manual motion correction in reducing bias and variance in MBF and MFR, particularly in the RCA territory.
Assuntos
Circulação Coronária/fisiologia , Processamento de Imagem Assistida por Computador/métodos , Imagem de Perfusão do Miocárdio/métodos , Tomografia por Emissão de Pósitrons/métodos , Radioisótopos de Rubídio , Idoso , Algoritmos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Movimento (Física) , Reconhecimento Automatizado de Padrão , Rubídio , SoftwareRESUMO
BACKGROUND: Left atrial (LA) remodeling is associated with structural, electric, and metabolic LA changes. Integrated evaluation of these features in vivo is lacking. METHODS: Patients undergoing 18F-fluorodeoxyglucose (FDG) PET-CT during a hyperinsulinemic-euglycemic clamp were classified into sinus rhythm (SR), paroxysmal AF (PAF), and persistent AF (PerAF). The LA was semiautomatically segmented, and global FDG uptake was quantified using standardized uptake values (SUVmax and SUVmean) in gated, attenuation-corrected images and normalized to LA blood pool activity. Regression was used to relate FDG data to AF burden and critical patient factors. Continuous variables were compared using t-tests or Mann-Whitney tests. RESULTS: 117 patients were included (76% men, age 66.4 ± 11.0, ejection fraction (EF) 25[22-35]%) including those with SR (n = 48), PAF (n = 55), and PerAF (n = 14). Patients with any AF had increased SUVmean (2.3[1.5-2.4] vs 2.0[1.5-2.5], P = 0.006), SUVmax (4.4[2.8-6.7] vs 3.2[2.3-4.3], P < 0.001), uptake coefficient of variation (CoV) 0.28[0.22-0.40] vs 0.25[0.2-0.33], P < 0.001), and hypometabolic scar (32%[14%-53%] vs 16.5%[0%-38.5%], P = 0.01). AF burden correlated with increased SUVmean, SUVmax, CoV, and scar independent of age, gender, EF, or LA size (P < 0.03 for all). CONCLUSIONS: LA structure and metabolism can be assessed using FDG PET/CT. Greater AF burden correlates with the increased LA metabolism and scar.
Assuntos
Remodelamento Atrial/fisiologia , Técnicas de Imagem Cardíaca/métodos , Fluordesoxiglucose F18 , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Compostos Radiofarmacêuticos , Idoso , Idoso de 80 Anos ou mais , Fibrilação Atrial/metabolismo , Feminino , Fluordesoxiglucose F18/farmacocinética , Átrios do Coração/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Projetos PilotoRESUMO
OBJECTIVES: We sought to determine the safety of regadenoson (REG) stress testing in patients who have undergone orthotopic heart transplantation (OHT). BACKGROUND: Routine screening for cardiac allograft vasculopathy (CAV) is necessary after OHT. Adenosine stress is contraindicated after heart transplantation due to supersensitivity in denervated hearts. Safety of regadenoson stress following OHT has not been well studied. METHODS: We retrospectively reviewed data from OHT patients (N = 123) who were referred to REG stress testing. Medical records were reviewed to determine hemodynamic and ECG response to regadenoson and to identify adverse reactions. RESULTS: No serious adverse events occurred. No life-threatening arrhythmias or hemodynamic changes occurred. Common side-effects related to regadenoson were observed, dyspnea being the most frequent (66.7%). On average the heart rate rose from 82.8 ± 12 to 95.7 ± 13.4 bpm (P < 0.001), systolic blood pressure decreased from 138.7 ± 20.9 to 115.9 ± 23.9 mmHg (P < 0.001) and mean arterial pressure decreased from 103.5 ± 14.1 to 84.72 ± 15.90 mmHg (P < 0.001) during stress protocol. There was no sustained ventricular tachycardia, ventricular fibrillation, or second-or third-degree atrioventricular block. CONCLUSION: Regadenoson stress testing appears to be well tolerated and safe in OHT patients.
