Assessing physicians' accuracy in diagnosing paediatric patients with acute abdominal pain: measuring accuracy for multiple diseases.

In evaluating the accuracy of diagnostic tests there are many situations where the true disease status can be one of multiple disorders. For example, when paediatric patients suffer acute abdominal pain, the underlying diagnosis could be appendicitis, intestinal obstruction, gastroenteritis, urinary tract infection, etc. In this paper we describe a format for collecting data for the case of multiple truth states. This new format allows one to make pairwise comparisons of the diagnostic accuracy between all of the different truth states. We propose a summary measure of accuracy which is a weighted average of the pairwise estimates of accuracy. Estimators are derived for the variance and covariance of the estimated summary accuracy. The small sample properties of the estimators are evaluated in a Monte Carlo simulation study. The new data collection format and summary measure were used in a paediatric acute abdominal pain study; data from this study are used to illustrate the methods.

The "differential diagnosis" for multiple diseases: comparison with the binary-truth state experiment in two empirical studies.

RATIONALE AND OBJECTIVES: In practice readers must often choose between multiple diagnoses. For assessing reader accuracy in these settings. Obuchowski et al have proposed the "differential diagnosis" method, which derives all pairwise estimates of accuracy for the various diagnoses, along with summary measures of accuracy. The current study assessed the correspondence between the differential diagnosis method and conventional binary-truth state experiments. MATERIALS AND METHODS: Two empirical studies were conducted at two institutions with different readers and diagnostic tests. Readers used the differential diagnosis format to interpret a set of cases. In subsequent readings they interpreted the cases in binary-truth state experiments. Spearman rank correlation coefficients and the percentages of agreement in scores were computed, and the areas under the receiver operating characteristic curves were estimated and compared. RESULTS: The between-format Spearman rank correlation coefficients were 0.697-0.718 and 0.750-0.780 for the two studies; the between-reader correlations were 0.417 and 0.792, respectively. The percentages of agreement between formats for the two studies were 50.0%-51.7% and 72.9%-78.8%; the percentages of agreement between readers were 45.0% and 80%, respectively. In the first study there were several significant differences in the areas under receiver operating characteristic curves; in the second study these differences were small. CONCLUSION: The differences observed between the two formats can be attributed to within-reader variability and inherent differences in the questions posed to readers in the multiple-diagnoses versus binary-truth state reading sessions. The differential diagnosis format is useful for estimating accuracy when there are multiple possible diagnoses.

Desmoplastic infantile ganglioglioma (DIG): cranial ultrasound findings.

Desmoplastic infantile ganglioglioma (DIG) is a rare brain tumor encountered in infants. In spite of its large size at presentation and occasional high mitotic activity on histopathology, the tumor has a good prognosis. A 7-month-old baby girl developed increasing head circumference. On ultrasound, a large multicystic mass was seen. We report the cranial ultrasound findings for the first time. Correlative imaging of this recently recognized entity is shown.

Pediatric radiologists: who we are and what we do. Results of a membership survey of the Society for Pediatric Radiology--1999.

BACKGROUND: There is a need for reliable monitoring of workforce trends in the field of pediatric radiology by the Society for Pediatric Radiology. In addition, the Society should periodically assess itself as to its mission and relevance to its members via membership surveys. OBJECTIVE: The Membership Committee of the Society for Pediatric Radiology, 1999, conducted a 54-question survey to determine the makeup of its members, job profiles, satisfaction with services of the Society for Pediatric Radiology, and its official journal, Pediatric Radiology. MATERIALS AND METHODS: Seven hundred fifty surveys were given to active members of the Society for Pediatric Radiology in the United States and Canada. There were 275 surveys returned for an overall response of 37%. RESULTS: Mean age of members is 48 years with 99% of respondents working. Membership is 34% female and 66% male. Women members of the Society are younger (45 vs 49 years, P = 0.0012) and work less hours (47.8 vs 51.0, P = 0.0135) than men. Fifty-seven percent of respondents practice in a freestanding children's hospital, 29% in a "children's hospital within a hospital," and 14% are in community hospitals or an office-based practice. Eighty-two percent of the responding pediatric radiologist's time is spent in performing examination on children, with only 18% spent on adult work or administration. Forty-eight percent work at more than one office. Sixty-one percent worked evenings or weekends, excluding night call. Two hundred twenty-two of 275 respondents had received a Certificate of Added Qualification. The meeting "for CME credit" was considered the most important benefit of Society membership. Most respondents read select articles in Pediatric Radiology. There was sentiment to decrease esoteric case reports in favor of review articles. Only 19% of respondents submitted their articles to Pediatric Radiology initially. CONCLUSION: Pediatric radiologists are a diverse membership with the common goal of advocating for healthcare and imaging in children. Survey information given to the leadership of the Society will help the organization remain responsive to its members.

