Characterization of gold electrodes in phosphate buffered saline solution by impedance and noise measurements for biological applications.

Impedance spectroscopy and noise measurements have been used to study gold electrodes of three different surface areas in phosphate buffered saline (PBS) solution. The gold-PBS solution interface can be modeled by a charge transfer resistance in parallel with an interfacial constant phase element (CPE) which are in series with the solution resistance. The voltage noise fluctuations were analyzed using the fast Fourier transform (FFT) method. It is found that the voltage noise power is characterized by a 1/f(alpha) spectrum in the low frequency range. The value of alpha is observed to be double that of the CPE coefficient beta. The authors suggest a link between the interface impedance and the measured noise.

Urinary basic fibroblast growth factor: a noninvasive marker of progressive cystic renal disease in a child.

Autosomal recessive polycystic kidney disease (ARPKD) is a hereditary condition with an estimated incidence of 1 in 20,000 live births. Various growth factors have been implicated in the causation of this disease. We describe a child with ARPKD whose levels of urinary basic fibroblast growth factor (bFGF) were markedly elevated. The concentrations of bFGF increased further following right nephrectomy, in response to the compensatory growth of the remaining kidney. We hypothesize that measurement of urinary bFGF may be useful as a noninvasive marker to assess progression of cystic renal development.

The development of hypertrophic pyloric stenosis in a patient with prostaglandin-induced foveolar hyperplasia.

BACKGROUND: Hypertrophic pyloric stenosis (HPS) has been described in association with several obstructive antropyloric lesions including idiopathic foveolar hyperplasia (gastric mucosal hypertrophy), feeding tubes, eosinophilic gastroenteritis, and hypertrophic antral polyps. Non obstructive antral webs have also been described with HPS. PATIENT AND METHODS: We present a case of gastric-outlet obstruction in association with HPS, namely, prostaglandin-induced foveolar hyperplasia. This entity has been previously described, but rarely in association with HPS. We report a female infant requiring prostaglandin therapy for pulmonary atresia who developed dose-related prostaglandin-induced foveolar hyperplasia and symptoms of progressive non-bilious vomiting. RESULTS: Initially, ultrasonography demonstrated evidence of antral mucosal hypertrophy as the cause for gastric-outlet obstruction. The patient subsequently developed progressive thickening of the antropyloric muscle, resulting in sonographic appearances of hypertrophic pyloric stenosis. Pyloromyotomy was eventually required for treatment of HPS. CONCLUSION: A common denominator of most of the above-described entities is thickening and/or hypertrophy of the antral mucosa. We suggest that the antropyloric musculature may hypertrophy in an effort to overcome the gastric-outlet obstruction caused by the adjacent thickened antral mucosa. In other words, these entities may represent examples of "secondary" hypertrophic pyloric stenosis.

Hypertrophic bursopathy of the subacromial-subdeltoid bursa in juvenile rheumatoid arthritis: sonographic appearance.

Hypertrophic bursopathy is a term used to describe the massive synovial proliferation occasionally seen in the bursae of patients with arthritis. Involvement of the subacromial-subdeltoid (SA-SD) bursa in adults in uncommon, and it is still rarer in children. It may simulate synovial proliferation or fluid within the adjacent shoulder joint. Sonography clearly shows the location and nature of the soft-tissue swelling. Two cases of this entity in children with juvenile rheumatoid arthritis are described, one with a uniquely severe sonographic picture.

Bicipital synovial cysts in juvenile rheumatoid arthritis: clinical description and sonographic correlation.

