Real-time Cardiac Magnetic Resonance Research Articles

A Mechatronic System for Interactive Scan Plan Prescription during Real-Time Cardiac Magnetic Resonance Imaging

Real-time magnetic resonance imaging (MRI) has many advantages as compared to traditional MRI and can be used for the visualization of dynamic moving cardiac structures and functions without cardiac gating, as the fast data acquisition apparently freezes the motion resulting from heart beating and lung breathing. During the past decades, fast pulse sequences and image reconstruction algorithms had been developed to improve the temporal resolution with acceptable spatial resolution. However, the bottle neck of current real-time MRI systems is the availability of a user-friendly prescription tool to allow a MRI technician to prescribe the 6-Degree-of-freedom imaging plane of the MRI system. To meet the needs of real-time MRI, a 3D input tool is developed which facilitates user interactive specification of the center position and plane orientation of the MRI imaging plane. This paper reports such a custom designed 6 degree-of-freedom 3D input device, which allows the user to interactively and intuitively manipulate the scan plane to direct the real-time imaging capability to a target position based on the visual feedback provided on the MRI console in the form of real-time MRI images

Right ventricular work increase during strenuous exercise is greater than for the left ventricle: results from a real-time exercise cardiac magnetic resonance study

Background: Exercise-induced augmentation of cardiac output demands an increase in ventricular work. We sought to quantify the relative increases of right and left ventricular work using gold standard pressure and volume measures during strenuous exercise. Methods: 10 male athletes (35±9 years, VO2=55±9ml/min/kg) and 10 male non-athletes (37±10 years, VO2=39±8ml/min/kg) underwent real-time cardiac magnetic resonance (CMR) imaging at rest and during 3 stages of increasing exercise to maximal exertion. After compensation for respiratory motion, left and right ventricular stroke volumes (LVSV and RVSV) were quantified from endocardial traces on bi-plane cine stacks (12-18 x8mm slices) using in-house developed software. Simultaneous mean pulmonary and radial artery pressures (mPAP and mBP) were measured invasively, and ventricular work was calculated as SV x mean pressure. Results: Cardiac output was greater in athletes than non-athletes at maximal exercise (25.8±4.4 vs. 20.6±4.0 L/min, p=0.014), as was mPAP (32±9 vs. 24±4 mmHg, p=0.021) and mBP (129±14 vs. 117±10, p=0.014). During exercise, the proportional increase in RV work was far greater than for LV work. This was true for athletes, non-athletes and in the combined cohort (figure). ![Figure][1] Greater RV than LV work during exercise Conclusion: As compared with the LV, strenuous exercise imposes a considerably greater workload on the RV. During exercise, the RV and pulmonary circulation may be a far more important determinant of cardiac performance than has previously been realized. [1]: pending:yes

Changes in biventricular volumes during respiration: assessment of the respiratory pump using real-time cardiac magnetic resonance imaging during exercise

Background: Real-time cardiac magnetic resonance (CMR) imaging has emerged as an accurate and reproducible tool for biventricular volume assessment during free-breathing and whilst exercising. The aim of this study was to examine the degree to which the respiratory pump influenced cardiac filling and performance at rest and during exercise. Methods: Nine healthy subjects (8 male, 1 female) underwent CMR during free-breathing using an ungated real-time CMR sequence. ECG and respiratory movements were retrospectively synchronized enabling compensation for cardiac cycle and respiratory phase and cardiac volumes were determined for the left and right ventricles (LV and RV) from stacks of bi-plane cine images using customized software. End-diastolic and end-systolic volumes (EDV and ESV) as well as diastolic and systolic eccentricity indexes were measured for the LV and RV during peak inspiration and peak expiration, both at rest (heart rate 58±10 bpm) and whilst cycling at low (110±17 bpm), moderate (138±18 bpm) and strenuous (153±20 bpm) workload intensities. Results: As compared with expiration, there was an increase in RV volumes during inspiration (RVEDV +11%, RVESV +12%, RVSV +10%, p<0.05) In contrast, LV EDV, LV ESV and LV SV reduced during inspiration (-6%, -6%, -6%, p<0.05). LVEF and RVEF did not change with respiration, at rest or during exercise. During inspiration, RV SV tended to be larger than LV SV (p=0.064), whilst LV SV was significantly larger than RV SV during expiration (p<0.0001). Mean SV, defined as the average of peak-inspiratory and peak expiratory SV, was slightly greater (5%, p=0.047) for the LV than for the RV, possibly reflecting the expected physiological excess due to the bronchial and thebesian circulation. The interventricular septum pushed toward the LV during inspiration as evidenced by a greater eccentricity index during inspiration than during expiration, which was greatest in diastole (+ 16%, p<0.0001) but also evident during systole (+ 6%, p=0.019). Conclusions: Ventricular volumes oscillate with respiratory phase such that RV volumes and LV volumes are maximal during inspiration and expiration, respectively. Thus, instantaneous measures of stroke volume should not be expected to be equal. Real-time CMR provides a novel means of quantifying the degree to which pulmonary disorders may impact on cardiac performance.

