MRI features of three paediatric intra-articular synovial lesions: a comparative study

AIM

To determine reliable magnetic resonance imaging (MRI) features differentiating three paediatric intra-articular congenital or neoplastic synovial lesions that contain blood products, from post-traumatic or haemorrhagic inflammatory processes.

MATERIALS AND METHODS

This was a retrospective review of MRI findings of 22 paediatric intra-articular congenital or neoplastic synovial lesions, including venous malformation (VM) (n=12), pigmented villonodular synovitis (PVNS; n=8), and synovial sarcoma (SS; n=2). These MRI features were compared with 22 paediatric post-traumatic or inflammatory intra-articular processes containing blood products and producing mass effect. The following imaging features were assessed: presence of a discrete mass, extension, extra-articular oedema, susceptibility, joint effusion, and size. Fisher's exact test was used and results were considered statistically significant when p<0.05.

RESULTS

The three intra-articular synovial lesions, compared with controls, were more likely to directly invade osseous structures when a discrete mass was present (13/16, 81.3% versus 1/9, 11.1%; p<0.002) and extend into extra-articular soft tissues (13/21, 61.9% versus 2/17, 11.8%; p<0.003), but were less likely to show extra-articular oedema (3/22, 13.6% versus 13/22, 59.1%; p<0.004), a joint effusion (10/22,45.5% versus 19/22, 86.4%, p<0.01), susceptibility within a joint effusion (0/22, 0% versus 11/22, 40.9%; p=0.00), osseous oedema (3/16, 18.8% versus 7/9, 77.8%; p<0.009), and synovial enhancement (8/21, 38.1% versus 14/16, 87.5%; p<0.003). VMs had characteristic tubular vessels with internal fluid-fluid levels (11/12) that extended into bone (10/12) and extracapsular soft tissues (11/12).

CONCLUSION

Our study indicates that, despite the overlapping presence of haemorrhagic products, intra-articular VM, PVNS, and SS show MRI features that permit distinction from acquired post-traumatic and haemorrhagic inflammatory lesions.

Nonenhanced limited CT in children suspected of having appendicitis: prospective comparison of attending and resident interpretations

PURPOSE

To prospectively compare resident and attending radiologic interpretations of nonenhanced limited computed tomographic (CT) scans obtained in children suspected of having appendicitis.

MATERIALS AND METHODS

Seventy-five consecutive children underwent nonenhanced limited CT for suspected appendicitis. The scans were prospectively interpreted by a resident and an attending radiologist, each unaware of the other's interpretation. The probability that the findings indicated a diagnosis of appendicitis, level of certainty in the interpretation, and presence of an alternate diagnosis were statistically analyzed.

RESULTS

Nineteen children (25%) had appendicitis. The area under the receiver operating characteristic curve was not significantly different between residents (0.97 +/- 0.02) and attendings (0.95 +/- 0.04). The percentage agreement between residents and attendings was 91% (kappa = 0.73 +/- 0.095). The average level of certainty tended to be higher for attendings (93% +/- 15) than residents (89% +/- 12). The sensitivity, specificity, and accuracy of resident interpretations were 63%, 96%, and 88%, respectively, compared with those of attending interpretations--95%, 98%, and 97%, respectively. Residents and attendings noted alternate diagnoses in 30% of children without appendicitis.

CONCLUSION

A high level of agreement exists between resident and attending radiologists in the interpretation of nonenhanced limited CT scans in children suspected of having appendicitis. Residents, however, tend to be less confident in their interpretations.

In vivo visualization of pyloric mucosal hypertrophy in infants with hypertrophic pyloric stenosis: is there an etiologic role?

OBJECTIVE

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition which presents in infants at 2-12 weeks of postnatal life, and whose cause remains obscure. Multiple associated abnormalities have been recognized within the external hypertrophied pyloric muscle layer, but the internal component of the pyloric mucosa has received scant attention in the literature to date. Our purpose in this study was to show that pyloric mucosal redundancy is a constant finding in infants with IHPS, to discuss its possible cause, and to explore the hypothesis of a relationship between pyloric mucosal redundancy and the development of IHPS.

MATERIALS AND METHODS

We identified 102 consecutive infants with surgically confirmed IHPS and determined the thickness of the pyloric mucosa compared with the thickness of the surrounding hypertrophied muscle. Fifty-one infants who did not have pyloric stenosis served as controls.

RESULTS

Mean mucosal thickness in patients with IHPS approximated mean muscle thickness, with a ratio of 0.89. In infants with IHPS, the pyloric mucosa constitutes approximately one third of the cross-sectional diameter of the pyloric mass and fills and obstructs the pyloric canal.

CONCLUSION

Mucosal redundancy is a constant associated finding in IHPS. Although the origin of the redundancy and a cause-and-effect relationship are difficult to establish, our findings support the hypothesis that hypergastrinemia may be implicated in the pathogenesis of IHPS, and suggest that mucosal thickening could be implicated as one of the initiating factors in its development.

Swelling at the angle of the mandible: imaging of the pediatric parotid gland and periparotid region

The pediatric parotid gland and periparotid region are subject to a variety of lesions and are most often evaluated with ultrasonography (US), contrast material-enhanced computed tomography (CT), and magnetic resonance (MR) imaging. US may be used to assess the size of the parotid gland, distinguish diffuse from focal disease, assess vascularity and adjacent vascular structures, distinguish cystic from solid lesions, and guide fine-needle aspiration. However, further evaluation with CT or MR imaging may be needed to better define the nature and extent of disease. CT is the imaging modality of choice for most pediatric parotid disease (including acute inflammation, abscess, calculi, and major salivary duct obstruction) and most solid masses and may obviate sedation. However, a mass associated with facial nerve symptoms should be evaluated with MR imaging because it is the only modality that can consistently demonstrate the facial nerve. Findings at US, CT, and MR imaging allow localization of parotid lesions and may suggest a specific cause. Clinical information, familiarity with normal parotid anatomy at various stages of its development, and knowledge of the imaging characteristics of parotid and periparotid lesions are essential for appropriate radiologic evaluation. This information can be used to guide therapy and plan a surgical approach.

