Orlando Simonetti | The Ohio State University (original) (raw)

Papers by Orlando Simonetti

Research paper thumbnail of Validation of VO2max Assessment and Magnetic Resonance Cardiac Function Measurements Utilizing an MRI Compatible Treadmill

Medicine and Science in Sports and Exercise, May 1, 2014

Research paper thumbnail of Simultaneous VO2 and cardiac output measurement to estimate oxygen extraction (a-v)O2

Journal of Cardiovascular Magnetic Resonance, Jan 27, 2016

Research paper thumbnail of Treadmill exercise stress cardiac MRI for the assessment of left ventricular wall motion: a comparison with stress echocardiography in healthy volunteers

Journal of Cardiovascular Magnetic Resonance, Feb 1, 2012

Research paper thumbnail of Abstract 16030: Myocardial Abnormalities in Competitive Athletes on T1 and T2 Parametric Mapping by Cardiovascular Magnetic Resonance Imaging

Circulation, Nov 17, 2020

Introduction: Athletic cardiac adaptation is associated with structural changes that can overlap ... more Introduction: Athletic cardiac adaptation is associated with structural changes that can overlap with disease states, unnecessarily limiting sports participation. Cardiovascular magnetic resonance (CMR) is useful in athlete’s heart and provides myocardial tissue characterization by T1 and T2 mapping. Hypothesis: CMR in competitive athletes will show abnormal T1 and T2 mapping due to intense exercise induced myocardial edema that can overlap with myocarditis. Methods: CMR data including left ventricular ejection fraction (LVEF) and T1/T2 maps were collected using standardized protocols on a 1.5 T scanner and compared between competitive athletes (N = 18, 83% male, median age 20 years), clinical myocarditis (N = 42, 71% male, median age 23 years) and controls (N = 35, 86% male, median age 22 years) between 2016-2020. T2 values of <59 ms and native T1 <1080 ms were defined as normal per institutional data. Extracellular volume fraction (ECV) and late gadolinium enhancement (LGE) were compared between athlete and myocarditis groups. Results: Figure 1 (panel A) shows participating sport and indications for CMR in athletes. There were 11 athletes (61%) with elevated T2 values (>59 ms), of which 9 (82%) were without clinical myocarditis. Average T2, native T1, ECV, and LVEF are shown in panels B-E. T2 values were highest in myocarditis, followed by athletes and controls (p = 0.001). ECV was higher in myocarditis compared to athletes (p = 0.002). LGE was present in 8/18 athletes and 41/42 myocarditis patients. 6 athletes had follow-up CMR after a period of deconditioning, with 3 (50%) demonstrating an improvement in T2 values and LGE. Conclusions: To conclude, we demonstrate abnormalities on T2 mapping in athletes consistent with myocardial edema or inflammation. Changes in T2 may be related to intense training. Additional studies are required to prospectively evaluate athletes for normative T1 and T2 mapping values, relationship to training, and their correlation with LGE.

Research paper thumbnail of Integrated treadmill stress testing and MR relaxometry (T1, T2, T2*): response in healthy calf muscles

Journal of Cardiovascular Magnetic Resonance, 2014

Research paper thumbnail of Abstract 12567: Reduced Myocardial Strain is Associated With Myocardial Inflammation and Fibrosis on Cardiovascular Magnetic Resonance Imaging in Collegiate Athletes Recovering From SARS-CoV-2 Infection

Circulation, Nov 16, 2021

Research paper thumbnail of Parametric mapping by cardiovascular magnetic resonance imaging in sudden cardiac arrest survivors

The International Journal of Cardiovascular Imaging

Research paper thumbnail of The Effects of a 6-Week Controlled, Hypocaloric Ketogenic Diet, With and Without Exogenous Ketone Salts, on Body Composition Responses

