The Experts below are selected from a list of 1744920 Experts worldwide ranked by ideXlab platform
Adriaan A. Lammertsma - One of the best experts on this subject based on the ideXlab platform.
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measurement of lv volumes and function using Oxygen 15 water gated pet and comparison with cmr imaging
Jacc-cardiovascular Imaging, 2016Co-Authors: Roel S Driessen, Janna E Van Timmeren, Wijnand J Stuijfzand, Mischa T Rijnierse, Ibrahim Danad, Pieter G Raijmakers, Aernout M Beek, Albert C Van Rossum, Robin Nijveldt, Adriaan A. LammertsmaAbstract:Myocardial perfusion imaging using positron emission tomography (PET) is a valuable tool in the diagnosis of coronary artery disease. And although PET using [15O]H2O has a high diagnostic accuracy for predicting coronary artery disease in routine clinical practices [(1)][1], left ventricular (LV)
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comparison of clinical non commercial tools for automated quantification of myocardial blood flow using Oxygen 15 labelled water pet ct
European Journal of Echocardiography, 2014Co-Authors: Hendrik J Harms, Adriaan A. Lammertsma, Juhani Knuuti, Ibrahim Danad, Pieter G Raijmakers, Sergey V Nesterov, Chunlei Han, Remigio Leonora, Paul KnaapenAbstract:Aims Absolute quantification of myocardial blood flow (MBF) with 15O-water cardiac positron emission tomography (PET)/CT has recently demonstrated to hold promising diagnostic value for the detection of coronary artery disease (CAD). However, methodological differences in utilized analysis software packages (SP) could affect generated MBF values, potentially prohibiting widespread clinical applicability of obtained normal thresholds. The aim of this study was to compare two validated non-commercial SP, Carimas and Cardiac VUer , for the quantification of MBF using 15O-water PET. Methods and results One hundred patients with intermediate likelihood of CAD and scanned in academic centres in Amsterdam ( n = 50) and Turku ( n = 50) were included in the study. Patients underwent a 15O-water PET/CT scan during rest and vasodilator stress based on clinical indications. A single observer, blinded from clinical results and with no prior experience in either SP, analysed all patients twice with both SP. Reproducibility of each SP was assessed using intraclass correlation coefficients (ICC). Intersoftware agreement was assessed using paired t-tests and linear regression. ICC was excellent for each SP for both global and regional MBF (ICC >0.90). Global MBF was comparable between Carimas and Cardiac VUer during rest (1.02 ± 0.28 vs. 0.99 ± 0.23 mL min–1g−1, respectively, P = 0.07), and slightly higher for Carimas during stress (2.73 ± 0.82 vs. 2.63 ± 0.84 mL min−1g−1, respectively, P = 0.01). At a regional level, for resting conditions small ( 0.94 for all). Conclusion For global and regional MBF, Carimas and Cardiac VUer showed excellent agreement and intra-observer reproducibility. These results confirm that, for patients with intermediate likelihood of CAD, these validated SP are interchangeable and can be utilized for routine clinical practice of 15O-water cardiac PET.
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intervention versus standard medical treatment in patients with symptomatic occlusion of the internal carotid artery a randomised Oxygen 15 pet study
EJNMMI research, 2013Co-Authors: Suzanne Persoon, Adriaan A. Lammertsma, Ronald Boellaard, Bart N M Van Berckel, Jochem P Bremmer, Ale Algra, Gert J De Borst, Jaap L Kappelle, Catharina J M KlijnAbstract:Background The aim of this randomised pilot study was to investigate the haemodynamic effects measured by Oxygen-15 positron emission tomography (PET) of interventional treatment consisting of either endarterectomy or endovascular treatment of stenosed cerebropetal arteries, or tapering of antihypertensive medication in comparison with standard medical treatment alone in patients with symptomatic internal carotid artery (ICA) occlusion.
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comparison of Oxygen 15 pet and transcranial doppler co2 reactivity measurements in identifying haemodynamic compromise in patients with symptomatic occlusion of the internal carotid artery
EJNMMI research, 2012Co-Authors: Suzanne Persoon, Adriaan A. Lammertsma, Ronald Boellaard, Bart N M Van Berckel, Jaap L Kappelle, Cyrille H Ferrier, Catharina J M KlijnAbstract:Background Transcranial Doppler (TCD) CO2-reactivity and Oxygen-15 positron emission tomography (PET) have both been used to measure the cerebral haemodynamic state in patients who may have a compromised blood flow. Our purpose was to investigate whether PET and TCD identify the same patients with an impaired flow state of the brain in patients with internal carotid artery (ICA) occlusion.
