Clinical concerns in the ultrasound exposure of the developing central nervous system.

Neurosonography is used as a primary imaging modality worldwide for visualization of the developing brain and spinal cord in fetuses, infants and children. During the entire process of brain development, there is rapid cell turnover, a condition that is favorable for genetic mutations once external stimuli are applied. No clinical studies in humans have been performed specifically to discuss the long-term impact of postnatal ultrasound exposure of the central nervous system. Currently published studies concerning the prenatal and postnatal use of Doppler or of ultrasound contrast agent use and the developing central nervous system are insufficient to draw meaningful conclusions regarding safety. By instituting a standardized examination and following appropriate patient handling guidelines, the risk of an adverse outcome associated with neurosonography is minimized. This paper recommends adoption of the ALARA principle and offers suggestions as to how to minimize the risk of adverse effects in neurosonography.

Intracatheter nitroglycerin infusion fails to prevent catheter-related venous thrombosis: a randomized, controlled trial.

OBJECTIVE: Catheter-related thrombosis is a common problem in the pediatric intensive care unit. Strategies that reduce the incidence of thrombosis may have significant clinical advantage. Nitroglycerin (NTG) infusions release nitric oxide (NO). NO is responsible for much of the vasodilating and antithrombotic properties of the vasculature. We hypothesized that an intracatheter NTG infusion would reduce the incidence of catheter-related thrombosis. DESIGN: Prospective, randomized, controlled trial. SETTING: Pediatric intensive care unit. PATIENTS AND PARTICIPANTS: Children of 6 years or less with femoral venous catheters who were not on antithrombotic therapy. INTERVENTIONS: Subjects were randomly assigned to NTG or control groups. NTG group patients received NTG at 0.1 mcg x kg x min in 5 % dextrose; control group patients received only 5 % dextrose. Infusions were delivered continuously through the catheter until the catheter was removed. Demographic data, physical and laboratory findings, catheter insertion attempts and infusate composition were recorded. Clinical evidence of vascular thrombosis or catheter malfunction was noted. Ultrasound examinations were performed within 2 days of catheter insertion and within 2 days after removal. MEASUREMENTS AND RESULTS: Forty-four patients (age 12.0 +/- 2.6 months) completed the study, 21 in the NTG group and 23 in the control group. Duration of catheter placement was 7.5 +/- 0.7 days. Twelve of 44 patients (27 %) had thrombi: 7/21 in the NTG group; 5/23 in the control group (p = NS). There were no significant differences between children with and without thrombi in age, gender, number of insertion attempts, duration of catheter placement, clinical signs of thrombosis or infections. CONCLUSIONS: Catheter-related thrombosis is common after placement of femoral venous catheters in children. Low dose intracatheter NTG infusion does not protect against catheter-related venous thrombosis in children.

The initial renal ultrasound examination in children with urinary tract infection: the prevalence of dilated uropathy has decreased.

BACKGROUND: Pelvocalyceal dilatation (PCD) is often detected by sonography during the prenatal period. Prenatal detection of PCD should affect the prevalence of PCD in children with urinary tract infection (UTI). PURPOSE: To determine the prevalence of abnormal sonographic findings in a population of children undergoing first imaging evaluations after UTI and to determine if the prevalence has changed from an earlier study at the same institution. MATERIALS AND METHODS: The findings on consecutive first renal and bladder sonographic examinations in 844 children (745 girls, 99 boys) with UTI were retrospectively reviewed. Cystograms were performed in 743/844 (494 nuclear, 249 fluoroscopic). Only children with known congenital malformations or other significant disease were excluded. RESULTS: Sonography was abnormal in 141/844 (16.7%). PCD was noted in 27/844 (3.2%), with mild PCD in 18/844 (2.1%) and moderate or severe PCD in 9/844 (1.1%). Hydroureter without PCD was noted in 6/844 (0.7%). Parenchymal abnormalities were present in 42/844 (5.0%) and bladder wall thickening in 43/844 (5.1%). Vesicoureteral reflux was present in 186/743 (25.0%). When compared to historical controls, PCD and hydroureter were significantly less prevalent than 1 decade earlier (P < 0.0001). CONCLUSION: The prevalence of PCD in children under first imaging evaluation for UTI declined significantly during the last decade. These data may be useful in the design of imaging strategies for children with UTI.

