Detailed semiautomated MRI based morphometry of the neonatal brain: preliminary results.
Neuroimage ;—9. Mapping the early cortical folding process in the preterm newborn brain.
Baby’s Brain Begins Now: Conception to Age 3
Cereb Cortex ; Volpe JJ. Brain injury in premature infants: a complex amalgam of destructive and developmental disturbances. Lancet Neurol ; Brain tissue volumes in preterm infants: prematurity, perinatal risk factors and neurodevelopmental outcome: a systematic review. J Matern Fetal Neonatal Med ;25 suppl 1 — Perinatal risk factors altering regional brain structure in the preterm infant. Brain ;— Clinical applications of 7 T MRI in the brain. Eur J Radiol ;— Comprehensive brain MRI segmentation in high risk preterm newborns.
PLoS One ;5:e Automatic segmentation of MR images of the developing newborn brain. Med Image Anal ;— Automatic segmentation and reconstruction of the cortex from neonatal MRI.
Neuroimage ;— A neonatal atlas template for spatial normalization of whole-brain magnetic resonance images of newborns: preliminary results. Neuroquantology ;—8. The benefit of stereology for quantitative radiology. Br J Radiol ;— Premature infant, Medline Plus. Accessed April 20, Preterm birth, World Health Organization. Accessed April 19, Laptook AR. Neonatal and infant death: the apgar score reassessed. Lancet ;—8. Engle WA. Age terminology during the perinatal period. Pediatrics ;—4. Volumetric quantification of brain development using MRI. Neuroradiology ;—6.
Surg Radiol Anat ;— Automatic detection of brain contours in MRI data sets. A fast, model-independent method for cerebral cortical thickness estimation using MRI. Brain volume segmentation in newborn infants using multi-modal MRI with a low inter-slice resolution. Cerebral maturation in premature infants: quantitative assessment using MR imaging.
Automatic quantification of normal cortical folding patterns from fetal brain MRI. NeuroImage ;— Regional growth and atlasing of the developing human brain. Reduction in cerebellar volumes in preterm infants: relationship to white matter injury and neurodevelopment at two years of age.
Pediatr Res ;— Displacement of brain regions in preterm infants with non-synostotic dolichocephaly investigated by MRI. Oxford, UK: Liverpool Bios; Nuclear magnetic resonance imaging of the brain in children. Br Med J ;—6. MR-determined hippocampal asymmetry in full-term and preterm neonates. Hippocampus ;— Quantitative MRI in the very preterm brain: assessing tissue organization and myelination using magnetization transfer, diffusion tensor and T1 imaging.
Brain microstructural development at near-term age in very-low-birth-weight preterm infants: an atlas-based diffusion imaging study. The effect of preterm birth on thalamic and cortical development. Cereb Cortex ;— Neonatal ultrasound results following very preterm birth predict adolescent behavioral and cognitive outcome. Dev Neuropsychol ;— Severity of perinatal illness and cerebral cortical growth in preterm infants. Acta Paediatr ;—5. The internal capsule in neonatal imaging. Semin Fetal Neonatal Med ;— Premature infants display increased noxious-evoked neuronal activity in the brain compared to healthy age-matched term-born infants.
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Procedural pain and brain development in premature newborns. Ann Neurol ;— The purpose of this study is to describe the normal findings of the newborn chest radiography, the criteria utilized for evaluating the quality radiographs and the correct catheter and tube positions, emphasizing the peculiarities inherent to the patient's age. In the neonatal period changes in the fetal circulation contribute to an increase in cardiac size, skin folds and variations in the thymic silhouette may simulate diseases, the evaluation of catheter and tube positions avoids iatrogenic complications, the abdominal gas pattern must be correlated with the patient's age and the presence of the secondary ossifications centers in the upper humerus and scapula is associated with the term newborn, providing a radiological sign for normal skeletal maturation.
