Comparison of weighting algorithms to mitigate respiratory motion in free-breathing neonatal pulmonary radial UTE-MRI

Background. Thoracoabdominal MRI is limited by respiratory motion, especially in populations who cannot perform breath-holds. One approach for reducing motion blurring in radially-acquired MRI is respiratory gating. Straightforward 'hard-gating' uses only data from a specified respiratory window and suffers from reduced SNR. Proposed 'soft-gating' reconstructions may improve scan efficiency but reduce motion correction by incorporating data with nonzero weight acquired outside the specified window. However, previous studies report conflicting benefits, and importantly the choice of soft-gated weighting algorithm and effect on image quality has not previously been explored. The purpose of this study is to map how variable soft-gated weighting functions and parameters affect signal and motion blurring in respiratory-gated reconstructions of radial lung MRI, using neonates as a model population.Methods. Ten neonatal inpatients with respiratory abnormalities were imaged using a 1.5 T neonatal-sized scanner and 3D radial ultrashort echo-time (UTE) sequence. Images were reconstructed using ungated, hard-gated, and several soft-gating weighting algorithms (exponential, sigmoid, inverse, and linear weighting decay outside the period of interest), with %Nprojrepresenting the relative amount of data included. The apparent SNR (aSNR) and motion blurring (measured by the maximum derivative of image intensity at the diaphragm, MDD) were compared between reconstructions.Results. Soft-gating functions produced higher aSNR and lower MDD than hard-gated images using equivalent %Nproj, as expected. aSNR was not identical between different gating schemes for given %Nproj. While aSNR was approximately linear with %Nprojfor each algorithm, MDD performance diverged between functions as %Nprojdecreased. Algorithm performance was relatively consistent between subjects, except in images with high noise.Conclusion. The algorithm selection for soft-gating has a notable effect on image quality of respiratory-gated MRI; the timing of included data across the respiratory phase, and not simply the amount of data, plays an important role in aSNR. The specific soft-gating function and parameters should be considered for a given imaging application's requirements of signal and sharpness.

Effects of decongestion on nasal cavity air conditioning efficiency: a CFD cohort study

Decongestion reduces blood flow in the nasal turbinates, enlarging the airway lumen. Although the enlarged airspace reduces the trans-nasal inspiratory pressure drop, symptoms of nasal obstruction may relate to nasal cavity air-conditioning. Thus, it is necessary to quantify the efficiency of nasal cavity conditioning of the inhaled air. This study quantifies both overall and regional nasal air-conditioning in a cohort of 10 healthy subjects using computational fluid dynamics simulations before and after nasal decongestion. The 3D virtual geometry model was segmented from magnetic resonance images (MRI). Each subject was under two MRI acquisitions before and after the decongestion condition. The effects of decongestion on nasal cavity air conditioning efficiency were modelled at two inspiratory flowrates: 15 and 30 L min-1 to represent restful and light exercise conditions. Results show inhaled air was both heated and humidified up to 90% of alveolar conditions at the posterior septum. The air-conditioning efficiency of the nasal cavity remained nearly constant between nostril and posterior septum but dropped significantly after posterior septum. In summary, nasal cavity decongestion not only reduces inhaled air added heat by 23% and added moisture content by 19%, but also reduces the air-conditioning efficiency by 35% on average.

Tracheomalacia Reduces Aerosolized Drug Delivery to the Lung

Rationale: Neonates with respiratory issues are frequently treated with aerosolized medications to manage lung disease or facilitate airway clearance. Dynamic tracheal collapse (tracheomalacia [TM]) is a common comorbidity in these patients, but it is unknown whether the presence of TM alters the delivery of aerosolized drugs. Objectives: To quantify the effect of neonatal TM on the delivery of aerosolized drugs. Methods: Fourteen infant subjects with respiratory abnormalities were recruited; seven with TM and seven without TM. Respiratory-gated 3D ultrashort echo time magnetic resonance imaging (MRI) was acquired covering the central airway and lungs. For each subject, a computational fluid dynamics simulation modeled the airflow and particle transport in the central airway based on patient-specific airway anatomy, motion, and airflow rates derived from MRI. Results: Less aerosolized drug reached the distal airways in subjects with TM than in subjects without TM: of the total drug delivered, less particle mass passed through the main bronchi in subjects with TM compared with subjects without TM (33% vs. 47%, p = 0.013). In subjects with TM, more inhaled particles were deposited on the surface of the airway (48% vs. 25%, p = 0.003). This effect becomes greater with larger particle sizes and is significant for particles with a diameter >2 μm (2-5 μm, p ≤ 0.025 and 5-15 μm, p = 0.004). Conclusions: Neonatal patients with TM receive less aerosolized drug delivered to the lungs than subjects without TM. Currently, infants with lung disease and TM may not be receiving adequate and/or expected medication. Particles >2 μm in diameter are likely to deposit on the surface of the airway due to anatomical constrictions such as reduced tracheal and glottal cross-sectional area in neonates with TM. This problem could be alleviated by delivering smaller aerosolized particles.

Predicting tracheal work of breathing in neonates based on radiological and pulmonary measurements

Tracheomalacia is an airway condition in which the trachea excessively collapses during breathing. Neonates diagnosed with tracheomalacia require more energy to breathe, and the effect of tracheomalacia can be quantified by assessing flow-resistive work of breathing (WOB) in the trachea using computational fluid dynamics (CFD) modeling of the airway. However, CFD simulations are computationally expensive; the ability to instead predict WOB based on more straightforward measures would provide a clinically useful estimate of tracheal disease severity. The objective of this study is to quantify the WOB in the trachea using CFD and identify simple airway and/or clinical parameters that directly relate to WOB. This study included 30 neonatal intensive care unit subjects (15 with tracheomalacia and 15 without tracheomalacia). All subjects were imaged using ultrashort echo time (UTE) MRI. CFD simulations were performed using patient-specific data obtained from MRI (airway anatomy, dynamic motion, and airflow rates) to calculate the WOB in the trachea. Several airway and clinical measurements were obtained and compared with the tracheal resistive WOB. The maximum percent change in the tracheal cross-sectional area (ρ = 0.560, P = 0.001), average glottis cross-sectional area (ρ = -0.488, P = 0.006), minute ventilation (ρ = 0.613, P < 0.001), and lung tidal volume (ρ = 0.599, P < 0.001) had significant correlations with WOB. A multivariable regression model with three independent variables (minute ventilation, average glottis cross-sectional area, and minimum of the eccentricity index of the trachea) can be used to estimate WOB more accurately (R2 = 0.726). This statistical model may allow clinicians to estimate tracheal resistive WOB based on airway images and clinical data.NEW & NOTEWORTHY The work of breathing due to resistance in the trachea is an important metric for quantifying the effect of tracheal abnormalities such as tracheomalacia, but currently requires complex dynamic imaging and computational fluid dynamics simulation to calculate it. This study produces a method to predict the tracheal work of breathing based on readily available imaging and clinical metrics.