Frontiers in Nutrition, 2021

Background: Ketogenic diets (KDs) that elevate beta-hydroxybutyrate (BHB) promote weight and fat ... more Background: Ketogenic diets (KDs) that elevate beta-hydroxybutyrate (BHB) promote weight and fat loss. Exogenous ketones, such as ketone salts (KS), also elevate BHB concentrations with the potential to protect against muscle loss during caloric restriction. Whether augmenting ketosis with KS impacts body composition responses to a well-formulated KD remains unknown.Purpose: To explore the effects of energy-matched, hypocaloric KD feeding (<50 g carbohydrates/day; 1.5 g/kg/day protein), with and without the inclusion of KS, on weight loss and body composition responses.Methods: Overweight and obese adults were provided a precisely defined hypocaloric KD (~75% of energy expenditure) for 6 weeks. In a double-blind manner, subjects were randomly assigned to receive ~24 g/day of a racemic BHB-salt (KD + KS; n = 12) or placebo (KD + PL; n = 13). A matched comparison group (n = 12) was separately assigned to an isoenergetic/isonitrogenous low-fat diet (LFD). Body composition parameters...

Research paper thumbnail of Comparison of Ketogenic Diets with and without Ketone Salts versus a Low-Fat Diet: Liver Fat Responses in Overweight Adults

Nutrients, 2021

Ketogenic diets (KDs) often contain high levels of saturated fat, which may increase liver fat, b... more Ketogenic diets (KDs) often contain high levels of saturated fat, which may increase liver fat, but the lower carbohydrate intake may have the opposite effect. Using a controlled feeding design, we compared liver fat responses to a hypocaloric KD with a placebo (PL) versus an energy-matched low-fat diet (LFD) in overweight adults. We also examined the added effect of a ketone supplement (KS). Overweight adults were randomized to a 6-week KD (KD + PL) or a KD with KS (KD + KS); an LFD group was recruited separately. All diets were estimated to provide 75% of energy expenditure. Weight loss was similar between groups (p > 0.05). Liver fat assessed by magnetic resonance imaging decreased after 6 week (p = 0.004) with no group differences (p > 0.05). A subset with nonalcoholic fatty liver disease (NAFLD) (liver fat > 5%, n = 12) showed a greater reduction in liver fat, but no group differences. In KD participants with NAFLD, 92% of the variability in change in liver fat was exp...

Research paper thumbnail of Cardiovascular Adaptations In Individuals Of Various Fitness Levels Following Vo2max Test Utilizing Mri-compatible Treadmill

Medicine & Science in Sports & Exercise, 2015

Research paper thumbnail of CMR-based blood oximetry via multi-parametric estimation using multiple T2 measurements

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 9, 2017

Measurement of blood oxygen saturation (O2 saturation) is of great importance for evaluation of p... more Measurement of blood oxygen saturation (O2 saturation) is of great importance for evaluation of patients with many cardiovascular diseases, but currently there are no established non-invasive methods to measure blood O2 saturation in the heart. While T2-based CMR oximetry methods have been previously described, these approaches rely on technique-specific calibration factors that may not generalize across patient populations and are impractical to obtain in individual patients. We present a solution that utilizes multiple T2 measurements made using different inter-echo pulse spacings. These data are jointly processed to estimate all unknown parameters, including O2 saturation, in the Luz-Meiboom (L-M) model. We evaluated the accuracy of the proposed method against invasive catheterization in a porcine hypoxemia model. Sufficient data diversity to estimate the various unknown parameters of the L-M model, including O2 saturation, was achieved by acquiring four T2 maps, each at a differ...

Research paper thumbnail of Quantification of aortic stenosis diagnostic parameters: comparison of fast 3 direction and 1 direction phase contrast CMR and transthoracic echocardiography

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 7, 2017

Aortic stenosis (AS) is a common valvular disorder, and disease severity is currently assessed by... more Aortic stenosis (AS) is a common valvular disorder, and disease severity is currently assessed by transthoracic echocardiography (TTE). However, TTE results can be inconsistent in some patients, thus other diagnostic modalities such as cardiovascular magnetic resonance (CMR) are demanded. While traditional unidirectional phase-contrast CMR (1Dir PC-CMR) underestimates velocity if the imaging plane is misaligned to the flow direction, multi-directional acquisitions are expected to improve velocity measurement accuracy. Nonetheless, clinical use of multidirectional techniques has been hindered by long acquisition times. Our goal was to quantify flow parameters in patients using 1Dir PC-CMR and a faster multi-directional technique (3Dir PC-CMR), and compare to TTE. Twenty-three patients were prospectively assessed with TTE and CMR. Slices above the aortic valve were acquired for both PC-CMR techniques and cine SSFP images were acquired to quantify left ventricular stroke volume. 3Dir P...