The knowledge of the peculiarities and normal radiological findings of the newborn chest radiography avoids ambiguous diagnosis, reduces iatrogenic complications and represents a valuable support in the diagnosis and clinical follow-up of these patients. Keywords: Newborn; Normal findings; Chest radiography. The chest x-ray is one of the most frequently requested radiological examinations in neonatal intensive care units ICU , representing an essential tool in the diagnosis of pulmonary diseases in preterm and term neonates.
The chest x-ray in neonates, especially the preterm ones, should preferably be performed in the neonatal ICU, with a portable x-ray equipment. In order to reduce the radiation dose for these small patients, only one anteroposterior view of the chest should be taken, since, in most of cases, this is enough to supply the necessary diagnostic information 6.
In the first radiological examination, it is advisable to include abdominal imaging, since this allows a preliminary evaluation of the presence of air in bowel loops and the ruling out of abdominal diseases likely to cause respiratory symptoms. In subsequent x-rays, lateral chest and abdomen views only should be included in cases where there is a clinical indication or necessity of evaluating umbilical probes and catheters localization 1,4.
Chest x-rays of neonates are in compliance the technical standards when they meet the following criteria 1,2,4 :. Main technical problems that may mimic pathological alterations inducing misdiagnosis are the following:. The knowledge of these criteria utilized for evaluating the technical quality of chest x-ray of neonates results in technically correct x-rays, besides reducing the possibility of misdiagnosis due inadequately performed examinations Figures 1 , 2 and 3.
The neonate chest undergoes significant birth-related changes during the first hours of life, and presents quite distinct aspects in its anatomic structures, so these normal, specific radiological features should be taken into consideration during the neonatal period. During the first hours of a neonate's life, transitory cardiomegaly may occur as a result of additional blood inflow from the placenta into the umbilical cord before its cutting, and of the presence of a bidirectional shunt through the arterial duct and oval foramen before its closure.
Also, a prominent pulmonary vascularization may be observed as a result of residual lung fluid absorption through the lymphatic-venous system. A still open arterial canal may be seen on a chest x-ray as a convex prominence to the left of the spine, between T3 and T4 vertebras, this configuration being denominated ductus bump , that is considered as a typical radiological finding at the neonate first hours of life 1,2 Figure 4. The oval foramen and arterial canal closure, the decrease in pulmonary vascular resistance and absorption of the remaining lung fluid in the hours subsequent to the birth reduce the cardiac dimensions and the chest vascular prominence.
In neonates, the thymus is radiologically characterized by a widening of the upper mediastinum, above the cardiac image, on the frontal view, and an increase in the supracardiac, retrosternal density on the profile incidence Figure 5. On the frontal view, the normal width of the thymic image must be higher than the double-width of the third thoracic vertebra, shorter dimensions representing a sign of thymic involution 7 Figure 6.
This accidental involution may revert once the stress situation is overcome, and the thymus returns to its normal dimensions. The concept of deformation imaging is a novel technique, recently introduced to the field of neonatology, and can be measured by either speckle tracking echocardiography STE or tissue Doppler imaging TDI. Both are feasible and reproducible markers of global and regional performance that provide fundamental information on myocardial properties and mechanics that would otherwise be unavailable with conventional imaging. This review explains the fundamental concepts of deformation imaging, describes in a comparative manner the two major deformation imaging methods, provides a practical guide to the acquisition and interpretation of data, and discusses the clinical applications and available reference ranges in the term and preterm population.
Deformation refers to the change in the shape of the myocardium from its baseline shape at end-diastole to its deformed shape at end-systole. The deformation leads to a reduction in cavity size and ejection of blood from the ventricle. Principles of deformation. Longitudinal strain refers to the change in length of a segment from its baseline length in end-diastole to its deformed shape in systole. Shortening reflects negative values and lengthening positive values. In this image, shortening of the mid-segment of the LV free wall is illustrated. Strain and strain curves in one cardiac cycle in the ventricle.