Impaired preload reserve during exercise limits exercise capacity in the better Fontan patients

Background: Factors controlling cardiac output in a Fontan circulation are still poorly understood. This study aimed at evaluating changes in exercise hemodynamics using a novel cardiac magnetic resonance (CMR) methodology during mild, moderate and high intensity exercise. Methods: Ten Fontan patients (6 male, age 20±4 years, NYHA I-II) underwent CMR at rest and during supine exercise on a programmable cycle ergometer. Systemic ventricular volumes were obtained at rest (heart rate 72±14 bpm) and during mild (100±10 bpm), moderate (122±15 bpm) and high intensity (144±15 bpm) exercise. Images were acquired using an ungated, free-breathing real-time CMR sequence (12-18 contiguous 8mm slices). Software was developed to allow for synchronization of short and long-axis images with compensation for respiratory phase translation. Endocardial borders were delineated using a bi-plane model. Simultaneously, radial and pulmonary artery pressures were measured. Results: Cardiac output (CO) increased from rest to moderate intensity exercise, but failed to increase further during high intensity exercise (6.8±1.6 vs 10.0±3.2 vs 11.8±3.2 vs 12.5±3.1 l/min; P<0.0001). The increase in CO depended on a 106±49% increase in heart rate as stroke volume (SV) decreased during high intensity exercise (95±19 vs 100±21 vs 96±20 vs 87±16 ml; P<0.0001). End-diastolic volume (EDV) decreased during high intensity exercise (169±38 vs 174±39 vs 170±38 vs 162±36 ml; P=0.002), whereas end-systolic volume (ESV) did not change during exercise (74±31 vs 74±31 vs 73±32 vs 75±32 ml; P=0.715). Ejection fraction (EF) decreased during exercise (57±10 vs 58±10 vs 59±11 vs 55±11%, P=0.037). Pulmonary artery pressures (9±3 vs 14±4 vs 17±4 vs 21±5 mmHg; P<0.0001) and mean arterial pressures (81±7 vs 92±7 vs 100±6 vs 106±4 mmHg; P<0.0001) increased during exercise. Total pulmonary resistance increased during high intensity exercise (P=0.004) whereas systemic vascular resistance decreased during exercise (P=0.003). Arteriovenous oxygen difference increased from 5.5±1.2 to 9.6±1.9 ml/100ml (P=0.001). Conclusions: A decreasing SV and EDV despite a blunted heart rate response during exercise reflect a limited ventricular preload which is presumably related to the increase in total pulmonary resistance. The decreased preload reserve in a Fontan circuit is an important determinant limiting exercise capacity.