Situs revisited: imaging of the heterotaxy syndrome.

Situs anomalies present a diagnostic challenge to radiologists because of the overlapping spectrum of findings commonly seen in asplenia and polysplenia. In a series of 21 patients with a diagnosis of heterotaxy syndrome, all 11 asplenic patients and seven of 10 polysplenic patients had congenital heart disease. Although there was a variety of complex congenital heart disease, the most common type in both patient groups was a common atrioventricular canal. In both groups, the laterality of the aorta and stomach was quite variable, but intestinal malrotation was a constant feature. In 11 asplenic patients, the most frequent findings were a bridging liver (10 cases), absent spleen (10 cases), and left-sided inferior vena cava (nine cases). Only seven of these patients had an aorta ipsilateral to the inferior vena cava, contrary to previous thought that this finding was specific for asplenia. In the 10 polysplenic patients, bridging livers were less frequent (five cases), single (six cases) or multiple (four cases) spleens were seen, and azygous continuation with interruption of the inferior vena cava was usually present (eight cases). Although not pathognomonic of polysplenia, inferior vena cava interruption with azygous or hemiazygous continuation is the most common anatomic finding of this condition. Although the terms asplenia and polysplenia are helpful in suggesting the typical anatomy, both syndromes encompass an overlapping spectrum that needs to be described individually and may best be called heterotaxy syndrome.

The "circle sign": a new sonographic sign of pneumatosis intestinalis - clinical, pathologic and experimental findings.

BACKGROUND: Pneumatosis intestinalis (PI) represents gas in the bowel wall. The appearance of PI using high-resolution ultrasound (HRUS) has not been well described. OBJECTIVE: The purpose of this report is to describe a new ultrasound sign of pneumatosis seen in three patients. This sign, called the "circle sign", is indicative of bubbles of gas within the circumference of the bowel, producing an appearance of a continuous echogenic ring on ultrasound. Further studies of the sonographic characteristics of pneumatosis were performed with an in vitro model. MATERIALS AND METHODS: HRUS was performed prospectively in three patients demonstrating extensive PI radiographically. The appearance of the gas was characterized and the behavior of the intramural bubbles was studied when the bowel was compressed with the ultrasound transducer. Either CT scan or pathologic correlation was obtained in all patients. Experimental models of PI using air injected into the wall of sausage casing were developed. RESULTS: The presence of echogenic gas bubbles within the circumference of the wall of the bowel seen with HRUS was shown to represent pneumatosis intestinalis at histologic examination or by CT scanning in the three study patients. In vitro studies confirmed the clinical impression that the use of compression is helpful in distinguishing intramural from intraluminal air. CONCLUSION: The presence of echogenic gas bubbles in the wall of the bowel, often seen as a circle within the circumference of the bowel, may be helpful in diagnosing PI on ultrasound using HRUS.

Imaging of patients with Wilms' tumor.

Continued advances in imaging technology have improved the ability to detect Wilms' tumor and its precursor, nephroblastomatosis, as well as tumor spread to other organs in a less invasive manner than in years past. However, there is still wide variation in clinical practice in the imaging of this tumor compared with the guidelines set forth by the National Wilms' Tumor Study Group. This article reviews current imaging options and recommendations for the evaluation of children with Wilms' tumor as well as for surveillance of children with associated disorders such as hemihypertrophy.

Superficial venous thrombosis presenting as a painful popliteal fossa mass in a child.

We report an unusual case of superficial venous thrombosis in a cyanotic 12-year-old child who had undergone recent appendectomy. Although compression, color Doppler, and duplex ultrasound techniques remain the keys to the diagnosis of venous thrombosis, SieScape sonography was beneficial in demonstrating the extent of the thrombi and their location along a superficial thrombosed vein.

Small bowel obstruction in rats: diagnostic accuracy of sonography versus radiography.

Our purposes were to determine whether sonography can distinguish between obstructed and nonobstructed rats and to compare the diagnostic accuracy of sonography and radiography in the diagnosis of small bowel obstruction. Nonstrangulating small bowel obstruction was created in 19 rats; sham laparotomies were performed in 18 controls. Serial radiographs and sonograms, including duplex Doppler sonography, were obtained. Bowel diameter and bowel wall thickness were evaluated retrospectively. Bowel diameter, bowel wall thickness, and resistive indices increased in the animals with obstruction; controls remained unchanged (P = 0.002). Sonography demonstrated a significantly higher diagnostic accuracy than radiography at 24 hours and beyond (P = 0.023). Ultrasonography is sensitive and more accurate than radiography in diagnosing small bowel obstruction using objective criteria in the animal model.

