127 research outputs found
Free breathing contrast-enhanced time-resolved magnetic resonance angiography in pediatric and adult congenital heart disease
Contrast enhanced magnetic resonance angiography (MRA) is generally performed during a long breath-hold (BH), limiting its utility in infants and small children. This study proposes a free-breathing (FB) time resolved MRA (TRA) technique for use in pediatric and adult congenital heart disease (CHD)
Perturbed spiral real-time phase-contrast MR with compressive sensing reconstruction for assessment of flow in children
PURPOSE: we implemented a goldenāangle spiral phase contrast sequence. A commonly used uniform density spiral and a new āperturbedā spiral that produces more incoherent aliases were assessed. The aim was to ascertain whether greater incoherence enabled more accurate Compressive Sensing reconstruction and superior measurement of flow and velocity. METHODS: A range of āperturbedā spiral trajectories based on a uniform spiral trajectory were formulated. The trajectory that produced the most noiseālike aliases was selected for further testing. For ināsilico and ināvivo experiments, data was reconstructed using total Variation L1 regularisation in the spatial and temporal domains. Ināsilico, the reconstruction accuracy of the āperturbedā golden spiral was compared to uniform density goldenāangle spiral. For the ināvivo experiment, stroke volume and peak mean velocity were measured in 20 children using āperturbedā and uniform density goldenāangle spiral sequences. These were compared to a reference standard gated Cartesian sequence. RESULTS: Ināsilico, the perturbed spiral acquisition produced more accurate reconstructions with less temporal blurring (NRMSE ranging from 0.03 to 0.05) than the uniform density acquisition (NRMSE ranging from 0.06 to 0.12). This translated in more accurate results ināvivo with no significant bias in the peak mean velocity (bias: ā0.1, limits: ā4.4 to 4.1 cm/s; P = 0.98) or stroke volume (bias: ā1.8, limits: ā9.4 to 5.8 ml, P = 0.19). CONCLUSION: We showed that a āperturbedā goldenāangle spiral approach is better suited to Compressive Sensing reconstruction due to more incoherent aliases. This enabled accurate realātime measurement of flow and peak velocity in children
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