Sildenafil improves exercise hemodynamics in Fontan patients

Background: Reduced preload reserve is a fundamental limitation of the Fontan circulation. Sildenafil may increase exercise capacity in patients with Fontan physiology, but the underlying mechanism is still unclear. Using a novel exercise cardiac magnetic resonance (CMR) methodology, we tested the hypothesis that sildenafil would improve exercise hemodynamics in Fontan patients. Methods: Ten Fontan patients (6 male, age 20±4 years) underwent CMR at rest and during supine exercise on a programmable cycle ergometer before (baseline) and after a single dose of sildenafil (50 mg oral). Systemic ventricular volumes were obtained at rest and during mild (104±11 bpm), moderate (127±16 bpm) and high intensity (147±15 bpm) exercise. Bi-plane cine images were acquired using an ungated, free-breathing real-time CMR sequence (12-18 contiguous 8mm slices) and analyzed using software developed enabling retrospective gating for cardiac phase and respiratory translation. Endocardial borders were delineated using a bi-plane model. Simultaneously, radial and pulmonary artery pressures (PAPs) were measured. Results: Under resting conditions as compared with baseline, sildenafil reduced PAPs (9±3 to 8±3 mmHg, P=0.029) and increased heart rate (72±14 to 82±13 bpm, P<0.0001) and cardiac output (6.8±1.6 to 8.1±2.1 L/min, P=0.006). Total pulmonary resistance (TPR) (1.49±0.86 to 1.13±0.66 mmHg.min/L; P=0.010) and systemic vascular resistance (SVR) (11.05±2.43 to 8.65±1.90 mmHg.min/L; P<0.0001) decreased. During exercise sildenafil resulted in improved hemodynamics. PAPs (mean difference -1.0±0.7 mmHg, P=0.010) and mean arterial pressures (mean difference -7.1±1.5 mmHg, P<0.0001) decreased, whilst cardiac output (mean difference +1.4±0.7 L/min, P=0.001), ejection fraction (mean difference +4.6±2.5%, P=0.003) and stroke volume (mean difference +6.7±4.8 ml, P=0.012) all increased. TPR (mean difference -0.34±0.21 mmHg.min/L, P=0.004) and SVR (mean difference -1.38±0.28 mmHg.min/L, P<0.0001) decreased. The decrease in SVR between exercise stages was similar before and after sildenafil (interaction P=0.137). However, in contrast to the increase in TPR before sildenafil, TPR did not increase between stages after sildenafil (interaction P=0.033). Conclusion: In patients with Fontan physiology, sildenafil improves cardiac output during exercise which is presumably related an improved response of the pulmonary vasculature, especially during exercise. This implies that pulmonary vasodilation is a potential physiological target for improving exercise hemodynamics, the clinical significance of which warrants further study.

Right ventricular fatigue limits cardiac performance during intense endurance exercise: a novel Cardiac Magnetic Resonance (CMR) study during exercise

Background: Cardiac dysfunction following prolonged intense exercise has been shown to predominantly affect the right ventricle (RV). However, these changes have only been observed at rest and we do not know whether cardiac dysfunction is also present during exercise. Methods: Real-time CMR imaging was performed in 14 male endurance athletes at rest and then during 3 stages of incremental exercise to maximal exertion. CMR was performed 1-3 weeks before (baseline) and immediately after (post-race) a 150 km cycling event. Images obtained during exercise and free-breathing were analyzed using in-house developed software in which end-diastolic and end-systolic volumes (EDV,ESV) were obtained from endocardial tracings of bi-plane cine stacks after compensation for respiratory motion. Stroke volume (SV) was calculated as EDV – ESV, cardiac output (CO) as SV x heart rate (HR) and ejection fraction (EF) as SV/EDV %. Results: As compared with baseline, CO increased to similar values at maximal exertion in the post-race setting (24.1±2.4 vs. 24.7±2.1 l/min; P=0.448). However, RVEDV (P=0.021) and RVESV (P<0.0001) were significantly higher post-race than baseline, with greater discrepancy throughout exercise intensities, whereas LVEDV (P=0.163) and LVESV (P=0.127) were similar throughout exercise at baseline and post-race. At baseline and post-race LVEF augmented normally whereas both resting and exercise RVEF was attenuated after prolonged intense exercise as compared to baseline (figure). ![Figure][1] Attenuated RVEF after endurance exercise Conclusions: Whilst LV function is unchanged, intense endurance exercise results in RV dilation and reduced RV function, both at rest and during exercise. This indicates that cardiac performance during extreme exercise is limited by right ventriculo-arterial interaction. [1]: pending:yes

Response to Letter Regarding Article, “Cardiac Magnetic Resonance Imaging: A New Gold Standard for Ventricular Volume Quantification During High-Intensity Exercise”

