Acute renal allograft rejection. Comparative value of ultrasound versus magnetic resonance imaging.

Both magnetic resonance imaging (MRI) and ultrasound (US) have been reported to be useful in differentiating between acute allograft rejection and other causes of graft dysfunction in renal transplantation. The aim of this study was to evaluate the comparative usefulness of these techniques in the assessment of patients with acutely rising serum creatinine levels. Seventeen patients with 19 episodes of acute serum creatinine elevations were evaluated for the presence of acute rejection. The ultimate diagnoses of acute rejection were based on either renal pathological findings, or the response to standard antirejection therapy. Clinical, US and MRI diagnoses were assessed independently, without knowledge of the results of the other evaluation techniques. We found that US alone was useful in diagnosing acute rejection (x2 = 4.95, P less than 0.05), and when taken in the clinical setting was an added advantage (x2 = 6.68, P less than 0.01). MRI did not increase the diagnostic accuracy significantly.

Renal malformations in patients with Turner syndrome: imaging in 141 patients.

Turner syndrome occurs in 1/2,000 to 1/5,000 live female births. The presence of renal malformations was evaluated in 141 patients with Turner syndrome and abnormalities were found in 47 (33%). Prior to 1980, IVP was the radiologic method used for initial screening, and subsequently, ultrasonography has been used as the initial imaging technique. With both methods, major malformations can be detected. Ten patients had a horseshoe kidney, 11 had double collecting systems, four had complete absence of one kidney, three had crossed ectopia, and one had a pelvic kidney. Three patients had ureteropelvic junction obstruction; two of these were asymptomatic and the obstructions were detected only because of the routine imaging. Two patients had ureterovesicular junction obstruction, with one studied as part of a routine evaluation for short stature. Four of these five patients required surgery. Ultrasonography should be used as the initial renal imaging study for all patients at the time the diagnosis of Turner syndrome is made.

Magnetic resonance imaging of Wilms tumor.

Magnetic resonance imaging (MRI) in 4 children with Wilms tumor suggests the usefulness of this newer imaging modality in evaluating the organ of origin and defining the extent of Wilms tumor. Coronal T1-weighted images were the most useful pulsing sequence for evaluating these children.

Normal MR appearance of the pituitary gland in the first 2 years of life.

PURPOSE: To investigate changes in the size, shape, and signal intensity of the pituitary gland during the first 2 years of life. METHODS: One hundred consecutive MR studies, spin-echo T1- and T2-weighted sequences, of children 0 to 2 years of age were analyzed. Signal intensity and shape of the gland were graded and its signal intensity measured. RESULTS: There was a statistically significant difference in the signal intensity of both the anterior and posterior pituitary gland and in the shape between children younger than and older than 6 weeks of age and younger than and older than 27 weeks of age. There were definite trends in the size of the gland with age (decrease in height and increase in anteroposterior diameter and width). CONCLUSIONS: There are changes in the pituitary gland in the newborn period that may reflect the ongoing changes in pituitary hormones reported to occur during this time.

MR of hypoxic encephalopathy in children after near drowning: correlation with quantitative proton MR spectroscopy and clinical outcome.

BACKGROUND AND PURPOSE: Quantitative MR spectroscopy has a proved role in the investigation of hypoxia caused by near drowning. To date, no studies have addressed the MR imaging changes that may also accompany this condition. The purpose of this study was to describe the MR imaging findings in children with hypoxic encephalopathy caused by near drowning and to compare these findings with the results of qualitative and quantitative proton MR spectroscopy and clinical outcome. METHODS: Twenty-two children (6 months to 11 years old) admitted to the pediatric intensive care unit after near drowning incidents underwent cerebral MR imaging and quantitative proton MR spectroscopy. Clinical and imaging studies were reviewed retrospectively, and subjects were grouped according to outcome: good result, persistent vegetative state, and death. Images were scored for edema, basal ganglia changes, and cortical changes, and were compared with MR spectra and outcome at days 1 to 2, 3 to 4, and 5 or more. RESULTS: Six patients had a good outcome, four remained in a persistent vegetative state, and 12 died. Generalized/occipital edema correlated with poor outcome. Indistinct lentiform nuclei margins on T1-weighted images were a frequent finding (78%). Basal ganglia T2 hyperintensity correlated with poor outcome, progressing from a patchy/peripheral distribution to diffuse high intensity. Patchy high T2 signal in the cortex or subcortical lines were specific but insensitive for poor outcome, as were brain stem infarcts. CONCLUSION: MR images in children with hypoxic encephalopathy after near drowning show a spectrum of changes. The most sensitive prognostic result may be achieved by combining MR imaging with qualitative and quantitative MR spectroscopic data.