Appendicitis and alternate diagnoses in children: findings on unenhanced limited helical CT

The objective of this manuscript is to review and illustrate the findings of appendicitis, and of alternate diagnoses that may clinically or radiographically simulate appendicitis, on unenhanced limited CT in children. Potential pitfalls in unenhanced limited CT interpretation of pediatric patients will also be discussed.

Unenhanced limited CT of the abdomen in the diagnosis of appendicitis in children: comparison with sonography

OBJECTIVE

The purpose of this investigation is to determine the sensitivity, specificity, and accuracy of unenhanced limited CT of the abdomen in children with suspected appendicitis and compare these results with graded compression sonography.

MATERIALS AND METHODS

Seventy-six children underwent unenhanced limited CT over a 11-month period for evaluation of suspected appendicitis. A historical cohort of 86 consecutive children who had undergone graded compression sonography was identified. Results were correlated with surgical, pathologic, chart, and clinical follow-up data. The sensitivity, specificity, accuracy, rate of alternate diagnosis, time to perform examinations, and charge at our institution were determined for unenhanced limited CT and sonography.

RESULTS

Sensitivity, specificity, and accuracy for unenhanced limited CT were 97%, 100%, 99%, respectively, and were 100%, 88%, 91%, respectively, for sonography. Alternate diagnoses were suggested in 35% and 28% children without appendicitis who had unenhanced limited CT and sonography, respectively. Unenhanced limited CT required 5 min and sonography required 20-30 min to perform. The charge at our institution was $408 for unenhanced limited CT and $295 for sonography.

CONCLUSIONS

CT can be performed rapidly in children without IV, oral, or rectal contrast medium. Unenhanced limited CT and sonography are highly sensitive, specific, and accurate in the evaluation of children with suspected appendicitis.

Pediatric renal masses: Wilms tumor and beyond

A variety of pediatric renal masses may be differentiated from Wilms tumor on the basis of their clinical and imaging features. Wilms tumor is distinguished by vascular invasion and displacement of structures and is bilateral in approximately 10% of cases. Nephroblastomatosis occurs most often in neonates and is characterized by multiple bilateral subcapsular masses, often associated with Wilms tumors. Renal cell carcinoma is unusual in children except in association with von Hippel-Lindau syndrome and typically occurs in the 2nd decade. Mesoblastic nephroma is the primary consideration in a neonate with a solid renal mass. Multilocular cystic renal tumor is suggested by a large mass with multiple cysts and little solid tissue. Clear cell sarcoma is distinguished by frequent skeletal metastases, and rhabdoid tumor is distinguished by its association with brain neoplasms. Angiomyolipoma frequently contains fat and is associated with tuberous sclerosis. Renal medullary carcinoma occurs in patients with sickle cell trait or hemoglobin SC disease and manifests as an infiltrative mass with metastases. Ossifying renal tumor of infancy is differentiated from mesoblastic nephroma by the presence of ossified elements. Metanephric adenoma lacks specific features but is always well defined. Renal lymphoma is characterized by multiple homogeneous masses, often with associated adenopathy.

Appendicolith revealed on CT in children with suspected appendicitis: how specific is it in the diagnosis of appendicitis?

OBJECTIVE

The purpose of this study was to determine the sensitivity, specificity, and positive and negative predictive values of a diagnosis of appendicitis when CT without enteric contrast material reveals an appendicolith in children with suspected appendicitis.

MATERIALS AND METHODS

A retrospective review of children who underwent abdominal CT for suspected appendicitis over a 25-month period was performed to identify patients with an appendicolith. An age-matched group of patients examined for trauma served as controls.

RESULTS

CT was performed in 104 children. Appendicitis was present in 60 (58%) of 104 children; 39 (65%) of 60 had an appendicolith. Appendicitis was not present in 44 (42%) of 104; six (14%) of 44 had an appendicolith. An appendicolith detected on CT had a sensitivity of 65% and a specificity of 86% for the radiologist diagnosing appendicitis. An appendicolith had a positive predictive value of 74% and a negative predictive value of 26%. Among the control population, two (3%) of 74 children had an appendicolith. This number was statistically significant compared with children in the study group with an appendicolith and abdominal pain, but without appendicitis (p = 0.02).

CONCLUSION

Although an appendicolith is significantly associated with appendicitis, the detection of an isolated appendicolith on CT is not sufficiently specific to be the sole basis for the diagnosis of acute appendicitis.

Muscle abnormalities in juvenile dermatomyositis patients: P-31 magnetic resonance spectroscopy studies

OBJECTIVE

To characterize metabolic abnormalities in the muscles of children with the juvenile variant of dermatomyositis (JDM) by the use of noninvasive P-31 magnetic resonance spectroscopy (MRS).

METHODS

Thirteen patients with JDM (ages 4-16 years) were studied. Biochemical status was evaluated with P-31 MRS by determining the concentrations of the high-energy phosphate compounds, ATP and phosphocreatine (PCr), ratios of inorganic phosphate (Pi) to PCr (Pi:PCr ratio), levels of free cytosolic ADP, and phosphorylation potentials (PPs) during rest, exercise, and recovery.