OBJECTIVE: To describe the presentation and clinical course of bicipital synovial cysts in 6 patients with juvenile rheumatoid arthritis (JRA) and to elucidate their anatomy using ultrasonography. METHODS: A clinical description of the cyst, JRA subtype, activity of concurrent arthritis, systemic disease features, and erythrocyte sedimentation rate was recorded for each patient. Ultrasonographic examination of the cyst was performed for each patient. RESULTS: Bicipital cysts generally presented as a sudden painless swelling on the flexor aspect of the upper arm, but on was in the forearm. Five of 6 patients had systemic disease. All patients had active arthritis when the cysts developed. Five of 6 cysts resolved spontaneously in less than 12 weeks. Ultrasonography confirmed a cystic structure in all patients, and in all cases was associated with thickening of the biceps tendon. Fluid was found within or adjacent to the biceps tendon in all cases. CONCLUSION: Bicipital synovial cysts should be considered a cause of acute arm swelling in patients with JRA, especially those with systemic disease. Ultrasonography is a useful diagnostic adjunct in this condition. This condition is generally self-resolving.

Incidence, management, and outcome of childhood empyema: a prospective study of children in Cambodian refugee camps.

To determine the incidence, outcome, and optimal management of empyema, all children less than 15 years of age admitted to Khao-I-Dang Hospital with a diagnosis of empyema during a 23-month period were prospectively studied. Khao-I-Dang Hospital provides care to 137,000 Cambodian children residing in eight refugee camps along the Thai-Cambodian border. Ninety-eight children with empyema were identified, for an annual incidence of 0.37 cases per 1,000 children. All patients had chest tubes inserted on admission, and all were treated with parenteral antibiotics, which included chloramphenicol in 92% of the patients and cloxacillin in 72%. Patients were hospitalized a mean of 30 days, and chest tubes were in place for a mean of 12 days. Surgery was performed on four patients who had bronchopleural fistulas that persisted for more than 14 days. Only one (1%) of the 70 patients treated with cloxacillin required thoracotomy, compared with three (11%) of the 28 patients who did not receive cloxacillin (P = 0.07). In a multiple regression analysis, the presence of pneumatoceles or mediastinal shift on admission chest radiograph, a history of tuberculosis in the family, and an age of more than five years were predictive of a longer duration of chest tube drainage. No patient died in the hospital, and only one patient died in the six months following discharge from the hospital. Chest radiographs that were obtained six months after discharge in 25 patients were all essentially normal, despite marked abnormalities on chest radiographs obtained at discharge. In summary, conservative medical management with the use of chest tubes for these 98 children with empyema resulted in a mortality rate of 1.0%, and should be considered as an effective alternative to the surgical management of patients presenting with this complication.

Ultrasonography in the study of prevalence and clinical evolution of popliteal cysts in children with knee effusions.

The prevalence and clinical evolution of popliteal cysts in children with knee arthritis is not well known. Using ultrasonography, we studied 44 children with clinically detectable knee effusions secondary to juvenile rheumatoid arthritis (n = 35), spondyloarthritis (n = 3) and psoriatic (n = 2), septic (n = 2) and lupus (n = 2) associated arthritis. Popliteal cysts, defined as anechoic or hypoechoic masses measuring at least 1 cm in 2 of 3 dimensions, were identified in 27 children (61%). Of the 30 children with bilateral arthritis, 11 (37%) had bilateral cysts. The size of the cysts ranged from 1 to 40 cm3 (median 3.0 cm3). There was a significant correlation between the presence of a cyst and popliteal pain and the size of the suprapatellar effusion (p less than 0.001) but not the child's age or underlying diagnosis (p greater than 0.05). A cohort of 25/27 children with cysts were followed prospectively with serial sonograms for 18-24 months. The resolution of the cyst followed that of the suprapatellar effusion in those children whose arthritis improved or resolved. Two children (8%) had rupture of the popliteal cysts. Popliteal cysts are readily documented in children with knee effusions using ultrasonography, and their presence and evolution correlates with the size of the suprapatellar effusion.

Benign hemorrhagic adrenocortical macrocysts in Beckwith-Wiedemann syndrome.