During diastole, the rate of strain returning to baseline is biphasic. Myocardial shear in the circumferential-longitudinal plane results in twist or torsional deformation of the LV during ejection. Only the three normal forms of strain and circumferential-longitudinal shear strain rotational mechanics have been investigated for clinical use in neonates. LV and RV deformation patterns differ based on their own unique myoarchitectural fiber orientation.
The LV myocardium consists of circumferential fibers in the midwall layer and longitudinal fibers in the endocardial and epicardial layers. Deformation is assigned a negative sign for shortening in longitudinal and circumferential planes and a positive sign for thickening in the radial plane. LV deformation. LV deformation occurring in three directions; L longitudinal, C circumferential, R radial. In the circumferential-longitudinal plane, the net difference in the systolic rotation of the myocardium between the apical and basal short-axis plane is referred to as twist measured in degrees and represents the wringing motion of the LV during systole.
LV rotational mechanics twist and torsion are assessed by STE. Compared with the LV, the RV myofiber architecture is composed of superficial oblique and dominant deep longitudinal layers. The myofibers in the RV are aligned in a more longitudinal direction than in the LV, and as the dominant pattern of RV deformation, longitudinal shortening provides the major contribution to stroke volume during systole and is a more sensitive indicator of RV dysfunction.
There are two established methods for assessing and calculating deformation entitled Lagrangian strain and Eulerian natural strain. Natural and Lagrangian strains are related so that one can be converted into the other. STE software packages will report Lagrangian strain, but natural strain i. Studies that utilized strain and SR measures to characterize ventricular function in neonates must therefore indicate the software package and the type of strain or SR.
Deformation is affected by several factors that should be considered when using strain imaging in clinical practice. Compared to strain, SR is thought to be less dependent on loading conditions, and is a more accurate reflection of intrinsic myocardial contractile function.
The relationship between loading conditions and deformation parameters. There is a negative relationship between strain and systemic vascular resistance a surrogate of afterload but a positive relationship between strain and left ventricle end-diastolic diameter a surrogate of preload. Note the lack of relationship between systolic strain rate and loading measures data set from ref. Three factors modulate variability in deformation imaging; these include variability in image acquisition, intra- and inter-observer variability in post-acquisition processing, and differences between echocardiographic equipment and proprietary software for image analysis.
First introduced as a post-processing feature of TDI with velocity data converted to strain and SR, strain imaging information has more recently also been derived from STE computer processing. Echocardiographic strain was first derived from TDI velocity data using the Doppler equation to convert ultrasound frequency shifts to velocity information along the scan lines. Basal myocardial tissue moves at a higher velocity toward the apex in systole than myocardial tissue at the apex due to the tethering effects and the stationary position of the apex Fig.
TD-derived longitudinal deformation imaging calculates SR by assessing the difference in velocity the velocity gradient between points along the longitudinal plane. Strain is then assessed by integrating the SR values by time. Only velocities along parallel to the beam of the ultrasound are measured by the TD method; therefore, deformation indices measured using TD are highly dependent on the angle of insonation. In neonates, TDI-derived deformation values can be obtained from several regions of the heart. Longitudinal deformation can be measured from most parts of the LV and RV and is more often measured in neonates.
Difference in velocity between two points along the long axis of the septum. The curves show tissue velocities by tissue Doppler during the cardiac cycle. The point closer to the base yellow has a higher systolic and diastolic velocity when compared with the point closer to the base green. The difference in velocity is used to calculate strain rate and derive strain of that segment bordered by the two points. To characterize ventricular function with longitudinal strain, some studies have reported values from many heart segments, 33 , 34 , 35 , 36 , 37 , 38 while others have obtained values from the basal segment of the LV and RV free walls, in addition to the septum.