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generation of myocardial factor images directly from the dynamic Oxygen 15 water scan without use of an Oxygen 15 carbon monoxide blood pool scan
The Journal of Nuclear Medicine, 1998Co-Authors: Flemming Hermansen, Paolo G Camici, John Ashburner, T J Spinks, Jaspal S Kooner, Adriaan A. LammertsmaAbstract:The measurement of regional myocardial blood flow (MBF) with (H2O)-O-15 and PET requires an additional (CO)-O-15 blood-pool scan for the purpose of region of interest (ROI) definition. This additional scan results in a substantially increased radiation dose, study duration and risk of movement artifacts. Therefore, a method was developed to generate myocardial factor images directly from the dynamic (H2O)-O-15 study without the need for a (CO)-O-15 scan. Methods: The factor sinograms were generated by means of linear dimension reduction of the dynamic sinograms, where the required variate and covariate factors (myocardial and blood time-activity curves) were modeled from the lung time-activity curve. The factor images were generated by iterative reconstruction. Results: No significant difference was found between MBF values from ROls drawn on the traditional images (using the (CO)-O-15 scan) and those drawn on the factor images. Conclusion: It is possible to generate myocardial images directly from the dynamic (H2O)-O-15 study, so that the (CO)-O-15 scan can be omitted from MBF studies. The proposed method is robust and results in nearly optimal signal-to-noise ratios in the factor images.
Paolo G Camici - One of the best experts on this subject based on the ideXlab platform.
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relationship between regional myocardial Oxygenation and perfusion in patients with coronary artery disease insights from cardiovascular magnetic resonance and positron emission tomography
Circulation-cardiovascular Imaging, 2010Co-Authors: Theodoros D Karamitsos, Lucia Leccisotti, Jayanth R Arnold, Alejandro Reciomayoral, Paul Bhamraariza, Ruairidh K Howells, Nick Searle, Matthew D Robson, Ornella Rimoldi, Paolo G CamiciAbstract:Background— It is recognized that the interplay between myocardial ischemia, perfusion, and Oxygenation in the setting of coronary artery disease (CAD) is complex and that myocardial Oxygenation and perfusion may become dissociated. Blood Oxygen level–dependent (BOLD) cardiovascular magnetic resonance (CMR) has the potential to noninvasively measure myocardial Oxygenation, whereas positron emission tomography (PET) with Oxygen-15 labeled water is the gold standard technique for myocardial blood flow quantification. Thus, we sought to apply BOLD CMR at 3 T and Oxygen-15–labeled water PET in patients with CAD and normal volunteers to better understand the relationship between regional myocardial Oxygenation and blood flow during vasodilator stress. Methods and Results— Twenty-two patients (age, 62±8 years; 16 men) with CAD (at least 1 stenosis ≥50% on quantitative coronary angiography) and 10 normal volunteers (age, 58±6 years; 6 men) underwent 3-T BOLD CMR and PET. For BOLD CMR, 4 to 6 midventricular short-axis images were acquired at rest and during adenosine stress (140 μg/kg/min). Using PET with Oxygen-15–labeled water, myocardial blood flow was measured at baseline and during adenosine in the same slices. BOLD images were divided into 6 segments, and mean signal intensities calculated. Taking ≥50% stenosis on quantitative coronary angiography as the gold standard, cutoff values for stress myocardial blood flow (<2.45 mL/min/g; AUC, 0.83) and BOLD signal intensity change (<3.74%; AUC, 0.78) were determined to define ischemic segments. BOLD CMR and PET agreed on the presence or absence of ischemia in 18 of the 22 patients (82%) and in all normal subjects. On a per-segment analysis, 40% of myocardial segments with stress myocardial blood flow below the cutoff of 2.45 mL/min/g did not show deOxygenation, whereas 88% of segments with normal perfusion also had normal Oxygenation measurements. Conclusions— Regional myocardial perfusion and Oxygenation may be dissociated, indicating that in patients with CAD, reduced perfusion does not always lead to deOxygenation. Received February 23, 2009; accepted October 29, 2009. # CLINICAL PERSPECTIVE {#article-title-2}
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accuracy of pet in predicting functional recovery after revascularisation in patients with chronic ischaemic dysfunction head to head comparison between blood flow glucose utilisation and water perfusable tissue fraction
European Journal of Nuclear Medicine and Molecular Imaging, 2002Co-Authors: Jeroen J Bax, William Wijns, Farzin Fathordoubadi, Eric Boersma, Paolo G CamiciAbstract:Accurate prediction of improvement in left ventricular ejection fraction (LVEF) after revascularisation is critical in the therapeutic decision-making process in patients with chronic ischaemic dysfunction. Positron emission tomography (PET) allows non-invasive evaluation of myocardial blood flow (MBF), metabolic rate of glucose (MRG, absolute and relative) and the water-perfusable tissue fraction (PTF). Each of these indices has been proposed for the prediction of functional recovery. Their relative merits, however, are unknown, because a direct head-to-head comparison of their predictive accuracy in the same patients has not been performed. In this study, MBF, MRG (absolute and relative) and PTF were evaluated in 34 patients with severe ischaemic LV dysfunction (LVEF 32%±9%). MBF and PTF were determined by Oxygen-15 labelled water PET, and MRG (absolute and relative) was determined by fluorine-18 fluorodeoxyglucose (FDG) PET during hyperinsulinaemic euglycaemic clamp. LVEF was measured by radionuclide ventriculography before and 4–6 months after surgery. Sensitivities of MBF, PTF, absolute MRG and relative MRG in predicting improvement in LVEF were 80%, 80%, 90% and 100%, respectively. Their specificities were 54%, 67%, 71% and 71%, respectively. The lowest specificity was obtained for MBF, an intermediate specificity was obtained for PTF and the highest specificities were obtained with FDG PET using absolute and relative MRG. It is concluded that metabolic imaging is superior to perfusion-based indexes for assessment of the potential for functional recovery after revascularisation.
