Correcting directional dark field x-ray imaging artefacts using position dependent image deblurring and attenuation removal.

In recent years, a novel x-ray imaging modality has emerged that reveals unresolved sample microstructure via a "dark-field image", which provides complementary information to conventional "bright-field" images, such as attenuation and phase-contrast modalities. This x-ray dark-field signal is produced by unresolved microstructures scattering the x-ray beam resulting in localised image blur. Dark-field retrieval techniques extract this blur to reconstruct a dark-field image.

The effect of vibrotactile stimulation on hypoxia-induced irregular breathing and apnea in preterm rabbits.

Background: Manual tactile stimulation is used to counteract apnea in preterm infants, but it is unknown when this intervention should be applied. We compared an anticipatory to a reactive approach using vibrotactile stimulation to prevent hypoxia induced apneas.

Methods: Preterm rabbit kittens were prematurely delivered and randomized to either group.

Sustained inflation improves initial lung aeration in newborn rabbits with a diaphragmatic hernia.

Background: Infants with a congenital diaphragmatic hernia (DH) have underdeveloped lungs and require mechanical ventilation after birth, but the optimal approach is unknown. We hypothesised that sustained inflation (SI) increases lung aeration in newborn kittens with a DH.

Methods: In pregnant New Zealand white rabbits, a left-sided DH was induced in two fetal kittens per doe at 24-days gestation (term = 32 days); litter mates acted as controls.

Directional dark-field retrieval with single-grid x-ray imaging.

Directional dark-field imaging is an emerging x-ray modality that is sensitive to unresolved anisotropic scattering from sub-pixel sample microstructures. A single-grid imaging setup can be used to capture dark-field images by looking at changes in a grid pattern projected upon the sample. By creating analytical models for the experiment, we have developed a single-grid directional dark-field retrieval algorithm that can extract dark-field parameters such as the dominant scattering direction, and the semi-major and -minor scattering angles.

Effect of prenatal diaphragmatic hernia on pulmonary arterial morphology.

Congenital diaphragmatic hernia (CDH) is a major cause of severe lung hypoplasia and pulmonary hypertension in the newborn. While the pulmonary hypertension is thought to result from abnormal vascular development and arterial vasoreactivity, the anatomical changes in vascular development are unclear. We have examined the 3D structure of the pulmonary arterial tree in rabbits with a surgically induced diaphragmatic hernia (DH).

Precise phase retrieval for propagation-based images using discrete mathematics.

The ill-posed problem of phase retrieval in optics, using one or more intensity measurements, has a multitude of applications using electromagnetic or matter waves. Many phase retrieval algorithms are computed on pixel arrays using discrete Fourier transforms due to their high computational efficiency. However, the mathematics underpinning these algorithms is typically formulated using continuous mathematics, which can result in a loss of spatial resolution in the reconstructed images.

Higher CPAP levels improve functional residual capacity at birth in preterm rabbits.

Background: Preterm infants are commonly supported with 4-8 cm HO continuous positive airway pressures (CPAP), although higher CPAP levels may improve functional residual capacity (FRC).

Methods: Preterm rabbits delivered at 29/32 days (~26-28 weeks human) gestation received 0, 5, 8, 12, 15 cm HO of CPAP or variable CPAP of 15 to 5 or 15 to 8 cm HO (decreasing ~2 cm HO/min) for up to 10 min after birth.

Results: FRC was lower in the 0 (6.

Improving lung aeration in ventilated newborn preterm rabbits with a partially aerated lung.

Preterm newborns commonly receive intermittent positive pressure ventilation (iPPV) at birth, but the optimal approach that facilitates uniform lung aeration is unknown, particularly in a partially aerated lung. As both inflation time and exogenous surfactant facilitate uniform lung aeration, we investigated whether they can improve lung aeration and lung mechanics in a partially aerated lung immediately after birth. Preterm rabbit kittens (29 days of gestation, term ~32 days) were delivered by caesarean section and partial lung aeration was created by intubating and mechanically ventilating the right lung.

Increasing Respiratory Effort With 100% Oxygen During Resuscitation of Preterm Rabbits at Birth.

Spontaneous breathing is essential for successful non-invasive respiratory support delivered by a facemask at birth. As hypoxia is a potent inhibitor of spontaneous breathing, initiating respiratory support with a high fraction of inspired O may reduce the risk of hypoxia and increase respiratory effort at birth. Preterm rabbit kittens (29 days gestation, term ~32 days) were delivered and randomized to receive continuous positive airway pressure with either 21% ( = 12) or 100% O ( = 8) via a facemask.