Research paper thumbnail of The global cardiovascular magnetic resonance registry (GCMR) of the society for cardiovascular magnetic resonance (SCMR): its goals, rationale, data infrastructure, and current developments

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 20, 2017

With multifaceted imaging capabilities, cardiovascular magnetic resonance (CMR) is playing a prog... more With multifaceted imaging capabilities, cardiovascular magnetic resonance (CMR) is playing a progressively increasing role in the management of various cardiac conditions. A global registry that harmonizes data from international centers, with participation policies that aim to be open and inclusive of all CMR programs, can support future evidence-based growth in CMR. The Global CMR Registry (GCMR) was established in 2013 under the auspices of the Society for Cardiovascular Magnetic Resonance (SCMR). The GCMR team has developed a web-based data infrastructure, data use policy and participation agreement, data-harmonizing methods, and site-training tools based on results from an international survey of CMR programs. At present, 17 CMR programs have established a legal agreement to participate in GCMR, amongst them 10 have contributed CMR data, totaling 62,456 studies. There is currently a predominance of CMR centers with more than 10 years of experience (65%), and the majority are lo...

Research paper thumbnail of Cardiopulmonary exercise testing in the MRI environment

Physiological measurement, Jan 17, 2016

Maximal oxygen consumption ([Formula: see text]max) measured by cardiopulmonary exercise testing ... more Maximal oxygen consumption ([Formula: see text]max) measured by cardiopulmonary exercise testing (CPX) is the gold standard for assessment of cardiorespiratory fitness. Likewise, cardiovascular magnetic resonance (CMR) is the gold standard for quantification of cardiac function. The combination of CPX and CMR may offer unique insights into cardiopulmonary pathophysiology; however, the MRI-compatible equipment needed to combine these tests has not been available to date. We sought to determine whether CPX testing in the MRI environment, using equipment modified for MRI yields results equivalent to those obtained in standard exercise physiology (EP) lab. Ten recreationally trained subjects completed [Formula: see text]max tests in different locations; an EP laboratory and an MRI laboratory, using site specific equipment. CMR cine images of the heart were acquired before and immediately after maximal exercise to measure cardiac function. Subjects in all tests met criteria indicating th...

Research paper thumbnail of Diagnostic performance of treadmill exercise cardiac magnetic resonance: the prospective, multicenter EXACT trial

Journal of Cardiovascular Magnetic Resonance, 2016

Research paper thumbnail of Peak velocity estimation in aortic stenosis patients using a fast three-directional two-dimensional phase contrast technique in a single breath-hold: comparison to unidirectional phase contrast MRI and transthoracic echocardiography

Journal of Cardiovascular Magnetic Resonance, 2016

Research paper thumbnail of Aortic Stenosis assessment with a 3-directional phase contrast magnetic resonance technique. Comparison to transthoracic echocardiography

Journal of Cardiovascular Magnetic Resonance, 2015

3DPC-MRI parameters (D-F) are shown in Figure 1. Note less overall bias for the 3DPC-MRI techniqu... more 3DPC-MRI parameters (D-F) are shown in Figure 1. Note less overall bias for the 3DPC-MRI technique. Conclusions Initial results in a small patient cohort support the hypothesis that 3DPC-MRI provides better estimation of hemodynamic parameters in AS patients in comparison to 1DPC-MRI.