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low density lipoprotein cholesterol and coronary microvascular dysfunction in hypercholesterolemia
Journal of the American College of Cardiology, 2000Co-Authors: Philipp A Kaufmann, Tomaso Gnecchiruscone, Klaus P Schafers, Thomas F Luscher, Paolo G CamiciAbstract:Abstract OBJECTIVES The present study evaluates the impact of total cholesterol (TC) and its subfractions on coronary flow reserve (CFR), an index of the integrated function of the coronary circulation, in asymptomatic subjects. BACKGROUND Endothelial dysfunction of the coronary microcirculation has been reported in asymptomatic subjects with hypercholesterolemia. METHODS Using Oxygen-15-labeled water and positron emission tomography, myocardial blood flow (MBF, in ml/min per g) was measured at rest and during intravenous adenosine (140 μg/kg body weight per min) in 80 asymptomatic nonsmoking men: group 1 (n = 61; age 45 ± 7 years) had normal TC (≤6.5 mmol/liter or ≤250 mg/dl) and group 2 (n = 19; age 48 ± 10 years) had elevated TC. RESULTS Total cholesterol were 5.1 ± 0.8 and 7.2 ± 0.7 mmol/liter in groups 1 and 2 (p CONCLUSIONS Low density lipoprotein cholesterol but not TC correlated inversely with CFR in hypercholesterolemic subjects. Thus, LDL-induced coronary microvascular dysfunction could play an important role in the pathogenesis of coronary artery disease and its complications.
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generation of myocardial factor images directly from the dynamic Oxygen 15 water scan without use of an Oxygen 15 carbon monoxide blood pool scan
The Journal of Nuclear Medicine, 1998Co-Authors: Flemming Hermansen, Paolo G Camici, John Ashburner, T J Spinks, Jaspal S Kooner, Adriaan A. LammertsmaAbstract:The measurement of regional myocardial blood flow (MBF) with (H2O)-O-15 and PET requires an additional (CO)-O-15 blood-pool scan for the purpose of region of interest (ROI) definition. This additional scan results in a substantially increased radiation dose, study duration and risk of movement artifacts. Therefore, a method was developed to generate myocardial factor images directly from the dynamic (H2O)-O-15 study without the need for a (CO)-O-15 scan. Methods: The factor sinograms were generated by means of linear dimension reduction of the dynamic sinograms, where the required variate and covariate factors (myocardial and blood time-activity curves) were modeled from the lung time-activity curve. The factor images were generated by iterative reconstruction. Results: No significant difference was found between MBF values from ROls drawn on the traditional images (using the (CO)-O-15 scan) and those drawn on the factor images. Conclusion: It is possible to generate myocardial images directly from the dynamic (H2O)-O-15 study, so that the (CO)-O-15 scan can be omitted from MBF studies. The proposed method is robust and results in nearly optimal signal-to-noise ratios in the factor images.
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measurement of myocardial blood flow with Oxygen 15 labelled water comparison of different administration protocols
European Journal of Nuclear Medicine and Molecular Imaging, 1998Co-Authors: Flemming Hermansen, Paolo G Camici, Jaspal S Kooner, Stuart D Rosen, Farzin Fathordoubadi, John C Clark, Adriaan A. LammertsmaAbstract:Positron emission tomography (PET) in conjunction with C15O2 or H215O can be used to measure myocardial blood flow (MBF) and tissue fraction (TF), i.e. the fraction of the tissue mass in the volume of the region of interest. However, with C15O2 inhalation, the tissue fraction in the septum is overestimated. Bolus injection of H215O together with arterial cannulation gives very precise results but is invasive. The purpose of this study was to develop a method which circumvents these problems. A four-parameter model with parameters for MBF, TF and spill-over fractions from both left and right ventricular cavities was developed. This method was compared with a three-parameter model (no right ventricular cavity spill-over) in both septal and non-septal regions of interest for three different administration protocols: bolus injection of H215O, infusion of H215O and inhalation of C15O2. It was found that MBF can be measured with intravenous administration of H215O without the requirement for arterial cannulation. The four-parameter protocol with bolus injection was stable in clinical studies. The four-parameter model proved essential for the septum, where it gave highly significantly better fits than did the three-parameter model (P<0.00003 in each of 15 subjects). Administration of H215O together with this four-parameter model also circumvented the problem of overestimation of TF in the septum seen with C15O2 inhalation. In addition, the radiation dose of H215O protocols is lower than that of C15O2 inhalation. Using a left atrial input curve instead of a left ventricular cavity input curve gave the same mean MBF and TF.
Hidehiro Iida - One of the best experts on this subject based on the ideXlab platform.