Assuntos
Teste de Esforço/métodos , Transplante de Coração/métodos , Tomografia por Emissão de Pósitrons/métodos , Purinas , Pirazóis , Adenosina/metabolismo , Idoso , Pressão Sanguínea , Eletrocardiografia , Feminino , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade , Imagem de Perfusão do Miocárdio/métodos , Segurança do Paciente , Estudos Retrospectivos , Fatores de Risco , Estresse Mecânico , Transplantados , Doenças Vasculares/complicações , Doenças Vasculares/diagnóstico por imagemRESUMO
BACKGROUND: Patient motion can lead to misalignment of left ventricular volumes of interest and subsequently inaccurate quantification of myocardial blood flow (MBF) and flow reserve (MFR) from dynamic PET myocardial perfusion images. We aimed to identify the prevalence of patient motion in both blood and tissue phases and analyze the effects of this motion on MBF and MFR estimates. METHODS: We selected 225 consecutive patients that underwent dynamic stress/rest rubidium-82 chloride (82Rb) PET imaging. Dynamic image series were iteratively reconstructed with 5- to 10-second frame durations over the first 2 minutes for the blood phase and 10 to 80 seconds for the tissue phase. Motion shifts were assessed by 3 physician readers from the dynamic series and analyzed for frequency, magnitude, time, and direction of motion. The effects of this motion isolated in time, direction, and magnitude on global and regional MBF and MFR estimates were evaluated. Flow estimates derived from the motion corrected images were used as the error references. RESULTS: Mild to moderate motion (5-15 mm) was most prominent in the blood phase in 63% and 44% of the stress and rest studies, respectively. This motion was observed with frequencies of 75% in the septal and inferior directions for stress and 44% in the septal direction for rest. Images with blood phase isolated motion had mean global MBF and MFR errors of 2%-5%. Isolating blood phase motion in the inferior direction resulted in mean MBF and MFR errors of 29%-44% in the RCA territory. Flow errors due to tissue phase isolated motion were within 1%. CONCLUSIONS: Patient motion was most prevalent in the blood phase and MBF and MFR errors increased most substantially with motion in the inferior direction. Motion correction focused on these motions is needed to reduce MBF and MFR errors.
Assuntos
Coração/diagnóstico por imagem , Imagem de Perfusão do Miocárdio , Miocárdio/patologia , Tomografia por Emissão de Pósitrons , Idoso , Doença da Artéria Coronariana/diagnóstico por imagem , Circulação Coronária , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Movimento (Física) , Radioisótopos de RubídioRESUMO
BACKGROUND: 82Rb kinetics may distinguish scar from viable but dysfunctional (hibernating) myocardium. We sought to define the relationship between 82Rb kinetics and myocardial viability compared with conventional 82Rb and 18F-fluorodeoxyglucose (FDG) perfusion-metabolism PET imaging. METHODS: Consecutive patients (N = 120) referred for evaluation of myocardial viability prior to revascularization and normal volunteers (N = 37) were reviewed. Dynamic 82Rb 3D PET data were acquired at rest. 18F-FDG 3D PET data were acquired after metabolic preparation using a standardized hyperinsulinemic-euglycemic clamp. 82Rb kinetic parameters K1, k2, and partition coefficient (KP) were estimated by compartmental modeling RESULTS: Segmental 82Rb k2 and KP differed significantly between scarred and hibernating segments identified by Rb-FDG perfusion-metabolism (k2, 0.42 ± 0.25 vs. 0.22 ± 0.09 min-1; P < .0001; KP, 1.33 ± 0.62 vs. 2.25 ± 0.98 ml/g; P < .0001). As compared to Rb-FDG analysis, segmental Rb KP had a c-index, sensitivity and specificity of 0.809, 76% and 84%, respectively, for distinguishing hibernating and scarred segments. Segmental k2 performed similarly, but with lower specificity (75%, P < .001) CONCLUSIONS: In this pilot study, 82Rb kinetic parameters k2 and KP, which are readily estimated using a compartmental model commonly used for myocardial blood flow, reliably differentiated hibernating myocardium and scar. Further study is necessary to evaluate their clinical utility for predicting benefit after revascularization.