RESULTS

Significant metabolic abnormalities were observed in the thigh muscles of 10 severely affected patients during rest, 2 graded levels of exercise, and recovery. Mean ATP and PCr levels in the muscles of JDM patients were 35-40% below the normal control values (P < 0.003). These data, along with elevated Pi:PCr ratios, higher ADP levels, and abnormal values for PPs, indicated defective oxidative phosphorylation in the mitochondria of diseased JDM muscles. MRS findings were normal in 2 additional patients who had improved with prednisone treatment and in 1 patient who had no muscle weakness (amyopathic variant of JDM).

CONCLUSION

JDM patients can be monitored with noninvasive P-31 MRS without sedation. Biochemical defects in energy metabolism are concordant with the weakness and fatigue reported by JDM patients. Quantitative MRS data are useful for evaluating patients and optimizing drug treatment regimens.

Experimental study of mortality and morbidity of contrast media and standardized fecal dose in the peritoneal cavity

BACKGROUND

The use of radiographic contrast media in the setting of possible bowel ischemia and potential perforation is known to be associated with increased clinical risk. However, there is a lack of controlled studies using a standard native fecal load to define and compare the intrinsic mortality and morbidity among options of contrast media currently available to the radiologist. We have compared the mortality and gross and histopathologic morbidity of a standard intraperitoneal native fecal dose in the guinea pig, using barium, two iodinated media, saline and air.

MATERIALS AND METHODS

The study was performed on adult Hartley guinea pigs. A standard native fecal solution with a colony count of 10(8) aerobes and 2 x 10(7) anaerobes was prepared, and the LD50 of intraperitoneal injection of the solution was determined. The standard solution at the LD50 dose was then used to compare the mortality and morbidity when commercial barium sulfate (18% w/v), Conray 30 (iothalamate meglumine 30%), 1:1 dilution of Conray 30 with sterile water, termed Conray "15" (iothalamate meglumine 15%), saline and air, were added to the intraperitoneal injection of the fecal solution in five groups of 20 animals each. Mortality and acute (96 h) and chronic (30 days) gross and histopathology were assessed and graded according to a standard system and analyzed statistically.

RESULTS

Barium was significantly more deleterious than the dilute water-soluble iodinated media, saline and air. Mortality occurred within 24 h in the barium group and within the initial 48 h in all groups as follows: barium 19/20 (95%); Conray 30 16/20 (80%); Conray "15" 7/20 (35%); saline 0; air 0. Acute gross and histopathology showed extensive grade 4 lesions in 19/19 barium animals; less severe lesions were present in a lesser percentage of the animals in the other four groups. Entirely chronic lesions were present only in the single surviving barium animal and were non-significant (< 400 microns) or absent in the other four groups.

CONCLUSIONS

In our study, barium incurred the most significant deleterious short and long-term effects in the setting of fecal peritonitis. Dilute water-soluble media offer a much greater margin of safety. Saline under sonographic guidance is less deleterious than any of the positive radiographic contrast media. However, in our study, air was the safest contrast medium in the setting of peritoneal soiling.

Effect of radiographic contrast agents on leukocyte metabolic response

BACKGROUND

The use of radiographic contrast media in the setting of possible bowel ischemia and potential perforation is known to carry a risk of morbidity and mortality. However, studies of the effect of available contrast media on host immunological defense mechanisms are lacking. We have examined the effect of barium and of two water-soluble contrast agents of differing iodine concentration and osmolality, Conray 30 and Cysto Conray II, on leukocyte phagocytosis.

MATERIALS AND METHODS

Blood samples were incubated with the contrast media alone (termed the "resting state"), and in combination with a standard phagocytic challenge (Zymosan polysaccharide extract) and with Staphylococcus epidermidis, Streptococcus faecalis and Escherichia coli, to determine the effect of contrast media upon leukocyte phagocytic response. Incubation with saline was used as control. In the case of barium, the "resting state" and standard challenge experiments were repeated at nine dilutions, ranging from 1:1 to 1:1000. The leukocyte phagocytic response was measured in two ways: CO2 generation (an index of metabolic activity) and chemiluminescence (an index of generation of reactive oxygen species and bacterial killing).

RESULTS

Barium, at clinical dilutions, causes a significant increase of baseline "resting state" phagocytic activity, which in turn leads to significant blunting of subsequent response to phagocytic challenge and adversely affects the response to all bacteria tested. There is no baseline activation of leukocytes by the water-soluble media, although there was some inhibition (rather than activation) of leukocyte metabolic activity. The effect of the water-soluble media on bacteria was more complex (although inhibition is minor compared to barium).

CONCLUSIONS

Our data demonstrate that barium is a significant activator of phagocytic cells, which results in deactivation of phagocytic response when challenged; these data serve to explain the enhanced adverse effect of barium in cases of fecal peritonitis.

Fetal surgery for myelomeningocele and the incidence of shunt-dependent hydrocephalus

CONTEXT

Intrauterine closure of exposed spinal cord tissue prevents secondary neurologic injury in animals with a surgically created spinal defect; however, whether in utero repair of myelomeningocele improves neurologic outcome in infants with spina bifida is not known.

OBJECTIVE

To determine whether intrauterine repair of myelomeningocele improves patient outcomes compared with standard care.

DESIGN

Single-institution, nonrandomized observational study conducted between January 1990 and February 1999.

SETTING

Tertiary care medical center.