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influence of residual Oxygen 15 labeled carbon monoxide radioactivity on cerebral blood flow and Oxygen extraction fraction in a dual tracer autoradiographic method
Annals of Nuclear Medicine, 2009Co-Authors: Katsuhiro Iwanishi, Yoshinori Miyake, Hiroshi Watabe, Takuya Hayashi, Kotaro Minato, Hidehiro IidaAbstract:Objective Cerebral blood flow (CBF), cerebral metabolic rate of Oxygen (CMRO2), Oxygen extraction fraction (OEF), and cerebral blood volume (CBV) are quantitatively measured with PET with 15O gases. Kudomi et al. developed a dual tracer autoradiographic (DARG) protocol that enables the duration of a PET study to be shortened by sequentially administrating 15O2 and C15O2 gases. In this protocol, before the sequential PET scan with 15O2 and C15O2 gases (15O2–C15O2 PET scan), a PET scan with C15O should be preceded to obtain CBV image. C15O has a high affinity for red blood cells and a very slow washout rate, and residual radioactivity from C15O might exist during a 15O2–C15O2 PET scan. As the current DARG method assumes no residual C15O radioactivity before scanning, we performed computer simulations to evaluate the influence of the residual C15O radioactivity on the accuracy of measured CBF and OEF values with DARG method and also proposed a subtraction technique to minimize the error due to the residual C15O radioactivity.
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optimal scan time of Oxygen 15 labeled gas inhalation autoradiographic method for measurement of cerebral Oxygen extraction fraction and cerebral Oxygen metabolic rate
Annals of Nuclear Medicine, 2008Co-Authors: Miho Shidahara, Hiroshi Watabe, Nobuyuki Kudomi, Hidehiro IidaAbstract:Objective Regional cerebral blood flow (CBF), cerebral blood volume, Oxygen extraction fraction (OEF), and cerebral metabolic rate of Oxygen (CMRO2) can be estimated from C15O, H2 15O, and 15O2 tracers and positron emission tomography (PET) using an autoradiographic (ARG) method. Our objective in this study was to optimize the scan time for 15O2 gas study for accurate estimation of OEF and CMRO2.
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quantitative assessment of regional myocardial blood flow using Oxygen 15 labelled water and positron emission tomography a multicentre evaluation in japan
European Journal of Nuclear Medicine and Molecular Imaging, 2000Co-Authors: Hidehiro Iida, Ikuo Yokoyama, Denis Agostini, Tatsuo Banno, Takashi Kato, Kengo Ito, Yasuo Kuwabara, Yohei Oda, Tohru Otake, Yoshikazu TamuraAbstract:Recently, a method has been proposed for the quantitative measurement of regional myocardial blood flow (MBF) using Oxygen-15-labelled water and positron emission tomography (PET). A multicentre project was organized with the intention of evaluating the accuracy of this method, particularly as a multicentre clinical investigative tool. Each of seven institutions performed PET studies on more than five normal volunteers following a specified protocol. The PET study included a transmission scan, a 15O-carbon monoxide static scan and a 15O-water dynamic scan, thereby yielding MBF values which should have been independent of the spatial resolution of the PET scanner employed. Fifty-three subjects (aged 20-63 years, mean+/-SD 36+/-12 years) were studied at rest, and 31 of these subjects were also studied after dipyridamole in five institutions. Inter-institution consistency and intra-subject variation in MBF values were then evaluated. MBF averaged for all subjects was 0.93+/-0.34 ml min(-1) g(-1) at rest and 3.40+/-1.73 ml min(-1) g(-1) after the administration of dipyridamole, and the flow reserve (defined as the ratio of the two MBF values) was 3.82+/-2.12; these values are consistent with previous reports. Resting MBF values were significantly correlated with the heart rate-blood pressure product (RPP) (y=0.31+6.56E-5x, P<0.010), and RPP was in resting MBF observed in all institutions was well explained by the age-dependent RPP. No significant difference was observed in resting MBF among the institutions. Except in one institution, no significant difference was seen in dipyridamole MBF or myocardial flow reserve. No significant difference was found among the myocardial segments. Regional variation was reasonably small in five institutions, but was not acceptable in two institutions, which was attributed to the scanner performance. These observations suggest that the 15O-water PET technique is useful for a multicentre clinical study if the PET scanner can provide time-activity data with good count statistics.