Intravenous sedation for MR imaging of the brain and spine in children: pentobarbital versus propofol.

The authors present a prospective study of single-agent pediatric sedation regimens for patients older than 2 years of age undergoing magnetic resonance (MR) imaging of the brain and spine. Thirty patients underwent MR imaging after intravenous administration of pentobarbital in successive boluses of 2.5 mg/kg to a maximum of 7.5 mg/kg. Thirty-one patients received an intravenous bolus followed by continuous infusion of propofol. The dosage schedule for propofol was 2 mg/kg (with supplemental 1 mg/kg boluses) followed by continuous infusion of 6 mg/kg per hour. There was no significant difference in the physiologic response to sedation between the two groups, although the magnitude of the drop in pulse was significantly greater in the group receiving propofol. Three patients receiving propofol experienced transient decreases in oxygen saturation, at variable times over the course of the procedure. However, patients recovered significantly faster from sedation with propofol. While propofol may represent a viable alternative to pentobarbital in selected patients, propofol requires constant physician supervision and meticulous technique.

Measurement of lung gas volume and regional density by computed tomography in dogs.

To determine if computed tomography (CT) can accurately measure lung volume, we compared lung gas volume measured by helium dilution with the equivalent volume calculated from CT total lung volume and density in 13 supine dogs. CT lung gas volume underestimated helium volume by 34% (range: -63 to 0%). Studies of wooden lung phantoms varying in density from 0.082g/cc to 0.776g/cc showed that only 15% of this error could be mimicked by the phantoms. The rest of the discrepancy is attributed to the lung's irregular borders, and the sharp density gradients surrounding and within the lung that result in x-ray beam hardening, sampling limitations, and partial volume measurement errors. Serial biweekly measurements in three dogs for 14 weeks showed CT gas volume to be highly reproducible with less scatter than seen in the helium measurements. Density in the lungs of all dogs showed a uniform gradual decrease from approximately 0.60g/cc at the dependent surface to 0.20g/cc at the superior surface with relatively constant density at any horizontal level. These studies show that whereas CT underestimates gas volume in the lungs, serial measurements are highly reproducible in experimental studies and are a promising technique to monitor diseases or response to therapy. Density gradients in the lungs were sufficiently uniform so that disruption of the normal gradient may be an indicator of early lung disease.

Internal derangements of the temporomandibular joint: findings in the pediatric age group.

Findings in 31 pediatric patients with pain and dysfunction of the temporomandibular joint (TMJ) are reported. The average age was 14 years (range, 8-16) and the average duration of symptoms was 21.4 months (range, 3 mo.-5 yr.). Internal derangements were found in 29 patients (94%) and degenerative arthritis in 13 (42%). In 12 patients (39%), the problem could be traced to an injury to the jaw. Secondary condylar hypoplasia was associated with the meniscal abnormality in 3 patients (10%). Further awareness of internal derangements of the TMJ in the pediatric population should permit greater recognition of their etiology. It is important that treatment be initiated as soon as possible, not only to minimize the development of osseous disease in young adults but also to prevent facial growth deformities.

Inguinal ovaries in children demonstrated by high resolution real-time ultrasound.

High resolution real-time ultrasound of two female infants showed normal ovaries located in the inguinal canal and demonstrated cysts within the solid ovarian tissue. As this appearance is quite distinct from that of the solid homogeneous testis, ultrasound can determine the nature of the gonad present.

Attenuation and contrast enhancement of gynecologic organs and tumors in CT.

CT scans were obtained of 11 normal women and 34 women with gynecologic tumors. Twenty-three of 26 women with known malignant tumors had abnormal CT scans while all control patients had normal. The tumor extent demonstrated by CT correlated with either pathologic or surgical staging in 78%. Contrast enhancement increased the diagnostic yield and accuracy of staging. Attenuation values of the normal uterus and uterine tumors are quite similar prior to contrast medium. After administration of contrast agent the normal myometrium attenuation values increase more than other pelvic tissues. Uterine tumors show substantially less enhancement and show a greater variation of density throughout the tumor than normal myometrium. Density readings are not predictive of histologic type or tumor grade. Tumor was best detected and its extent best seen after high doses of intravenous contrast medium infusion, which should be considered a routine part of the diagnostic evaluation of these patients.