Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies.

BACKGROUND: Tension in the spinal cord is a trademark of tethered cord syndrome. Unfortunately, existing tests cannot quantify tension across the bulk of the cord, making the diagnostic evaluation of stretch ambiguous. A potential non-destructive metric for spinal cord tension is ultrasound-derived shear wave velocity (SWV). The velocity is sensitive to tissue elasticity and boundary conditions including strain. We use the term Ultrasound Tensography to describe the acoustic evaluation of tension with SWV. METHODS: Our solution Tethered cord Assessment with Ultrasound Tensography (TAUT) was utilized in three sub-studies: finite element simulations, a cadaveric benchtop validation, and a neurosurgical case series. The simulation computed SWV for given tensile forces. The cadaveric model with induced tension validated the SWV-tension relationship. Lastly, SWV was measured intraoperatively in patients diagnosed with tethered cords who underwent treatment (spinal column shortening). The surgery alleviates tension by decreasing the vertebral column length. RESULTS: Here we observe a strong linear relationship between tension and squared SWV across the preclinical sub-studies. Higher tension induces faster shear waves in the simulation (R2 = 0.984) and cadaveric (R2 = 0.951) models. The SWV decreases in all neurosurgical procedures (p < 0.001). Moreover, TAUT has a c-statistic of 0.962 (0.92-1.00), detecting all tethered cords. CONCLUSIONS: This study presents a physical, clinical metric of spinal cord tension. Strong agreement among computational, cadaveric, and clinical studies demonstrates the utility of ultrasound-induced SWV for quantitative intraoperative feedback. This technology is positioned to enhance tethered cord diagnosis, treatment, and postoperative monitoring as it differentiates stretched from healthy cords.

Tethered spinal cord syndrome occurs when surrounding tissue attaches to and causes stretching across the spinal cord. People with a tethered cord can experience weakness, pain, and loss of bladder control. Although increased tension in the spinal cord is known to cause these symptoms, evaluating the amount of stretching remains challenging. We investigated the ability of an ultrasound imaging approach to measure spinal cord tension. We studied our method in a computer simulation, a benchtop validation model, and in six people with tethered cords during surgery that they were undergoing to reduce tension. In each phase, the approach could detect differences between stretched spinal cords and spinal cords in a healthy state. Our method could potentially be used in the future to improve the care of people with a tethered cord.

Ultrasound monitoring of microcirculation: An original study from the laboratory bench to the clinic.

OBJECTIVE: Monitoring microcirculation and visualizing microvasculature are critical for providing diagnosis to medical professionals and guiding clinical interventions. Ultrasound provides a medium for monitoring and visualization; however, there are challenges due to the complex microscale geometry of the vasculature and difficulties associated with quantifying perfusion. Here, we studied established and state-of-the-art ultrasonic modalities (using six probes) to compare their detection of slow flow in small microvasculature. METHODS: Five ultrasonic modalities were studied: grayscale, color Doppler, power Doppler, superb microvascular imaging (SMI), and microflow imaging (MFI), using six linear probes across two ultrasound scanners. Image readability was blindly scored by radiologists and quantified for evaluation. Vasculature visualization was investigated both in vitro (resolution and flow characterization) and in vivo (fingertip microvasculature detection). RESULTS: Superb Microvascular Imaging (SMI) and Micro Flow Imaging (MFI) modalities provided superior images when compared with conventional ultrasound imaging modalities both in vitro and in vivo. The choice of probe played a significant difference in detectability. The slowest flow detected (in the lab) was 0.1885 ml/s and small microvasculature of the fingertip were visualized. CONCLUSIONS: Our data demonstrated that SMI and MFI used with vascular probes operating at higher frequencies provided resolutions acceptable for microvasculature visualization, paving the path for future development of ultrasound devices for microcirculation monitoring.

Automatic detection of cotton balls during brain surgery: Where deep learning meets ultrasound imaging to tackle foreign objects.

Cotton balls are a versatile and efficient tool commonly used in neurosurgical procedures to absorb fluids and manipulate delicate tissues. However, the use of cotton balls is accompanied by the risk of accidental retention in the brain after surgery. Retained cotton balls can lead to dangerous immune responses and potential complications, such as adhesions and textilomas. In a previous study, we showed that ultrasound can be safely used to detect cotton balls in the operating area due to the distinct acoustic properties of cotton compared with the acoustic properties of surrounding tissue. In this study, we enhance the experimental setup using a 3D-printed custom depth box and a Butterfly IQ handheld ultrasound probe. Cotton balls were placed in variety of positions to evaluate size and depth detectability limits. Recorded images were then analyzed using a novel algorithm that implements recently released YOLOv4, a state-of-the-art, real-time object recognition system. As per the radiologists' opinion, the algorithm was able to detect the cotton ball correctly 61% of the time, at approximately 32 FPS. The algorithm could accurately detect cotton balls up to 5mm in diameter, which corresponds to the size of surgical balls used by neurosurgeons, making the algorithm a promising candidate for regular intraoperative use.