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noninvasive quantitation of cerebral blood flow using Oxygen 15 water and a dual pet system
The Journal of Nuclear Medicine, 1998Co-Authors: Hidehiro Iida, Shuichi Miura, Yasuaki Shoji, Toshihide Ogawa, Hirotsugu Kado, Y Narita, Jun Hatazawa, Stefan Eberl, Iwao Kanno, K UemuraAbstract:UNLABELLED Measurement of the arterial input function is essential for quantitative assessment of physiological function in vivo using PET. However, frequent arterial blood sampling is invasive and labor intensive. Recently, a PET system has been developed that consists of two independent PET tomographs for simultaneously scanning the brain and heart, which should avoid the need for arterial blood sampling. The aim of this study was to validate noninvasive quantitation with this system for 15O-labeled compounds. METHODS Twelve healthy volunteers underwent a series of PET studies after C15O inhalation and intravenous H2(15)O administration using a Headtome-V-Dual tomograph (Shimadzu Corp., Kyoto, Japan). The C15O study provided gated blood-pool images of the heart simultaneously with quantitative static blood-volume images of both the brain and heart. Weighted-integrated H2(15)O sinograms were acquired for estimating rate constant (K1) and distribution-volume (Vd) images in the brain, in addition to single-frame sinograms for estimating autoradiographic cerebral blood flow images. Noninvasive arterial input functions were determined from the heart scanner (left ventricular chamber) according to a previously developed model and compared directly to invasive input functions measured with an on-line beta probe in six subjects. RESULTS The noninvasive input functions derived from this PET system were in good agreement with those obtained by continuous arterial blood sampling in all six subjects. There was good agreement between quantitative values obtained noninvasively and those using the invasive input function: average autoradiographic regional cerebral blood flow was 0.412 +/- 0.058 and 0.426 +/- 0.062 ml/min/g, K1 of H2(15)O was 0.416 +/- 0.073 and 0.420 +/- 0.067 ml/min/ml and Vd of H2(15)O was 0.800 +/- 0.080 and 0.830 +/- 0.070 ml/ml for the noninvasive and invasive input functions, respectively. In addition to the brain functional parameters, the system also simultaneously provided cardiac function such as regional myocardial blood flow (0.84 +/- 0.19 ml/min/g), left ventricular volume (132 +/- 22 mm at end diastole and 45 +/- 14 ml at end systole) and ejection fraction (66% +/- 5%). CONCLUSION This PET system allows noninvasive quantitation in both the brain and heart simultaneously without arterial cannulation, and may prove useful in clinical research.
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early impairment of coronary flow reserve in young men with borderline hypertension
Journal of the American College of Cardiology, 1998Co-Authors: Hanna Laine, Harri Niinikoski, Ollipekka Pitkanen, Hidehiro Iida, Pirjo Nuutila, Jorma Viikari, Olli T Raitakari, Juhani KnuutiAbstract:Abstract Objectives. The purpose of this study was to investigate whether functional abnormalities in coronary vasomotion are present in young healthy asymptomatic men fulfilling the World Health Organization (WHO) criteria for borderline hypertension. Background. Previous studies have reported reduced coronary flow reserve in middle-aged subjects with sustained hypertension and hypertension-induced microvascular heart disease or left ventricular hypertrophy. Methods. Myocardial blood flow was measured at baseline and during dipyridamole-induced hyperemia by means of positron emission tomography and Oxygen-15–labeled water in asymptomatic young men with borderline hypertension (group 1: n = 16, mean ± SD age 37 ± 4 years, 24-h ambulatory blood pressure 135 ± 10/81 ± 9 mm Hg) and matched healthy control subjects (group 2: n = 19, age 35 ± 3 years, 24-h ambulatory blood pressure 119 ± 8/69 ± 8 mm Hg, p Results. LV mass, dimensions and diastolic function were similar in the study groups. Baseline myocardial blood flow was similar (0.83 ± 0.21 vs. 0.80 ± 0.22 ml/g per min, group 1 vs. group 2, respectively, p = NS), and a significant increase in flow was detected after dipyridamole infusion (0.56 mg/kg body weight in 4 min intravenously) in both groups. However, the flow response to dipyridamole was significantly lower in group 1, leading to lower hyperemic flow in group 1 than in group 2 (2.85 ± 1.20 vs. 3.80 ± 1.44 ml/g per min, respectively). Consequently, the coronary flow response was lower in hypertensive than in normotensive men (3.46 ± 1.23 vs. 4.99 ± 2.5 ml/g per min, group 1 vs. group 2, respectively, p Conclusions. These results demonstrate reduced coronary reactivity present in young asymptomatic men with borderline hypertension and no signs of hypertension-induced angina or left ventricular hypertrophy. Because baseline basal myocardial blood flow was unchanged, the reduction in coronary flow reserve depends on an impaired maximal vasodilator capacity.
Nagara Tamaki - One of the best experts on this subject based on the ideXlab platform.
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reduction of coronary flow reserve in areas with and without ischemia on stress perfusion imaging in patients with coronary artery disease a study using Oxygen 15 labeled water pet
Journal of Nuclear Cardiology, 2003Co-Authors: Keiichiro Yoshinaga, Chietsugu Katoh, Kazuyuki Noriyasu, Yasuyoshi Iwado, Hideto Furuyama, Yoshinori Ito, Yuji Kuge, Tetsuro Kohya, Akira Kitabatake, Nagara TamakiAbstract:Background Myocardial perfusion single photon emission computed tomography (SPECT) occasionally fails to detect coronary stenosis in patients with coronary artery disease (CAD). We evaluated coronary flow reserve (CFR) using Oxygen 15-labeled water in areas with and without ischemia on technetium 99m tetrofosmin stress perfusion SPECT in patients with angiographically documented CAD.