The effect of pre-calving injection of trace mineral supplements on periparturient disease incidence in pasture based dairy cows

Trace minerals, have a role in immune function and a trace mineral supplement (TMS) can improve animal health in dairy herds. This prospective randomised clinical study assessed whether subcutaneous injection of 5.5 mL of TMS (40 mg zinc, 10 mg manganese, 5 mg selenium, 15 mg copper per mL), 14-28 days before planned start of calving (PSC) reduced clinical mastitis (CM), subclinical mastitis (SCM) and purulent vaginal discharge (PVD). From four farms, half of 1700 cows stratified on somatic cell count, age and breed were randomly allocated to treatment or no treatment. Occurrence of CM from - 7 to PSC + 100 days, SCM at PSC + 60 days and PVD at PSC + 24 days was analysed using survival analysis and Bayesian generalised mixed multivariable models. From -7 to PSC +30 days, TMS reduced the adjusted hazard ratio (HR) for CM at quarter and cow level (P < 0.001), with no evidence for an effect beyond 30 days. The adjusted OR (and 95% highest density interval, HDI) for the effect of TMS on CM from -7 to PSC +30 days was 0.40 (95% HDI, 0.26-0.63) at quarter level, 0.51 (95% HDI, 0.38-0.69) at cow level and for SCM, 0.72 (95% HDI, 0.54-0.95). The difference in CM incidence from TMS at the cow level was -2.0% (95% HDI, -3.4 to -1.1%) and -1.2% (95% HDI, -3.2 to - 0.6%) at quarter level. No clear effect was identified of TMS on cumulative incidence of PVD.

Dynamic imaging using motion-compensated smoothness regularization on manifolds (MoCo-SToRM)

Objective. We introduce an unsupervised motion-compensated reconstruction scheme for high-resolution free-breathing pulmonary magnetic resonance imaging.Approach. We model the image frames in the time series as the deformed version of the 3D template image volume. We assume the deformation maps to be points on a smooth manifold in high-dimensional space. Specifically, we model the deformation map at each time instant as the output of a CNN-based generator that has the same weight for all time-frames, driven by a low-dimensional latent vector. The time series of latent vectors account for the dynamics in the dataset, including respiratory motion and bulk motion. The template image volume, the parameters of the generator, and the latent vectors are learned directly from the k-t space data in an unsupervised fashion.Main results. Our experimental results show improved reconstructions compared to state-of-the-art methods, especially in the context of bulk motion during the scans.Significance. The proposed unsupervised motion-compensated scheme jointly estimates the latent vectors that capture the motion dynamics, the corresponding deformation maps, and the reconstructed motion-compensated images from the raw k-t space data of each subject. Unlike current motion-resolved strategies, the proposed scheme is more robust to bulk motion events during the scan.

Tracheostomy prediction model in neonatal bronchopulmonary dysplasia via lung and airway MRI

RATIONALE

Clinical management of neonatal bronchopulmonary dysplasia (BPD) is often imprecise and can vary widely between different institutions and providers, due to limited objective measurements of disease pathology severity. There is critical need to improve guidance on the application and timing of interventional treatments, such as tracheostomy.

OBJECTIVES

To generate an imaging-based clinical tool for early identification of those patients with BPD who are likely to require later tracheostomy and long-term mechanical ventilation.

METHODS

We conducted a prospective cohort study of n = 61 infants (55 BPD, 6 preterm non-BPD). Magnetic resonance imaging (MRI) scores of lung parenchymal disease were used to create a binomial logistic regression model for predicting tracheostomy requirement. This model was further investigated using clinical variables and MRI-quantified tracheomalacia (TM).

MEASUREMENTS AND MAIN RESULTS

A model for predicting tracheostomy requirement was created using MRI parenchymal score. This model had 89% accuracy, 100% positive predictive value (PPV), and 85% negative predictive value (NPV), compared with 84%, 60%, and 83%, respectively, when using only relevant clinical variables. In a subset of patients with airway MRI (n = 36), a model including lung and TM measurements had 83% accuracy, 92% PPV, and 78% NPV.

CONCLUSIONS

MRI-based measurements of parenchymal disease and TM can be used to predict need for tracheostomy in infants with BPD, more accurately than clinical factors alone. This prediction model has strong potential as a clinical tool for physicians and families for early determination of tracheostomy requirement.

Global climate-driven trade-offs between the water retention and cooling benefits of urban greening

Urban greening can potentially help mitigate heat-related mortality and flooding facing the >4 billion urban population worldwide. However, the geographical variation of the relative combined hydrological and thermal performance benefits of such interventions are unknown. Here we quantify globally, using a hydrological model, how climate-driven trade-offs exist between hydrological retention and cooling potential of urban greening such as green roofs and parks. Using a Budyko framework, we show that water retention generally increases with aridity in water-limited environments, while cooling potential favors energy-limited climates. Our models suggest that common urban greening strategies cannot yield high performance simultaneously for addressing both urban heat-island and urban flooding problems in most cities globally. Irrigation, if sustainable, may enhance cooling while maintaining retention performance in more arid locations. Increased precipitation variability with climate change may reduce performance of thinner green-infrastructure more quickly compared to greened areas with thicker soils and root systems. Our results provide a conceptual framework and first-order quantitative guide for urban development, renewal and policymaking.

Bronchopulmonary dysplasia from chest radiographs to magnetic resonance imaging and computed tomography: adding value

Bronchopulmonary dysplasia (BPD) is a common long-term complication of preterm birth. The chest radiograph appearance and survivability have evolved since the first description of BPD in 1967 because of improved ventilation and clinical strategies and the introduction of surfactant in the early 1990s. Contemporary imaging care is evolving with the recognition that comorbidities of tracheobronchomalacia and pulmonary hypertension have a great influence on outcomes and can be noninvasively evaluated with CT and MRI techniques, which provide a detailed evaluation of the lungs, trachea and to a lesser degree the heart. However, echocardiography remains the primary modality to evaluate and screen for pulmonary hypertension. This review is intended to highlight the important findings that chest radiograph, CT and MRI can contribute to precision diagnosis, phenotyping and prognosis resulting in optimal management and therapeutics.

Neonates With Tracheomalacia Generate Auto-Positive End-Expiratory Pressure via Glottis Closure

BACKGROUND

In pediatrics, tracheomalacia is an airway condition that causes tracheal lumen collapse during breathing and may lead to the patient requiring respiratory support. Adult patients can narrow their glottis to self-generate positive end-expiratory pressure (PEEP) to raise the pressure in the trachea and prevent collapse. However, auto-PEEP has not been studied in newborns with tracheomalacia. The objective of this study was to measure the glottis cross-sectional area throughout the breathing cycle and to quantify total pressure difference through the glottis in patients with and without tracheomalacia.

RESEARCH QUESTION

Do neonates with tracheomalacia narrow their glottises? How does the glottis narrowing affect the total pressure along the airway?