The split notochord syndrome with dorsal enteric fistula.

Split notochord syndrome with dorsal enteric fistula is an extremely rare congenital anomaly that may be associated with meningomyelocele or meningocele, and genitourinary anomalies. This case presented with an additional finding of bladder exstrophy, raising the possibility of a relationship between this syndrome and the OEIS complex.

Resective surgery for intractable epilepsy in children: radiologic evaluation.

Epilepsy surgery is gaining popularity for the treatment of children with intractable seizures in whom either a focal or extensive unilateral structural brain lesion is demonstrated. We evaluated the pre- and postoperative imaging findings in 29 patients (aged 22 days to 19 years) who underwent hemispherectomies, 12 total and 17 subtotal. Pathologic correlation was obtained in all cases. Preoperatively, positron emission tomography and electroencephalography demonstrated abnormalities in all of the 28 children studied, but frequently could not characterize the lesion. CT or MR or both demonstrated focal or unilateral lesions in only 19 of these but gave additional information regarding the nature of the lesion. Preoperative angiographic findings were abnormal in five of 17 patients studied and were particularly useful in the evaluation of the extent of abnormality in patients with Sturge-Weber syndrome. Postoperatively, CT and MR demonstrated early complications such as the development of epidural blood and fluid collections, parenchymal hemorrhage, infection, and early hydrocephalus. Postoperatively, MR demonstrated the early development of septations, the presence of subarachnoid hemorrhage, and/or the deposition of hemosiderin in four patients, findings that historically have been associated with the development of devastating clinical complications. From these data, a recommended protocol of radiologic evaluation for patients undergoing hemispherectomy has been established.

The Proteus syndrome: CNS manifestations.

Proteus syndrome is a complex hamartomatous disorder characterized by multiple, diverse, somatic manifestations. We present a case in which severe, evolving CNS abnormalities were also exhibited. Imaging findings at presentation included hemimegalencephaly, subependymal calcified nodules, and periventricular cysts. Subsequently, dural sinus thrombosis developed. Eight previously reported patients may also have had hemimegalencephaly. When neuroimaging studies show hemimegalencephaly in a child with pigmented skin lesions, Proteus syndrome should be considered in the differential diagnosis.

Premature aging in persons with Down syndrome: MR findings.

PURPOSE: To determine whether persons with Down syndrome have features of premature aging on routine MR imaging sequences. METHODS: Sixty MR studies (in 30 persons with Down syndrome and 30 age- and sex-matched control subjects) were reviewed retrospectively by two blinded examiners. Sagittal T1-weighted and axial T2-weighted spin-echo images were evaluated for the presence and severity of three markers of brain aging: atrophy, white matter lesions, and T2 hypointensity of the basal ganglia, referenced to the examiner's internal standard of normal for that age and sex. RESULTS: Persons with Down syndrome had higher prevalence and severity of the three markers studied than the control subjects. Atrophy and white matter lesions increased in prevalence with age; abnormal T2 hypointensity of the basal ganglia was more equally distributed with age. CONCLUSION: Persons with Down syndrome have features of premature aging detectable at routine MR imaging.

Magnetic resonance imaging of normal brain maturation.

At this time, the unique ability of MRI to show both brain anatomy and pathology, with a high degree of sensitivity, makes it an indispensible tool with which to evaluate infants and children. Before interpreting such images, however, it is essential to be fully aware of the spectrum of normal age-related appearances of the neonatal brain, in order to avoid a normal child being erroneously given an abnormal diagnosis. The MRI literature already contains early reports of follow-up studies on children with abnormal myelin patterns. In the future, the noninvasive nature of MRI will allow sequential studies to be performed on larger groups of children, offering an unprecedented opportunity to study the progression of both normal and abnormal myelination.

Normal and abnormal white matter maturation.