Neonatal cranial ultrasound.

Neonatal cranial ultrasound continues to be a popular initial imaging modality because of the safety, low-cost, and portability of the examination. The higher frequency transducers and enhanced ability for signal processing that is possible with current ultrasound machines improves visualization of complex congenital anomalies, complications of pregnancy, and birth and neoplastic processes. This article reviews these conditions so that the reader will have a baseline knowledge of the ultrasound findings. With the use of neonatal cranial ultrasound, recognition of the maximum diagnostic information available on the sonogram and appropriate use of other cross-sectional imaging modalities are improved.

Purulent pericarditis presenting as acute abdomen in children: abdominal imaging findings.

Purulent pericarditis is rapidly fatal if untreated [1,2]. With increased development of bacterial resistance to antibiotics, severe bacterial infections in children are becoming more frequent [3,4]. We report two children with purulent pericarditis who presented in a 1-month period for evaluation of acute abdominal distention and signs of sepsis. In both, one evaluated with computed tomography (CT) and one with ultrasound, abdominal findings included periportal edema, gallbladder wall thickening, and ascites secondary to right heart failure from cardiac tamponade. Radiologists should be aware that children with purulent pericarditis may have a normal heart size on radiographs, present with acute abdominal symptoms, and demonstrate findings of right sided heart failure on abdominal imaging.

Proposed criteria for preoperative endoscopic retrograde cholangiography in candidates for laparoscopic cholecystectomy.

BACKGROUND: There has been a dramatic increase in the number of endoscopic retrograde cholangiograms (ERC) performed on patients who are candidates for laparoscopic cholecystectomy (LC). The majority of these procedures result in normal findings. This study is an attempt to determine useful clinical criteria and strategy for predicting the presence or absence of common bile duct stones (CBDS) and the need for ERC in patients who are candidates for LC. METHODS: The observational portion of this study explored laboratory and ultrasound data from 134 consecutive patients who had undergone preoperative ERC, followed by LC, over a 4-year period. The data were then analyzed by multivariate logistic regression to determine the best models for predicting the presence or absence of stones in the common bile duct. Models using gamma glutamyl transpeptidase (GGT), alkaline phophatase (AP), common bile duct diameter (CBDIA), and amylase (AMY) were then evaluated retrospectively in 36 additional patients (validation group). RESULTS: A model based on GGT and common bile duct diameter as positive predictors and amylase as a negative predictor correctly classified 78% of the patients in the validation group. This model resulted in a negative predictive value (NPV), positive predictive value (PPV), sensitivity, and specificity of 0.88, 0.68, 0.87, and 0.71, respectively. The model utilizing AP was almost as effective. This model resulted in a NPV, PPV, sensitivity, and specificity of 0.83, 0.67, 0.80, and 0.71, respectively. CONCLUSIONS: Although a number of laboratory values and imaging techniques correlate with the presence or absence of CBDS, our study confirms that individually they have poor predictive value. Our data and models suggest that elevated serum amylase is a negative predictor for CBDS. Elevated GGT and/or AP with widened CBDIA and normal AMY strongly suggest the presence of CBDS and the need for preoperative ERC. Elevated GGT, AP, or widened CBDIA with elevated amylase, in the absence of clinical pancreatitis, may suggest that small stones have passed through the ampulla of Vater and that the CBD is generally cleared of stones.

Laparoscopic hiatal herniorrhaphy with posterior fundoplication for gastroesophageal reflux.

Complications and side effects following laparoscopic antireflux procedures are common. This article describes an alternative laparoscopic technique to prevent gastroesophageal reflux. This method consists of posterior approximation of the diaphragmatic crura followed by a posterior fundoplication of approximately 270 degrees wrap. In avoiding the 360 degree wrap and obtaining length from the longitudinal axis of the stomach, it is not necessary to take down the gastrosplenic vessels. The principle of the procedure is to accentuate the cardioesophageal angle of His. No sutures are placed in the esophagus. While this article primarily concerns technique, it also constitutes a brief report on the first 50 patients who have been followed up for 1 year or more. All patients but one are free of reflux symptoms and have discontinued taking all medication. There has been no dysphagia to liquids, and solid food dysphagia has not lasted >1 month. Bloating from gas is minimal, as most patients are able to burp early in their recovery. An outcome paper describing preoperative and postoperative objective testing and evaluation is in process.