STUDY DESIGN AND METHODS

Ultrashort echo time MRI was performed in 21 neonatal ICU patients (11 with tracheomalacia, 10 without tracheomalacia). MRI scans were reconstructed at four different phases of breathing. All patients were breathing room air or using noninvasive respiratory support at the time of MRI. Computational fluid dynamics simulations were performed on patient-specific virtual airway models with airway anatomic features and motion derived via MRI to quantify the total pressure difference through the glottis and trachea.

RESULTS

The mean glottis cross-sectional area at peak expiration in the patients with tracheomalacia was less than half that in patients without tracheomalacia (4.0 ± 1.1 mm2 vs 10.3 ± 4.4 mm2; P = .002). The mean total pressure difference through the glottis at peak expiration was more than 10 times higher in patients with tracheomalacia compared with patients without tracheomalacia (2.88 ± 2.29 cm H2O vs 0.26 ± 0.16 cm H2O; P = .005).

INTERPRETATION

Neonates with tracheomalacia narrow their glottises, which raises pressure in the trachea during expiration, thereby acting as auto-PEEP.

Human upper-airway respiratory airflow: In vivo comparison of computational fluid dynamics simulations and hyperpolarized 129Xe phase contrast MRI velocimetry

Computational fluid dynamics (CFD) simulations of respiratory airflow have the potential to change the clinical assessment of regional airway function in health and disease, in pulmonary medicine and otolaryngology. For example, in diseases where multiple sites of airway obstruction occur, such as obstructive sleep apnea (OSA), CFD simulations can identify which sites of obstruction contribute most to airway resistance and may therefore be candidate sites for airway surgery. The main barrier to clinical uptake of respiratory CFD to date has been the difficulty in validating CFD results against a clinical gold standard. Invasive instrumentation of the upper airway to measure respiratory airflow velocity or pressure can disrupt the airflow and alter the subject's natural breathing patterns. Therefore, in this study, we instead propose phase contrast (PC) velocimetry magnetic resonance imaging (MRI) of inhaled hyperpolarized 129Xe gas as a non-invasive reference to which airflow velocities calculated via CFD can be compared. To that end, we performed subject-specific CFD simulations in airway models derived from 1H MRI, and using respiratory flowrate measurements acquired synchronously with MRI. Airflow velocity vectors calculated by CFD simulations were then qualitatively and quantitatively compared to velocity maps derived from PC velocimetry MRI of inhaled hyperpolarized 129Xe gas. The results show both techniques produce similar spatial distributions of high velocity regions in the anterior-posterior and foot-head directions, indicating good qualitative agreement. Statistically significant correlations and low Bland-Altman bias between the local velocity values produced by the two techniques indicates quantitative agreement. This preliminary in vivo comparison of respiratory airway CFD and PC MRI of hyperpolarized 129Xe gas demonstrates the feasibility of PC MRI as a technique to validate respiratory CFD and forms the basis for further comprehensive validation studies. This study is therefore a first step in the pathway towards clinical adoption of respiratory CFD.

Quantitative Evaluation of Subglottic Stenosis Using Ultrashort Echo Time MRI in a Rabbit Model

OBJECTIVE/HYPOTHESIS

To assess the ability of ultra-short echo time (UTE)-MRI to detect subglottic stenosis (SGS) and evaluate response to balloon dilation. To correlate measurements from UTE-MRI with endotracheal-tube (ETT)-sizing and to investigate whether SGS causes change in airway dynamics.

STUDY DESIGN

Animal research study.

METHODS

Eight adult New-Zealand white rabbits were used as they approximate neonatal airway-size. The airways were measured using ETT-sizing and 3D UTE-MRI at baseline, 2 weeks post-cauterization induced SGS injury, and post-balloon dilation treatment. UTE-MR images were acquired to determine airway anatomy and motion. Airways were segmented from MR images. Cross-sectional area (CSA), major and minor diameters (D_major and D_minor ), and eccentricity were measured.

RESULTS

Post-injury CSA at SGS was significantly reduced (mean 38%) compared to baseline (P = .003) using UTE-MRI. ETT-sizing correlated significantly with MRI-measured CSA at the SGS location (r = 0.6; P < .01), particularly at the post-injury timepoint (r = 0.93; P < .01). Outer diameter from ETT-sizing (OD) correlated significantly with D_major (r = 0.63; P < .01) from UTE-MRI at the SGS location, especially for the post-injury timepoint (r = 0.91; P < .01). Mean CSA of upper trachea did not change significantly between end-expiration and end-inspiration at any timepoint (all P > .05). Eccentricity of the upper trachea increased significantly post-balloon dilation (P < .05).

CONCLUSIONS

UTE-MRI successfully detected SGS and treatment response in the rabbit model, with good correlation to ETT-sizing. Balloon dilation increased CSA at SGS, but not to baseline values. SGS did not alter dynamic motion for the trachea in this rabbit model; however, tracheas were significantly eccentric post-balloon dilation. UTE-MRI can detect SGS without sedation or ionizing radiation and may be a non-invasive alternative to ETT-sizing.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E1971-E1979, 2021.

The effect of airway motion and breathing phase during imaging on CFD simulations of respiratory airflow

RATIONALE

Computational fluid dynamics (CFD) simulations of respiratory airflow can quantify clinically useful information that cannot be obtained directly, such as the work of breathing (WOB), resistance to airflow, and pressure loss. However, patient-specific CFD simulations are often based on medical imaging that does not capture airway motion and thus may not represent true physiology, directly affecting those measurements.

OBJECTIVES

To quantify the variation of respiratory airflow metrics obtained from static models of airway anatomy at several respiratory phases, temporally averaged airway anatomies, and dynamic models that incorporate physiological motion.

METHODS

Neonatal airway images were acquired during free-breathing using 3D high-resolution MRI and reconstructed at several respiratory phases in two healthy subjects and two with airway disease (tracheomalacia). For each subject, five static (end expiration, peak inspiration, end inspiration, peak expiration, averaged) and one dynamic CFD simulations were performed. WOB, airway resistance, and pressure loss across the trachea were obtained for each static simulation and compared with the dynamic simulation results.

RESULTS

Large differences were found in the airflow variables between the static simulations at various respiratory phases and the dynamic simulation. Depending on the static airway model used, WOB, resistance, and pressure loss varied up to 237%, 200%, and 94% compared to the dynamic simulation respectively.

CONCLUSIONS

Changes in tracheal size and shape throughout the breathing cycle directly affect respiratory airflow dynamics and breathing effort. Simulations incorporating realistic airway wall dynamics most closely represent airway physiology; if limited to static simulations, the airway geometry must be obtained during the respiratory phase of interest for a given pathology.