PARTICIPANTS

A sample of 29 study patients with isolated fetal myelomeningocele referred for intrauterine repair that was performed between 24 and 30 gestational weeks and 23 controls matched to cases for diagnosis, level of lesion, practice parameters, and calendar time. All infants were followed up for a minimum of 6 months after delivery.

MAIN OUTCOME MEASURES

Requirement for ventriculoperitoneal shunt placement, obstetrical complications, gestational age at delivery, and birth weight for study vs control subjects.

RESULTS

The requirement for ventriculoperitoneal shunt placement for decompression of hydrocephalus was significantly decreased among study infants (59% vs 91%; P = .01). The median age at shunt placement was also older among study infants (50 vs 5 days; P = .006). This may be explained by the reduced incidence of hindbrain herniation among study infants (38% vs 95%; P<.001). Following hysterotomy, study patients had an increased risk of oligohydramnios (48% vs 4%; P = .001) and admission to the hospital for preterm uterine contractions (50% vs 9%; P = .002). The estimated gestational age at delivery was earlier for study patients (33.2 vs 37.0 weeks; P<.001), and the birth weight of study neonates was less (2171 vs 3075 g; P<.001).

CONCLUSIONS

Our study suggests that intrauterine repair of myelomeningocele decreases the incidence of hindbrain herniation and shunt-dependent hydrocephalus in infants with spina bifida, but increases the incidence of premature delivery.

Imaging of neonatal gastrointestinal obstruction

This article discusses the various origins of gastrointestinal obstruction in the newborn infant in a progressive fashion, from the gastric outlet to the colon. The various entities are considered within the paradigm of high or low obstruction, with particular emphasis on the contribution of the radiologist in diagnosis and non-surgical treatment, outlining the role of plain films, sonography, and contrast studies.

Effect of intrauterine myelomeningocele repair on central nervous system structure and function

BACKGROUND

It has been postulated that intrauterine myelomeningocele repair might improve neurologic outcome in patients with myelomeningocele. A total of 59 such procedures have been performed at Vanderbilt University. Preliminary results suggested that the degree of hindbrain herniation is reduced by intrauterine repair. In an attempt to further quantify the possible benefits of this surgery, a subset of these patients was brought back to Vanderbilt for study.

METHODS

A group of 26 patients who had undergone intrauterine myelomeningocele repair underwent an extensive evaluation which included manual muscle testing, MR imaging and precise determination of the anatomic level of their lesions as well as multiple other tests. The results of this analysis were compared to those in 2 groups of historical controls.

RESULTS

In this group of patients intrauterine myelomeningocele repair substantially reduced the incidence of moderate to severe hindbrain herniation (4 vs. 50%). The incidence of shunt-dependent hydrocephalus was more modestly reduced (58 vs. 92%). The average level of leg function closely matched the average anatomic level of the lesion in both the fetal surgery and control groups.

CONCLUSION

The most dramatic effect of intrauterine repair appears to be on hindbrain herniation. A less dramatic, but significant, reduction in shunt-dependent hydrocephalus is also seen. Prospective patients should be cautioned not to expect improvement in leg function as the result of this surgery. The potential benefits of surgery must be carefully weighed against the potential risks of prematurity.

Intrauterine myelomeningocele repair reverses preexisting hindbrain herniation

BACKGROUND

It has been reported that intrauterine myelomeningocele repair reduces the amount of hindbrain herniation normally seen in association with the Chiari type II malformation. It is not yet known, however, whether hindbrain herniation is prevented, or whether preexisting herniation is reversed. The following study was designed to elucidate this issue.

METHODS

A series of 9 patients underwent intraoperative ultrasound examinations immediately prior to intrauterine myelomeningocele repair. These same patients were then evaluated postnatally using ultrasound and/or MRI. The degree of hindbrain herniation before and after repair was compared using a grading system devised by the authors.

RESULTS

Eight patients had clear evidence of moderate to severe hindbrain herniation on intraoperative scans while one was mild. In contrast, on postnatal studies 5 of 9 patients had no evidence of hindbrain herniation, while the other 4 had only mild herniation.

CONCLUSION

Intra-uterine myelomeningocele repair appears to reverse preexisting hindbrain herniation. It is postulated that continuous flow of cerebrospinal fluid through the neural placode is the force responsible for inducing migration of the cerebellum and brain stem downward through the foramen magnum. By interrupting that flow during gestation, intrauterine myelomeningocele repair enables the cerebellum and brain stem to resume a normal, or nearly normal, configuration.

Reduced hindbrain herniation after intrauterine myelomeningocele repair: A report of four cases

BACKGROUND

It has been theorized that fetal myelomeningocele repair may reduce ongoing intrauterine injury and perhaps allow healing and regeneration of dysplastic neural tissue. We report on the postnatal imaging studies of the first 4 patients to have undergone intrauterine myelomeningocele repair at our institution.

METHODS

Each of the 4 patients underwent postnatal sonographic and MRI. In addition, the postnatal ultrasounds of these 4 were compared to a group of retrospective controls.

RESULTS

MRI scans of the 4 experimental subjects revealed no evidence of hindbrain herniation while other stigmata of the Chiari-II malformation persisted. In comparison to the retrospective controls this absence of herniation was distinctly unusual.

CONCLUSION

Intrauterine myelomeningocele repair may reduce the degree of hindbrain herniation normally seen in patients with myelomeningocele. This raises the possibility that intrauterine repair may decrease the morbidity associated with the Chiari type-II malformation including brainstem dysfunction, hydrocephalus and syringomyelia.

Use of P-31 magnetic resonance spectroscopy to detect metabolic abnormalities in muscles of patients with fibromyalgia

OBJECTIVE

To investigate the metabolic and functional status of muscles of fibromyalgia (FM) patients, using P-31 magnetic resonance spectroscopy (MRS).

