Damian Craiem

Objective: Among myxomatous mitral valve disease (MMVD), mitral annular disjunction (MAD) is associated with severe mitral regurgitation (MR). However, functional analyses are lacking to fully understand the mechanisms leading to bileaflet prolapse in MAD. Using multiphase cardiac computed tomography imaging (4D-MCCTI), we aim to characterize left atrio-ventricular junction morphological alterations throughout the cardiac cycle in patients with MAD. Methods: Imaging datasets were obtained via 4D-MCCTI for 2 groups of consecutive patients with severe MR due to MMVD: 22 with MAD (MMVD + MAD+) and 20 without (MMVD + MAD−). A control group of 30 patients (MMVD−) was also included. Semi-automated delineation of 18 points around the mitral annulus (MA) allowed 3D calculation of areas, perimeters, 360°-diameters, and planar/vertical deformation across time. Left ventricular (LV) and atrial (LA) inner contours were also delineated, and systolic shortening distances from the annulus to the anterior and posterior papillary muscles (MA-APM and MA-PPM) were estimated. Results: Groups were comparable for age, pulmonary pressures, and LV ejection fraction. In MMVD + MAD+, MA expansion began earlier in systole, following LA expansion, and peaking at end-systole: 3D-area: 10.9±3.7cm ² /m ² , compared to 8.9±2.4 cm ² /m ² for MMVD + MAD− ( P < .001) and 6.1±1.3 cm ² /m ² for MMVD− ( P < .001). However, MA perimeter reduction remained unaltered in MMVD + MAD + patients (−14.7±5.2%). In systole, MA-APM and MA-PPM reduction were greater in MMVD + MAD+: −6.58±1.99 mm, −8.12±1.26 mm versus −2.53±2.01 mm, −3.25±2.31 mm in MMVD− and −2.18±1.79 mm, −3.86±2.77 mm in MMVD + MAD− ( P < .001). Conclusions: In MAD, MA becomes desynchronized from LV function. The extent of systolic MA deformation and papillary muscle movement may promote bileaflet prolapse.

Background: Transthoracic echocardiography (TTE) remains the gold standard for assessing left ventricular (LV) diastolic dysfunction (DD), but noninvasive alternatives are needed to overcome geometric and acoustic limitations. 4D-Flow MRI enables comprehensive assessment of intraventricular pressure differences (IVPDs) and flow propagation velocity (VP). We aimed to evaluate 4D-Flow-derived IVPDs and VP in patients with hypertrophic cardiomyopathy (HCM). Methods: Thirty-eight HCM patients and 38 age- and sex-matched healthy controls underwent TTE and 4D-Flow MRI. Spatiotemporal maps of velocity and IVPDs, decomposed into inertial and convective components, were derived along the main inflow streamline from the mitral valve to the apex. Peak early filling rate (PEFR) was used to normalize IVPDs and VP. Results: While absolute peak flow rates were comparable, HCM patients exhibited significantly faster VP (100.4 vs. 60.2 cm/s, p < 0.01) and higher positive early E IVPD (1.40 vs. 0.92 mmHg, p < 0.01) compared to controls. Normalizing IVPDs by PEFR amplified group differences, revealing a markedly increased flow-normalized E-IVPD (5.13 vs. 2.94 × 10⁻³ mmHg·ml⁻¹·s, p < 0.001) and deeper reverse ER IVPD (-6.06 vs. -4.61 × 10⁻³ mmHg·ml⁻¹·s, p < 0.01) in HCM. These differences were primarily driven by the inertial components. Multivariable analysis demonstrated that ER IVPD is independently determined by PEFR and the TTE E/E’ ratio (r = 0.65, p < 0.001). Conclusions: 4D-Flow MRI-derived, flow-normalized IVPDs and propagation velocity provide robust, noninvasive markers of altered LV chamber stiffness and impaired diastolic filling in HCM, offering deeper 3D hemodynamic insights into diastolic dysfunction. Visual

Abdominal aortic aneurysm (AAA) is a critical condition with high rupture risk, and the maximum diameter alone is insufficient for prediction. Pulse wave velocity (PWV), a surrogate of aortic stiffness, can be estimated using 4D-Flow magnetic resonance imaging (MRI), but requires validation under dilated conditions. This in vitro study examined the relationship between PWV and stiffness by comparing healthy and aneurysmal compliant aortic models. Two latex phantoms were fabricated to represent normal and AAA geometries. A circulatory MRI-compatible system simulated physiological inlet flow, with flow rates measured across perpendicular planes using 4D- and 2D-Flow MRI. PWV was derived from transit times of the systolic upstroke and interplane distances. Complementary 1D numerical simulations and laboratory flowmeter measurements were performed. Although the wall elasticity and thickness were identical, PWV in the healthy model ranged from 6.2 to 7.7 m/s and in the aneurysmal model it ranged from 14.2 to 15 m/s. This increase was confirmed by temporal overlap of thoracic flow curves and reduced slope in the transit time–distance regression. Results were consistent across simulations, 2D-Flow, and flowmeter data. Findings highlight that indirect 4D-Flow assessment of thoracic stiffness in the presence of AAA must account for wave reflections introduced by dilation, which significantly alter PWV estimation.