The unique ability of MR to demonstrate both normal and abnormal white matter maturation with a high degree of sensitivity makes it an indispensable tool with which to evaluate children with clinical developmental delay or suspected dysmyelinating processes. Because the noninvasive nature of MRI allows sequential studies to be performed without additional risk to the patient, it offers an unprecedented opportunity to study the process of myelination in normal infants, developmentally delayed infants and to better understand the dysmyelinating disorders, a relatively rare, poorly understood group of diseases.

Hepatic abscess in liver transplantation. Accurate diagnosis and treatment.

Serial HIDA scanning was performed on a patient following liver transplantation. During the patient's course he developed biliary obstruction that manifested as a photopenic region in the liver, on the HIDA scan which filled in on the delayed views. The patient subsequently developed a region in the superior portion of the right lobe of the liver that did not fill in with activity on delayed views. The patient was experiencing low-grade fevers and was clinically believed to have either an abscess or an episode of rejection. A gallium scan was performed revealing a photopenic defect in the same region as the HIDA. Because of the clinical suspicion of abscess, a percutaneous transhepatic drainage study was performed, revealing a large abscess cavity in the suspect area within the liver. Following the drainage the patient did well. This case illustrates the usefulness of serial HIDA scanning in patients who have received liver transplants. It also is important to note that the gallium scan was negative in this hepatic abscess. In the authors' opinions, the finding of an intrahepatic fluid collection in a septic patient that does not fill with activity on the HIDA study, should be considered the source of the infection, until proven otherwise, and should be drained regardless of the findings of other studies.

Distinguishing 3 classes of corpus callosal abnormalities in consanguineous families.

OBJECTIVE: We sought to create a classification system for pediatric corpus callosal abnormalities (CCA) based upon midline sagittal brain MRI. We used the term CCA for patients with structural variants of the corpus callosum, excluding patients with interhemispheric cyst variant or pure dysplasia without hypoplasia. Currently, no system exists for nonsyndromic forms of CCA, and attempts to create such a system have been hampered by highly variable morphology in patients with sporadic CCA. We reasoned that any useful strategy should classify affected family members within the same type, and that phenotypic variability should be minimized in patients with recessive disease. METHODS: We focused recruitment toward multiplex consanguineous families, ascertained 30 patients from 19 consanguineous families, and analyzed clinical features together with brain imaging. RESULTS: We identified 3 major CCA classes, including hypoplasia, hypoplasia with dysplasia, and complete agenesis. Affected individuals within a given multiplex family usually displayed the same variant of the class of abnormality and they always displayed the same class of abnormality within each family, or they displayed complete agenesis. The system was validated among a second cohort of 10 sporadic patients with CCA. CONCLUSIONS: The data suggest that complete agenesis may be a common end-phenotype, and implicate multiple overlapping pathways in the etiology of CCA.

Iron accumulation in the basal ganglia following severe ischemic-anoxic insults in children.

Increased iron deposition is described in four children following severe ischemic-anoxic insult and subsequent resuscitation. All cases demonstrated on T2-weighted magnetic resonance images areas of hypointensity in the basal ganglia, thalami, and white matter that were attributed to iron deposition. Associated areas of hyperintensity were also seen in the periventricular and subcortical white matter, and these were attributed to gliosis. In one case calcium deposition was also present within the areas of hypointensity. These findings suggest that after anoxic-ischemic damage, normal axonal transportation of brain iron can no longer occur. This may lead to increased accumulation of iron centrally at the sites of iron uptake in the basal ganglia and in the white matter. Additional iron deposition may occur more rapidly due to direct injury by lipid peroxidation degradation products catalyzed by iron.

Kidneys in infants and children: evaluation with MR.

Magnetic resonance (MR) imaging was performed in 58 children aged 1 day to 17 years. In 43 patients with suspected renal abnormalities, the results of MR were compared with those obtained by ultrasonography, computed tomography, or excretory urography. The remaining 15 children with no known renal disease were initially imaged to define the appearance on MR images of the normal kidneys according to the child's age. The signal intensity from hilar adipose tissue increased with age; corticomedullary differentiation was best seen in younger children. Compared with other imaging modalities, MR added useful information in evaluating the complications associated with renal failure and in patients with renal neoplasms. The use of MR in children with possible renal disease is limited, and the modality should be used as an adjunct to renal ultrasonography in a carefully selected group of patients.