METHODS

Twelve patients with FM and 11 healthy subjects were studied. Clinical status was assessed by questionnaire. Biochemical status of muscle was evaluated with P-31 MRS by determining concentrations of inorganic phosphate (Pi), phosphocreatine (PCr), ATP, and phosphodiesters during rest and exercise. Functional status was evaluated from the PCr/Pi ratio, phosphorylation potential (PP), and total oxidative capacity (Vmax).

RESULTS

Patients with FM reported greater difficulty in performing activities of daily living as well as increased pain, fatigue, and weakness compared with controls. MRS measurements showed that patients had significantly lower than normal PCr and ATP levels (P < 0.004) and PCr/Pi ratios (P < 0.04) in the quadriceps muscles during rest. Values for PP and Vmax also were significantly reduced during rest and exercise.

CONCLUSION

P-31 MRS provides objective evidence for metabolic abnormalities consistent with weakness and fatigue in patients with FM. Noninvasive P-31 MRS may be useful in assessing clinical status and evaluating the effectiveness of treatment regimens in FM.

Implications of early sonographic evaluation of parapneumonic effusions in children with pneumonia

OBJECTIVE

To devise a clinically relevant grading system for the sonographic evaluation of parapneumonic effusions, and to evaluate length of hospital stay as a function of treatment approach and sonographic grades.

METHODS

Chest sonograms of 46 pediatric patients diagnosed with empyemas and admitted to two medical centers in the last 8 years were retrospectively evaluated using a grading system based on the degree of fibrinous organization within the parapneumonic effusions. Hospital charts were reviewed to determine the method of treatment and length of hospital stay. Patients were divided into two treatment groups: nonoperative (n = 26) (antibiotics alone, or combined with thoracentesis, or tube thoracostomy) and operative (n = 20) (open decortication, or video thoracoscopy and pleural debridement). Patients in the nonoperative group were further subdivided into two groups: those who received antibiotics alone (n = 11) and those who received antibiotics plus nonoperative drainage thoracentesis and/or tube thoracostomy (n = 15). Within each treatment group, patients were subdivided into two ultrasound grades: low (no evidence of organization) and high (evidence of organization such as fronds, septations, or loculations). Student's t test was performed to compare the lengths of hospital stay for each of the treatment groups and ultrasound grades.

RESULTS

The length of hospitalization was no different for patients with low-grade ultrasounds in the nonoperative (9.8 days) and operative groups (8.0 days). In contrast, length of hospitalization was significantly shorter for patients with high-grade sonograms in the operative group (8.6 days), when compared with the nonoperative group (16.4 days). Length of hospitalization for patients in the nonoperative group with high-grade sonograms was significantly longer (16.4 days) than for those with low-grade ultrasounds (9.8 days). Furthermore, when the nonoperative patients were divided into an antibiotics alone group and a nonoperative drainage group, the patients with low-grade sonograms had no difference in the length of hospitalization (9.0 days vs. 10.4 days), whereas those patients with high-grade sonograms in the nonoperative drainage group had a significantly longer hospitalization (19.9 days) than the antibiotics alone (high-grade) group (11.4 days).

CONCLUSIONS

Patients with a low-grade sonogram had similar length of hospitalization if treated with either nonoperative or operative measures. Patients with high-grade sonograms had significantly shorter length of hospitalization when treated with decortication. Our retrospective study suggests that patients with high-grade ultrasound studies treated nonoperatively do not benefit from pleural drainage procedures or chest tube placement. This study demonstrates the usefulness of early sonographic evaluation of parapneumonic effusions. A prospective study evaluating the usefulness of sonographic assessment of severity of disease in the treatment of children with parapneumonic effusions is warranted on the basis of our retrospective data.

Predictive measures of vascular access thrombosis: a prospective study

Malfunction of permanent vascular accesses remains a cause of frequent and costly morbidity in patients receiving chronic hemodialysis (CHD). Several recommendations for routine monitoring of these permanent vascular accesses for incipient failure have been proposed. In this study, multiple indicators of incipient vascular access dysfunction, including "venous" and "arterial" pressures at serial blood flows (200 ml/min, 300 ml/min, and 400 ml/min), percent urea recirculation, Doppler ultrasound, and access blood flow by ultrasound dilution technique were simultaneously evaluated in a total of 220 vascular accesses in 170 chronic hemodialysis patients in two separate study periods (6 months apart). The rate of thrombosis was determined within the subsequent 12 weeks of each study period to assess the short-term predictive power of access thrombosis. During the period of follow-up, there were 34 thrombotic events in 172 polytetrafluoroethylene (PTFE) grafts and only one thrombotic event in 48 arterio-venous fistulas (AVF). Therefore, the statistical analysis was limited to the PTFE grafts. When grafts with thromboses were compared to those without thrombosis by univariate analysis, access blood flow measured either by ultrasound dilution technique (875 +/- 426 ml/min with thrombosis vs. 1193 +/- 677 ml/min without thrombosis, P = 0.001) or by Doppler ultrasound (762 +/- 420 ml/min with thrombosis vs. 1171 +/- 657 ml/min without thrombosis, P = 0.001) were significantly different in the two groups. There was good correlation (r = 0.79, P = 0.0001) between the blood flows determined by both techniques. The grade of stenosis determined by ultrasound was also a statistically significant predictor (P = 0.02). "Venous" and "arterial" pressures were numerically similar and were not statistically different between the accesses that did and those that did not thrombose. When multivariate analysis was used, there was a significantly increased risk of thrombosis only with decreasing access blood flow determined by ultrasound dilution techniques after adjusting for other confounding variables. When the average blood flow of all grafts (1134 ml/min) is considered as the reference access blood flow (relative risk of 1.0), the relative risk of a PTFE thrombotic event within the subsequent 12 weeks was 1.23 at a blood flow 950 ml/min, 1.67 at a blood flow of 650 ml/min and to 2.39 at a blood flow of 300 ml/min. In summary, access blood flow measured by either Dilution or Doppler is a reliable indicator of subsequent short-term thrombosis risk. Other proposed methods of evaluating access dysfunction were not useful in our patients. If simple to use, cost-effective devices to measure dialysis access blood flow become readily available, the measurement of access blood flow will likely become the method of choice for screening of PTFE vascular access dysfunction in hemodialysis patients.