The reliability of the results obtained from the LV base is reduced because artifacts arising from the lungs often obscure the base. The feasibility and reproducibility of TD-derived deformation parameters have been established in term and preterm neonates. James et al. To obtain reliable deformation values, strain by TD imaging and post-processing analysis protocols have been developed and implemented in neonates. Pulsed wave Doppler of the aortic and mitral valves should be used to annotate the timing of events. Timing of the aortic valve closure may also be obtained from the TDI curves.
The transducer should be manipulated to align the wall of interest parallel to the ultrasound beam. The velocity scale pulse repetition frequency, PRF should be adjusted to avoid aliasing. Three-cycle analysis is more reproducible than single-cycle analysis in TD imaging, and a minimum of three cycles must be recorded for offline processing. Strain and SR values are generated during offline analysis. The parameters are derived from a sample area segment.
The size of the segment is set by the size of a specific region of interest ROI within the myocardial wall, which is determined by the operator length and width and a strain length SL. The length of the ROI should be adequate for optimal calculation, while minimizing noise, and the width should not be larger than the width of the actual wall of interest.
The operator must set the SL, also referred to as a computational distance.
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The SL is the length along the ultrasound beam against which the velocities for each point within the ROI are compared to derive the velocity gradient. The segment size will be larger than the ROI as it stretches parallel to the ultrasound beams toward the apex and the base of the heart. The SL should not project outside the borders of the wall into the atrial tissue for example; Fig.
Offline measurement of SR and strain using tissue Doppler. The sector width should be narrowed to increase the frame rate. The basal segment of the wall is usually interrogated to obtain SR and strain values. The ROI dimensions length and width are set by the operator. Strain length is also set while ensuring that the borders of the segment are not in contact with artifact or atrial tissue.
An example of clear and artifact-free strain and strain rate curves over three cardiac cycles. Note the timing of events within the cardiac cycle. The RV free wall has higher strain values when compared with LV free wall and septum; however, SR values are comparable. The differences between LV and RV strain values may reflect the differing loading conditions between the RV and LV in the early neonatal period that may have an impact on strain but not SR.
Imaging the term neonatal brain | Paediatrics & Child Health | Oxford Academic
HR and the persistence of fetal shunts during the early transitional period appear to have a negligible impact on the measurements, but age may play a role in the first year of age. There is early evidence of the utility of deformation parameters in several disease states in term infants. Nestaas et al. Two studies have examined the maturational changes of basal deformation parameters over the first few weeks of age.
Septal and RV free wall show a steadier increase over the first week of age and through 36 weeks PMA. However, in the early transitional period, there is a negative correlation between echocardiography-derived estimates of SVR and LV and septal strain values, and a positive correlation between increasing preload associated with a PDA and LV strain.
CLD was shown to be associated with increased pulmonary arterial pressure, which may explain this association. Two-dimensional STE 2D STE is an imaging technique that uses standard B-mode images to measure deformation by tracking the movement of speckles within the myocardial wall.
The movement of this speckled pattern follows myocardial tissue motion as it tracks the defined region of speckles, frame by frame and eventually over the entire heart cycle deriving the following information from segments of the myocardial wall: displacement the movement of those speckles , velocity the speed at which this movement occurs , strain the relative change in distance between those speckles , and SR the speed at which the change in distance occurs; 9.
Specialized measuring software programs divide the myocardial walls of interest into segments and generate strain and strain rate values for each region Fig. Both regional and global functional parameters can be derived using this 2D STE deformation. With this relative freedom, enhanced imaging of the myocardial walls is possible. This is of particular importance to the LV free wall, as it can now be imaged at an angle to avoid lung artifact.
Although 2D STE is less influenced by artifact, it remains highly reliant on clear imaging of the walls without dropouts. Speckles are acoustic back scatter that form a unique pattern within the myocardial walls. Those can be tracked throughout the cardiac cycle to derive deformation measurements. In this apical 3-chamber view of the LV, the myocardial walls are divided into segments and deformation parameters are presented individually for each segment to determine regional function. In addition, deformation for the whole region of interest is used to determine global function. Regional and global LV longitudinal deformation parameters are obtained from the apical four-, two-, and three-chamber views Fig.