A new pseudotumorous lesion found in the adrenal cortex of six infants with Beckwith-Wiedemann syndrome is described. These cystic masses were discovered either prenatally by using sonography or early in the neonatal period as palpable flank masses. Imaging studies, including sonography and CT, could not confidently exclude malignancy. After the masses were removed surgically, histologic examination showed them all to be benign hemorrhagic macrocysts within the capsule or permanent cortex (in contrast to neonatal adrenal hemorrhage, which usually occurs more centrally in the fetal cortex). The cysts were as large as 8 cm in diameter, and in one case a solitary cyst was predominant. Hemihypertrophy was present in all cases. Four of the six lesions were right-sided, and there was a male-female ratio of 5:1. Benign hemorrhagic adrenocortical macrocysts are a cause of abdominal mass in the fetus and neonate with Beckwith-Wiedemann syndrome.

Milk of calcium fluid collection in dermatomyositis: ultrasound findings.

Extensive subcutaneous and intermuscular calcium laden fluid collections (milk of calcium) were found in two young girls with severe dermatomyositis. Sonographic examination clearly showed the nature and extent of the collections. Knowledge of this new feature of dermatomyositis should help avoid confusing these fluid collections with soft tissue infection and deep abscess in these often steroid dependent children.

Multicystic dysplasia and crossed renal ectopia.

Multicystic renal dysplasia in a crossed fused or nonfused ectopic kidney is a rare occurrence that produces unusual imaging findings. In four such cases in neonates, three presented with a palpable abdominal mass and one was discovered in utero with maternal sonography. In three cases, sonography showed a multicystic mass, contiguous with the lower pole of the orthotopic kidney. In the fourth infant, a crossed, tiny dysplastic kidney was not visualized, but its markedly dilated ectopic ureter was seen traversing the spine on CT. Ureteropelvic junction obstruction was present in the three fused orthotopic kidneys. The characteristic imaging findings of multicystic dysplasia and crossed renal ectopia include a multicystic mass of variable size that is contiguous with the lower pole of a hydronephrotic, malrotated kidney; ureteral displacement and/or dilatation; and contralateral absence of the kidney and its renal artery.

Sonography as a substitute for excretory urography in children with urinary tract infection.

The possibility was explored of substituting renal sonography for excretory urography in children with urinary tract infection. Seventy-one patients were studied prospectively with voiding cystourethrography, sonography, and excretory urography; each examination was reviewed independently and without knowledge of the results of the others. Compared with urography the sensitivity and specificity of sonography was 100% and 51%, respectively, provided sonograms were of good technical quality. In a few instances, however, focal renal parenchymal scars were clearly seen only on urography. The findings suggest that in the absence of vesicoureteral reflux children with urinary tract infection should be studied with sonography. No further study is needed if a good-quality sonogram is within normal limits. In the presence of vesicoureteral reflux, however, or a suspicious or abnormal sonogram, excretory urography appears to be still necessary, at least at the present level of knowledge and technical expertise.

Diaphragmatic paralysis evaluated by phrenic nerve stimulation during fluoroscopy or real-time ultrasound.

Stimulation of the phrenic nerve by applying an electrical impulse to the neck during fluoroscopy or real-time ultrasound (sonoscopy) of the diaphragm allows more precise functional evaluation than fluoroscopy and/or sonoscopy alone. This is especially true of patients who are unable to cooperate because they are on a ventilator, unconscious, or very young. The authors cite cases in which diaphragmatic paralysis was diagnosed by conventional methods but stimulation of the phrenic nerve demonstrated good diaphragmatic motion, leading to a change in prognosis in some cases and a change in therapy in others.

The one-film urogram in urinary tract infection in children.

The sensitivity and specificity of the 5 min postinjection radiograph during urography were studied in 131 children. The 5 min film was overall accurate in 83.2%, with a 56% sensitivity and 91.3% specificity in patients with urinary tract infection (n = 62). In cases in which the 5 min film was not diagnostic, it nevertheless raised enough suspicions to dictate additional films. It is suggested that in urinary tract infection, errors will not be made if the single 5 min postinjection film is reviewed and additional films are obtained only if parts of the urinary tract are incompletely visualized or appear questionable. Further study is necessary to explore the merits of a similar approach for pediatric urography unrelated to urinary tract infection.