Pediatric emergency gastrointestinal ultrasonography: pearls & pitfalls.

Ultrasonography is an essential tool in pediatric imaging, particularly in the emergency setting. Although ultrasound is often the favored initial modality for abdominal imaging in children, it is highly operator-dependent and therefore prone to misinterpretation which can lead to false positive or negative exams, or even incorrect diagnoses. Conditions discussed in this series include ileocolic intussusception, hypertrophic pyloric stenosis, appendicitis, and ingested foreign bodies. We will review diagnostic criteria, highlight crucial findings, and illustrate commonly-encountered difficulties and mimics.

Effect of radiologist pregnancy on the performance of pediatric fluoroscopic studies: a survey of Society for Pediatric Radiology members.

BACKGROUND: To our knowledge, the fluoroscopic practice patterns of pregnant diagnostic radiologists have not been documented. OBJECTIVE: To describe the fluoroscopic practice patterns during pregnancy among members of the Society for Pediatric Radiology (SPR) and potential impact on career and professional relationships. MATERIALS AND METHODS: After approval from the SPR, we sent all 1,847 SPR members an email link to an anonymous online survey that queried how pregnancy affects a practicing radiologist who performs fluoroscopy. RESULTS: Of the 398 responses (65% female, 35% male), most female respondents (78%) reported having been pregnant while practicing radiology and the majority (85%) performed fluoroscopy during pregnancy. Most performed fluoroscopy during all three trimesters (first 78%, second 90%, third 87%) and the majority (81%) used double-lead. Forty-six percent indicated that their fluoroscopic responsibilities during pregnancy were stressful. Of those who opted to perform fewer fluoroscopy studies, 20% indicated that it impacted negatively on their career or professional relationships. After witnessing a pregnant co-worker perform fewer fluoroscopic studies, 11% (4% male; 16% female; P<0.05) of respondents observed a subsequent negative impact on the co-worker's career or professional relationships. CONCLUSION: The majority of responding female SPR members had performed fluoroscopy during pregnancy and most performed fluoroscopy during their entire pregnancy with double-lead. Differences between self-reported adversity and observed adversity of performing less fluoroscopy during pregnancy speak to the lack of awareness of the issues, particularly among male colleagues. A clear policy with regard to performing fluoroscopy during pregnancy for all radiologists in every department is necessary.

MR Imaging Evaluation of Pediatric Genital Disorders:: MR Technologic Overview and Interpretation.

MR imaging is frequently used to assess pediatric genital disorders. The ability to obtain 3-dimensional sequences allowing for multiplanar reformations and sequences designed to minimize motion artifact have aided in the imaging evaluation in the pediatric population. For certain genital disorders, such as Müllerian duct anomalies, MR imaging has become the standard imaging technique. This article discusses up-to-date MR imaging techniques and the interpretation of findings including normal anatomy, as well as congenital and acquired genital disorders seen in the pediatric population.

Identification of clinical parameters to increase the diagnostic yield of the non-emergent upper gastrointestinal series in pediatric outpatients.