Effects of various laser wavelengths and energy levels on pig rectal submucosal tissue.

This phase I animal study attempts to develop a nonexcisional method of treating hemorrhoidal varicosities submucosally using interstitial laser beam. Three laser wavelengths at four energy levels were applied interstitially to pig rectal submucosa to evaluate the effects on the vasculature, mucosa, and the muscle. As expected YAG laser caused a "cooking" of the tissue with necrosis and abscess formation. KTP laser was intermediate in its effect, causing less mucosal injury and muscle necrosis. Pulse dye laser had more specific effects on the vessels with little damage to the mucosa or muscle layers. Further studies using pulse laser are warranted as a possible nonexcisional interstitial treatment for hemorrhoids.

Minimally invasive tube gastrostomy.

With the increasing use of surgically placed enteral feeding tubes, we have seen a marked increase in the number of complications related to the tubes and their management. This has resulted in an increase in returns to emergency departments, readmissions to hospitals, and returns to the operating room. This, in turn, has led to a dramatic increase in the cost to society for the aftercare of the feeding tubes. This article describes a technique designed to reduce complications and revisits to hospitals, while at the same time allowing greater flexibility and ease of management in patients who require long-term enteral feeding.

Quantitative sonographic feature analysis of clinical infant hypoxia: a pilot study.

PURPOSE: To determine whether textural features derived from sonographic pixel intensities differ significantly between healthy infants and infants who have had acute clinical hypoxic episodes. METHODS: Neurosonographic and calibration phantom-processed image data were evaluated prospectively from 9 infants (age range, 1 to 163 days) with at least 1 episode of hypoxia and compared with image data from a control population of 16 healthy infants (age range, 1 to 191 days). Custom software was used to make 45 textural feature measurements on 40 x 40-pixel regions of interest within brain parenchyma in the distribution of each major cerebral artery, the thalami, and the cerebellum and in a tissue-mimicking calibration phantom. Means comparison testing was followed by logistic regression to assess statistical variation between the patients and the control group. RESULTS: Nine of 45 textural features showed statistically significant differences between mean values comparing the two groups. Mean gray level was the most sensitive predictor of differences between the two populations (mean gray level for healthy subjects was 46.8; mean gray level for patients was 56.3). An average of mean gray values in areas supplied by the posterior cerebral arteries and the cerebellum was even more sensitive for differentiating healthy subjects from patients. CONCLUSIONS: Quantitative sonographic textural feature analysis showed differences between the brains of healthy infants and those of infants with clinical hypoxia.

Doppler contrast sonography for detecting reduced perfusion in experimental ischemia of prepubertal rabbit testes.

RATIONALE AND OBJECTIVES: We examined whether the intravenous (IV) Doppler ultrasound contrast agent SHU 508 would improve the detection of reduced perfusion of rabbit testes when normal flow was otherwise difficult to detect. METHODS: Seventeen anesthetized prepubertal rabbits underwent random unilateral spermatic cord ligation and a contralateral sham operation. Immediate, blinded, and systematic color Doppler examination of each pair of testes was recorded before and after IV administration of 1 ml (300 mg) SHU 508, a gas-containing microparticle. Recorded examinations were reviewed by two pediatric radiologists who were unaware of experimental conditions and who graded intratesticular flow. RESULTS: For 34 pairs of observations (17 animals x 2 observers), intratesticular flow was absent in the sham-operated testes in 18 precontrast and two postcontrast images. The false-positive rate in this group decreased from 53% to 6%. This improvement in the detection of normal blood flow was statistically significant. The absence of flow in the ischemic testis was not significantly different before or after contrast agent administration. CONCLUSION: IV SHU 508 enhances color Doppler ultrasound detection of flow not otherwise evident in prepubertal rabbit testes. Doppler ultrasound contrast agents may be used in a setting of suspected torsion when routine Doppler sonography is indeterminate.

Gastroesophageal reflux: recognizing atypical presentations.