HomeCirculation: Cardiovascular ImagingVol. 6, No. 3Response to Letter Regarding Article, “Cardiac Magnetic Resonance Imaging: A New Gold Standard for Ventricular Volume Quantification During High-Intensity Exercise” Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticlePDF/EPUBResponse to Letter Regarding Article, “Cardiac Magnetic Resonance Imaging: A New Gold Standard for Ventricular Volume Quantification During High-Intensity Exercise” Andre La Gerche, MD, PhD, Guido Claessen, MD, Alexander Van de Bruaene, MD, Nele Pattyn, MSc, Johan Van Cleemput, MD, PhD, Marc Gewillig, MD, PhD, Jan Bogaert, MD, PhD, Steven Dymarkowski, MD, PhD, Piet Claus, PhD and Hein Heidbuchel, MD, PhD Andre La GercheAndre La Gerche University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Guido ClaessenGuido Claessen University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Alexander Van de BruaeneAlexander Van de Bruaene University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Nele PattynNele Pattyn University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Johan Van CleemputJohan Van Cleemput University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Marc GewilligMarc Gewillig University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Jan BogaertJan Bogaert University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Steven DymarkowskiSteven Dymarkowski University Hospital of LeuvenLeuven, Belgium Search for more papers by this author , Piet ClausPiet Claus University Hospital of LeuvenLeuven, Belgium Search for more papers by this author and Hein HeidbuchelHein Heidbuchel University Hospital of LeuvenLeuven, Belgium Search for more papers by this author Originally published1 May 2013https://doi.org/10.1161/CIRCIMAGING.113.000389Circulation: Cardiovascular Imaging. 2013;6:e20We thank Drs Yoneyama and Akashi for their important reference to the confounding influence of respiration on biventricular volume assessment by real-time cardiac magnetic resonance imaging. As we noted in the Discussion, changes in biventricular volumes “may be caused by physiological differences in preload attributable to the fall in intrathoracic pressures during inspiration and cardiac translation through the imaging plane.”1 Real-time cardiac magnetic resonance imaging provides a novel means of expanding on the eloquent work of Natarajan et al2 on assessing the influence of the respiratory pump on cardiac filling and function. This interaction between breathing and cardiac function has received limited attention, but now we have an excellent noninvasive tool for very accurately detailing changes in both right and left ventricular volumes with various respiratory maneuvers. We hope to provide novel data in the peer-reviewed literature soon that will detail the importance of this respiratory pump in enhancing cardiac filling. We slightly disagree with the assertion that breath-hold imaging should be considered a gold standard. Breath-holding is a nonphysiological surrogate that has previously been necessary to enable gating of cardiac magnetic resonance images. Real-time imaging enables the investigator to apply the accuracy of cardiac magnetic resonance to real physiological settings. We can neither ignore the fact that our patients breathe nor ignore the fact that most of our patients develop symptoms with exertion. This new methodology finally enables us to accurately measure cardiac function when it really matters.Andre La Gerche, MD, PhDGuido Claessen, MDAlexander Van de Bruaene, MDNele Pattyn, MScJohan Van Cleemput, MD, PhDMarc Gewillig, MD, PhDJan Bogaert, MD, PhDSteven Dymarkowski, MD, PhDPiet Claus, PhDHein Heidbuchel, MD, PhDUniversity Hospital of LeuvenLeuven, BelgiumDisclosuresNone.

Self-calibrating through-time spiral GRAPPA for real-time CMR

Background Through-Time non-Cartesian GRAPPA, a novel parallel imaging method for non-Cartesian trajectories, has recently been shown to provide real-time, free-breathing cardiac images with temporal resolutions of less than 35 ms per frame [Seiberlich N, et al. MRM 2011 Dec;66 (6):1682-8]. The drawback to this method is the need for several fully-sampled datasets for calibration stemming from the non-Cartesian nature of the data, which leads to a longer overall scan time. By acquiring interleaved spiral datasets and combining them to form fully-sampled datasets for the generation of the GRAPPA weights, as in TGRAPPA [Breuer FA, et al. MRM 2005 Apr;53(4):9815.], there is no need for additional calibration data. However, this interleaved calibration method poses the risk of increased artifacts if the temporal footprint of the calibration data is too long. The goal of this study is to test the extent to which self-calibrating through-time spiral GRAPPA can be used for real-time free-breathing CMR.