Subglottic Stenosis Position Affects Work of Breathing

OBJECTIVES

Subglottic stenosis (SGS) is the most common type of laryngeal stenosis in neonates. SGS severity is currently graded based on percent area of obstruction (%AO) via the Myer-Cotton grading scale. However, patients with similar %AO can have widely different clinical courses. Computational fluid dynamics (CFD) based on patient-specific imaging can quantify the relationship between airway geometry and flow dynamics. We investigated the effect of %AO and axial position of SGS on work of breathing (WOB) in neonates using magnetic resonance imaging.

METHODS

High-resolution ultrashort echo-time MRI of the chest and airway was obtained in three neonatal patients with no suspected airway abnormalities; images were segmented to construct three-dimensional (3D) models of the neonatal airways. These models were then modified with virtual SGSs of varying %AO and axial positioning. CFD simulations of peak inspiratory flow were used to calculate patient-specific WOB in nonstenotic and artificially stenosed airway models.

RESULTS

CFD simulations demonstrated a relationship between stenosis geometry and WOB increase. WOB rapidly increased with %AO greater than about 70%. Changes in axial position could also increase WOB by approximately the same amount as a 10% increase in %AO. Increased WOB was particularly pronounced when the SGS lumen was misaligned with the glottic jet.

CONCLUSION

The results indicate a strong, predictable relationship between WOB and axial position of the stenotic lumen relative to the glottis, which has not been previously reported. These findings may lead to precision diagnosis and treatment prediction tools in individual patients.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1220-E1226, 2021.

Increased Work of Breathing due to Tracheomalacia in Neonates

Rationale: Dynamic collapse of the tracheal lumen (tracheomalacia) occurs frequently in premature neonates, particularly in those with common comorbidities such as bronchopulmonary dysplasia. The tracheal collapse increases the effort necessary to breathe (work of breathing [WOB]). However, quantifying the increased WOB related to tracheomalacia has previously not been possible. Therefore, it is also not currently possible to separate the impact of tracheomalacia on patient symptoms from parenchymal abnormalities.Objectives: To measure the increase in WOB due to airway motion in individual subjects with and without tracheomalacia and with different types of respiratory support.Methods: Fourteen neonatal intensive care unit subjects not using invasive mechanical ventilation were recruited. In eight, tracheomalacia was diagnosed via clinical bronchoscopy, and six did not have tracheomalacia. Self-gated three-dimensional ultrashort-echo-time magnetic resonance imaging (MRI) was performed on each subject with clinically indicated respiratory support to obtain cine images of tracheal anatomy and motion during the respiratory cycle. The component of WOB due to resistance within the trachea was then calculated via computational fluid dynamics (CFD) simulations of airflow on the basis of the subject's anatomy, motion, and respiratory airflow rates. A second CFD simulation was performed for each subject with the airway held static at its largest (i.e., most open) position to determine the increase in WOB due to airway motion and collapse.Results: The tracheal-resistive component of WOB was increased because of airway motion by an average of 337% ± 295% in subjects with tracheomalacia and 24% ± 14% in subjects without tracheomalacia (P < 0.02). In the tracheomalacia group, subjects who were treated with continuous positive airway pressure (CPAP) using a RAM cannula expended less energy for breathing compared with the subjects who were breathing room air or on a high-flow nasal cannula.Conclusions: Neonatal subjects with tracheomalacia have increased energy expenditure compared with neonates with normal airways, and CPAP may be able to attenuate the increase in respiratory work. Subjects with tracheomalacia expend more energy on the tracheal-resistive component of WOB alone than nontracheomalacia patients expend on the resistive WOB for the entire respiratory system, according to previously reported values. CFD may be able to provide an objective measure of treatment response for children with tracheomalacia.

Ultrashort Echo-Time MRI for the Assessment of Tracheomalacia in Neonates

BACKGROUND

Bronchoscopy is the gold standard for evaluating tracheomalacia; however, reliance on an invasive procedure limits understanding of normal airway dynamics. Self-gated ultrashort echo-time MRI (UTE MRI) can assess tracheal dynamics but has not been rigorously evaluated.

METHODS

This study was a validation of UTE MRI diagnosis of tracheomalacia in neonates using bronchoscopy as the gold standard. Bronchoscopies were reviewed for the severity and location of tracheomalacia based on standardized criteria. The percent change in cross-sectional area (CSA) of the trachea between end-inspiration and end-expiration was determined by UTE MRI, and receiver-operating curves were used to determine the optimal cutoff values to predict tracheomalacia and determine positive and negative predictive values.

RESULTS

Airway segments with tracheomalacia based on bronchoscopy had a more than threefold change in CSA measured from UTE MRI (54.4 ± 56.1% vs 14.8 ± 19.5%; P < .0001). UTE MRI correlated moderately with bronchoscopy for tracheomalacia severity (ρ = 0.39; P = .0001). Receiver-operating curves, however, showed very good ability of UTE MRI to identify tracheomalacia (area under the curve, 0.78). A "loose" definition (> 20% change in CSA) of tracheomalacia had good sensitivity (80%) but low specificity (64%) for identifying tracheomalacia based on UTE MRI, whereas a "strict" definition (> 40% change in CSA) was poorly sensitive (48%) but highly specific (93%).

CONCLUSIONS

Self-gated UTE MRI can noninvasively assess tracheomalacia in neonates without sedation, ionizing radiation, or increased risk. This technique overcomes major limitations of other diagnostic modalities and may be suitable for longitudinal population studies of tracheal dynamics.

Assessing Changes in Airflow and Energy Loss in a Progressive Tracheal Compression Before and After Surgical Correction

The energy needed to drive airflow through the trachea normally constitutes a minor component of the work of breathing. However, with progressive tracheal compression, patient subjective symptoms can include severe breathing difficulties. Many patients suffer multiple respiratory co-morbidities and so it is important to assess compression effects when evaluating the need for surgery. This work describes the use of computational prediction to determine airflow resistance in compressed tracheal geometries reconstructed from a series of CT scans. Using energy flux analysis, the regions that contribute the most to airway resistance during inhalation are identified. The principal such region is where flow emerging from the zone of maximum constriction undergoes breakup and turbulent mixing. Secondary regions are also found below the tongue base and around the glottis, with overall airway resistance scaling nearly quadratically with flow rate. Since the anatomical extent of the imaged airway varied between scans-as commonly occurs with clinical data and when assessing reported differences between research studies-the effect of sub-glottic inflow truncation is considered. Analysis shows truncation alters the location of jet breakup and weakly influences the pattern of pressure recovery. Tests also show that placing a simple artificial glottis in the inflow to a truncated model can replicate patterns of energy loss in more extensive models, suggesting a means to assess sensitivity to domain truncation in tracheal airflow simulations.