Pelvic abnormalities in children: assessment with MR imaging.

Multiplanar images of 62 pelvic lesions in 58 children and adolescents (aged 7 months to 19 years; mean, 10.6 years) were obtained with 0.3-T magnetic resonance (MR) imaging. Lesions were divided into three categories: congenital anomalies, cystic lesions and fluid collections, and neoplasms. MR demonstrated lesions well in all categories. Midline lesions were best imaged sagittally, and lesions of paired structures, axially. The coronal plane was useful in evaluating the superoinferior extent of lesions and in defining the extent of lymphadenopathy. T1-weighted sequences were sufficient to depict most congenital and cystic lesions. T2-weighted sequences were useful in demonstrating the extent of neoplasms and the position of ectopic gonads. Ultrasonography (US) was also performed in 45 cases. MR and US delineated lesions equally well in 25 cases (55.5%), MR was superior in 19 (42.4%), and US was superior in one (2.2%). Computed tomography (CT) was performed in 13 cases. MR and CT delineated lesions equally well in eight cases (61.5%), MR was superior in four (30.8%), and CT was superior in one (7.7%).

Imaging of groin masses: inguinal anatomy and pathologic conditions revisited.

The groin region is subdivided into two distinct anatomic areas: the inguinal canal and the femoral triangle. A series of cross-sectional imaging cases illustrate that a good understanding of the local anatomic characteristics of the groin allows confident characterization of groin pathologic conditions. Such conditions can be classified into five major groups: congenital abnormalities, noncongenital hernias, vascular conditions, infectious or inflammatory processes, and neoplasms. Congenital entities include hernias, cysts, undescended testis, and retractile testes. Ultrasound (US) is useful in depicting these conditions. In the second group, noncongenital hernias, US allows visualization of bowel loops in peristalsis within the hernia. Herniography, computed tomography (CT), and magnetic resonance (MR) imaging are also helpful in diagnosis. Among vascular conditions, false aneurysms may be detected from the turbulent flow through the tract at Doppler US. The characteristic venous flow of varicoceles is best diagnosed with US during the Valsalva maneuver. Infectious or inflammatory conditions include, among others, hematomas, which appear hyperattenuating at CT and have variable appearances, depending on the age of the blood products, at MR imaging. The origins of neoplasms may be assessed at CT and MR imaging, although appearances of solid tumors are relatively nonspecific.

MR imaging of the calvarium: pictorial essay.

Magnetic resonance is unique in its ability to directly image the bone marrow. Thus, primary or secondary processes involving the bone marrow of the calvarium can be well visualized. In cases of superficial lesions, magnetic resonance demonstrates calvarial and bone marrow invasion. This is particularly important in cases where surgical preservation of the inner table in contemplated. Both erosion and involvement of the calvarium by intracranial processes can also be well visualized. Because of the ability of magnetic resonance to image in multiple orthogonal planes, it is particularly useful for precise delineation of the extent of lesions. Its ability to also image in oblique planes may aid in better demonstration of pathology. Use of both T1 and T2 weighted imaging sequences may also be of help in determination of the tissue type.

The significance of increased echogenicity in the detection and differentiation of pediatric disease.

Increased renal echogenicity, by ultrasonography, is seen in various pathological conditions. Correlation of renal size with the pattern and distribution of the increased echogenicity, and the patient's age and clinical data will limit the differential diagnosis and suggest the appropriate radiographic follow-up studies, obviating the need for unnecessary procedures.

Myelin disorders of childhood: correlation of MR findings and severity of neurological impairment.

Twenty-five children and young adults with myelin disorders were studied to determine how magnetic resonance (MR) findings correlated with the clinical severity of their disease. The MR images were evaluated using both subjective and objective criteria and graded for extent of white matter involvement. Patients were also graded for severity of their neurological and psychological impairment. The assessment of MR severity of white matter involvement using subjective and objective methods showed moderate to good correlation (r2 = 0.473). There was poor correlation between clinical severity of disease and extent of MR involvement for the overall group of children, however (subjective r2 = 0.038, objective r2 = 0.072). Moderate correlation was seen when clinical severity and MR subjective assessment were compared for the specific diseases metachromatic leukodystrophy and subacute sclerosing panencephalitis.