Assuntos
Cicatriz/diagnóstico por imagem , Fluordesoxiglucose F18 , Coração/diagnóstico por imagem , Miocárdio/patologia , Tomografia por Emissão de Pósitrons , Radioisótopos de Rubídio , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Imageamento Tridimensional , Insulina/metabolismo , Cinética , Masculino , Pessoa de Meia-Idade , Imagem de Perfusão do Miocárdio , Revascularização Miocárdica , Miocárdio Atordoado , Projetos Piloto , Estudos RetrospectivosRESUMO
BACKGROUND: Ischemia contributes to arrhythmogenesis though its role is incompletely understood. Abnormal myocardial perfusion measured by PET imaging may predict ventricular arrhythmias (VAs) in a high-risk population. METHODS: Patients with implantable cardiac defibrillators who had undergone rubidium-82 cardiac PET imaging were identified. Patients were stratified by median MBF and MFR values for analysis. The Cox proportional hazards model was used to assess the impact of myocardial perfusion on survival free of VT independent of critical covariates. RESULTS: A total of 159 patients (124 (78%) males, median age 65.9 years, IQR [56.76-72.63]) were followed for 1.43 years IQR [0.83-2.21]. VA occurred in 29 patients (23.7%). After adjustment for ejection fraction, age, and sex, impaired stress MBF was associated with an increased risk of VA (adjusted HR per ml/min/g 1.52, 95% CI (1.01-2.31), P = 0.04). Summed rest and stress scores were not predictive of VA. Among patients with severe LV dysfunction, stress MBF remained an independent predictor of VA (adjusted HR per 1 ml/min/g HR 1.69, 95% CI (1.03-11.36), P = 0.03), while residual EF, summed rest, and summed stress scores were not (P > 0.05). CONCLUSIONS: Impaired stress myocardial blood flow was associated with less survival free of ventricular arrhythmias.
Assuntos
Arritmias Cardíacas/diagnóstico por imagem , Circulação Coronária , Desfibriladores Implantáveis/efeitos adversos , Ventrículos do Coração/diagnóstico por imagem , Coração/diagnóstico por imagem , Idoso , Cardiomiopatias/diagnóstico por imagem , Feminino , Seguimentos , Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/patologia , Imagem de Perfusão do Miocárdio , Perfusão , Tomografia por Emissão de Pósitrons , Modelos de Riscos Proporcionais , Estudos Prospectivos , Taquicardia Ventricular/diagnóstico por imagem , Taquicardia Ventricular/terapia , Resultado do TratamentoRESUMO
INTRODUCTION: Coronary microvascular dysfunction (MVD) may contribute to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). Using myocardial flow reserve (MFR) measured by positron emission tomography (PET) as an assessment of microvascular function, we hypothesized that abnormal MFR is associated with LV diastolic dysfunction (DD) and reduced LV and LA strain in patients with risk factors for HFpEF and normal epicardial perfusion on cardiac PET. METHODS AND RESULTS: Retrospective study of patients without heart failure who underwent cardiac rubidium-82 PET and echocardiography. Global MFR was calculated as the ratio of global stress to rest myocardial blood flow. Echocardiographic measures of diastolic function were recorded. Global longitudinal LA and LV strain were measured with a 2-dimensional speckle-tracking technique. Relationships among MFR and echocardiographic measures were assessed with linear regression, analysis of variance, and test for trend. Seventy-three patients (age 64 ± 11 years, 52% male) were identified with no epicardial perfusion defect on cardiac PET and an ejection fraction ≥50%. Decreased MFR was associated with LV DD (P = .02) and increased E/e', an estimation of LV filling pressure (low E/e' [<8] vs. high E/e' [>15], P < .001). MFR was associated with LA strain independent of age, gender, and common comorbidities (adjusted ß = 2.6% per unit MFR, P = 0.046); however, MFR was only marginally related to LV strain. CONCLUSIONS: In patients with risk factors for HFpEF, MVD assessed with MFR was associated with DD, increased estimated LV filling pressure, and abnormal LA strain.