The role of reflux in the development of esophagitis, stricture, and Barrett's esophagus is well recognized. However, reflux is not an infrequent cause of atypical chest pain, chronic pulmonary disorders, and pharyngeal and laryngeal changes. Increased insight into the pathogenesis of reflux and the relationship between the gastroesophageal junction and the diaphragmatic crura has led to more effective treatment approaches. Medical therapy, including lifestyle changes, antacids, and systemic agents, is effective in most patients. However, surgery may be necessary in patients with anatomic abnormalities or mechanical dysfunction.

Quantification of intravenous contrast-enhanced Doppler power spectrum in the rabbit carotid artery.

In vivo evaluation of Doppler contrast agent (DCA) enhancement has been principally qualitative. To quantitate the enhancement of the Doppler signal by perflubron emulsion, an investigational DCA, the audio-Doppler signal from the rabbit carotid artery was recorded during 0.5-ml/kg incremental doses to a total dose of 2.5 ml/kg. A representation of the recorded signal intensity, the Doppler power spectrum (DPS), was determined using a personal computer and commercially available software package. The dose related enhancement from perflubron emulsion was linear (r = 0.986, p = 0.0124) with a 710% (8.5 dB) overall enhancement at 2.5 ml/kg (p = 0.0001). Significant differences in enhancement could be detected with doses as low as 1.0 ml/kg and compared favorably with observer assessment of dose-related enhancement. This relatively simple method of computer analysis can quantify in vivo Doppler signal intensity and enhancement by perflubron emulsion and may enable quantitative comparisons between different DCAs.

Induction of gastroduodenal prolapse by antral heterotopic pancreas.

Ectopic pancreas is the most common congenital anomaly in the gastric antrum. In some patients, there is a distinct tendency for this lesion to produce intermittent crampy abdominal pain by provoking gastroduodenal prolapse. This condition should be considered after a more distal prolapse from intussusception is excluded. An upper gastrointestinal series performed during an episode of symptoms may be diagnostic of this entity.

Understanding the process of quantitative ultrasonic tissue characterization.

Because the human vision system cannot distinguish the broad range of gray values that a computer visual system can, computerized image analysis may be used to obtain quantitative information from ultrasonographic (US) real-time B-mode scans. Most quantitative US involves programming an off-line computer to accept, analyze, and display US image data in a way that enhances the detection of changes in small-scale structures and blood flow that occur with disease. Common image textural features used in quantitative US tissue characterization consist of first-order gray-level statistics (eg, occurrence frequency of gray levels independent of location or spatial relationship) and second-order gray-level statistics dependent on location and spatial relationship, including statistical analysis of gradient distribution, co-occurrence matrix, covariance matrix, run-length histogram, and fractal features. A customized tissue signature software has been developed to analyze image data obtained from clinical US scanners. Means comparison testing and multivariate analysis techniques are used to compare the numbers generated for a particular region of interest. By integrating these techniques into the radiologist's interpretation of the sonogram, the quantitative information gained may lead to earlier detection of lesions difficult to see with the human eye.

Sonography in the infant with acute abdominal symptoms.

The sonogram is a reliable diagnostic tool in the evaluation of acute abdominal disorders in infants and children. Portability, noninvasiveness, and ease of examination make sonography an invaluable diagnostic method. This article considers the principle acute disorders of infancy and childhood that are minimal to sonographic diagnosis. Included are pyloric stenosis, appendicitis, necrotizing enterocolitis, intussusception, as well as unexplained abdominal distention and acutely presenting masses. Although some of these entities have nonspecific sonographic appearances, consideration of age, symptoms, and laboratory results usually permits a specific diagnosis.

Age-related variability in elbow joint capsule thickness in asymptomatic children and adults.

The purpose of this study was to establish normal ultrasonographic measurements for elbow joint capsule thickness in children. Transverse posterior ultrasonographic images of 53 elbow joints in asymptomatic patients were digitized, and off-line measurements were performed and compared to the corresponding scale present on each image to yield a reliable measurement in millimeters. Joint capsule thickness measurements regressed with age. Significant differences existed between three age groups. Joint capsule thickness is under 1 mm in children 1 month to 2 years of age, increased significantly to just over 1 mm from 2 to 15 years of age, and approached 2 mm in thickness at and after 15 years of age.