Research paper thumbnail of An improved preparation pulse for quantitative t2 mapping of blood in the cardiac chambers

Journal of Cardiovascular Magnetic Resonance, 2015

Background T2 is sensitive to hemoglobin oxygen saturation (%HbO2). Non-invasive, rapid in-vivo q... more Background T2 is sensitive to hemoglobin oxygen saturation (%HbO2). Non-invasive, rapid in-vivo quantification of %HbO2 based on the T2 of blood may be useful in patients with congenital heart disease. Although singleshot, T2-prepared SSFP enables rapid myocardial T2 quantification [1], flow sensitivity of the T2 preparation, especially at later echo times, may cause an underestimation of T2 values in flowing blood. We aim to reduce flow sensitivity of the T2 preparation pulse for rapid and accurate quantification of T2 in blood.

Research paper thumbnail of Aliskiren effect on plaque progression in established atherosclerosis using high resolution 3D MRI (ALPINE): a double-blind placebo-controlled trial

Journal of the American Heart Association, Jan 17, 2013

The renin-angiotensin system is well recognized as a mediator of pathophysiological events in ath... more The renin-angiotensin system is well recognized as a mediator of pathophysiological events in atherosclerosis. The benefits of renin inhibition in atherosclerosis, especially when used in combination with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs) are currently not known. We hypothesized that treatment with the renin inhibitor aliskiren in patients with established cardiovascular disease will prevent the progression of atherosclerosis as determined by high-resolution magnetic resonance imaging (MRI) measurements of arterial wall volume in the thoracic and abdominal aortas of high-risk patients with preexisting cardiovascular disease. This was a single-center, randomized, double-blind, placebo-controlled trial in patients with established cardiovascular disease. After a 2-week single-blind placebo phase, patients were randomized to receive either placebo (n=37, mean ± SD age 64.5 ± 8.9 years, 3 women) or 150 mg of aliskiren (n=34, mean ± SD ag...

Research paper thumbnail of Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study

Journal of Magnetic Resonance Imaging, 2013

Purpose-To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in... more Purpose-To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation. Materials and Methods-28 healthy volunteers (aged 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study. Results-Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 seconds, p<0.001) and time to acquire stress images (20 vs. 51 seconds, p<0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% versus 96.4%, p=0.002) and stress (99.8% versus 94.1%, p=0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs 60%, p=0.005). Conclusion-Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo.

Research paper thumbnail of Validation of VO2max Assessment and Magnetic Resonance Cardiac Function Measurements Utilizing an MRI Compatible Treadmill

Medicine and Science in Sports and Exercise, May 1, 2014

Research paper thumbnail of Simultaneous VO2 and cardiac output measurement to estimate oxygen extraction (a-v)O2

Journal of Cardiovascular Magnetic Resonance, Jan 27, 2016

Research paper thumbnail of Treadmill exercise stress cardiac MRI for the assessment of left ventricular wall motion: a comparison with stress echocardiography in healthy volunteers

Journal of Cardiovascular Magnetic Resonance, Feb 1, 2012

Research paper thumbnail of Abstract 16030: Myocardial Abnormalities in Competitive Athletes on T1 and T2 Parametric Mapping by Cardiovascular Magnetic Resonance Imaging

Circulation, Nov 17, 2020

Introduction: Athletic cardiac adaptation is associated with structural changes that can overlap ... more Introduction: Athletic cardiac adaptation is associated with structural changes that can overlap with disease states, unnecessarily limiting sports participation. Cardiovascular magnetic resonance (CMR) is useful in athlete’s heart and provides myocardial tissue characterization by T1 and T2 mapping. Hypothesis: CMR in competitive athletes will show abnormal T1 and T2 mapping due to intense exercise induced myocardial edema that can overlap with myocarditis. Methods: CMR data including left ventricular ejection fraction (LVEF) and T1/T2 maps were collected using standardized protocols on a 1.5 T scanner and compared between competitive athletes (N = 18, 83% male, median age 20 years), clinical myocarditis (N = 42, 71% male, median age 23 years) and controls (N = 35, 86% male, median age 22 years) between 2016-2020. T2 values of &amp;amp;lt;59 ms and native T1 &amp;amp;lt;1080 ms were defined as normal per institutional data. Extracellular volume fraction (ECV) and late gadolinium enhancement (LGE) were compared between athlete and myocarditis groups. Results: Figure 1 (panel A) shows participating sport and indications for CMR in athletes. There were 11 athletes (61%) with elevated T2 values (&amp;amp;gt;59 ms), of which 9 (82%) were without clinical myocarditis. Average T2, native T1, ECV, and LVEF are shown in panels B-E. T2 values were highest in myocarditis, followed by athletes and controls (p = 0.001). ECV was higher in myocarditis compared to athletes (p = 0.002). LGE was present in 8/18 athletes and 41/42 myocarditis patients. 6 athletes had follow-up CMR after a period of deconditioning, with 3 (50%) demonstrating an improvement in T2 values and LGE. Conclusions: To conclude, we demonstrate abnormalities on T2 mapping in athletes consistent with myocardial edema or inflammation. Changes in T2 may be related to intense training. Additional studies are required to prospectively evaluate athletes for normative T1 and T2 mapping values, relationship to training, and their correlation with LGE.