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reduction of coronary flow reserve in areas with and without ischemia on stress perfusion imaging in patients with coronary artery disease a study using Oxygen 15 labeled water pet
Journal of Nuclear Cardiology, 2003Co-Authors: Keiichiro Yoshinaga, Chietsugu Katoh, Kazuyuki Noriyasu, Yasuyoshi Iwado, Hideto Furuyama, Yoshinori Ito, Yuji Kuge, Tetsuro Kohya, Akira Kitabatake, Nagara TamakiAbstract:Abstract Background Myocardial perfusion single photon emission computed tomography (SPECT) occasionally fails to detect coronary stenosis in patients with coronary artery disease (CAD). We evaluated coronary flow reserve (CFR) using Oxygen 15–labeled water in areas with and without ischemia on technetium 99m tetrofosmin stress perfusion SPECT in patients with angiographically documented CAD. Methods and results Twenty-seven patients with CAD and eleven age-matched normal subjects were studied. Baseline myocardial blood flow (MBF) and MBF during hyperemia induced by intravenous adenosine triphosphate infusion (0.16 mg · kg−1 · min−1) were determined with the use of O-15–labeled water positron emission tomography, and the CFR was calculated. Tc-99m tetrofosmin stress/rest SPECT was performed for comparison. On the basis of the results of coronary angiography and SPECT, coronary segments were divided into 3 types: segments with coronary stenosis and a perfusion abnormality on stress SPECT imaging (group A, n = 16), segments with coronary stenosis without a perfusion abnormality (group B, n = 42), and remote segments with no coronary stenosis or perfusion abnormality (group C, n = 18). Baseline MBF values were similar among the 3 groups. CFR in group A was lower (1.82 ± 0.54) than in group B (2.22 ± 0.87, P Conclusions Areas with a perfusion abnormality on stress SPECT had reduced CFR. In the areas without a perfusion abnormality and with coronary stenosis, lowering of CFR was intermediate between the areas with a perfusion abnormality and remote segments. Moreover, CFR was slightly, but significantly, lower in remote segments in patients with CAD compared with normal segments.
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decreased endothelium dependent coronary vasomotion in healthy young smokers
European Journal of Nuclear Medicine and Molecular Imaging, 2002Co-Authors: Yasuyoshi Iwado, Keiichiro Yoshinaga, Chietsugu Katoh, Kazuyuki Noriyasu, Hideto Furuyama, Yoshinori Ito, Yuji Kuge, Eriko Tsukamoto, Nagara TamakiAbstract:Chronic cigarette smoking alters coronary vascular endothelial response. To determine whether altered response also occurs in young individuals without manifest coronary disease we quantified coronary blood flow at rest, following adenosine vasodilator stress and during the cold pressor test in healthy young smokers. Myocardial blood flow (MBF) was quantified by Oxygen-15 labelled water positron emission tomography in 30 healthy men aged from 20 to 35 years (18 smokers and 12 non-smokers, aged 27.4±4.4 vs 26.3±3.3). The smokers had been smoking cigarettes for 9.4±4.9 pack-years. MBF was measured at rest, during intravenous adenosine triphosphate (ATP: 0.16 mg kg–1 min–1) infusion (hyperaemic response), and during cold pressor test (CPT) (endothelial vasodilator response). Rest MBF and hyperaemic MBF did not differ significantly between the smokers and the non-smokers (rest: 0.86±0.11 vs 0.92±0.14 and ATP: 3.20±1.12 vs 3.69±0.76 ml g–1 min–1; P=NS). Coronary flow reserve was similar between the two groups (smokers: 3.78±1.83; non-smokers: 4.03±0.68; P=NS). Although CPT induced a similar increase in rate-pressure product (RPP) in the smokers and the non-smokers (10,430±1,820 vs 9,236±1,356 beats min–1 mmHg–1), CPT MBF corrected by RPP was significantly decreased in the smokers (0.65±0.12 ml g–1 min–1) compared with the non-smokers (0.87±0.12 ml g–1 min–1) (P<0.05). In addition, the ratio of CPT MBF to resting MBF was inversely correlated with pack-years (r=–0.57, P=0.014). Endothelium-dependent coronary artery vasodilator function is impaired in apparently healthy young smokers.
