S. Treves

Quantitative Radionuclide Angiocardiography Determination of Qp : Qs in Children

A new method of determining pulmonary-to-systemic flow ratios (Qp/Qs) in patients with left-to-right shunts using radionuclide angiocardiography is described. It involves the analysis of pulmonary time-activity histograms using a gamma-variate model. It appears to be simple, relatively atraumatic, and superior to the methods using C2/C1 ratios because, in addition to accurately detecting the presence of left-to-right shunts, it permits precise quantitation. In the 35 patients studied, it was found that Qp/Qs <1.2 could be separated from Qp/Qs > 1.2 and that when the Qp/Qs is between 1.2 and <3 the shunts could be accurately quantified.

Lung Growth and Airway Function after Lobectomy in Infancy for Congenital Lobar Emphysema

To characterize the outcome of lobectomy in infancy and the low expiratory flows which persist after lobectomy for congenital lobar emphysema, 15 subjects with this history were studied at age 8-30 yr. Total lung capacity was normal in all, but higher values (P < 0.05) were observed in nine subjects with upper lobectomy than in five subjects with right middle lobectomy. Ratio of residual volume to total lung capacity was correlated (P < 0.05) with the amount of lung missing as estimated from normal relative weights of the respective lobes. Xe(133) radiospirometry in eight subjects showed that the operated and unoperated sides had nearly equal volumes at total lung capacity, but that the operated side was larger than the unoperated side at residual volume. Perfusion was equally distributed between the two sides. Similar findings were detected radiographically in four other subjects. Forced expiratory volume in 1 s and maximal midexpiratory flow rate averaged 72 and 45% of predicted, respectively. Low values of specific airway conductance and normal density dependence of maximal flows in 12 subjects suggested that obstruction was not limited to peripheral airways. Pathologic observations at the time of surgery and morphometry of the resected lobes were not correlated with any test of pulmonary function. These data show that lung volume can be completely recovered after lobectomy for congenital lobar emphysema in infancy. The volume increase occurs on the operated side, and probably represents tissue growth rather than simple distension. The response to resection is influenced by the particular lobe resected and may be associated with decreased lung recoil near residual volume. Low expiratory flows in these subjects could be explained by several mechanisms, among which a disproportion between airway and parenchymal growth in infancy (dysanaptic growth) is most compatible with our data.

The lung following repair of congenital diaphragmatic hernia

To determine the effects of the pulmonary hypoplasia present at birth in infants with congenital diaphragmatic hernia upon subsequent development of the lung, 19 patients who had undergone surgical repair before the age of one year were studied at ages 6 to 18 years. Total lung capacity and vital capacity averaged 99% of predicted value. Diffusing capacity for carbon monoxide was normal. Forced expiratory volume in one second averaged 89% of predicted value and 80% of vital capacity. Total respiratory system conductance and maximum expiratory flow volume curves obtained during air and helium-oxygen breathing were normal. Xenon 133 radiospirometry performed in nine patients revealed equal distribution of lung volumes on the two sides. Ventilation to the hernia side was reduced in only two patients. Blood flow to the hernia side was reduced in all nine patients. Chest radiographs supported the physiologic observations. These findings are consistent with the persistence of a reduction in the number of branches or generations of pulmonary arteries and bronchi on the side of the hernia. Since a substantial part of the vascular resistance resides in peripheral vessels, this developmental abnormality influences the distribution of pulmonary blood flow, although it has little effect on tests reflecting airway resistance or the distribution of ventilation.

An improved radionuclide method for the diagnosis of gastroesophageal reflux and aspiration in children (milk scan).

A radionuclide study using technetium-99m-labelled milk feeding is described for the detection of gastroesophageal reflux and aspiration in children. A comparison of findings in 39 patients referred for both radiographic and radionuclide studies showed that barium studies were positive in 25.6% and radionuclide studies in 59% of cases, reflecting the sensitivity of the radionuclide technique. This technique is also physiological and allows prolonged patient monitoring. It is simple to perform and should prove useful in the evaluation of patients suspected of having gastroesophageal reflux and aspiration.

Sibling vesicoureteral reflux in multiple gestation births.

Background. Vesicoureteral reflux (VUR) is the most commonly inherited disease of the genitourinary tract. Although the majority of evidence supports a genetic cause, the tendency for this condition to spontaneously improve over time has made it difficult to determine the actual mode of transmission. We report the incidence of VUR in siblings of multiple gestation births and for the first time compare the relative incidence of reflux between identical and fraternal twins. Methods. A database consisting of all radionuclide cystograms and voiding cystourethrograms performed between the years 1986 and 1996 was searched for multiple gestation births. The medical records of each patient were evaluated for age at presentation, zygosity, reflux grade, and time to resolution. Children with secondary causes of VUR (eg, posterior urethral valves) were excluded. Triplets were treated as 2 pairs of twins for statistical analysis. Results. Forty-six pairs met the inclusion criteria (31 dizygotic and 15 monozygotic). Overall, 23 (50%) of 46 siblings of index cases had demonstrable VUR. Comparison of VUR prevalence between identical and nonidentical twins was revealing with 80% (12/15) of identical twins and 35% (11/31) of fraternal twins having VUR. When only the youngest individuals in each group were considered, 100% (7/7) of the monozygotics and 50% (5/10) of the dizygotics demonstrated this trait. Conclusions. High concordance for VUR in identical twin siblings supports a genetic basis for the transmission of this disease. Results obtained from fraternal twin siblings provides convincing evidence that this trait is transmitted in an autosomal dominant fashion.