Assuntos
Função do Átrio Esquerdo/fisiologia , Ecocardiografia Doppler de Pulso/métodos , Reserva Fracionada de Fluxo Miocárdico/fisiologia , Átrios do Coração/fisiopatologia , Insuficiência Cardíaca Diastólica/fisiopatologia , Pericárdio/diagnóstico por imagem , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Idoso , Feminino , Seguimentos , Átrios do Coração/diagnóstico por imagem , Insuficiência Cardíaca Diastólica/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
OBJECTIVES: We sought to determine the safety of regadenoson stress testing in patients with PH. BACKGROUND: PH is increasingly recognized at more advanced ages. As many as one-third of patients with PH have coronary artery disease. Because of their physical limitations, patients with PH are unable to adequately exercise. Regadenoson can potentially have an adverse impact due to their tenuous hemodynamics. Current guidelines suggest performing a coronary angiography in patients with PH who have angina or multiple coronary risk factors. METHODS: We identified 67 consecutive patients with confirmed PH by catheterization (mean PA > 25 mmHg not due to left heart disease) who underwent MPI with regadenoson stress. Medical records were reviewed to determine hemodynamic and ECG response to regadenoson. RESULTS: No serious events occurred. Common side effects related to regadenoson were observed, dyspnea being the most common (70.6%). No syncope occurred. Heart rate increased from 74.6 ± 14 to 96.3 ± 18.3 bpm, systolic blood pressure increased from 129.8 ± 20.9 to 131.8 ± 31 mmHg, and diastolic blood pressure decreased from 77.1 ± 11.4 to 72.9 ± 15.3 mmHg. There was no ventricular tachycardia, ventricular fibrillation, or second- or third-degree atrioventricular block. CONCLUSION: Regadenoson stress MPI appears to be well tolerated and safe in patients with PH.
Assuntos
Agonistas do Receptor A2 de Adenosina/efeitos adversos , Pressão Sanguínea/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Hipertensão Pulmonar/fisiopatologia , Imagem de Perfusão do Miocárdio , Purinas/efeitos adversos , Pirazóis/efeitos adversos , Idoso , Doença da Artéria Coronariana/complicações , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/fisiopatologia , Dispneia , Eletrocardiografia , Teste de Esforço , Feminino , Humanos , Hipertensão Pulmonar/complicações , Hipertensão Pulmonar/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons , Estudos Retrospectivos , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
INTRODUCTION: Weight-adjusted dosing is important to maintain accurate quantification for dynamic cardiac three-dimensional positron emission tomography (PET). However, the manufacturer of the only Food and Drug Administration approved rubidium-82 (Rb-82) generator (CardioGen-82, Bracco Diagnostics, Inc.) recommends recalibration after each change in dose which is inefficient in a busy clinical PET lab. The objective of this study was to evaluate the accuracy of Rb-82 dosing without this recalibration. METHODS: After daily calibration to either 30 mCi (1110 MBq) or 12 mCi (444 MBq), Rb-82 doses between 6 and 45 mCi (222-1665 MBq) were eluted and measured on an external dose calibrator. This was repeated for four generators at weeks 1, 2, or 4 of the generator cycle. The measurements were compared with values reported by the infusion system. RESULTS: For requested doses less than 30 mCi, the measured dose was consistently lower than the requested dose, ranging from -3.2 mCi at 25 mCi to -5.5 mCi at 10 mCi. The error exceeded 10% for doses less than or equal to 26 mCi for the 30 mCi calibration. Residual activity in the infusion system dead volume accounted for the discrepancy between requested and delivered doses for calibration to 30 mCi but not 12 mCi. CONCLUSIONS: The CardioGen-82 infusion system is capable of accurate weight-adjusted doses without recalibration for Rb-82 doses as low as 26 mCi when calibrated to 30 mCi. For doses less than 26 mCi, the generator-reported residual activity within the infusion system can be used to correct the delivered dose.
Assuntos
Tomografia por Emissão de Pósitrons/métodos , Doses de Radiação , Radioisótopos de Rubídio , Calibragem , HumanosRESUMO
BACKGROUND: Suboptimal temporal sampling of left ventricular (LV) blood pool and tissue time-activity curves (TACs) may introduce bias and increased variability in estimates of myocardial blood flow (MBF) and flow reserve (MFR) from dynamic PET myocardial perfusion images. We aimed to optimize temporal sampling for estimation of MBF and MFR. METHODS: Twenty-four normal volunteers and 32 patients underwent dynamic stress/rest rubidium-82 chloride (82Rb) PET imaging. Fine temporal sampling was used to estimate the full width at half maximum (FWHM) of the LV blood pool TAC. Fourier analysis was used to determine the longest sampling interval, T S, as a function of FWHM, which preserved the information content of the blood phase. Dynamic datasets were reconstructed with frame durations varying from 2 to 20 seconds over the first 2 minutes for the blood phase and 30 to 120 seconds for the tissue phase. The LV blood pool and tissue TACs were sampled using regions of interest (ROI) and fit to a compartment model for quantification of MBF and MFR. The effects of temporal sampling on MBF and MFR were evaluated using clinical data and simulations. RESULTS: T S increased linearly with input function FWHM (R = 0.93). Increasing the blood phase frame duration from 5 to 15 seconds resulted in MBF and MFR biases of 6-12% and increased variability of 14-24%. Frame durations <5 seconds had biases of less than 5% for both MBF and MFR values. Increasing the tissue phase frame durations from 30 to 120 seconds resulted in <5% biases. CONCLUSIONS: A two-phase framing of dynamic 82Rb PET images with frame durations of 5 seconds (blood phase) and 120 seconds (tissue phase) optimally samples the blood pool TAC for modern 3D PET systems.