Retroperitoneal pulmonary sequestration: imaging findings, histopathologic correlation, and relationship to cystic adenomatoid malformation

OBJECTIVE

Retroperitoneal bronchopulmonary sequestrations are rare congenital lesions that have been increasingly reported as incidental findings in utero. We present our case material of congenital retroperitoneal sequestration, discuss the reported imaging and histopathologic characteristics of this entity, and provide an approach to subsequent clinical and surgical management.

CONCLUSION

Our data suggest that the imaging findings in retroperitoneal sequestration are characteristic and that faulty mesenchymal induction of pulmonary tissue within the retroperitoneum renders internal development into cystic adenomatoid malformation the rule rather than the exception. In the typical case, surgical removal is nonemergent.

Evaluation of renal resistive index, maximum velocity, and mean arterial flow velocity in a hydronephrotic partially obstructed pig model

RATIONALE AND OBJECTIVES

The authors investigate, in a controlled pig model, the usefulness of Doppler sonographic measurements of resistive index (RI), maximum velocity (Vmax), and mean velocity (Vmean) in diagnostic evaluation of the partially obstructed kidney.

METHODS

Seven female pigs underwent surgical partial unilateral renal obstruction at the ureteropelvic junction. Doppler parameters of RI, Vmax, and Vmean were measured preoperatively and postoperatively in obstructed and contralateral nonobstructed kidneys. The General Linear Model multivariate analysis of variance was used for statistical analysis of data.

RESULTS

There was no significant difference in the preoperative control values of RI (P = 0.71), Vmax (P = 0.27), and Vmean (P = 0.12). There was a statistically significant decrease in the Vmax and Vmean after postoperative day 5 in the obstructed kidney compared with the contralateral nonobstructed kidney (P = 0.01 and 0.03, respectively). There was no statistically significant difference in RI during the study.

CONCLUSIONS

In this study, RI was not a reliable indicator of partial renal obstruction. Measurements of maximal and mean blood flow velocities reached discriminatory significance only after the fifth postobstructive day, proving insensitive in the immediate postobstructive period. Vmax and Vmean demonstrated a decrease in the partially obstructed renal collecting system after 5 days of obstruction and may serve as useful parameters in the evaluation of obstruction after the immediate acute period, when compared with a nonobstructed contralateral system.

The value of Doppler resistive index and peak systolic velocity in the evaluation of porcine renal obstruction

PURPOSE

We evaluated the use of Doppler resistive indexes and systolic velocities as diagnostic tools in a partially obstructed animal model.

MATERIALS AND METHODS

We studied 12 normal pigs by Doppler sonography, which served as control units. In 9 subjects partial ureteral obstruction was then created surgically, and 3 continued as controls. The presence or absence of obstruction was confirmed by ultrasound, antegrade nephrostography and intrapelvic pressure monitoring. Doppler parameters were measured 1 hour to 21 days postoperatively. Resistive index, and angle corrected peak and mean systolic velocities were measured bilaterally from samplings of interlobar and arcuate arteries. An average of 4 samplings per kidney was obtained at each session. Data from the control and obstruction groups were compared for statistical differences.

RESULTS

In controls mean resistive index was 0.53, and peak and mean systolic velocities were 0.38 and 0.26 m. per second, respectively. In the subacute period after obstruction (defined as days 4 to 21) mean resistive index was 0.54, and peak and mean systolic velocities were 0.33 and 0.22 m. per second, respectively. Compared to control data there was no significant change in resistive index after obstruction (p = 0.6). However, peak and mean systolic velocities showed significant downward trends (p < 0.05).

CONCLUSIONS

Known small sequential changes in renal blood flow after ureteral obstruction are reflected in flow velocities, as measured by duplex Doppler sonography. However, resistive indexes are not useful in assessing these changes in renal blood flow, and they do not correlate with the presence or absence of obstruction in this animal model.

Hemoperitoneum in a newborn secondary to antenatal hemorrhage into a retroperitoneal lymphangioma

Hemoperitoneum in the newborn is an uncommon event, occurring most often in the setting of traumatic delivery. Hemoperitoneum resulting from antenatal hemorrhage into an abdominal mass is rare. We present a case of neonatal hemoperitoneum secondary to antenatal hemorrhage into a retroperitoneal lymphangioma. The differential diagnosis of neonatal hemoperitoneum is discussed.

Recurrent necrotizing jejunitis in a child

We report the case of a 5-year-old boy with segmental necrotizing jejunitis, present a review of the literature including a single previously described North American child, and give evidence to document disease recurrence. This uncommon disease must be differentiated from Crohn disease because the treatment and prognosis are different.

Common bile duct in children: sonographic dimensions

PURPOSE

To determine the normal caliber and rate of growth of the extrahepatic biliary ducts in the pediatric population.

