Spatiotemporal Image Correlation and Volumetric Impedance Indices in the Neonatal Brain: Proof of Concept and Preliminary Reproducibility

Objectives—

Changes in tissue perfusion can be critically important in the vulnerable neonate, but they are very difficult to assess at the bedside. Spatiotemporal image correlation (STIC) sonography is an exciting concept that allows assessment of blood flow by rearranging and merging multiple 2-dimensional color images to create serial 3-dimensional images showing regional blood flow throughout the cardiac cycle. Variations in tissue blood flow may reflect tissue impedance and perfusion. The aim of this study was to demonstrate that it is possible to use STIC images to evaluate tissue impedance in the neonatal brain.

Methods—

Spatiotemporal image correlation data sets were acquired by cranial sonography in 19 neonates. Offline data analysis was performed by using virtual organ computer-aided analysis. With the use of STIC images from different phases of the cardiac cycle, impedance indices were calculated, based on maximum (systolic), minimum (diastolic), and mean virtual organ computer-aided analysis values, in the same way that resistive indices are calculated in 2-dimensional sonography.

Results—

Volumetric indices for tissue impedance were obtained for all neonates. Intraclass correlation coefficients (95% confidence intervals) for volumetric impedance indices were as follows: systolic/diastolic ratio, 0.793 (0.615–0.906); pulsatility index, 0.790 (0.609–0.905); and resistive index, 0.783 (0.598–0.901). Interclass correlation coefficients for image processing and analysis were as follows: systolic/diastolic ratio, 0.868 (0.692–0.947); pulsatility index, 0.904 (0.772–0.962); and resistive index, 0.914 (0.794–0.966).

Conclusions—

This study shows that STIC data sets can be used to calculate volumetric impedance indices in the neonatal brain. Preliminary assessment shows that this technique appears reliable and allows evaluation of regional tissue impedance in the neonate.

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Evanescent Hyperechoic Changes After Fine-Needle Aspiration Biopsy of the Thyroid in a Series With a Low Overall Prevalence of Complications

Objectives—

The purpose of this study was to assess the frequency of and risk factors for fine-needle aspiration biopsy (FNAB)-related complications in Japanese patients with thyroid nodules evaluated by standard FNAB techniques.

Methods—

Six hundred fifty-three consecutive Japanese patients with 742 nodules who had undergone FNAB were enrolled. Nodule characteristics were evaluated, and thyroid volumes were measured. Fine-needle aspiration biopsy–related complications were identified on the basis of sonographic findings and patients' conditions after undergoing FNAB. Comparisons of patients' backgrounds and nodule characteristics were made between those with and without complications.

Results—

The prevalence rates for FNAB-related complications, including acute transient thyroid swelling after FNAB and appearance of anechoic lesions, were 0.13% and 0.94%. In this study, we could not identify risk factors for FNAB-related complications. The sudden appearance of bright hyperechoic foci within the thyroid immediately after biopsy was reported as an FNAB-related unfamiliar appearance in 5 cases. Experimental FNA using resected porcine thyroid tissue suggested that the etiology of the hyperechoic appearance may be artificial air bubbles or reversed flow of aspirated fluid.

Conclusions—

Fine-needle aspiration biopsy–related complications are rare if preventive measures are performed and are not specific to Japanese patients with thyroid nodules. The sudden appearance of bright hyperechoic foci may be cause by contamination from air or fluid.

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Prognostic Value of Fetal Thymus Size in Intrauterine Growth Restriction

Objectives—

Our aim was to evaluate the size of the fetal thymus by sonography in pregnancies with intrauterine growth restriction (IUGR) and to search for a possible relationship between a small fetal thymus and adverse perinatal outcomes.

Methods—

The transverse diameter of the fetal thymus was prospectively measured in 150 healthy and 143 IUGR fetuses between 24 and 40 weeks' gestation. The fetuses with IUGR were further divided according to normal or abnormal Doppler assessment of the umbilical and middle cerebral arteries and ductus venosus. Measurements were compared with reference ranges from controls. To determine which perinatal outcomes were independently associated with a small fetal thymus, a multivariate logistic regression analysis was performed.

Results—

Thymus size was significantly lower in IUGR fetuses compared to controls (P < .05). Among IUGR fetuses, thymus size was significantly smaller in IUGR fetuses with abnormal Doppler flow compared to normal flow (P < .05). A small thymus in IUGR fetuses was independently associated with early delivery (odds ratio [OR], 1.24; 95% confidence interval [CI], 1.05–1.49; P= .023), respiratory distress syndrome (OR, 1.36; 95% CI, 1.09–1.78; P= .005), early neonatal sepsis (OR, 1.65; 95% CI, 1.11–2.42; P= .001), and a longer stay in the neonatal intensive care unit (OR, 1.33; 95% CI, 1.08–1.71; P = .017).

Conclusions—

Intrauterine growth restriction is associated with fetal thymic involution, and a small fetal thymus is an early indicator of adverse perinatal outcomes in pregnancies complicated by IUGR.