Research paper thumbnail of Integrated treadmill stress testing and MR relaxometry (T1, T2, T2*): response in healthy calf muscles

Journal of Cardiovascular Magnetic Resonance, 2014

Research paper thumbnail of Abstract 12567: Reduced Myocardial Strain is Associated With Myocardial Inflammation and Fibrosis on Cardiovascular Magnetic Resonance Imaging in Collegiate Athletes Recovering From SARS-CoV-2 Infection

Circulation, Nov 16, 2021

Research paper thumbnail of Parametric mapping by cardiovascular magnetic resonance imaging in sudden cardiac arrest survivors

The International Journal of Cardiovascular Imaging

Research paper thumbnail of The Effects of a 6-Week Controlled, Hypocaloric Ketogenic Diet, With and Without Exogenous Ketone Salts, on Body Composition Responses

Frontiers in Nutrition, 2021

Background: Ketogenic diets (KDs) that elevate beta-hydroxybutyrate (BHB) promote weight and fat ... more Background: Ketogenic diets (KDs) that elevate beta-hydroxybutyrate (BHB) promote weight and fat loss. Exogenous ketones, such as ketone salts (KS), also elevate BHB concentrations with the potential to protect against muscle loss during caloric restriction. Whether augmenting ketosis with KS impacts body composition responses to a well-formulated KD remains unknown.Purpose: To explore the effects of energy-matched, hypocaloric KD feeding (<50 g carbohydrates/day; 1.5 g/kg/day protein), with and without the inclusion of KS, on weight loss and body composition responses.Methods: Overweight and obese adults were provided a precisely defined hypocaloric KD (~75% of energy expenditure) for 6 weeks. In a double-blind manner, subjects were randomly assigned to receive ~24 g/day of a racemic BHB-salt (KD + KS; n = 12) or placebo (KD + PL; n = 13). A matched comparison group (n = 12) was separately assigned to an isoenergetic/isonitrogenous low-fat diet (LFD). Body composition parameters...

Research paper thumbnail of Comparison of Ketogenic Diets with and without Ketone Salts versus a Low-Fat Diet: Liver Fat Responses in Overweight Adults

Nutrients, 2021

Ketogenic diets (KDs) often contain high levels of saturated fat, which may increase liver fat, b... more Ketogenic diets (KDs) often contain high levels of saturated fat, which may increase liver fat, but the lower carbohydrate intake may have the opposite effect. Using a controlled feeding design, we compared liver fat responses to a hypocaloric KD with a placebo (PL) versus an energy-matched low-fat diet (LFD) in overweight adults. We also examined the added effect of a ketone supplement (KS). Overweight adults were randomized to a 6-week KD (KD + PL) or a KD with KS (KD + KS); an LFD group was recruited separately. All diets were estimated to provide 75% of energy expenditure. Weight loss was similar between groups (p > 0.05). Liver fat assessed by magnetic resonance imaging decreased after 6 week (p = 0.004) with no group differences (p > 0.05). A subset with nonalcoholic fatty liver disease (NAFLD) (liver fat > 5%, n = 12) showed a greater reduction in liver fat, but no group differences. In KD participants with NAFLD, 92% of the variability in change in liver fat was exp...