A comparison of machine learning and logistic regression in modelling the association of body condition score and submission rate

The effect of body condition score (BCS) on reproductive outcomes is complex, dynamic and non-linear with interaction and confounding. The flexibility inherent in machine learning algorithms makes them attractive for analysing complex data. This study was designed to compare the ability of a range of machine learning techniques in estimating the probability of service within 21 days of the planned start of mating. We hypothesised that if there were complex and unknown interactions or non-linearity in the data, some machine learning algorithms would result in superior model performance compared to regression models. For a period of six months from the planned start of calving, BCS was visually assessed once a month for 6127 cows on 8 commercial New Zealand dairy farms by a trained veterinarian using the DairyNZ 10-point range for every cow in the herd. Cow, lactation and reproductive data was extracted from the national herd database. This data was used to predict probability of service within 21 days of planned start of mating (PSM) using mixed multivariable logistic regression and decision tree, k-nearest neighbour, random forest and neural network analysis. Models were adjusted for herd, cow age, breed, days in milk, BCS at calving, BCS change between calving and mating, BCS change after mating, volume adjusted milk protein and fat concentration pre-mating. Models were constructed on a training data set using 10-fold cross validation repeated 10 times and evaluated on a test data set using discrimination and calibration techniques. In all models, days calved at PSM was the most important variable for predicting submission rate, followed by BCS at PSM. Factors associated with an increased probability of insemination were calving at a BCS of 5.0, losing less BCS after calving, having a higher BCS at nadir, losing BCS rapidly after calving, nadir occurring before PSM and calving early. All the models except for the decision tree had an area under the receiver operating characteristic curve (AUC) in the range 0.68-0.73 indicating good overall discriminatory power, but calibration analysis suggested all models were better at predicting cows that got inseminated than correctly identifying animals that did not get inseminated. Overall, the machine learning techniques were no better than a generalised logistic regression model. These results highlight the importance of BCS targets at calving and indicate BCS loss, milk characteristics and days calves may be useful indicators identifying cows at risk of poor reproductive outcomes.

Elevated lung volumes in neonates with bronchopulmonary dysplasia measured via MRI

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of prematurity defined by requirement for respiratory support at 36 weeks postmenstrual age (PMA), but structural sequelae like lung hyperinflation are often not quantified. Quiet-breathing, nonsedated magnetic resonance imaging (MRI) allows tomographic quantification of lung volumes and densities. We hypothesized that functional residual capacity (FRC) and intrapleural volume (IV) are increased in BPD and correlate with qualitative radiological scoring of hyperinflation.

METHODS

Ultrashort echo time (UTE) MRI of 17 neonates (acquired at ~39 weeks PMA) were reconstructed at end-expiration and end-inspiration via the time course of the k₀ point in k-space. Images were segmented to determine total lung, tidal, parenchymal tissue, and vascular tissue volumes. FRC was calculated by subtracting parenchymal and vascular tissue volumes from IV. Respiratory rate (RR) was calculated via the UTE respiratory waveform, yielding estimates of minute ventilation when combined with tidal volumes (TVs). Two radiologists scored hyperinflation on the MR images.

RESULTS

IV at FRC increased in BPD: for control, mild, and severe (patients the median volumes were 32.8, 33.5, and 50.9 mL/kg, respectively. TV (medians: 2.21, 3.64, and 4.84 mL/kg) and minute ventilation (medians: 493, 750, and 991 mL/min) increased with increasing severity of BPD (despite decreasing RR, medians: 75.6, 63.0, and 56.1 breaths/min). FRC increased with increasing severity of BPD (39.3, 38.3, and 56.0 mL, respectively). Findings were consistent with increased hyperinflation scored by radiologists.

CONCLUSIONS

This study demonstrates that UTE MRI can quantify hyperinflation in neonatal BPD and that lung volumes significantly increase with disease severity.

Assessing the relationship between movement and airflow in the upper airway using computational fluid dynamics with motion determined from magnetic resonance imaging

BACKGROUND

Computational fluid dynamics simulations of respiratory airflow in the upper airway reveal clinically relevant information, including sites of local resistance, inhaled particle deposition, and the effect of pathological constrictions. Unlike previous simulations, which have been performed on rigid anatomical models from static medical imaging, this work utilises ciné imaging during respiration to create dynamic models and more closely represent airway physiology.

METHODS

Airway movement maps were obtained from non-rigid image registration of fast-cine MRI and applied to high-spatial-resolution airway surface models. Breathing flowrates were recorded simultaneously with imaging. These data formed the boundary conditions for large eddy simulation computations of the airflow from exterior mask to bronchi. Simulations with rigid geometries were performed to demonstrate the resulting airflow differences between airflow simulations in rigid and dynamic airways.

FINDINGS

In the analysed rapid breathing manoeuvre, incorporating airway movement significantly changed the findings of the CFD simulations. Peak resistance increased by 19.8% and occurred earlier in the breath. Overall pressure loss decreased by 19.2%, and the proportion of flow in the mouth increased by 13.0%. Airway wall motion was out-of-phase with the air pressure force, demonstrating the presence of neuromuscular motion. In total, the anatomy did 25.2% more work on the air than vice versa.

INTERPRETATIONS

Realistic movement of the airway is incorporated into CFD simulations of airflow in the upper airway for the first time. This motion is vital to producing clinically relevant computational models of respiratory airflow and will allow novel analysis of dynamic conditions, such as sleep apnoea.

Quantitative Assessment of Regional Dynamic Airway Collapse in Neonates via Retrospectively Respiratory-Gated 1 H Ultrashort Echo Time MRI

BACKGROUND

Neonatal dynamic tracheal collapse (tracheomalacia, TM) is a common and serious comorbidity in infants, particularly those with chronic lung disease of prematurity (bronchopulmonary dysplasia, BPD) or congenital airway or lung-related conditions such as congenital diaphragmatic hernia (CDH), but the underlying pathology, impact on clinical outcomes, and response to therapy are not well understood. There is a pressing clinical need for an accurate, objective, and safe assessment of neonatal TM.

PURPOSE

To use retrospectively respiratory-gated ultrashort echo-time (UTE) MRI to noninvasively analyze moving tracheal anatomy for regional, quantitative evaluation of dynamic airway collapse in quiet-breathing, nonsedated neonates.

STUDY TYPE

Prospective.

POPULATION/SUBJECTS

Twenty-seven neonatal subjects with varying respiratory morbidities (control, BPD, CDH, abnormal polysomnogram).

FIELD STRENGTH/SEQUENCE

High-resolution 3D radial UTE MRI (0.7 mm isotropic) on 1.5T scanner sited in the neonatal intensive care unit.

ASSESSMENT

Images were retrospectively respiratory-gated using the motion-modulated time-course of the k-space center. Tracheal surfaces were generated from segmentations of end-expiration/inspiration images and analyzed geometrically along the tracheal length to calculate percent-change in luminal cross-sectional area (A % ) and ratio of minor-to-major diameters at end-expiration (r D,exp ). Geometric results were compared to clinically available bronchoscopic findings (n = 14).

STATISTICAL TESTS

Two-sample t-test.