Pediatric nuclear medicine

Dramatic improvements in gamma cameras, computers, and radiopharmaceuticals have occurred in recent years. These improvements have permitted the development of safe, accurate, and quantitative radionuclide diagnostic methods that are applicable to pediatric patients. The use of these procedures in pediatric patients is increasing because they provide unique information in a relatively simple, rapid, and/or convenient way. Although most of the procedures in common use in nuclear medicine rely on imaging, it is very important to emphasize the chemical and physiologic nature of this field. Radionuclide methodology has the capability of conceptualizing abnormality even before it results in anatomic abnormality which can then be visualized by imaging techniques that rely on morphology. The newer methods in nuclear medicine tend to be quantitative as well as qualitative and they require newer and more sophisticated computerized gamma camera systems. Diagnostic methods in nuclear medicine require the administration of a radiopharmaceutical, most frequently intravenously. In some instances, the material is given orally. A gamma scintillation camera is positioned over or under the patient9s body and focuses on the area to be studied. Gamma scintillation cameras are image converters which record the spatial distribution of radiopharmaceuticals in the body. The camera is connected to a specialized digital computer system which allows digital display and numerical analysis.

Quantitative radionuclide angiocardiography: Detection and quantitation of left to right shunts

In 105 patients defection and quantitation of left to right shunts was performed using quantitative radionuclide angiocardiography. The radionuclide angiocardiograms were acquired and analyzed by a gamma camera interfaced to a digital computer system. Pulmonary to systemic flow (Qp/As) ratios were calculated by analysis of pulmonary time-activity histograms using a gamma variate model. All patients were studied with cardiac catheterization, left ventricular angiocardiography and radionuclide angiocardiography. The radionuclide method allowed precise detection and quantitation of left to right shunts with a Qp/Qs ratio of 1.2 to 3.0. There was good agreement between the Ap/As ratio calculated by oximetry at cardiac catheterization and radionuclide angiocardiography (r = 0.94). The information gathered with this nontraumatic method appears sufficiently reliable to be used in the management of patients.

The infant with possible biliary atresia: Evaluation by ultrasound and nuclear medicine

Twenty-eight infants with jaundice were evaluated with ultrasound and radionuclide scans. Comparison of these studies with pathologic, surgical and clinical examinations demonstrated good correlation between ultrasonic and radionuclide studies. Ultrasound is an important preliminary study in the workup of such patients. Combined imaging provides the most information in a patient with suspected biliary atresia.

Assessment of mandibular growth by skeletal scintigraphy

Accurate assessment of facial skeletal growth remains a major problem in craniomaxillofacial surgery. Current methods include 1) comparisons of chronologic age with growth histories of the patient and the family, 2) hand-wrist radiographs compared with a standard, and 3) serial cephalometric radiographs. Uptake of technetium-99m methylene diphosphonate into bone is a reflection of current metabolic activity and blood flow. Therefore, scintigraphy with this radiopharmaceutical might serve as a good method of assessing skeletal growth. Thirty-four patients, ranging in age from 15 months to 22 years, who were undergoing skeletal scintigrams for acute pathologic conditions of the extremities, were used to develop standards of uptake based on age and skeletal maturation. The results indicate that skeletal scintigraphy may be useful in evaluation of mandibular growth.

Long-term evaluation of esophageal and pulmonary function in patients with repaired esophageal atresia and tracheoesophageal fistula

Patients who have undergone repair of esophageal atresia and tracehoesophageal fistula as infants have been noted to have residual esophageal dysmotility and pulmonary dysfunction during their childhood years. However, limited information is available about the long-term follow-up of these patients. In this study we performed esophageal and pulmonary function studies on 12 adults who had required surgical repair of these defects in the first week of life. Most patients had symptoms of dysphagia and heartburn at time of evaluation. Pathologic gastroesophageal reflux was documented in 67% of patients and esophagitis was noted in 34%. All patients had esophageal motility abnormalities characterized by low-amplitude nonperistaltic waves throughout most of the esophagus. In addition, although most patients had no respiratory symptoms, mild restrictive lung volumes were noted in many patients. However, airflow obstruction and airway hyperreactivity were not present. These data demonstrate that clinical symptoms and abnormal esophageal manometry and pulmonary function persist well into the third and beginning of the fourth decade after repair of esophageal atresia and tracheoesophageal fistula in infancy.