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Sonography of Abdominal Pain in Children: Appendicitis and Its Common Mimics

Abdominal pain is very common in the pediatric population (<18 years of age). Sonography is a safe modality that can often differentiate the frequently encountered causes of abdominal pain in children. This pictorial essay will discuss the sonographic findings of acute appendicitis, including the imaging appearance of a perforated appendicitis. It will also present the sonographic features of the relatively common mimics of appendicitis, such as mesenteric adenitis/gastroenteritis, intussusception, Meckel diverticulum, and ovarian torsion.

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Evaluation of Underlying Lymphocytic Thyroiditis With Histogram Analysis Using Grayscale Ultrasound Images

Objectives—

The purpose of this study was to evaluate diagnostic performance of histogram analysis using grayscale ultrasound (US) images in the diagnosis of lymphocytic thyroiditis.

Methods—

Three radiologists reviewed a total of 505 US images and classified the images according to the presence/existence of lymphocytic thyroiditis. After 2 months, each reviewer repeated the process with the same 505 images in a randomly mixed order. The intraobserver and interobserver variability was analyzed with a generalized value. Four histogram parameters (mean value, standard deviation, skewness, and kurtosis) were obtained, and an index was calculated from principal component analysis. Diagnostic performances were compared.

Results—

Of 505 patients, 125 (24.8%) had lymphocytic thyroiditis, and 380 (75.2%) had normal thyroid parenchyma on pathologic analysis. The value for intraobserver variance ranged from –0.002 to 0.781, and the overall values for interobserver variance were 0.570 and 0.214 in the first and second tests, respectively. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for the 3 reviewers versus the principal component analysis index were 28.0% to 83.2%, 43.7% to 82.6%, 53.5% to 79.0%, 24.6% to 56.2%, and 75.2% to 88.9% versus 58.4%, 72.4%, 68.9%, 41.0%, and 84.1%.

Conclusions—

Histogram analysis of grayscale US images provided confirmable and quantitative information about lymphocytic thyroiditis and was comparable with performers' assessments in diagnostic performance.

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A Novel Method for Sensitive Determination of Subclinical Left-Ventricular Systolic Dysfunction in Subjects With Obstructive Sleep Apnea

BACKGROUND:This study was to evaluate the subclinical left-ventricular (LV) systolic dysfunction with 2-dimensional speckle-tracking echocardiography in subjects with obstructive sleep apnea (OSA) with normal left ventricular ejection fraction and without any confounding disease that can cause myocardial dysfunction.METHODS:Nineteen healthy individuals and 60 subjects with OSA were included in this study. According to the severity of disease, OSA subjects were examined in 3 groups: mild, moderate, and severe OSA. LV apical views (for longitudinal strain) and short-axis views (for circumferential strain) were acquired for evaluation. Three-layer longitudinal strain values and circumferential strain values were determined for each view, and averages of these were used in comparison with other groups.RESULTS:Three-layer longitudinal strain values of the subjects with OSA were lower than those of the healthy individuals, and these values were decreased along with the OSA severity. The difference was significant between severe OSA and all other groups. Three-layer circumferential strain values of the OSA subjects were lower than those of the healthy individuals, and the difference was significant between the control group and all other groups. The apnea hypopnea index was found to be correlated with the 3-layer longitudinal strain (r = −0.74, P < .001; r = −0.72, P < .001; r = −0.69, P = <.001).CONCLUSIONS:Three-layer longitudinal and circumferential LV systolic functions in OSA subjects with normal left ventricular ejection fraction are deteriorated in the subclinical stage. Two-dimensional speckle-tracking echocardiography can be used as an effective method in the determination of subclinical myocardial dysfunction in subjects with OSA.

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Effects of Nebulizer Position, Gas Flow, and CPAP on Aerosol Bronchodilator Delivery: An In Vitro Study

BACKGROUND:The aim of this study was to investigate the effects of different delivery circuit configurations, nebulizer positions, CPAP levels, and gas flow on the amount of aerosol bronchodilator delivered during simulated spontaneous breathing in an in vitro model.METHODS:A pneumatic lung simulator was connected to 5 different circuits for aerosol delivery, 2 delivering CPAP through a high-flow generator tested at 30, 60, and 90 L/min supplementary flow and 5, 10, and 15 cm H2O CPAP and 3 with no CPAP: a T-piece configuration with one extremity closed with a cap, a T-piece configuration without cap and nebulizer positioned proximally, and a T-piece configuration without cap and nebulizer positioned distally. Albuterol was collected with a filter, and the percentage amount delivered was measured by infrared spectrophotometry.RESULTS:Configurations with continuous high-flow CPAP delivered higher percentage amounts of albuterol compared with the configurations without CPAP (9.1 ± 6.0% vs 6.2 ± 2.8%, P = .03). Among configurations without CPAP, the best performance was obtained with a T-piece with one extremity closed with a cap. In CPAP configurations, the highest delivery (13.8 ± 4.4%) was obtained with the nebulizer placed proximal to the lung simulator, independent of flow. CPAP at 15 cm H2O resulted in the highest albuterol delivery (P = .02).CONCLUSIONS:Based on our in vitro study, without CPAP, a T-piece with a cap at one extremity maximizes albuterol delivery. During high-flow CPAP, the nebulizer should always be placed proximal to the patient, after the T-piece, using the highest CPAP clinically indicated.

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