RESULTS

Maximum A % significantly identified subjects with/without a bronchoscopic TM diagnosis (with: 46.9 ± 10.0%; without: 27.0 ± 5.8%; P < 0.001), as did minimum r D,exp (with: 0.346 ± 0.146; without: 0.671 ± 0.218; P = 0.008). Subjects with severe BPD exhibited a far larger range of minimum r D,exp than subjects with mild/moderate BPD or controls (0.631 ± 0.222, 0.782 ± 0.075, and 0.776 ± 0.030, respectively), while minimum r D,exp was reduced in CDH subjects (0.331 ± 0.171) compared with controls (P < 0.001).

DATA CONCLUSION

Respiratory-gated UTE MRI can quantitatively and safely evaluate neonatal dynamic tracheal collapse, as validated with the clinical standard of bronchoscopy, without requiring invasive procedures, anesthesia, or ionizing radiation.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:659-667.

A new method of administering local anesthesia for calf disbudding: Findings from a comparative on-farm study in New Zealand

Anesthesia of the horn bud for calf disbudding commonly is attained by injection of local anesthetic over branches of the cornual nerve, with anesthesia achieved in 3 to 20 min. With experienced and trained staff, this method is effective in 88 to 100% of calves. Variability in response and time of onset can compromise calf welfare if calves are disbudded before anesthesia is attained. Proposed legislative reliance on effective local anesthetic as the minimal method of pain relief for calves at disbudding means that administration of local anesthetic must achieve a repeatable level and rapid onset of analgesia. We describe an alternative method of local anesthesia administration that uses local site infiltration of anesthetic over the horn bud. However, this method has not yet been scientifically validated. This study assessed differences between disbudding using the cornual nerve block and disbudding with local anesthesia administered by local site infiltration. Efficacy of local anesthesia was assessed at 30-s intervals after administration by absence of reaction to 3 consecutive needle pricks over the horn buds. Behavior indicating pain was assessed during disbudding and scored from 0 to 3. Calf behavior was also recorded for 3 h after disbudding. Accelerometer data loggers were fitted to each calf for 24 h before and after disbudding to assess lying and standing times. Median time to cutaneous desensitization for local infiltration was 60 s compared with 225 s for cornual nerve block, and the variance in time to desensitization was less with local infiltration. Calves disbudded under cornual block had a larger behavioral response (indicated by a graded aversive body reaction) than calves disbudded under local infiltration. A multivariable model predicted that the mean body reaction score would be 0.6 for calves disbudded under local infiltration and 1.2 for calves disbudded under cornual block. There was no difference in any behaviors between the treatment groups in the 3 h after disbudding. Method of analgesia had no effect on lying time over the 24 h after disbudding. In this study, local infiltration was at least as effective in providing analgesia for disbudding as the cornual nerve block. Our results suggest that a more consistent, effective level of analgesia during disbudding was achieved using local infiltration and that there was no difference in postoperative expressions of pain.

A novel method to generate dynamic boundary conditions for airway CFD by mapping upper airway movement with non-rigid registration of dynamic and static MRI

Computational fluid dynamics (CFD) simulations of airflow in the human airways have the potential to provide a great deal of information that can aid clinicians in case management and surgical decision making, such as airway resistance, energy expenditure, airflow distribution, heat and moisture transfer, and particle deposition, as well as the change in each of these due to surgical interventions. However, the clinical relevance of CFD simulations has been limited to date, as previous models either did not incorporate neuromuscular motion or any motion at all. Many common airway pathologies, such as obstructive sleep apnea (OSA) and tracheomalacia, involve large movements of the structures surrounding the airway, such as the tongue and soft palate. Airway wall motion may be due to many factors including neuromuscular motion, internal aerodynamic forces, and external forces such as gravity. Therefore, to realistically model these airway diseases, a method is required to derive the airway wall motion, whatever the cause, and apply it as a boundary condition to CFD simulations. This paper presents and validates a novel method of capturing in vivo motion of airway walls from magnetic resonance images with high spatiotemporal resolution, through a novel combination of non-rigid image, surface, and surface-normal-vector registration. Coupled with image-synchronous pneumotachography, this technique provides the necessary boundary conditions for dynamic CFD simulations of breathing, allowing the effect of the airway's complex motion to be calculated for the first time, in both normal subjects and those with conditions such as OSA.

Effect of using an internal teat sealant at drying-off in cows wintered on forage crops in New Zealand on culling in the dry period and early lactation

AIMS

To determine the impact of treatment with internal teat sealant (ITS) compared to no treatment at drying-off on culling during the dry period and 90 days after calving, for cows wintered on forage crops.

METHODS

In four dairy herds in the South Island of New Zealand, cows with no history of clinical mastitis or somatic cell counts >100,000 cells/mL during the 2015-16 season were randomly assigned to treatment with ITS in each quarter (ITS group) or no treatment (Control group). Cows were otherwise treated similarly, wintered on forage crops and transferred to pasture for calving and lactation. Culling was defined as an unplanned exit from the herd, including cows sold for slaughter, cows slaughtered for salvage value and cows that died on farm. Culls and cull dates were recorded between drying-off and 90 days after calving.

RESULTS

Between drying-off and 90 days after calving 24/491 (4.9%) cows in the ITS group and 45/473 (9.5%) cows in the Control group were culled (RR=0.51; 95% CI=0.75-0.83), and between 30 days before calving and 90 days after calving 20/491 (4.1%) cows in the ITS group and 40/473 (8.5%) cows in the Control group were culled (RR=0.48; 95% CI=0.29-0.81). In the final multivariable logistic regression model, adjusting for dry-period length, cow age, breed and farm, the OR for culling in the study period was 0.43 (95% CI=0.23-0.81) for cows in the ITS compared with the Control group. For a Friesian/Jersey cow, aged 4-8 years, with a dry period of 30-80 days, dried-off without ITS, the probability of culling in the study period was 0.10 (95% CI=0.06-0.16), and for such a cow treated with ITS the probability was 0.05 (95% CI=0.03-0.08).

CONCLUSIONS AND CLINICAL RELEVANCE

In these four herds, the use of ITS at drying-off reduced the incidence of culling between drying-off and 90 days after calving. The use of ITS at drying-off in cows prior to wintering on forage crops may provide additional benefit to farmers through reduced incidence of culling and should be considered in any cost-benefit analysis of its use.

Pre- and post-operative visualization of neonatal esophageal atresia/tracheoesophageal fistula via magnetic resonance imaging

Esophageal atresia (EA) is a relatively uncommon congenital anomaly, often observed in conjunction with tracheoesophageal fistula (TEF). Surgical repair in neonates typically takes place with little information about the pre-existing EA/TEF structure because there are currently no acceptable tools for evaluating EA/TEF anatomy prior to repair; chest x-ray radiograph does not identify malformation sub-type or gap length, while x-ray computed tomography (CT) demonstrate an unacceptably high exposure to ionizing radiation. There is a need for safe imaging methods to evaluate pre-operative EA/TEF anatomy, which would add value in surgical planning; this need may be met with high-resolution structural MRI. We report three cases of Type-C EA/TEF in neonates. Patients were imaged prior to surgical repair using high-resolution ultrashort echo time (UTE) magnetic resonance imaging (MRI) to visualize tracheoesophageal anatomy and allow for informed surgical planning and risk management. One of the three patients was imaged post-repair to evaluate surgical efficacy and evolution of the tracheoesophageal anatomy.