MATERIALS AND METHODS

The diameter of the common bile duct was measured with sonography in 173 children aged 1 day to 13 years (mean, 6.0 years; median, 5.0 years) who were examined for reasons other than hepatic or biliary tract disease. Results were subjected to regression analysis and compared with similar measurements of the extrahepatic portal vein and hepatic artery. The size of the gallbladder was subjectively estimated as distended, moderately full, and contracted. Differences in the diameter of the common bile duct in these three groups were evaluated with the Mann-Whitney U test.

RESULTS

The average diameter of the common bile duct in this population was 1.27 mm +/- 0.67 (< 3.3 mm in all patients and < 1.2 mm in children aged 3 months or less). The slope of the curve describing the growth of the common bile duct was relatively flat, similar to that of the hepatic artery and half that of the portal vein. There was a significant difference in the diameter of the common bile duct between patients with distended gallbladders and those with contracted gallbladder (P = .02).

CONCLUSION

The pediatric common bile duct is significantly smaller than adult norms; it is a distensible structure responsive to fluctuations in prandial bile flow.

The antral nipple sign of pyloric mucosal prolapse: endoscopic correlation of a new sonographic observation in patients with pyloric stenosis

This study describes the antral nipple sign of pyloric mucosal prolapse, a newly delineated sonographic observation in patients with pyloric stenosis, correlates the endoscopic findings, and examines its prevalence and significance in 31 consecutive patients with pyloric stenosis. Fifty patients who did not have pyloric stenosis served as the control population. The antral nipple sign consists of visualization of prolapsed, hypertrophied pyloric mucosa protruding into the gastric antrum. Using the Wilcoxon scores (rank sums), there was no significant difference among the patients in age, weight, or pyloric muscle dimensions. Although the diagnosis of pyloric stenosis is made on the basis of muscle thickness, we have documented that the pyloric mucosa becomes redundant in infants with pyloric stenosis, permitting a fuller understanding of the anatomic correlate underlying the sonographic images.

Use of magnetic resonance imaging and P-31 magnetic resonance spectroscopy to detect and quantify muscle dysfunction in the amyopathic and myopathic variants of dermatomyositis

OBJECTIVE

To investigate the use of magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (MRS) in characterizing the metabolic and functional status of muscles in patients with amyopathic dermatomyositis (DM) and to compare the findings with those in patients with classic myopathic DM.

METHODS

Nine patients with amyopathic DM, 11 patients with myopathic DM, and 11 normal individuals were studied. MRI images of thigh muscles were obtained, and T1 and T2 relaxation times were calculated. Biochemical status was quantitated with P-31 MRS, by determining concentrations of phosphate metabolites during rest and exercise.

RESULTS

Patients with amyopathic DM showed no muscle inflammation, and MRS data obtained during rest were normal. During exercise at 25% and 50% maximum voluntary contractile force, the MRS data revealed significant differences between amyopathic DM patients and control subjects indicating inefficient metabolism. In contrast, muscles of patients with myopathic DM showed inflammation and metabolic abnormalities even during rest.

CONCLUSION

Metabolic deficiencies in patients with amyopathic DM were unmasked by exercise, suggesting that the 2 DM syndromes may share muscle abnormalities. MRI/MRS may be useful in diagnosis and optimization of treatment.

Hypertrophic pyloric stenosis in the infant without a palpable olive: accuracy of sonographic diagnosis

PURPOSE

To evaluate the accuracy of sonography for both diagnosis and exclusion of pyloric stenosis in the infant with nonbilious vomiting without a palpable olive and to clarify the relationship between infant age and size and the dimensions of the hypertrophic pylorus.

MATERIALS AND METHODS

The sonograms of 152 infants with suspected pyloric stenosis were evaluated. The prospective diagnoses were categorized as pyloric stenosis, normal pylorus, and pylorospasm with potential to progress to pyloric stenosis. Positive findings were confirmed at surgery; negative findings were confirmed by means of chart review.

RESULTS

Sensitivity, specificity, and accuracy of sonography in determination of appropriate surgical referral were 100%. A significant (P < .05) correlation was found between the size of the hypertrophied muscle and the age of the patient at initial examination.

CONCLUSION

Sonography is highly sensitive and, in this patient population, highly specific, and by virtue of direct visualization of the pyloric muscle, it is the method of choice for both diagnosis and exclusion of pyloric stenosis.

Monitoring of girls undergoing medical therapy for isosexual precocious puberty

We evaluated the use of sonography in monitoring the efficacy of suppressive therapy with a gonadotropin releasing hormone analogue in girls being treated for isosexual precocious puberty. Ten girls 5 to 9 years of age underwent serial sonography and hormonal stimulation tests on the same day. Sonographic trends of decreasing ovarian volume and uterine length indicated early suppression even when absolute values were above threshold. Changes in ovarian volume were the most sensitive predictor of pituitary-gonadal suppression. Sonography is a sensitive and accurate method of monitoring medical therapy; ovarian volume and analysis of interval change are the most sensitive barometers of change.

Magnetic resonance imaging and P-31 magnetic resonance spectroscopy provide unique quantitative data useful in the longitudinal management of patients with dermatomyositis

OBJECTIVE

To evaluate the utility of magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (MRS) in the longitudinal management of patients with dermatomyositis (DM).

METHODS

The study group consisted of 11 patients, including 3 children, all of whom had a clinical diagnosis of DM. A control group of 8 subjects was studied simultaneously. MRI included images as well as calculations of T1 and T2 relaxation times. The P-31 MRS protocol evaluated metabolic status (i.e., inorganic phosphate/phosphocreatine ratios and phosphocreatine and ATP levels) during rest, exercise, and recovery.