Assuntos
Cardiopatias/diagnóstico por imagem , Imagem de Perfusão do Miocárdio , Tomografia por Emissão de Pósitrons , Radioisótopos de Rubídio/uso terapêutico , Adulto , Idoso , Estudos de Casos e Controles , Doença da Artéria Coronariana/diagnóstico por imagem , Circulação Coronária , Feminino , Análise de Fourier , Voluntários Saudáveis , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
A number of exciting advances in PET/CT technology and improvements in methodology have recently converged to enhance the feasibility of routine clinical quantification of myocardial blood flow and flow reserve. Recent promising clinical results are pointing toward an important role for myocardial blood flow in the care of patients. Absolute blood flow quantification can be a powerful clinical tool, but its utility will depend on maintaining precision and accuracy in the face of numerous potential sources of methodological errors. Here we review recent data and highlight the impact of PET instrumentation, image reconstruction, and quantification methods, and we emphasize (82)Rb cardiac PET which currently has the widest clinical application. It will be apparent that more data are needed, particularly in relation to newer PET technologies, as well as clinical standardization of PET protocols and methods. We provide recommendations for the methodological factors considered here. At present, myocardial flow reserve appears to be remarkably robust to various methodological errors; however, with greater attention to and more detailed understanding of these sources of error, the clinical benefits of stress-only blood flow measurement may eventually be more fully realized.
Assuntos
Coração/diagnóstico por imagem , Miocárdio/patologia , Tomografia por Emissão de Pósitrons/métodos , Animais , Doença da Artéria Coronariana/diagnóstico por imagem , Circulação Coronária , Teste de Esforço , Coração/fisiopatologia , Humanos , Processamento de Imagem Assistida por Computador , Movimento (Física) , Prevalência , Reprodutibilidade dos Testes , Projetos de Pesquisa , Radioisótopos de Rubídio/química , Espalhamento de Radiação , Software , Tomografia Computadorizada por Raios X , Função Ventricular EsquerdaAssuntos
Dor no Peito/diagnóstico por imagem , Refluxo Gastroesofágico/diagnóstico por imagem , Idoso , Cardiologia , Diabetes Mellitus Tipo 2/complicações , Neoplasias Esofágicas/complicações , Esofagectomia , Humanos , Hiperlipidemias/complicações , Hipertensão/complicações , Masculino , Microcirculação , Compostos Organofosforados , Compostos de Organotecnécio , Fatores de Risco , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único , Acidente Vascular Cerebral/complicações , Tecnécio Tc 99m SestamibiAssuntos
Cardiologia/normas , Doenças Cardiovasculares/diagnóstico por imagem , Circulação Coronária , Imagem de Perfusão do Miocárdio/métodos , Tomografia por Emissão de Pósitrons/métodos , Tomografia por Emissão de Pósitrons/normas , Fluxo Sanguíneo Regional , Amônia , Sistema Cardiovascular , Ensaios Clínicos como Assunto , Doença da Artéria Coronariana/diagnóstico por imagem , Reserva Fracionada de Fluxo Miocárdico , Humanos , Processamento de Imagem Assistida por Computador , Radioisótopos de Nitrogênio , Prognóstico , Compostos Radiofarmacêuticos , Valores de Referência , Reprodutibilidade dos Testes , Radioisótopos de Rubídio , Sociedades Médicas , Estados UnidosRESUMO
Nuclear medicine has long played an important role in the noninvasive evaluation of known or suspected coronary artery disease. The development of single photon emission computed tomography (SPECT) led to improved assessments of myocardial perfusion, and the use of electrocardiographic gating made accurate measurements of ventricular wall motion, ejection fractions, and ventricular volumes possible. With the use of hybrid SPECT/computed tomography (CT) scanning systems, the cardiac functional parameters can be measured in a single imaging session. These recent advances in imaging technology have not only enhanced image quality but also improved diagnostic sensitivity and specificity in the detection of clinically relevant coronary artery disease. The CT-based attenuation maps obtained with hybrid SPECT/CT systems also have been useful for improving diagnostic accuracy. However, when attenuation correction and other advanced image data postprocessing techniques are used, unexpected artifacts may arise. The artifacts most commonly encountered are related to the characteristics either of the technology or of the patient. Thus, close attention to the details of acquisition protocols, processing techniques, and image interpretation is needed to ensure high diagnostic quality in myocardial perfusion studies.