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extraction and retention of technetium 99m ecd in human brain dynamic spect and Oxygen 15 water pet studies
The Journal of Nuclear Medicine, 1996Co-Authors: Koichi Ishizu, Yoshiharu Yonekura, Yasuhiro Magata, Hidehiko Okazawa, Hidenao Fukuyama, Fumiko Tanaka, Naoya Hattori, Haruhiro Kitano, T Fujita, Nagara TamakiAbstract:UNLABELLED The kinetic behavior of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in the human brain was investigated in six normal volunteers. METHODS Dynamic SPECT and a three-compartmental model were used to estimate the rate constants of 99mTc-ECD in normal human brain. Extraction fraction (E), retention fraction (R) and permeability surface area product (PS product) of 99mTc-ECD were calculated using the rate constants. Regional cerebral blood flow (rCBF) was measured by PET with 15O-water. RESULTS The rate constants in the cerebral cortex were estimated as 0.307 +/- 0.021 for K1 (influx constant), 0.201 +/- 0.047 for k2 (backdiffusion rate constant), 0.547 +/- 0.103 for k3 (lipophilic-to-hydrophilic conversion constant) and 0.0028 +/- 0.0012 for k5 (rate constant from lipophilic compartment to blood) at rCBF of 0.509 +/- 0.055 ml/g/min (mean +/- s.d.). The first-pass extraction, retention fraction and PS product were calculated as 0.608 +/- 0.069, 0.734 +/- 0.047 and 0.477 +/- 0.060, respectively. The first-pass extraction of 99mTc-ECD decreased significantly with increases in rCBF. The retention fraction and PS product of 99mTc-ECD did not show significant changes within the normal range of rCBF. The net extraction of 99mTc-ECD calculated from the static SPECT image obtained from 20 to 40 min was 0.358 +/- 0.039 in the cortex. CONCLUSION Technetium-99m-ECD has a fairly high brain extraction, and its retention fraction and PS product appear to be independent of rCBF in the healthy human brain.
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pet and the autoradiographic method with continuous inhalation of Oxygen 15 gas theoretical analysis and comparison with conventional steady state methods
The Journal of Nuclear Medicine, 1993Co-Authors: Norihiro Sadato, Nagara Tamaki, Yoshiharu Yonekura, Yasuhiro Magata, Michio Senda, Yasushi Iwasaki, N Matoba, Satoshi Sasayama, J KonishiAbstract:The steady-state method using 15O gas inhalation and positron emission tomography (PET) is a simple and practical way of imaging cerebral blood flow (CBF) and Oxygen metabolism. Several disadvantages do exist, however, including prolonged examination time, requirement of steady-state and a large tissue heterogeneity effect. To avoid the drawbacks of the steady-state method but to preserve its simplicity, we applied the PET/autoradiographic method to the build-up phase during the continuous inhalation of 15O-gas with intermittent arterial sampling. A simulation study was performed to determine the optimal scanning period, evaluate the delay and dispersion effect of the input function and estimate the tissue heterogeneity effect. To assess the clinical feasibility of the proposed technique for the study of Oxygen metabolism, sequential measurements with this method and the conventional steady-state method were performed in eight patients. The simulation study showed that a 5-min scan started 3 min after the commencement of 15O-gas inhalation was optimal. With this method, the delay and dispersion effect on CBF was the same as that of the conventional steady-state method, but the tissue heterogeneity effect was reduced. In eight patients, CBF values calculated by this method showed time dependency and were slightly higher than those obtained by the steady-state method. The Oxygen extraction fraction showed no significant time dependency and was well correlated with that obtained by the steady-state method. We conclude that the proposed method is a simple and acceptable alternative to the conventional steady-state method.
Terry Jones - One of the best experts on this subject based on the ideXlab platform.
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Oxygen metabolism, Oxygen extraction and positron emission tomography: Historical perspective and impact on basic and clinical neuroscience.
NeuroImage, 2011Co-Authors: Jeanclaude Baron, Terry JonesAbstract:Oxygen utilization is central to the human brain's high metabolic rate. Measurement of this fundamental process, in both disease and health, has been a focus of research attention over the last 35 years. This review plots the course of the use of Oxygen-15 to study regional cerebral Oxygen extraction and metabolism using Positron Emission Tomography (PET) in disease and in health. The scientific discoveries and resulting conceptual changes to both basic and clinical neuroscience, as well as the new methodological approaches brought about by this area of research, are also summarized. We conclude with a brief overview of the current status of Oxygen-15 PET in neuroscience, along with our visions for future developments and applications.
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Blood flow and Vd (water): both biomarkers required for interpreting the effects of vascular targeting agents on tumor and normal tissue
Molecular cancer therapeutics, 2009Co-Authors: Barbara Kötz, Terry Jones, Catharine M L West, Azeem Saleem, Patricia PriceAbstract:Positron emission tomography studies with Oxygen-15-labeled water provide in vivo quantitative tissue perfusion variables-blood flow and fractional volume of distribution of water [V(d) (water)]. To investigate the relationship between perfusion variables and the effect of vascular-targeting agents on vasculature, we measured tissue perfusion in tumors, spleen, kidney, and liver before and after treatment with combretastatin-A4-phosphate, a combination of nicotinamide and carbogen (N/C), and interferon (IFN). We observed that mean tumor blood flow and V(d) (water) was lower than in kidney, liver, and spleen at baseline. Blood flow and V(d) (water) were related in tumor (r = 0.62; P = 0.004) at baseline, but not in other normal tissues evaluated, where minimal variations in V(d) (water) were observed over a wide range of blood flow. Despite the relationship between blood flow and V(d) (water) in tumors before intervention, vascular-targeting agent-induced changes in these perfusion variables were not correlated. In contrast, changes in blood flow and V(d) (water) correlated in kidney and spleen after N/C and in kidney after combretastatin-A4-phosphate. The close relation between blood flow and V(d) (water) in tumors but not normal tissue may reflect barriers to fluid exchange in tumors because of necrosis and/or increased interstitial fluid pressure and underlies the importance and interdependence of these positron emission tomography perfusion variables under these conditions. As blood flow and V(d) (water) signify different aspects of tissue perfusion, the differential effects of interventions on both variables, flow and V(d) (water), should therefore be reported in future studies.
