Quantification of regurgitation in mitral valve prolapse with four-dimensional flow cardiovascular magnetic resonance.

BACKGROUND: Four-dimensional cardiovascular magnetic resonance (CMR) flow assessment (4D flow) allows to derive volumetric quantitative parameters in mitral regurgitation (MR) using retrospective valve tracking. However, prior studies have been conducted in functional MR or in patients with congenital heart disease, thus, data regarding the usefulness of 4D flow CMR in case of a valve pathology like mitral valve prolapse (MVP) are scarce. This study aimed to evaluate the clinical utility of cine-guided valve segmentation of 4D flow CMR in assessment of MR in MVP when compared to standardized routine CMR and transthoracic echocardiography (TTE). METHODS: Six healthy subjects and 54 patients (55 ± 16 years; 47 men) with MVP were studied. TTE severity grading used a multiparametric approach resulting in mild/mild-moderate (n = 12), moderate-severe (n = 12), and severe MR (n = 30). Regurgitant volume (RVol) and regurgitant fraction (RF) were also derived using standard volumetric CMR and 4D flow CMR datasets with direct measurement of regurgitant flow (4DFdirect) and indirect calculation using the formula: mitral valve forward flow - left ventricular outflow tract stroke volume (4DFindirect). RESULTS: There was moderate to strong correlation between methods (r = 0.59-0.84, p < 0.001), but TTE proximal isovelocity surface area (PISA) method showed higher RVol as compared with CMR techniques (PISA vs. CMR, mean difference of 15.8 ml [95% CI 9.9-21.6]; PISA vs. 4DFindirect, 17.2 ml [8.4-25.9]; PISA vs. 4DFdirect, 27.9 ml [19.1-36.8]; p < 0.001). Only indirect CMR methods (CMR vs. 4DFindirect) showed moderate to substantial agreement (Lin's coefficient 0.92-0.97) without significant bias (mean bias 1.05 ± 26 ml [- 50 to 52], p = 0.757). Intra- and inter-observer reliability were good to excellent for all methods (ICC 0.87-0.99), but with numerically lower coefficient of variation for indirect CMR methods (2.5 to 12%). CONCLUSIONS: In the assessment of patients with MR and MVP, cine-guided valve segmentation 4D flow CMR is feasible and comparable to standard CMR, but with lower RVol when TTE is used as reference. 4DFindirect quantification has higher intra- and inter-technique agreement than 4DFdirect quantification and might be used as an adjunctive technique for cross-checking MR quantification in MVP.

Dynamic 3-dimensional stress cardiac magnetic resonance perfusion imaging: detection of coronary artery disease and volumetry of myocardial hypoenhancement before and after coronary stenting.

OBJECTIVES: The aim of this study was to establish a new, dynamic 3-dimensional cardiac magnetic resonance (3D-CMR) perfusion scan technique exploiting data correlation in k-space and time with sensitivity-encoding and to determine its value for the detection of coronary artery disease (CAD) and volumetry of myocardial hypoenhancement (VOLUME(hypo)) before and after percutaneous coronary stenting. BACKGROUND: Dynamic 3D-CMR perfusion imaging might improve detection of myocardial perfusion deficits and could facilitate direct volumetry of myocardial hypoenhancement. METHODS: In 146 patients with known or suspected CAD, a 3.0-T CMR examination was performed including cine imaging, 3D-CMR perfusion under adenosine stress and at rest followed by delayed enhancement imaging. Quantitative invasive coronary angiography defined significant CAD (≥ 50% luminal narrowing). Forty-eight patients underwent an identical repeat CMR examination after percutaneous stenting of at least 1 coronary lesion. The 3D-CMR perfusion scans were visually classified as pathologic if ≥ 1 segment showed an inducible perfusion deficit in the absence of delayed enhancement. The VOLUME(hypo) was measured by segmentation of the area of inducible hypoenhancement and normalized to left-ventricular myocardial volume (%VOLUME(hypo)). RESULTS: The 3D-CMR perfusion resulted in a sensitivity, specificity, and diagnostic accuracy of 91.7%, 74.3%, and 82.9%, respectively. Before and after coronary stenting, %VOLUME(hypo) averaged to 14.2 ± 9.5% and 3.2 ± 5.2%, respectively, with a relative VOLUME(hypo) reduction of 79.4 ± 25.4%. Intrareader and inter-reader reproducibility of VOLUME(hypo) measurements was high (Lin's concordance correlation coefficient, 0.96 and 0.96, respectively). CONCLUSIONS: The 3D-CMR stress perfusion provided high image quality and high diagnostic accuracy for the detection of significant CAD. The VOLUME(hypo) measurements were highly reproducible and allowed for the assessment of the treatment effect achievable by percutaneous coronary stenting.

4D FLOW: una nueva herramienta de diagnóstico para cardiopatías congénitas / 4D Flow MRI: a new diagnostic tool for congenital heart diseases

Purpose. To demonstrate the utility of 4D flow MR imaging for analyzing blood flow patterns and flow distribution in patients with congenital heart diseases. Methods: Six patients with congenital heart diseases were scanned using a standard cardiac MRI protocol, according to their condition. Additionally, 2D flow sequences of the great vessels, and a 4D flow sequence covering the entire heart were acquired. Flow patterns were visualized by using vector fields, streamlines and particle traces. Results: 4D flow technique depicted vortices and helical flow in the pulmonary artery of most patients, as well as in the aorta and superior vena cava of one patient with corrected aortic coarctation and a levoatrial cardinal vein. Conclusion: 4D flow MR imaging enables the identification of flow patterns difficult to detect with other diagnostic modalities. Comprehensive evaluation of flow patterns might help to understand the hemodynamic consequences of congenital heart diseases and their surgical procedures.

Objetivo. Demostrar la utilidad de 4D flow para el análisis de patrones y distribución de flujos en pacientes con cardiopatías congénitas. Métodos: Seis pacientes con cardiopatías congénitas fueron escaneados con un protocolo de resonancia magnética cardíaca estándar. Además se incluyeron secuencias de flujo 2D en los principales vasos del tórax y una secuencia 4D flow que cubría todo el corazón. Para la visualización de los patrones de flujo se emplearon vectores de velocidad, líneas de flujo y trazadores de partículas. Resultados: 4D flow reveló vórtices y hélices en la arteria pulmonar de la mayoría de los pacientes, y en la aorta y vena cava superior de un paciente con coartación aórtica reparada y vena cardinal levoatrial. Conclusiones: 4D flow permite identificar patrones de flujo en pacientes con cardiopatías congénitas, difíciles de observar con otros métodos diagnósticos. La evaluación de patrones de flujo podría contribuir a comprender las consecuencias hemodinámicas de diferentes cardiopatías congénitas.