4-D Intracardiac Ultrasound Vector Flow Imaging-Feasibility and Comparison to Phase-Contrast MRI.

In vivo characterization of intracardiac blood velocity vector fields may provide new clinical information but is currently not available for bedside evaluation. In this paper, 4-D vector flow imaging for intracardiac flow assessment is demonstrated using a clinical ultrasound (US) system and a matrix array transducer, without the use of contrast agent. Two acquisition schemes were developed, one for full volumetric coverage of the left ventricle (LA) at 50 vps and a 3-D thick-slice setup with continuous frame acquisition (4000 vps), both utilizing ECG-gating. The 3-D vector velocity estimates were obtained using a novel method combining phase and envelope information. In vitro validation in a rotating tissue-mimicking phantom revealed velocity estimates in compliance with the ground truth, with a linear regression slope of 0.80, 0.77, and 1.03 for the , , and velocity components, and with standard deviations of 2.53, 3.19, and 0.95 cm/s, respectively. In vivo measurements in a healthy LV showed good agreement with PC-MRI. Quantitative analysis of energy loss (EL) and kinetic energy (KE) further showed similar trends, with peak KE at 1.5 and 2.4 mJ during systole and 3.6 and 3.1 mJ for diastole for US and PC-MRI. Similar for EL, 0.15- 0.2 and 0.7 mW was found during systole and 0.6 and 0.7 mW during diastole, for US and PC-MRI, respectively. Overall, a potential for US as a future modality for 4D cardiac vector flow imaging was demonstrated, which will be further evaluated in clinical studies.

[A 50-year old woman with cor triatriatum]. / 50 år gammel kvinne med rask hjerteaksjon.

BACKGROUND: Cor triatriatum is a rare congenital malformation in the heart. A recently published report has indicated that real time transthoracic 3-dimensional echocardiography (3DE) may replace transoesophageal echocardiography (TEE) in the diagnosis of this entity. MATERIAL AND METHODS: A patient with cor triatriatum was examined with 3DE. The results were compared to established echocardiographic methods, inclusive TEE, and to magnetic resonance imaging (MR). RESULTS AND INTERPRETATION: Due to excellent resolution, TEE is still unrivalled in the assessment of some congenital heart diseases such as cor triatriatum. Real time 3DE may have the potential to replace TEE in the future, but refinement of the method is necessary.