BACKGROUND: Outpatient, non-emergent upper gastrointestinal (GI) series are frequently requested in children with no surgical history who have nonspecific symptoms such as abdominal pain, failure to thrive and vomiting. The positive yield of an upper GI series in these patients, and, thus, its utility, has not been studied. OBJECTIVES: We evaluated the incidence of positive upper GI findings in children without a history of GI pathology or abdominal surgery in order to identify clinical indications associated with a greater diagnostic yield. MATERIALS AND METHODS: Findings of upper GI series performed between October 2015 and October 2017 in three institutions in children younger than 18 years of age were retrospectively reviewed. The upper GI series protocol for each institution was also reviewed. Children with a medical or surgical GI history, children with insufficient history in the chart and those with an incomplete upper GI series were excluded from the study. Exam indications, patient demographics and clinical history were obtained from the electronic medical records. RESULTS: Of 1,267 children who underwent outpatient upper GI series, 720 (median age: 2 years) had no GI history and were included in the study. The most common indications were non-bilious vomiting (62%), reflux symptoms (28%) and abdominal pain (20%). Upper GI series were normal in 605/720 cases (84%), including 25/26 children with reported bilious emesis. Of the 115 positive studies, 78 (68%) showed only gastroesophageal reflux (GER) (median age: 11 months). Of the remaining 37 studies, 19 demonstrated esophageal findings. One case of malrotation without midgut volvulus was identified in a patient who presented with dysphagia and reflux symptoms. Using a multinomial logistic regression model and adjusting for other variables, reflux symptoms and younger patient age were independent predictors of GER on upper GI series (relative risk ratios of 2.2 and 0.9, respectively). Dysphagia and/or foreign body sensation and older patient age were independent predictors of the presence of esophageal findings (relative risk ratios of 3.3 and 1.1, respectively). CONCLUSION: The yield of routine upper GI series in children with nonspecific symptoms, such as abdominal pain and vomiting, and no surgical history is low. Diagnostic yield was improved in older children and in those complaining of dysphagia and/or foreign body sensation. Routine upper GI series should be avoided in clinically well children with symptoms only of uncomplicated GER and no significant GI history. In children with a history of dysphagia and/or foreign body sensation, an esophagram/barium swallow can suffice.

Transperineal ultrasonography.

Transperineal US has increased in use in the last decade. It is helpful in the evaluation of distal genitourinary structures, the rectum and overlying soft tissues. When used in conjunction with transabdominal US, transperineal US can further delineate anatomy and assess abnormalities that affect the lower pelvis. This paper describes optimal technique and common indications for transperineal US in children with examples of congenital and acquired lesions in pediatric patients.

A risk adjustment method for newborns undergoing noncardiac surgery.

OBJECTIVE: To develop a risk adjustment method for in-hospital mortality in newborns undergoing noncardiac surgery. SUMMARY OF BACKGROUND DATA: Understanding variation in outcomes is critical to guide quality improvement. Reliable outcome assessments need risk adjustment to allow comparisons. METHODS: Infants or=20 cases in the data set were placed into 4 risk categories by in-hospital mortality rates. Clinical variables were added to the model to better predict mortality; areas under the receiver-operator characteristic (ROC) curves were compared. The final model was validated in the KID 2003 database. RESULTS: Among 6103 eligible cases in the KID 2000, 5117 (83.8%) could be assigned to a risk category. Mortality rates were 0.2% in risk category 1, 2.5% in category 2, 6.4% in 3, and 18.4% in 4. The odds of mortality increased in each risk category relative to category 1 (P < 0.001 for each). In multivariable models adjusting for risk category, the clinical variables most predictive of in-hospital death were serious respiratory conditions and necrotizing enterocolitis. The area under the ROC curve for the full model including clinical risk factors was 0.92 in the KID 2000. The model was validated using data for KID 2003 and showed excellent discrimination (ROC = 0.90). CONCLUSION: This validated method provides a means of risk adjustment in groups of newborns undergoing noncardiac surgery, and should allow for comparative analyses of in-hospital mortality.

Gata4 is required for maintenance of postnatal cardiac function and protection from pressure overload-induced heart failure.

An important event in the pathogenesis of heart failure is the development of pathological cardiac hypertrophy. In cultured cardiomyocytes, the transcription factor Gata4 is required for agonist-induced hypertrophy. We hypothesized that, in the intact organism, Gata4 is an important regulator of postnatal heart function and of the hypertrophic response of the heart to pathological stress. To test this hypothesis, we studied mice heterozygous for deletion of the second exon of Gata4 (G4D). At baseline, G4D mice had mild systolic and diastolic dysfunction associated with reduced heart weight and decreased cardiomyocyte number. After transverse aortic constriction (TAC), G4D mice developed overt heart failure and eccentric cardiac hypertrophy, associated with significantly increased fibrosis and cardiomyocyte apoptosis. Inhibition of apoptosis by overexpression of the insulin-like growth factor 1 receptor prevented TAC-induced heart failure in G4D mice. Unlike WT-TAC controls, G4D-TAC cardiomyocytes hypertrophied by increasing in length more than width. Gene expression profiling revealed up-regulation of genes associated with apoptosis and fibrosis, including members of the TGF-beta pathway. Our data demonstrate that Gata4 is essential for cardiac function in the postnatal heart. After pressure overload, Gata4 regulates the pattern of cardiomyocyte hypertrophy and protects the heart from load-induced failure.