Two years after breast cancer radiotherapy, cardiac CT demonstrated dose-associated progression of coronary artery calcification, particularly in the presence of preexisting calcification, while coronary stenosis progression was unrelated to radiation dose.

Background: Ebstein's anomaly (EA) is a congenital heart disorder involving tricuspid valve dysplasia and right heart abnormalities resulting in severe tricuspid regurgitation (TR). Multiple techniques assess regurgitation severity, but their correlation with EA severity markers remains unclear. Purpose: To compare MRI techniques for quantifying TR and regurgitant volume (RVol) in adults with EA. Study Type: Retrospective. Subjects: Thirty‐three adult patients with EA (15 males/18 females). Field Strength/Sequence: 3T or 1.5‐Tesla, 2D‐phase contrast (2D‐PC gradient echo) and 4D‐flow (gradient echo). Assessment: RVol was measured using three methods: (1) 2D‐indirect: subtraction of systolic pulmonary artery (PA) forward flow (2D‐PC) from functional right ventricular stroke volume (fRVSV); (2) 4D‐indirect: subtraction of PA systolic forward flow from tricuspid diastolic forward flow using 4D‐flow; (3) 4D‐direct: direct jet measurement with 4D‐flow. Correlations were evaluated between RVol and severity markers (left ventricular ejection fraction [LVEF], functional right ventricular end‐diastolic volume [fRVEDV], fRV/LV ratio, severity index volume, total right/left volume index, fRVEF). Statistical Tests: Pearson or Spearman correlation coefficients ( p < 0.05) significant. Results: The 4D‐direct method had the highest correlation with the mean RVol (2D‐indirect: r = 0.93, 4D‐indirect: r = 0.93; 4D‐direct: r = 0.95) and with severity markers: total right/left volume index (0.84, 0.64, 0.87), the fRVEDV (0.66, 0.58, 0.71), fRV/LVratio (0.81, 0.75, 0.87), and severity index volume (0.45, 0.59, 0.66). Data Conclusion: 4D‐flow enables intrinsic RVol quantification independent of fRV segmentation, with the direct jet method outperforming indirect approaches. Level of Evidence: 3. Technical Efficacy: Stage 2.

Objective. Assessing diastolic function (DF) using 4D-flow MRI may offer valuable physiological insights during left ventricular (LV) filling. We aimed to test DF parameters typically obtained with transthoracic echocardiography (TTE) but derived from 4D-flow MRI, including inflow velocity, flow filling rate, and propagation velocity ( V _P ), by characterizing LV diastolic filling associated with aging. Approach. Sixty healthy volunteers (34 women, 26 men; mean age, 52 ± 18 years; range: 20–80 years) underwent cardiac 4D-flow MRI and TTE as part of cardiac aging studies. Early ( E ) and atrial ( A ) mitral inflow peak velocities were obtained at the leaflet tips with and without normal projection ( E and A _{LT_PROJ,} E and A _{LT_NON-PROJ} ). Peak early and atrial filling rates (PEFR, PAFR) were derived from flow curves. V _P was calculated mimicking TTE approach ( V _P _ _SLOPE ) and by taking the slope of a plane fitting the velocity curves on a 3D streamline within the LV ( V _{P_PLANE} ). Associations between age, velocity-derived indices related to DF and LV geometry were assessed. Main results. All 4D-flow velocity parameters were associated with age ( p < 0.001). E / A _{LT_NON-PROJ} and E / A _{LT_PROJ} ratios correlated with TTE ( r = 0.69 and r = 0.67 respectively, p < 0.001). PEFR showed a stronger inverse association with age ( r = −0.75, p < 0.001) than TTE peak velocities ( r = −0.19, p = 0.149). V _{P_PLANE} correlated better with age ( r = −0.47, p < 0.001) than V _P _ _SLOPE ( r = −0.26, p < 0.05) and with indicators of DF such as E / E ’ _TTE , PEFR/PAFR ratio and PEFR normalized to filling volume. Significance. Indices derived from 4D-flow MRI were sensitive to age-related variations in LV filling dynamics, indicating potential for validation in pathological cohorts with confirmed diastolic dysfunction.