High resolution real-time CMR of function and flow: initial clinical results

Background A new MRI technology for real-time MRI at high temporal and high spatial resolution was applied to CMR. First clinical applications cover dynamic imaging of wall motion and volume changes during cardiac arrhythmias as well as quantitative flow measurements under physiologic stress maneuvers. Methods A recently introduced real-time MRI method based on undersampled radial FLASH sequences with image reconstruction by regularized nonlinear inversion was applied to CMR. Anatomical imaging in real time was performed at 34 ms temporal resolution (30 fps) using 1.5 mm in-plane resolution and 6 mm slice thickness. Real-time quantitative flow measurements employed two acquisitions at 20 ms resolution, yielding a temporal resolution of 40 ms (25 fps) at 1.3 mm in-plane resolution and 6 mm slice thickness. Healthy volunteers as well as patients with arrhythmia were examined in a clinical 3T MR scanner. The image series were analyzed using a modified standard software capable of dealing with 100 to 900 images per slice position. The ECG signal was co-registered for documentation and ease of image analysis. Results The new high-resolution real-time MRI technique was used to analyze the beat-to-beat variability of patients with arrhythmia and to define ejection fractions in normal and arrhythmic episodes. Quantitative flow measurements were obtained in all major intrathoracic vessels during free breathing. Specific measurements during increased (Valsalva maneouver) and reduced intrathoracic pressure (Mueller maneouver) were obtained in healthy volunteers to document cardiovascular response to physiologic stressors. Regional wall motion, ventricular volumes, myocardial mass and ejection fraction were derived including standard deviations based on temporal variability of the heart cycle. Suitable software strategies for the analysis of the large datasets are indispensible to bring real-time CMR into clinical routine.

Left ventricular function, aortic velocity, and late gadolinium enhancement assessed by real-time and single shot CMR is comparable to breath-held segmented imaging: a prospective study

Methods Thirteen patients referred to the CMR lab for evaluation of undiagnosed cardiomyopathy were prospectively enrolled. All patients were in regular cardiac rhythm and able to breath-hold. Standard segmented k-space images (including cine, velocity mapping (VM), and late-gadolinium enhancement (LGE)) were acquired during breathhold; real-time images (including cine, VM, and LGE) were acquired during free-breathing. Relevant imaging parameters are listed in Table 1. Breath-held and real-time studies for LGE were blinded and scored on a segmental basis for presence or absence of enhancement by two reviewers. LVEF was calculated using Simpson’s rule on short-axis BH cines, and biplane area-length methodology on long-axis RT cines. EF results were averaged across cardiac cycles when RT cine spanned more than one heartbeat. Peak velocity through the aortic valve was assessed in BH and RT images and compared. Maximum peak velocity was used when RT images spanned more than one heartbeat.

Transthoracic delivery of large devices into the left ventricle through the right ventricle and interventricular septum: preclinical feasibility.

BackgroundWe aim to deliver large appliances into the left ventricle through the right ventricle and across the interventricular septum. This transthoracic access route exploits immediate recoil of the septum, and lower transmyocardial pressure gradient across the right versus left ventricular free wall. The route may enhance safety and allow subxiphoid rather than intercostal traversal.MethodsThe entire procedure was performed under real-time CMR guidance. An “active” CMR needle crossed the chest, right ventricular free wall, and then the interventricular septum to deliver a guidewire then used to deliver an 18Fr introducer. Afterwards, the right ventricular free wall was closed with a nitinol occluder. Immediate closure and late healing of the unrepaired septum and free wall were assessed by oximetry, angiography, CMR, and necropsy up to four weeks afterwards.ResultsThe procedure was successful in 9 of 11 pigs. One failed because of refractory ventricular fibrillation upon needle entry, and the other because of inadequate guidewire support. In all ten attempts, the right ventricular free wall was closed without hemopericardium. There was neither immediate nor late shunt on oximetry, X-ray angiography, or CMR. The interventricular septal tract fibrosed completely. Transventricular trajectories planned on human CT scans suggest comparable intracavitary working space and less acute entry angles than a conventional atrial transseptal approach.ConclusionLarge closed-chest access ports can be introduced across the right ventricular free wall and interventricular septum into the left ventricle. The septum recoils immediately and heals completely without repair. A nitinol occluder immediately seals the right ventricular wall. The entry angle is more favorable to introduce, for example, prosthetic mitral valves than a conventional atrial transseptal approach.