Research paper thumbnail of Cardiovascular Adaptations In Individuals Of Various Fitness Levels Following Vo2max Test Utilizing Mri-compatible Treadmill

Medicine & Science in Sports & Exercise, 2015

Research paper thumbnail of CMR-based blood oximetry via multi-parametric estimation using multiple T2 measurements

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 9, 2017

Measurement of blood oxygen saturation (O2 saturation) is of great importance for evaluation of p... more Measurement of blood oxygen saturation (O2 saturation) is of great importance for evaluation of patients with many cardiovascular diseases, but currently there are no established non-invasive methods to measure blood O2 saturation in the heart. While T2-based CMR oximetry methods have been previously described, these approaches rely on technique-specific calibration factors that may not generalize across patient populations and are impractical to obtain in individual patients. We present a solution that utilizes multiple T2 measurements made using different inter-echo pulse spacings. These data are jointly processed to estimate all unknown parameters, including O2 saturation, in the Luz-Meiboom (L-M) model. We evaluated the accuracy of the proposed method against invasive catheterization in a porcine hypoxemia model. Sufficient data diversity to estimate the various unknown parameters of the L-M model, including O2 saturation, was achieved by acquiring four T2 maps, each at a differ...

Research paper thumbnail of Quantification of aortic stenosis diagnostic parameters: comparison of fast 3 direction and 1 direction phase contrast CMR and transthoracic echocardiography

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 7, 2017

Aortic stenosis (AS) is a common valvular disorder, and disease severity is currently assessed by... more Aortic stenosis (AS) is a common valvular disorder, and disease severity is currently assessed by transthoracic echocardiography (TTE). However, TTE results can be inconsistent in some patients, thus other diagnostic modalities such as cardiovascular magnetic resonance (CMR) are demanded. While traditional unidirectional phase-contrast CMR (1Dir PC-CMR) underestimates velocity if the imaging plane is misaligned to the flow direction, multi-directional acquisitions are expected to improve velocity measurement accuracy. Nonetheless, clinical use of multidirectional techniques has been hindered by long acquisition times. Our goal was to quantify flow parameters in patients using 1Dir PC-CMR and a faster multi-directional technique (3Dir PC-CMR), and compare to TTE. Twenty-three patients were prospectively assessed with TTE and CMR. Slices above the aortic valve were acquired for both PC-CMR techniques and cine SSFP images were acquired to quantify left ventricular stroke volume. 3Dir P...

Research paper thumbnail of The global cardiovascular magnetic resonance registry (GCMR) of the society for cardiovascular magnetic resonance (SCMR): its goals, rationale, data infrastructure, and current developments

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 20, 2017

With multifaceted imaging capabilities, cardiovascular magnetic resonance (CMR) is playing a prog... more With multifaceted imaging capabilities, cardiovascular magnetic resonance (CMR) is playing a progressively increasing role in the management of various cardiac conditions. A global registry that harmonizes data from international centers, with participation policies that aim to be open and inclusive of all CMR programs, can support future evidence-based growth in CMR. The Global CMR Registry (GCMR) was established in 2013 under the auspices of the Society for Cardiovascular Magnetic Resonance (SCMR). The GCMR team has developed a web-based data infrastructure, data use policy and participation agreement, data-harmonizing methods, and site-training tools based on results from an international survey of CMR programs. At present, 17 CMR programs have established a legal agreement to participate in GCMR, amongst them 10 have contributed CMR data, totaling 62,456 studies. There is currently a predominance of CMR centers with more than 10 years of experience (65%), and the majority are lo...