RESULTS

T2-weighted images of the thigh muscles showed inflammation even when serum creatine phosphokinase levels were in the normal range. Metabolic abnormalities, which were accentuated with exercise, were found in 10 patients. In some individuals, bioenergetic defects preceded other changes and persisted after resolution of inflammation. In general, clinical impressions correlated with MRI/MRS data.

CONCLUSION

MRI and MRS provide unique data which are quantitative and which cannot be obtained from routine laboratory tests. These MR evaluations appear to be of value in assessing the status of DM patients during treatment with steroids and immunosuppressive drugs.

Cystic lung disease in Down syndrome

It is well known that Down syndrome (DS) affects multiple organ systems, including cardiovascular, gastrointestinal, hematological, and musculoskeletal. Involvement of the lungs by a characteristic form of subpleural cystic disease is well described in the pathology literature. The imaging characteristics of changes caused by this disease have not been previously described in detail in the radiology literature, possibly because they are not well appreciated on plain chest radiographs. We present a child with DS in whom extensive cystic lung disease was discovered incidentally at CT, and review the current literature regarding the pathogenesis of cystic pulmonary abnormalities in children with DS.

Cysts and cystlike lesions of the lung

This article has reviewed the major pulmonary cystic lesions occurring in infants and children. The chest radiograph will initially reveal either single or multiple well-circumscribed radiopaque or radiolucent areas. In younger patients, radiopaque lesions are best evaluated with sonography, which can define the internal architecture of the mass, its location, and vascular supply. On the other hand, radiolucent lesions, lesions inaccessible to the sonographic beam, and lesions requiring analysis of the pulmonary parenchyma are best assessed with CT. MR is helpful in the preoperative evaluation of sequestration after infancy. Thus within the framework of an age-dependent algorithm, pulmonary cystic lesions can be analyzed effectively and an appropriate diagnosis established.

Pediatric chest disease: evaluation by computerized tomography, magnetic resonance imaging, and ultrasonography

The initial method for evaluating pediatric chest disease remains the plain chest roentgenogram. When more precise definition of chest disease is required, computerized tomography (CT), magnetic resonance imaging (MRI), or ultrasonography (US) may be useful. In general, CT offers the widest spectrum of applicability. MRI is especially useful because no ionizing radiation is used and images can be acquired in multiple planes. MRI is most valuable when vascular anatomy needs to be defined or when tumor invasion of the spinal canal is suspected. US is helpful in evaluating diseases of the pleura and for characterizing and localizing pleural fluid and masses. US can differentiate normal thymus from other anterior mediastinal masses. Doppler techniques are valuable in evaluating suspected pulmonary sequestration and identifying the feeding vessel.

Pulmonary sequestration: diagnosis with color Doppler sonography and a new theory of associated hydrothorax

The diagnosis of pulmonary sequestration has traditionally relied on angiographic demonstration of a systemic artery to the sequestered lung tissue. Rarely, extralobar sequestration can be associated with tension hydrothorax, which in the past has invariably led to fetal hydrops and death. The authors report the cases of three infants who had initially undergone color and spectral Doppler analysis; in two of them, extralobar sequestrations were associated with congenital hydrothorax. All three patients underwent surgical resection and histopathologic evaluation of their sequestrations. On the basis of the findings, the authors believe that torsion of the sequestration occludes the efferent venous and lymphatic channels, initiating the accumulation of pleural fluid and subsequent hydrops through systemic venous obstruction. Color Doppler made possible the identification of minute feeding vessels, obviating further diagnostic studies.

Imaging of pediatric mediastinal histoplasmosis

Histoplasmosis can present a diagnostic dilemma if unusually large masses of lymph nodes, invasive mediastinal fibrosis, or pericarditis result from the infection. These rare, late sequelae are often first suspected from findings on chest radiographs obtained for unrelated reasons. Organisms are not always evident at histologic analysis at this stage. Mediastinal granulomas consist of lobulated masses of enlarged lymph nodes with central caseation, a peripheral thin capsule, and, occasionally, calcification. The mass does not invade or compromise adjacent anatomic structures. Mediastinal fibrosis invades and can seriously compromise the function of the tracheobronchial tree, superior vena cava, pulmonary arteries and veins, and esophagus; its symptoms mimic those of many other disorders. Pericarditis is commonly accompanied by pericardial effusion, pneumonia, and adenopathy. Although the radiologic findings of these conditions are nonspecific, they can be used with the clinical findings to suggest a diagnosis. Complications of histoplasmosis should be included in the differential diagnosis for patients residing in areas endemic to Histoplasma capsulatum.

New applications of conventional and Doppler sonography in pediatrics

Sonography is assuming an increasingly dynamic role in pediatric diagnosis. The small size of the patient and the use of short-focus, higher frequency transducers, coupled with continuous improvement in sonographic equipment, provide remarkably detailed images. The introduction of Doppler technology has catapulted sonography from the realm of purely anatomic information to that of physiologic and angiographic data. In neurosonography, there has been refinement of the nomenclature, quantification, and prognosis of intracranial hemorrhage and ischemic disorders. Doppler technology has helped us in understanding the vascular dynamics that occur after acute interruption of right internal carotid flow in patients who undergo extracorporeal membrane oxygenation. In abdominal diagnosis, sonography is also playing an increasingly important role in assessing both gastrointestinal and renal conditions. This review outlines some of the important concepts underlying pediatric sonography today and reviews some salient contributions of recent literature.