Respiratory ventricular area changes measured with real-time cardiac magnetic resonance: A new, accurate, and reproducible approach for the diagnosis of pericardial constriction

Demonstration of pericardial pathology and/or constrictive physiology remains the basis for the diagnosis of pericardial constriction (PC). Cardiovascular magnetic resonance (CMR) is increasingly used to depict pericardial abnormalities [1–6]. Moreover, the Society of CMR endorses visual determination of abnormal respiratory septal motion characteristic of constrictive physiology on real-time cine imaging [7], and preliminary CMR studies have attempted to quantify this sign of increased ventricular interdependence [8,9] (Fig. 1).

Impact of reduction in right ventricular pressure and/or volume overload by percutaneous pulmonary valve implantation on biventricular response to exercise: an exercise stress real-time CMR study

To assess the impact of relief of pulmonary stenosis (PS) and pulmonary regurgitation (PR) by percutaneous pulmonary valve implantation (PPVI) on biventricular function during exercise stress. Seventeen patients, who underwent PPVI for PS or PR, were included. Magnetic resonance imaging was performed at rest and during supine exercise stress pre- and within 1-month post-PPVI, using a radial k - t SENSE real-time sequence. In patients with PS (n = 9), there was no reserve in right ventricular (RV) ejection fraction (EF) in response to exercise prior to PPVI (48.2 ± 12.1% at rest vs. 48.4 ± 14.8% during exercise, P = 0.87). Post-PPVI, reserve in RVEF in response to exercise was re-established (53.4 ± 15.0% at rest vs. 59.6 ± 17.3% during exercise, P = 0.003) with improvement in left ventricular stroke volume (LVSV) (45.4 ± 6.2 mL/m(2) at rest vs. 52.8 ± 8.8 mL/m(2) during exercise, P = 0.001). In patients with PR prior to PPVI (n = 8), LVSV during exercise increased (43.0 ± 8.5 vs. 54.3 ± 6.6 mL/m(2), P < 0.001) due to reduction in PR fraction during exercise (29.2 ± 5.2 vs. 13.6 ± 6.1%, P < 0.001). After PPVI, LVSV increased from rest to exercise (48.4 ± 8.8 vs. 57.2 ± 8.1 mL/m(2), P < 0.001) due to improved RVEF (45.5 ± 8.3 vs. 50.4 ± 6.9%, P = 0.001). There was a significantly higher increase in LVSV at exercise from pre- to post-PPVI in PS patients than in PR patients (ΔLVSV 8.2 ± 4.1 vs. Δ2.9 ± 4.1 mL/m(2), P = 0.01). The reduction in the RV outflow tract gradient correlated significantly with the improvement in LVSV during exercise (r = -0.73, P < 0.001). Percutaneous pulmonary valve implantation in patients with PS leads to restoration of reserve in RVEF during exercise stress. In patients with PR, SV augmentation improves only mildly post-PPVI. Improvement in SV augmentation during exercise stress after PPVI is dependent mainly on afterload reduction.

Real-time and single shot CMR increases throughput and improves reliability

Summary The purpose of this study is to compare exam time and quality of images obtained using standard segmented kspace acquisitions versus single-shot and real time techniques that require no breath-holds. Background The typical CMR exam utilizes segmented k-space acquisitions that require repeated breath-holds, regular cardiac rhythm, and total exam times on the order of forty-five minutes. Widespread utilization of CMR has been hampered by these prolonged exam times and limited reliability in patients with irregular rhythm and/or inability to breath-hold. Methods Cardiac MRI studies performed at our lab over a twenty-five day period were retrospectively reviewed and 16 consecutive studies identified that did not involve stress imaging or MR angiography; the majority included cine, late gadolinium enhancement (LGE), and velocity mapping. Indications for CMR were: cardiomyopathy 11, cardiac mass 2, valvular 1, viability 1, pericardial 1. Studies were separated into two groups: eight were performed using standard segmented k-space acquisitions and eight in which cardiac arrhythmia or inability to breath-hold led to the use of real-time and single-shot methods exclusively. All images were qualitatively assessed for image quality, ability to estimate function.