Assuntos
Artefatos , Doença da Artéria Coronariana/diagnóstico , Aumento da Imagem/métodos , Imagem de Perfusão do Miocárdio/métodos , Técnica de Subtração , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Tomografia Computadorizada por Raios X/métodos , HumanosRESUMO
OBJECTIVE: To study the association of the fragmented QRS complex versus the Q wave with myocardial scar and viability. BACKGROUND: A prior study has suggested that the fragmented QRS complex on an electrocardiogram (ECG) is a highly sensitive and specific marker of myocardial scar as detected by regional perfusion abnormalities on a nuclear stress test. There is no external validation of this data. METHODS: We correlated the ECG and nuclear perfusion images of 460 consecutive patients with known or suspected coronary artery disease. The presence of fragmented QRS or Q waves in two contiguous ECG leads was correlated with major coronary artery distributions on nuclear perfusion imaging. RESULTS: For the 1842 evaluated territories, the fragmented QRS complex was not superior to the Q wave in detecting fixed or mixed myocardial defects. The fragmented QRS complex was associated with worse sensitivity (1.7%) in comparison to the Q wave (31.7%) for identifying myocardial scar. The fragmented QRS complex carried a higher false positive rate in patients with normal perfusion scans (15.8%, 221 segments), in comparison to Q waves (1.4%, 17 segments). CONCLUSION: In our study population, both the fragmented QRS and Q wave had poor sensitivity and specificity in detecting fixed or mixed myocardial scar. Larger studies are needed to evaluate fragmented QRS as a surrogate of myocardial scar before it can be incorporated into clinical practice.
Assuntos
Cicatriz/diagnóstico , Cicatriz/fisiopatologia , Eletrocardiografia/métodos , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/fisiopatologia , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Cicatriz/etiologia , Estudos de Coortes , Teste de Esforço/métodos , Coração/diagnóstico por imagem , Humanos , Infarto do Miocárdio/complicações , Variações Dependentes do Observador , Sensibilidade e EspecificidadeRESUMO
OBJECTIVES: The purpose of this study was to describe our experience with fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography computed tomography (PET/CT) in diagnosing left ventricular assist device (LVAD) infections and perform a meta-analysis of published studies to determine overall diagnostic accuracy. BACKGROUND: Device-related infections are a common complication of LVADs and are linked to worse outcomes. Diagnosis of LVAD infections remains challenging. FDG PET/CT has demonstrated good diagnostic accuracy in several other infectious conditions. METHODS: This was a single-center, retrospective case series of FDG PET/CT scans in suspected LVAD infection between September 2015 and February 2018. A systematic review of PubMed from database inception through March 2018 was also conducted to identify additional studies. RESULTS: Nineteen FDG PET/CT scans were identified for the retrospective case series. The systematic review identified an additional 3 publications, for a total of 4 studies involving 119 scans assessing diagnostic performance. Axial (n = 36) and centrifugal (n = 83) flow LVADs were represented. Pooled sensitivity was 92% (95% confidence interval [CI]: 82% to 97%) and specificity was 83% (95% CI: 24% to 99%) for FDG PET/CT in diagnosing LVAD infections. Summary receiver-operating characteristic curve analysis demonstrated an AUC of 0.94 (95% CI: 0.91 to 0.95). CONCLUSIONS: FDG PET/CT for suspected LVAD infections demonstrates good diagnostic accuracy, with overall high sensitivity but variable specificity.