The child with peptic esophagitis: a correlation of radiologic signs with esophageal pathology.

Thirty-five children with gastroesophageal reflux were examined in a prospective study in which radiologic findings were correlated with the esophageal biopsy. No consistent radiologic abnormality was found in 24 children with minimal to moderate esophagitis and in three children with normal histology. Positive radiologic findings were found in five out of seven patients with severe, or severe ulcerative, esophagitis and in one child with moderate esophagitis. The positive radiologic findings consisted of signs of mucosal inflammation (mucosal edema, ulceration, esophageal narrowing) in five cases and abnormalities of esophageal function (aperistalsis, continuous reflux) in three. In children with peptic esophagitis, the barium examination of the esophagus appeared to be of diagnostic value only in the small number of patients with advanced disease; the absence of radiologic signs (with one exception) excluded severe inflammation. A statistically significant correlation was found between age and the histologic severity of esophagitis.

Mucolipidosis I (acid neuraminidase deficiency). Three cases and delineation of the variability of the phenotype.

Isolated deficiency of the lysosomal hydrolase acid neuraminidase results in multisystem storage of sialic acid-rich oligosaccharides. Wide phenotypic diversity occurs within this biochemical defect. We studied three cases of an infantile form of mucolipidosis I in which the phenotype is dominated by severe Hurloid features. These patients excreted excessive amounts of sialic acid-rich oligosaccharides in their urine, and storage of similar compounds was shown in tissues and cultured fibroblasts. Cultured fibroblasts demonstrated an isolated deficiency of acid neuraminidase; beta-galactosidase levels were normal.

Air embolism as a complication of hip arthrography.

As an aid to correctly placing the needle tip within the hip joint during arthrography, injection of small amounts of air has been used to outline the joint space. Over a period of seven years, air embolus has been noted in three pediatric patients, twice with minor symptoms, and once with cardiac arrest. Even small amounts of air (less than 5 cc) injected accidentally intravenously may cause dangerous complications in small infants. If this technique is to be used, it is recommended that small amounts of carbon dioxide or oxygen be used instead of air.

Referred pain in the lower leg -- a cause of delayed diagnosis.

Three patients presenting with ankle pain are described. In each case the pain was referred from a lesion in the proximal tibia (two osteoid osteomas; one stress fracture). There was considerable delay in diagnosis in two of these cases. It would appear that pain referred from the proximal lower leg to the ankle is not well recognized as a clinical entity. In such cases, radiography of the more proximal limb is suggested. If this proves negative, a bone scan may then be performed.

Pediatric radiologists in the United States and Canada: involvement with newer imaging modalities.

A survey of the members of the Society for Pediatric Radiology indicates that currently the majority of pediatric radiologists do not perform or interpret examinations using radionuclides, ultrasound, or computed tomography (CT). A decisive factor determining involvement with these techniques is the type of institution in which the radiologists practices. Most of those involved with newer imaging modalities practice in autonomous children's hospitals, which also have the highest concentration of subspecialists. However, equipment is not always available in children's hospitals. Those practicing in major academic centers do not usually perform or interpret such imaging studies despite the widespread availability of equipment. The few pediatric radiologists in community hospitals almost always have equipment available and are involved with newer imaging techniques.

Intussusception and total body opacification.

Because of atypical clinical presentations, two children with intussusception had intravenous urography as their initial examination of following plan films. In both patients the intussusception was outlined by an opaque rim due to the total body opacification effect on the bowel wall. One patient had a target-like blush on following films which strongly suggested the correct diagnosis. The authors do not advocate intravenous urography to diagnosis intussusception, but if this study is performed because of atypical clinical findings, the radiographic sign should be recognized and lead to a barium enema.