An Approach To Imaging Adult Congenital Heart Disease : Pitfals And Pearls

Noninvasive cardiovascular evaluation of an adult congenital heart disease (ACHD) patient is a multimodality endeavor that can include chest roentgenograms, electrocardiograms, echocardiography (including stress, three-dimensional, intravascular and intracardiac ultrasound, and transesophageal), cardiac magnetic resonance imaging (CMR), computed tomography angiography (CTA), single photon emission computed tomographic (SPECT) perfusion imaging, and positron emission tomography (PET). The cost-benefit ratio and limitations of each modality should always be considered (Table 1). Adults with ACHD often need repetitive imaging, making them vulnerable to radiation-induced cancer; hence, modalities using ionizing radiation should be minimized. A transthoracic echocardiogram remains the initial noninvasive modality of choice due to its real-time imaging capability with excellent temporal resolution and its ability to quickly assess hemodynamics along with anatomic delineation. A transesophageal echocardiogram is extremely helpful in further defining intracardiac anatomy and guiding surgical and interventional procedures. Cardiac magnetic resonance imaging is an adjunctive modality to an echocardiogram because ACHD patients frequently have intra-thoracic abnormalities (e.g., adhesions from multiple cardiac operations and lung disease) that can limit the resolution of the ultrasound beam. A CMR is especially helpful in periodic evaluation of the right ventricle, visceral situs, extracardiac anatomy, lesions of the pericardium, pulmonary veins, systemic veins, pulmonary arteries, and aorta. For real-time CMR, special techniques such as echo planar can be used; for hemodynamic evaluation by CMR, techniques like velocity-vector mapping, myocardial tagging, echo planar, and fast gradient echo can be used. Besides excellent spatial resolution, the advantage of CTA over other techniques is an extremely fast acquisition time. Furthermore, CTA can replace an invasive procedure such as catheterization and angiography for anatomical diagnosis where hemodynamics is not required, such as the diagnosis of arch or coronary artery anomalies. Nuclear scans such as lung perfusion scans and splenic scans are very helpful in determining differential pulmonary blood flow and splenic function, respectively. Both SPECT and PET are valuable in assessing tissue perfusion and metabolism and help to determine viable versus nonviable myocardium after surgery for hypoplastic left heart syndrome and coronary artery anomaly, after arterial switch operation for d-transposition of great arteries, and in acquired illness such as Kawasaki disease. When considering imaging a patient with ACHD, and overall evaluation strategy should include the aspects found in Table 2.

Can real-time cmr provide adequate morphologic or functional data? A real-time CMR/SSFP comparison trial

The objective of this trial was to assess the accuracy of cardiac magnetic resonance (CMR) images obtained via real-time CMR (RT-CMR) (GE: MR Echo) imaging sequences in comparison to steady-state free precession (SSFP).

Detailed assessment of the hemodynamic response to psychosocial stress using real‐time MRI

To demonstrate that combining the Montreal Imaging Stress Task (MIST) with real-time cardiac magnetic resonance imaging (MRI) allows detailed assessment of the cardiovascular mental stress response. 22 healthy volunteers (1:1 M:F, 26-64 years) underwent MRI during rest and the MIST. Real-time spiral phase contrast MR, accelerated with sensitivity encoding (SENSE) was used to assess stroke volume (SV), and radial k-t SENSE was used to assess ventricular volumes. Simultaneous heart rate (HR) and blood pressure (BP) measures allowed calculation of cardiac output (CO), systemic vascular resistance (SVR), and arterial compliance (TAC). Endocrine responses were assessed using salivary cortisol. In response to stress, BP increased due to increased CO and reduced TAC but not increased SVR, which fell. HR, not SV, determined CO increases. Greater BP responses occurred in men due to greater CO increases and relatively higher SVR. Older participants had greater BP responses due to greater falls in TAC. Greater cortisol response was correlated with greater falls in TAC but resting cortisol and TAC were not related. This new approach allows detailed, accurate assessment of stress physiology. Preliminary findings suggest stress exposes relationships, not seen at rest, of cardiovascular function with age, sex, and endocrine function.

Integrated Assessment of Diastolic and Systolic Ventricular Function Using Diagnostic Cardiac Magnetic Resonance Catheterization: Validation in Pigs and Application in a Clinical Pilot Study

This study sought to develop and validate a method for the integrated analysis of systolic and diastolic ventricular function. An integrated approach to assess ventricular pump function, myocontractility (end-systolic pressure-volume relationship [ESPVR]), and diastolic compliance (end-diastolic pressure-volume relation [EDPVR]) is of high clinical value. Cardiac magnetic resonance (CMR) is well established for measuring global pump function, and catheterization-combined CMR was previously shown to accurately measure ESPVR, but not yet the EDPVR. In 8 pigs, the CMR technique was compared with conductance catheter methods (gold standard) for measuring the EDPVR in the left and right ventricle. Measurements were performed at rest and during dobutamine administration. For CMR, the ESPVR was estimated with a single-beat approach by synchronizing invasive ventricular pressures with cine CMR-derived ventricular volumes. The EDPVR was determined during pre-load reduction from additional volume data that were obtained from real-time velocity-encoded CMR pulmonary/aortic blood flow measurements. Pre-load reduction was achieved by transient balloon occlusion of the inferior vena cava. The stiffness coefficient beta was calculated by an exponential fit from the EDPVR. After validation in the animal experiments, the EDPVR was assessed in a pilot study of 3 patients with a single ventricle using identical CMR and conductance catheter techniques. Bland-Altman tests showed good agreement between conductance catheter-derived and CMR-derived EDPVR. In both ventricles of the pigs, dobutamine enhanced myocontractility (p < 0.01), increased stroke volume (p < 0.01), and improved diastolic function. The latter was evidenced by shorter early relaxation (p < 0.05), a downward shift of the EDPVR, and a decreased stiffness coefficient beta (p < 0.05). In contrast, in the patients, early relaxation was inconspicuous but the EDPVR shifted left-upward and the stiffness constant remained unchanged. The observed changes in diastolic function were not significantly different when measured with conductance catheter and CMR. This novel CMR method provides differential information about diastolic function in conjunction with parameters of systolic contractility and global pump function.

Pectus Excavatum With Compression of the Inferior Vena Cava

Pectus excavatum (PE) is a common disorder of the chest wall that affects 1 in 500 of the general population. Affected individuals have cosmetic and, less commonly, cardiopulmonary consequences that typically present during the adolescent years. The latter is appreciated only in those with severe phenotypes, especially if associated with a “straight back” that further limits the anterior-posterior thoracic dimensions. Although the cardiopulmonary complications of PE have been well described, we describe a unique presentation of a patient who had experienced years of intractable syncope before receiving corrective surgery for severe PE. The role of cardiovascular magnetic resonance imaging (CMR) in her diagnosis and subsequent treatment is also highlighted. A 22-year-old woman presented with a long-standing history of recurrent syncope, beginning in early adolescence. These episodes typically occurred after prolonged periods of standing or walking, beginning with a prodrome of diaphoresis and blurred vision and culminating in loss of consciousness. She described self-taught maneuvers that reduced these symptoms, including twisting her torso to the side and performing rapid, shallow breathing. In spite of these maneuvers, she continued to be limited by frequent syncope and ultimately stopped attending school at 16 years of age. On examination, she had a marked pectus deformity with a straight back appearance. Her heart sounds were normal, with a Grade II out of VI systolic ejection murmur at the left sternal border. There was no jugular venous distention and no peripheral edema. Following indentification of the chest wall deformity further questioning revealed that both her brother and paternal uncle had severe PE, suggesting an autosomal dominant inheritance …

Cardiovascular magnetic resonance guided electrophysiology studies.

Catheter ablation is a first line treatment for many cardiac arrhythmias and is generally performed under x-ray fluoroscopy guidance. However, current techniques for ablating complex arrhythmias such as atrial fibrillation and ventricular tachycardia are associated with suboptimal success rates and prolonged radiation exposure. Pre-procedure 3D CMR has improved understanding of the anatomic basis of complex arrhythmias and is being used for planning and guidance of ablation procedures. A particular strength of CMR compared to other imaging modalities is the ability to visualize ablation lesions. Post-procedure CMR is now being applied to assess ablation lesion location and permanence with the goal of indentifying factors leading to procedure success and failure. In the future, intra-procedure real-time CMR, together with the ability to image complex 3-D arrhythmogenic anatomy and target additional ablation to regions of incomplete lesion formation, may allow for more successful treatment of even complex arrhythmias without exposure to ionizing radiation. Development of clinical grade CMR compatible electrophysiology devices is required to transition intra-procedure CMR from pre-clinical studies to more routine use in patients.