LV circumferential, radial, and rotational deformation are obtained from the parasternal short axis view at the level of the mitral valve base , papillary muscles mid-ventricular , and the apex. Global longitudinal strain often referred to as GLS is the peak value in a compound curve made from the region of interest from the three planes. Strain and strain rate curves from the LV four-chamber view and the RV free walls. The colored lines represent the deformation values from each segment and the dotted white line represents the values from the whole region of interest.
Notice the relative increased level of noise in the strain rate curves see text. Echocardiographic evaluation can be acquired in the resting state without sedation and gray scale images need to illustrate walls clearly and without artifact. An ECG signal is also mandatory in addition to event timing annotation, as described earlier. Fundamental and harmonic imaging with different probe types have not shown differences in strain and SR values in an in vitro study.
Sanchez et al. Manipulations of depth and sector width can be used to achieve this ratio. In neonates, analysis of deformation parameters is performed offline using dedicated vendor-customized analysis software. Vendor-independent software packages are available for speckle tracking analysis with any image acquisition platform.
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The width of the ROI is set to match the width of the wall of interest Fig. The software then automatically tracks the movement of speckles to derive the deformation parameters. The acceptability of the tracking is automatically suggested by the software. The user can also visually inspect the quality of the tracking before finally accepting or rejecting analysis of the segment. To enhance the STE capabilities, the ROI is readjusted repeatedly to avoid free wall base over excursion, tracking of the trabeculations, and avoid artifact.
Cine-loop images with persistently inadequate tracking should be excluded from analysis. Once the integrity of myocardial STE is visually confirmed by the user, the software algorithm generates seven curves for each view of heart i. Each curve represents the measured myocardial deformation strain for the six specific myocardial segments basal septum, mid-septum, apical septum, basal lateral, mid-lateral, and apical lateral and one global value representing the combined strain from all segments within the specific echocardiographic view Fig.
Normative data and reference ranges are still emerging for deformation parameters obtained using 2D STE in the preterm and term infants. Reference ranges have been published in healthy uncomplicated term 10 , 35 , 37 , 45 , 51 , 55 , 56 , 57 , 58 and preterm population, 11 , 19 , 26 , 32 , 53 , 59 , 60 or reported results from control groups of neonates who were recruited for specific studies; 61 , 62 , 63 , 64 , 65 , The process of standardization and reference values in neonates stems from relatively small number of infants included in each study, the varying time points at which echocardiograms were acquired in the first year of age, and the multitude of vendors and software versions utilized for acquisition and post-processing.
Radial deformation values and diastolic SR parameters early and atrial measured using 2D STE remain unreliable in the neonatal population. In the early transitional period, another study demonstrated that the administration of antenatal magnesium sulfate is associated with a lower SVR and a higher LV GLS on day 1 of age. The influence of common cardiopulmonary abnormalities in preterm infants such as CLD and pulmonary hypertension appear to leave a negative effect on RV and septal strain, with preservation of LV strain patterns. Myocardial shear deformation in the circumferential-longitudinal plane results in torsional deformation of the LV during ejection and is utilized to characterize functional changes in systole and diastole.
The myofiber orientation changes continuously from a right-handed helix in the subendocardium to a left-handed helix in subepicardium, enabling the LV to have unique rotational properties. Twist degrees is defined as the difference between apical and basal systolic rotation Fig. Untwisting is the motion opposite to the direction of twist occurring in diastole. During diastole, the LV untwists to return to its baseline un-deformed and untwisted shape. The act of untwisting also aids in diastolic function and contributes to early diastolic filling.
This process is highly dependent on the elasticity of the LV. Left ventricle rotational mechanics. There is a small, yet growing literature on the validation of rotational mechanics in neonates. Two-dimensional STE method is also used to derive rotational parameters. The methodology for image acquisition and offline assessment is similar to deformation assessment described above.
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