Les nouvelles technologies d'imagerie basées sur la tomodensitométrie en coupe permettent l'évaluation de très haute qualité de la structure 3D de l'aorte thoracique. La reconstruction virtuelle et les modèles géométriques de l'aorte sont indispensables à l'exploitation des images dont le temps de traitement manuel reste cependant considérable et les outils numériques insuffisants ou inadaptés pour mesurer correctement sa morphologie. L'aorte n'est pas un simple tube de conduction du sang mais un organe de régulation de la pulsatilité des ondes de pression provoquées par l'éjection cardiaque. Ses désordres biomécaniques peuvent accélérer la formation de calcifications dans sa paroi et entrainer des risques de graves complications, comme les anévrismes et les dissections. La réparation aortique basée sur l'implantation d'endoprothèses est en pleine évolution et requiert des renseignements morphologiques précis pour en améliorer le taux de succès. Notre objectif a été d'étudier la géométrie tridimensionnelle de l'aorte en développant des algorithmes appropriés. Une plateforme informatique a été conçue et testée pour étudier trois pathologies de l'aorte: l'athérosclérose calcifiée, l'anévrisme et la dissection. L'hypothèse du travail a été que la géométrie spécifique des artères de chaque individu joue un rôle complémentaire à celui des facteurs de risque traditionnels dans le développement de ces pathologies. Notre premier travail a montré que trois facteurs résument 80% de la variabilité géométrique de l'aorte thoracique: le volume aortique, le déroulement et la symétrie de l'arche aortique, avec des taux de variabilité respectifs de 46%, 22% et 12%. Dans deux travaux suivants, nous avons montré que les calcifications de l'aorte thoracique se concentrent principalement dans la crosse et dans le segment descendant proximal, et que cette distribution était associée à la morphologie de l'aorte indépendamment de l'âge, du sexe, de la surface corporelle et des facteurs de risque traditionnels. Le quatrième travail a montré que le score de dépôt calcique dans toute l'aorte thoracique incluant la crosse était plus étroitement associé aux complications non-cardiaques, vasculaires périphériques et cérébrales, que le score traditionnel de calcium coronaire. Il faut noter que la crosse aortique n'est pas visualisée dans les études de routine de calcium coronaire sans injection. Le cinquième travail décrit un modèle déformable capable de segmenter la lumière aortique dans un contexte pathologique. Il a été appliqué pour étudier de façon automatisée la taille d'un anévrisme abdominal avant et après la pose d'une endoprothèse. Dans le dernier travail, la méthode précédente a été adaptée pour étudier la géométrie aortique des patients atteints de dissection comparativement à un groupe témoin de patients qui en étaient indemnes. Trois variables géométriques ont été identifiées dans le modèle de prédiction du risque de dissection: le diamètre de la crosse, la longueur de l'aorte thoracique et l'âge. En conclusion, nos résultats montrent que les maladies aortiques sont étroitement associées à la géométrie de l'aorte indépendamment des facteurs de risque traditionnels. Les algorithmes que nous avons développés ouvrent la voie à l'automatisation et à une réduction de la variabilité des mesures.

Objectives. Aortic dilatation is a severe pathology that increases the risk of rupture and its hemodynamics could be accurately assessed by using the 4D flow cardiovascular magnetic resonance (CMR) technique but flow assessment under complex flow patterns require validation. The aim of this work was to develop an in vitro system compatible with CMR to assess the accuracy of volume flow measurements in dilated aortas. Approach. Two latex models, one with ascending and the other with abdominal aortic aneurysms were manufactured to ensure a constant and controlled net flow volume along the aortic length. A pneumatic piston driven by a stepper motor and controlled by an embedded system located in the control room modulated a pulsatile fluid flow using a pump with an elastic membrane placed in the magnet near the elastic models. All the visualization and measurement algorithms were integrated into a custom computer platform. 4D flow imaging was used to estimate the flow rate and volume through multiple aortic planes and compared to the reference assessed by weight method and to 2D flow measurements. Main results. The errors of flow volume assessment using 4D flow remained within reasonable limits along the length of the aortic models. Mean differences in net flow volume from the reference were less than 2 ml (range −4 to 6 ml), corresponding to mean relative differences of less than 4% (range −8% to 11%). Averaged net, forward and backward flow volume estimations along the aortic length were similar using 2D and 4D flow measurements (p > 0.05). Peak forward and backward flow rates increased in the dilated regions and were comparable to those observed in patients. Significance. The accuracy of flow volume estimates in complex flow patterns, such as those observed in patients with aneurysms, was validated in vitro using 4D flow.