Attitudes of farm consultants in the South Island of New Zealand towards the role of veterinarians in farm businesses

AIMS

To assess the attitude of dairy farm consultants to the role of veterinarians on dairy farms and whether they viewed veterinary advice as impartial, free from commercial bias and central to farm productivity and profitability.

METHODS

A telephone survey was commissioned in September 2014 of 36 full-time farm consultants in the Canterbury and Otago region of New Zealand using a pre-prepared questionnaire to explore their attitudes towards the veterinary profession. Of those approached, 25 completed the survey.

RESULTS

The consultants surveyed agreed or strongly agreed (21/23) that they were the custodians of animal health expenditure on farms, which was seen as an expense to be controlled (19/25 agreed or strongly agreed). This view was held more strongly (9/9 agreed or strongly agreed) by consultants with >5 years' professional experience, compared to 10/16 consultants with ≤5 years' experience. Most consultants (24/25) disagreed that they did not respect veterinary advice, but agreed (24/25) that veterinarians almost always had a vested interest in the advice that they gave. The role of veterinarians was seen by respondents to be mainly treatment of sick animals (22/25) and provision of animal health products (24/25), but not in maximising farm profitability (selected by 8/25 respondents). Consultants viewed their own roles as providing advice on the influence of animal health on farm profitability (21/25), nutrition (22/25) and reproduction (20/25). Most respondents (21/25) stated that reducing disease and animal health issues was important, but they (21/25) also identified a reduction in farm animal health expenditure as a measure of success. Only 7/25 consultants felt that they should work in partnership with veterinarians.

CONCLUSIONS

This was a small scale study from one region of New Zealand but it indicates that consultants are ambivalent about the role and value of working more closely with veterinarians, and about the benefit that veterinary intervention may bring to a farm's profitability.

CLINICAL RELEVANCE

More successful veterinary involvement on dairy farms will follow from a better understanding of how other rural professionals are involved in the farm's management and in meeting the individual farmer's goals and motivations.

Large-scale CFD simulations of the transitional and turbulent regime for the large human airways during rapid inhalation

The dynamics of unsteady flow in the human large airways during a rapid inhalation were investigated using highly detailed large-scale computational fluid dynamics on a subject-specific geometry. The simulations were performed to resolve all the spatial and temporal scales of the flow, thanks to the use of massive computational resources. A highly parallel finite element code was used, running on two supercomputers, solving the transient incompressible Navier-Stokes equations on unstructured meshes. Given that the finest mesh contained 350 million elements, the study sets a precedent for large-scale simulations of the respiratory system, proposing an analysis strategy for mean flow, fluctuations and wall shear stresses on a rapid and short inhalation (a so-called sniff). The geometry used encompasses the exterior face and the airways from the nasal cavity, through the trachea and up to the third lung bifurcation; it was derived from a contrast-enhanced computed tomography (CT) scan of a 48-year-old male. The transient inflow produces complex flows over a wide range of Reynolds numbers (Re). Thanks to the high fidelity simulations, many features involving the flow transition were observed, with the level of turbulence clearly higher in the throat than in the nose. Spectral analysis revealed turbulent characteristics persisting downstream of the glottis, and were captured even with a medium mesh resolution. However a fine mesh resolution was found necessary in the nasal cavity to observe transitional features. This work indicates the potential of large-scale simulations to further understanding of airway physiological mechanics, which is essential to guide clinical diagnosis; better understanding of the flow also has implications for the design of interventions such as aerosol drug delivery.

Comparison of cephalonium alone and in combination with an internal teat sealant for dry cow therapy in seasonally calving dairy cows

AIM

To assess the effect of combining an internal teat sealant (ITS) and a long-acting cephalonium-based dry cow therapy (DCT) on the prevalence of cows with a somatic cell count (SCC) >150,000 cells/mL 60-80 days after calving, and the incidence of clinical mastitis diagnosed by farm staff in the first 100 days after calving.

METHODS

Cows from a spring-calving, pasture-based, dairy farm in the South Canterbury region of New Zealand were randomly allocated to receive cephalonium DCT (n=289) or cephalonium and internal teat sealant (n=304) at the end of lactation. Cows were inspected twice daily by farm staff during the dry period and following calving for signs of mastitis. Individual SCC were determined from herd tests conducted in the previous lactation and following calving. Logistic regression models were used to determine relationships with the prevalence of cows with a SCC >150,000 cells/mL after calving, and survival analysis was used to model time to the first case of clinical mastitis following calving at the cow and quarter level.

RESULTS

The OR for a cow with a SCC >150,000 cells/mL after calving, including age and individual SCC in the preceding lactation in the model, was 0.53 (95% CI=0.32-0.89) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.017). At the cow level, including age and preceding SCC in the model, the hazard ratio for diagnosis of clinical mastitis by farm staff in the first 100 days of lactation was 0.60 (95% CI=0.39-0.98) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.04). At the quarter level, the hazard ratio for diagnosis of clinical mastitis, with age included in the model, was 0.41 (95% CI=0.23-0.74) for the combination therapy compared to cephalonium alone (p<0.001).

CONCLUSIONS

The combination of internal teat sealant and cephalonium DCT was more effective than cephalonium alone at reducing clinical mastitis diagnosed by farm staff in the 100 days after calving, and the prevalence of cows with a SCC >150,000 cells/mL 60-80 days after calving.

CLINICAL RELEVANCE

This study adds to the evidence that the prevention of intra mammary infections throughout the dry period and up to calving by using combination therapy is important in reducing the incidence of farmer-diagnosed clinical mastitis and prevalence of cows with a SCC >150,000 cells/mL 60-80 days after calving.

Tissue-Engineered Tracheal Replacement in a Child: A 4-Year Follow-Up Study

In 2010, a tissue-engineered trachea was transplanted into a 10-year-old child using a decellularized deceased donor trachea repopulated with the recipient's respiratory epithelium and mesenchymal stromal cells. We report the child's clinical progress, tracheal epithelialization and costs over the 4 years. A chronology of events was derived from clinical notes and costs determined using reference costs per procedure. Serial tracheoscopy images, lung function tests and anti-HLA blood samples were compared. Epithelial morphology and T cell, Ki67 and cleaved caspase 3 activity were examined. Computational fluid dynamic simulations determined flow, velocity and airway pressure drops. After the first year following transplantation, the number of interventions fell and the child is currently clinically well and continues in education. Endoscopy demonstrated a complete mucosal lining at 15 months, despite retention of a stent. Histocytology indicates a differentiated respiratory layer and no abnormal immune activity. Computational fluid dynamic analysis demonstrated increased velocity and pressure drops around a distal tracheal narrowing. Cross-sectional area analysis showed restriction of growth within an area of in-stent stenosis. This report demonstrates the long-term viability of a decellularized tissue-engineered trachea within a child. Further research is needed to develop bioengineered pediatric tracheal replacements with lower morbidity, better biomechanics and lower costs.