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assessment of pharmacodynamic vascular response in a phase i trial of combretastatin a4 phosphate
Journal of Clinical Oncology, 2003Co-Authors: Helen Anderson, Terry Jones, Jeffrey T Yap, Mathew P Miller, Adele Robbins, P B PriceAbstract:Purpose: Clinical evaluation of novel agents that target tumor blood vessels requires pharmacodynamic end points that measure vascular damage. Positron emission tomography (PET) was used to measure the effects of the vascular targeting agent combretastatin A4 phosphate (CA4P) on tumor and normal tissue perfusion and blood volume. Patients and Methods: Patients with advanced solid tumors were enrolled onto part of a phase I, accelerated-titration, dose-escalation study. The effects of 5 to 114 mg/m2 CA4P on tumor, spleen, and kidney were investigated. Tissue perfusion was measured using Oxygen-15 (15O)–labeled water and blood volume was measured using 15O-labeled carbon monoxide (C15O). Scans were performed immediately before, and 30 minutes and 24 hours after the first infusion of each dose level of CA4P. All statistical tests were two sided. Results: PET data were obtained for 13 patients with intrapatient dose escalation. Significant dose-dependent reductions were seen in tumor perfusion 30 minutes afte...
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comparison of regional myocardial blood flow in syndrome x and one vessel coronary artery disease
American Journal of Cardiology, 1993Co-Authors: Alfredo R. Galassi, Terry Jones, Juan Carlos Kaski, Adriaan A. Lammertsma, Luis I Araujo, Giuseppe Pupita, Yusuke Yamamoto, Eldad Rechavia, Attilio MaseriAbstract:Myocardial blood flow (MBF) was measured using continuous inhalation of Oxygen-15-labeled carbon dioxide, and positron emission tomography before and after intravenous dipyridamole in 13 patients with syndrome X (angina pectoris, angiographically normal coronary arteries, positive exercise test and negative ergonovine test), 7 healthy subjects and 8 patients with 1-vessel coronary artery disease (CAD). In patients with syndrome X, baseline MBF was greater than in healthy subjects and patients with CAO (1.24 ± 0.27 vs 0.87 ± 0.07 and 1.03 ± 0.23 ml/g/min, respectively; p < 0.05), and more heterogeneous (34 ± 7 vs 26 ± 5 and 25 ± 6, respectively; p < 0.05) as assessed by the coefficient of variation among myocardial regions ≤2.3 cm3. After dipyridamole, MBF in patients with syndrome X was similar to that in healthy subjects (2.95 ± 0.75 vs 3.40 ± 0.82 ml/g/min; p = NS) and greater than in patients with CAD (1.78 ± 0.76 ml/g/min; p < 0.05). However in patients with both syndrome X and CAD, MBF was more heterogeneous than in healthy subjects (48 ± 12 and 48 ± 11, respectively, vs 30 ± 7; p < 0.01). Thus, in patients with syndrome X, MBF is abnormally heterogeneous both at baseline and after dipyridamole. These findings are compatible with the presence of dynamic alterations of small coronary arteries. Because these alterations appear to be very sparse within the myocardium, they can be undetected when myocardial perfusion, function and metabolism are assessed using conventional methods that are unable to detect small myocardial regions.
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use of the left ventricular time activity curve as a noninvasive input function in dynamic Oxygen 15 water positron emission tomography
The Journal of Nuclear Medicine, 1992Co-Authors: Hidehiro Iida, Adriaan A. Lammertsma, Luis I Araujo, C G Rhodes, Ranil De Silva, Peter Bloomfield, Terry JonesAbstract:Noninvasive recording of arterial input functions using regions of interest (ROIs) in the left ventricular (LV) chamber obviates the need for arterial cannulation in PET, but it is compromised by the limited recovery coefficient of the LV chamber and by statistical noise. In the present study, a new mathematical model has been developed, which corrects for the spillover of radioactivity both from the myocardium into the LV ROI and the blood into the myocardial ROI. The method requires the measurement of a time-activity curve in the LV chamber during the dynamic H2(15)O PET study and the measurement of the recovery coefficient of the LV ROI using a 15O-carbon monoxide (C15O) scan and venous blood sampling. This approach was successfully validated against direct measurements of the arterial input function using an on-line beta detector in five greyhounds undergoing dynamic H2(15)O PET imaging. This technique also yielded myocardial blood flow (MBF) values which were not significantly different from those obtained with the beta-probe analyses (maximum difference less than 2%), provided that the LV ROIs were sufficiently large to provide good counting statistics. When this model was not applied for large ROIs (small recovery in LV ROI), systematic overestimations in MBF compared with beta-probe analysis (e.g., a factor by 40% for a recovery coefficient of 0.7) were observed. Thus, this technique enabled the prediction of an accurate input function using the LV time-activity curve, and hence, noninvasive quantification of MBF without arterial cannulation.