Research paper thumbnail of Cardiopulmonary exercise testing in the MRI environment

Physiological measurement, Jan 17, 2016

Maximal oxygen consumption ([Formula: see text]max) measured by cardiopulmonary exercise testing ... more Maximal oxygen consumption ([Formula: see text]max) measured by cardiopulmonary exercise testing (CPX) is the gold standard for assessment of cardiorespiratory fitness. Likewise, cardiovascular magnetic resonance (CMR) is the gold standard for quantification of cardiac function. The combination of CPX and CMR may offer unique insights into cardiopulmonary pathophysiology; however, the MRI-compatible equipment needed to combine these tests has not been available to date. We sought to determine whether CPX testing in the MRI environment, using equipment modified for MRI yields results equivalent to those obtained in standard exercise physiology (EP) lab. Ten recreationally trained subjects completed [Formula: see text]max tests in different locations; an EP laboratory and an MRI laboratory, using site specific equipment. CMR cine images of the heart were acquired before and immediately after maximal exercise to measure cardiac function. Subjects in all tests met criteria indicating th...

Research paper thumbnail of Diagnostic performance of treadmill exercise cardiac magnetic resonance: the prospective, multicenter EXACT trial

Journal of Cardiovascular Magnetic Resonance, 2016

Research paper thumbnail of Peak velocity estimation in aortic stenosis patients using a fast three-directional two-dimensional phase contrast technique in a single breath-hold: comparison to unidirectional phase contrast MRI and transthoracic echocardiography

Journal of Cardiovascular Magnetic Resonance, 2016

Research paper thumbnail of Aortic Stenosis assessment with a 3-directional phase contrast magnetic resonance technique. Comparison to transthoracic echocardiography

Journal of Cardiovascular Magnetic Resonance, 2015

3DPC-MRI parameters (D-F) are shown in Figure 1. Note less overall bias for the 3DPC-MRI techniqu... more 3DPC-MRI parameters (D-F) are shown in Figure 1. Note less overall bias for the 3DPC-MRI technique. Conclusions Initial results in a small patient cohort support the hypothesis that 3DPC-MRI provides better estimation of hemodynamic parameters in AS patients in comparison to 1DPC-MRI.

Research paper thumbnail of An improved preparation pulse for quantitative t2 mapping of blood in the cardiac chambers

Journal of Cardiovascular Magnetic Resonance, 2015

Background T2 is sensitive to hemoglobin oxygen saturation (%HbO2). Non-invasive, rapid in-vivo q... more Background T2 is sensitive to hemoglobin oxygen saturation (%HbO2). Non-invasive, rapid in-vivo quantification of %HbO2 based on the T2 of blood may be useful in patients with congenital heart disease. Although singleshot, T2-prepared SSFP enables rapid myocardial T2 quantification [1], flow sensitivity of the T2 preparation, especially at later echo times, may cause an underestimation of T2 values in flowing blood. We aim to reduce flow sensitivity of the T2 preparation pulse for rapid and accurate quantification of T2 in blood.

Research paper thumbnail of Aliskiren effect on plaque progression in established atherosclerosis using high resolution 3D MRI (ALPINE): a double-blind placebo-controlled trial

Journal of the American Heart Association, Jan 17, 2013

The renin-angiotensin system is well recognized as a mediator of pathophysiological events in ath... more The renin-angiotensin system is well recognized as a mediator of pathophysiological events in atherosclerosis. The benefits of renin inhibition in atherosclerosis, especially when used in combination with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs) are currently not known. We hypothesized that treatment with the renin inhibitor aliskiren in patients with established cardiovascular disease will prevent the progression of atherosclerosis as determined by high-resolution magnetic resonance imaging (MRI) measurements of arterial wall volume in the thoracic and abdominal aortas of high-risk patients with preexisting cardiovascular disease. This was a single-center, randomized, double-blind, placebo-controlled trial in patients with established cardiovascular disease. After a 2-week single-blind placebo phase, patients were randomized to receive either placebo (n=37, mean ± SD age 64.5 ± 8.9 years, 3 women) or 150 mg of aliskiren (n=34, mean ± SD ag...

Research paper thumbnail of Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study

Journal of Magnetic Resonance Imaging, 2013

Purpose-To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in... more Purpose-To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation. Materials and Methods-28 healthy volunteers (aged 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study. Results-Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 seconds, p<0.001) and time to acquire stress images (20 vs. 51 seconds, p<0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% versus 96.4%, p=0.002) and stress (99.8% versus 94.1%, p=0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs 60%, p=0.005). Conclusion-Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo.