insights on the right ventricle. A cardiovascular magnetic resonance study

OBJECTIVES Pectus excavatum (PE) is often regarded as a cosmetic disease, while its effect on cardiac function is under debate. Data regarding cardiac function before and after surgical correction of PE are limited. We aimed to assess the impact of surgical correction of PE on cardiac function by cardiovascular magnetic resonance (CMR). METHODS CMR at 1.5 T was performed in 38 patients (mean age 21 ± 8.3; 31 men) before and after surgical correction to evaluate thoracic morphology, indices and its relation to three-dimensional left and right ventricular cardiac function. RESULTS Surgery was successful in all patients as shown by the Haller Index ratio of maximum transverse diameter of the chest wall and minimum sternovertebral distance [pre: 9.64 (95% CI 8.18–11.11) vs post: 3.0 (2.84–3.16), P < 0.0001]. Right ventricular ejection fraction (RVEF) was reduced before surgery and improved significantly at the 1-year follow-up [pre: 45.7% (43.9–47.4%) vs 48.3% (46.9–49.5%), P = 0.0004]. Left ventricular ejection fraction was normal before surgery, but showed a further improvement after 1 year [pre: 61.0% (59.3–62.7%) vs 62.7% (61.3–64.2%), P = 0.0165]. Cardiac compression and the asymmetry index changed directly after surgery and were stable at the 1-year follow-up [3.93 (3.53–4.33) vs 2.08 (1.98–2.19) and 2.36 (2.12–2.59) vs 1.38 (1.33–1.44), respectively; P < 0.0001 for both]. None of the obtained thoracic indices were predictors of the improvement of cardiac function. A reduced preoperative RVEF was predictive of RVEF improvement. CONCLUSIONS PE is associated with reduced RVEF, which improves after surgical correction. CMR has the capability of offering additional information prior to surgical correction

Biom Biostat Int J

CC999999/Intramural CDC HHS/United States2016-06-17T00:00:00Z27331197PMC491222

Acoustic cardiac triggering: a practical solution for synchronization and gating of cardiovascular magnetic resonance at 7 Tesla

<p>Abstract</p> <p>Background</p> <p>To demonstrate the applicability of acoustic cardiac triggering (ACT) for imaging of the heart at ultrahigh magnetic fields (7.0 T) by comparing phonocardiogram, conventional vector electrocardiogram (ECG) and traditional pulse oximetry (POX) triggered 2D CINE acquisitions together with (i) a qualitative image quality analysis, (ii) an assessment of the left ventricular function parameter and (iii) an examination of trigger reliability and trigger detection variance derived from the signal waveforms.</p> <p>Results</p> <p>ECG was susceptible to severe distortions at 7.0 T. POX and ACT provided waveforms free of interferences from electromagnetic fields or from magneto-hydrodynamic effects. Frequent R-wave mis-registration occurred in ECG-triggered acquisitions with a failure rate of up to 30% resulting in cardiac motion induced artifacts. ACT and POX triggering produced images free of cardiac motion artefacts. ECG showed a severe jitter in the R-wave detection. POX also showed a trigger jitter of approximately Δt = 72 ms which is equivalent to two cardiac phases. ACT showed a jitter of approximately Δt = 5 ms only. ECG waveforms revealed a standard deviation for the cardiac trigger offset larger than that observed for ACT or POX waveforms.</p> <p>Image quality assessment showed that ACT substantially improved image quality as compared to ECG (image quality score at end-diastole: ECG = 1.7 ± 0.5, ACT = 2.4 ± 0.5, p = 0.04) while the comparison between ECG vs. POX gated acquisitions showed no significant differences in image quality (image quality score: ECG = 1.7 ± 0.5, POX = 2.0 ± 0.5, p = 0.34).</p> <p>Conclusions</p> <p>The applicability of acoustic triggering for cardiac CINE imaging at 7.0 T was demonstrated. ACT's trigger reliability and fidelity are superior to that of ECG and POX. ACT promises to be beneficial for cardiovascular magnetic resonance at ultra-high field strengths including 7.0 T.</p

A medical device-grade T1 and ECV phantom for global T1 mapping quality assurance - the T1_1 Mapping and ECV Standardization in cardiovascular magnetic resonance (T1MES) program

$\textbf{Background:}$ T$_1$ mapping and extracellular volume (ECV) have the potential to guide patient care and serve as surrogate end-points in clinical trials, but measurements differ between cardiovascular magnetic resonance (CMR) scanners and pulse sequences. To help deliver T$_1$ mapping to global clinical care, we developed a phantom-based quality assurance (QA) system for verification of measurement stability over time at individual sites, with further aims of generalization of results across sites, vendor systems, software versions and imaging sequences. We thus created T1MES: The T1 Mapping and ECV Standardization Program. $\textbf{Methods:}$ A design collaboration consisting of a specialist MRI small-medium enterprise, clinicians, physicists and national metrology institutes was formed. A phantom was designed covering clinically relevant ranges of T$_1$ and T$_2$ in blood and myocardium, pre and post-contrast, for 1.5 T and 3 T. Reproducible mass manufacture was established. The device received regulatory clearance by the Food and Drug Administration (FDA) and Conformité Européene (CE) marking. $\textbf{Results:}$ The T1MES phantom is an agarose gel-based phantom using nickel chloride as the paramagnetic relaxation modifier. It was reproducibly specified and mass-produced with a rigorously repeatable process. Each phantom contains nine differently-doped agarose gel tubes embedded in a gel/beads matrix. Phantoms were free of air bubbles and susceptibility artifacts at both field strengths and T$_1$ maps were free from off-resonance artifacts. The incorporation of high-density polyethylene beads in the main gel fill was effective at flattening the $B_1$ field. T$_1$ and T$_2$ values measured in T1MES showed coefficients of variation of 1 % or less between repeat scans indicating good short-term reproducibility. Temperature dependency experiments confirmed that over the range 15-30 °C the short-T$_1$ tubes were more stable with temperature than the long-T$_1$ tubes. A batch of 69 phantoms was mass-produced with random sampling of ten of these showing coefficients of variations for T$_1$ of 0.64 ± 0.45 % and 0.49 ± 0.34 % at 1.5 T and 3 T respectively. $\textbf{Conclusion:}$ The T1MES program has developed a T$_1$ mapping phantom to CE/FDA manufacturing standards. An initial 69 phantoms with a multi-vendor user manual are now being scanned fortnightly in centers worldwide. Future results will explore T$_1$ mapping sequences, platform performance, stability and the potential for standardization.This project has been funded by a European Association of Cardiovascular Imaging (EACVI part of the ESC) Imaging Research Grant, a UK National Institute of Health Research (NIHR) Biomedical Research Center (BRC) Cardiometabolic Research Grant at University College London (UCL, #BRC/ 199/JM/101320), and a Barts Charity Research Grant (#1107/2356/MRC0140). G.C. is supported by the National Institute for Health Research Rare Diseases Translational Research Collaboration (NIHR RD-TRC) and by the NIHR UCL Hospitals Biomedical Research Center. J.C.M. is directly and indirectly supported by the UCL Hospitals NIHR BRC and Biomedical Research Unit at Barts Hospital respectively. This work was in part supported by an NIHR BRC award to Cambridge University Hospitals NHS Foundation Trust and NIHR Cardiovascular Biomedical Research Unit support at Royal Brompton Hospital London UK

first experiences: lesson learned from 7.0 Tesla

Einleitung: Die kardiovaskuläre Magnetresonanztomographie stellt durch die myokardiale Gewebedifferenzierung und Detektion von morphologischen Details wertvolle Informationen bereit. CMR am 7,0 Tesla (T) verbessert die räumliche Auflösung im Vergleich zum heutigen klinischen Standard. Die Möglichkeiten bei Patienten mit HCM sind noch nicht erforscht. Unser Ziel ist es, die Durchführbarkeit vom 7,0 T MRT bei Patienten mit HCM zu zeigen und die Darstellung von kleinsten morphologischen Auffälligkeiten zu evaluieren. Methoden: Wir überprüften 131 HCM Patienten. Bei 13 HCM Patienten (9 Männlich 56 ± 31 Jahre) und 13 gesunde Probanden (9 Männlich, 55±31 Jahre) konnte eine Untersuchung am 7,0 T und 3,0 T (Siemens, Erlangen Deutschland) durchgeführt werden. Für die Auswertung der kardialen Funktion und Morphologie erfolgten die Aufnahmen von 2D CINE Bildern am 7,0 T mit einer Voxelgröße von (1,4x1,4x2,5) mm³ und (1,4x1,4x4,0) mm³. Am 3,0 T wurde eine Voxelgröße von (1,8x1,8x6,0) mm³ verwendet. Mittels Kontrastmittel-unterstützter Technik „Late gadolinium Enhancement“ (LGE) erfolgte am 3,0 T. die Detektion von Fibrose. Ergebnisse: Alle Untersuchungen wurden erfolgreich durchgeführt und waren auswertbar. Die Quantifizierung der linksventrikulären Funktion am 3,0 T zeigte ähnliche Ergebnisse in der Kurzachsen- gegenüber der biplanaren Auswertung (LVEDV, LVESV, LVMASS, LVEF) (p=0,286, p=0,534, p=0,155, p=0,131). Die linksventrikulären Parameter, die am 7,0 T gemessen wurden, waren mit denen des 3,0 T übereinstimmend (pLVEDV=0,110, pLVESV=0,091, pLVMASS=0,131, pLVEF=0,182). LGE wurde bei 12 von 13 (92%) der Patienten mit HCM detektiert. Die räumlich hochaufgelöste CINE Bildgebung am 7,0 T ermöglicht kontrastmittelfrei die Darstellung von hyperintensen Regionen, welche als myokardiale Krypten in 7 von 13 Patienten (54%) identifiziert wurden. Alle myokardialen Krypten waren im Bereich des positiven LGE lokalisiert. Die myokardialen Krypten wurden nicht am 3,0 T beim Standard CINE-Protokoll detektiert. Schlussfolgerung: Die kardiovaskuläre MRT am 7,0 T ist bei Patienten mit HCM gut durchführbar. Die räumlich hochaufgelöste Gradientenecho 2D CINE Bildgebung am 7,0 T erlaubt die Detektion von kleinsten morphologischen Details in Regionen mit maximaler Hypertrophie und positivem LGE.Background: Cardiovascular Magnetic Resonance (CMR) provides valuable information in patients with hypertrophic cardiomyopathy (HCM) based on myocardial tissue differentiation and the detection of small morphological details. CMR at 7.0 T improves spatial resolution versus today's clinical protocols. This capability is as yet untapped in HCM patients. We aimed to examine the feasibility of CMR at 7.0 T in HCM patients and to demonstrate its capability for the visualization of subtle morphological details. Methods: We screened 131 patients with HCM. 13 patients (9 males, 56 ± 31 years) and 13 healthy age- and gender-matched subjects (9 males, 55 ± 31years) underwent CMR at 7.0 T and 3.0 T (Siemens, Erlangen, Germany). For the assessment of cardiac function and morphology, 2D CINE imaging was performed (voxel size at 7.0 T: (1.4x1.4x2.5) mm³ and (1.4x1.4x4.0) mm³; at 3.0 T: (1.8x1.8x6.0) mm³). Late gadolinium enhancement (LGE) was performed at 3.0 T for detection of fibrosis. Results: All scans were successful and evaluable. At 3.0 T, quantification of the left ventricle (LV) showed similar results in short axis view versus the biplane approach (LVEDV, LVESV, LVMASS, LVEF) (p = 0.286; p = 0.534; p = 0.155; p = 0.131). The LVparameters obtained at 7.0 T where in accordance with the 3.0T data (pLVEDV = 0.110; pLVESV = 0.091; pLVMASS = 0.131; pLVEF = 0.182). LGE was detectable in 12/13 (92%) of the HCM patients. High spatial resolution CINE imaging at 7.0 T revealed hyperintense regions, identifying myocardial crypts in 7/13 (54%) of the HCM patients. All crypts were located in the LGE-positive regions. The crypts were not detectable at 3.0 T using a clinical protocol. Conclusions: CMR at 7.0 T is feasible in patients with HCM. High spatial resolution gradient echo 2D CINE imaging at 7.0 T allowed the detection of subtle morphological details in regions of extended hypertrophy and LG