Effect of analgesia and anti-inflammatory treatment on weight gain and milk intake of dairy calves after disbudding

AIM

To assess the effect of analgesia at disbudding on weight gain and milk intake of dairy calves.

METHODS

Four disbudding protocols were used on 3- to 6-week-old Friesian-Jersey calves. Farm staff disbudded 101 calves without sedation or local analgesia, of which 51 received 20 mg meloxicam S/C. Veterinary staff disbudded 101 calves with sedation and local analgesia, of which 51 also received 20 mg meloxicam S/C. Calves were weighed before disbudding, 15 and 30 days later, and individual milk consumption was recorded for 11 days. Daily weight gain and milk consumption were analysed using mixed models and ANOVA.

RESULTS

From disbudding (Day 0) to Day 15 farmer-disbudded calves receiving meloxicam grew faster (0.65 kg/day) than calves without meloxicam (0.55 kg/day; p=0.011), but an interaction between operator and meloxicam treatment (p=0.056) meant that meloxicam treatment did not increase growth rates in veterinary-disbudded calves (0.63 vs. 0.64 kg/day; p=0.872). From Days 16-30 there was no significant effect of meloxicam on growth rate, but veterinarian-disbudded calves grew faster (0.76 kg/day) than farmer-disbudded calves (0.66 kg/day; p=0.034). Overall, for the first 30 days after disbudding, if meloxicam was not used', veterinarian-disbudded calves grew faster than farmer-disbudded calves (p=0.002). However if meloxicam was used at disbudding there was no difference in growth rate between veterinarian- and farmer-disbudded calves (p=0.878). Mean cumulative milk consumption for the 11 days after disbudding was greater for calves disbudded by veterinary staff than by farm staff (p<0.001), but there was no effect of meloxicam treatment (p=0.618) and no interaction with operator (p=0.86) on cumulative milk consumption.

CONCLUSIONS

Three to 6-week-old dairy calves disbudded by farm staff with no analgesia grew significantly slower over the next 15 days than farmer-disbudded calves given meloxicam, and slower over the next 30 days than veterinarian-disbudded calves given xylazine and lignocaine. However addition of meloxicam to the latter protocol had no effect on growth rate. Milk intake was significantly higher for 11 days for veterinarian- compared with farmer-disbudded calves.

CLINICAL RELEVANCE

This study adds to the evidence that analgesia during disbudding is beneficial for calf productivity as well as calf welfare.

Regional Patterns of Nasal Decongestion

Objective: We present a study investigating the effect of a decongestant on the nasal mucosa, showing results in terms of the change in erectile tissue volume (ETV) in normal subjects using high resolution 3T-MRI scanning.

Method: Seven volunteers with no nasal complaints (SNOT-22) or obvious rhinoscopic abnormalities were studied. Each subject underwent 2 MRI scans producing a series of 120 contiguous 1.2 mm sections pre- and postdecongestion. Patients were decongested with xylometazoline-HCL, remaining immobilized following the first scan. The scans were segmented using ITK-Snap and analyzed using MATLAB.

Results: Subject age ranged from 21-38 years (mean = 28). The SNOT-22 scores ranged from 1-10 (mean = 4.8). Decongestion had the greatest effect in 3 sites: the inferior turbinates, middle turbinates, and septum. The greatest change in ETV was observed in the inferior turbinates ( P <.005), reducing by up to 1/3 at the posterior aspect of the inferior turbinate following decongestion. Changes were also seen in ETV of the middle turbinate and septal mucosa to a lesser extent.

Conclusion: The effect of decongestion on ETV has been investigated here in far greater detail than previously studied, and at higher spatial resolution. 3T-MRI was found to be an excellent modality for mapping changes in nasal mucosa. Our results demonstrate the significant effect of decongestion on ETV of the inferior turbinates.

Water as consumed and its impact on the consumer--do we understand the variables?

Water is the most important natural resource in the world, without it life cannot exist. In 1854 a cholera outbreak in London caused 10, 000 deaths and positively linked enteric disease with bacterial contamination of drinking water by sewage pollution. Since then, adequate water hygiene standards and sewage purification have played the most significant role in disease eradication and public health improvements everywhere. Standards for drinking water have become an extensive range of microbiological and chemical parametric values. Which has not increased consumer, if the media is to be believed. Customers rightly expect that the water they drink is safe and wholesome. Standard setting is perceived as a precise science and meaningful to health. Is this justified and do scientists and regulators who derive and set the standards understand the uncertainties in the system? Water is the universal solvent, therefore it will never be pure; it will contain impurities prior to and after treatment. Knowledge of its potential to become contaminated is necessary to understand the epidemiology associated with waterborne contaminants and their effects. Water use patterns vary considerably and affect assumptions based on toxicology derived from laboratory studies under tightly controlled conditions. Consideration must be given to the model systems used to assess toxicity and translate results from the laboratory to the real world, if sensible scientifically-based water quality standards are to be set and achieved cost effectively.

The Rhnull phenotype in an English individual: haematological, serological and immunological studies

We have characterized the first case of Rhnull phenotype to be identified in England. The red cells were serologically negative for C, c, Cw, D, E, e, f, hr B, Rh17, Lw a, Lw ab and Duclos, while the patient's serum contained anti-Rh29, which was subsequently boosted by transfusion. The Rh phenotype of the patient's son (R1r) confirmed that this was a regulator type of Rhnull in the patient. Follow up studies confirmed the presence of a mild chronic anaemia with stomatocytes and spherocytes; electron microscopy revealed the presence of cells with deep central indentations. Osmotic fragility was increased to a level intermediate between normal and hereditary spherocytic controls. The presence of ongoing haemolysis was indicated by a mild reticulocytosis and splenomegaly. The potent anti-Rh29 has made the provision of compatible blood difficult and autologous units have been frozen. The case illustrates the rare phenomenon of the Rhnull phenotype which not only causes problems for the transfusionist but should also be recognized as a cause of haemolytic anaemia secondary to a membrane defect. Blood film and Rh phenotyping are useful preliminary investigations in suspected cases.

Biologically based water quality management

A method of reporting water quality and assessing compliance with targets, based on the Biological Monitoring Working Party score system, is proposed. The use of the technique enables biologists to present operations managers, and other professionals, with quality data from any freshwater habitat in the form of a simple index. Results obtained can be compared with predefined targets based on river use, National Water Council class, or both. It may also be used to assess the degree of pollution in specific cases. The method is currently being used throughout the Anglian Water Authority region for small stream monitoring and, in some Divisions, for the presentation of all biological results. The technique has the potential to fully integrate biological monitoring into an operational role.