Occult lumbosacral dysraphism in children and young adults: diagnostic performance of fast screening and conventional MR imaging

PURPOSE

To compare fast screening and conventional magnetic resonance (MR) imaging for the detection of occult dysraphic myelodysplasias in children and young adults.

MATERIALS AND METHODS

A retrospective case-control study included 101 patients (mean age, 4.9 years; range, 1 day to 26 years) suspected of having occult lumbosacral dysraphism. Sixty case patients had myelodysplastic lesions (19 filar lipoma, 14 syringomyelia, 10 intradural lipoma, eight dermal sinus, five diastematomyelia, five lipomyelomeningocele, two caudal regression syndrome); 41 control patients had no dysraphic lesions; 17 patients had associated renal anomalies. Two neuroradiologists reviewed MR images from conventional and fast screening protocols. Diagnostic performance parameters included sensitivity, specificity, and area under the receiver operating characteristic curve (Az value).

RESULTS

The sensitivity of conventional and fast screening MR studies was 97.1% and 98.5%, respectively, the specificity was 90.9% and 84.8%, respectively. The Az value was 0.973 for the fast screening and 0.976 for the conventional MR studies (P = .83). Interobserver agreement was very good for fast screening images (kappa = 0.68) and excellent for conventional images (kappa = 0.75). For renal anomalies, the Az value was 0.786 and 0.853 for fast screening and conventional MR imaging, respectively (P = .28).

CONCLUSION

Conventional three-plane lumbosacral MR imaging in children and young adults suspected of having occult dysraphism provides better diagnostic information than does fast screening two-plane MR imaging because of its higher specificity and interobserver agreement.

Structural anomalies revealed by neuroimaging studies in the brains of patients with neurofibromatosis type 1 and large deletions

PURPOSE

The basis for cognitive problems in patients with neurofibromatosis type 1 (NF1) is unknown. A subset of NF1 patients with deletion of the entire NF1 gene has severe learning problems or mental retardation. We have reviewed neuroimaging studies (CT and MRI) in five such patients to determine whether structural anomalies in the brain are present and might explain the impaired cognitive function.

METHODS

Five patients with NF1 and deletion of the entire gene were identified by FISH studies. A retrospective review was conducted of CT and MRI images, as well as of data from developmental assessments.

RESULTS

All five patients had severe developmental impairment. None had been exposed to chemotherapy or radiation therapy. All had multiple regions of bright T2 signal intensity. Structural anomalies were seen in three of the five patients and included callosal dysgenesis in one, septum cavum vergae and pellucidum in two, mega cisterna magna in one, and Chiari I malformation with severe hydrocephalus in one patient.

CONCLUSION

Individuals with NF1 and large gene deletions have an increased frequency of structural anomalies of the brain not usually seen in NF1 patients. This suggests that the mental retardation in these individuals is due, at least in part, to abnormal brain development rather than a defect in brain function due to haplosufficiency of the NF1 gene product.

Imaging of neuroendocrine disorders of childhood

This article focuses on the neuroendocrine disorders of childhood. The commonly associated neuroradiologic abnormalities of the hypothalamic-pituitary axis are covered in detail.

Neuroimaging of scoliosis in childhood

A curvature abnormality may be the initial or major presenting feature in a child with disease of the spinal column or spinal neuraxis. A simplified classification of common spinal curvature abnormalities of childhood include idiopathic, congenital/dysraphic, skeletal dysplasia, neurofibromatosis, and painful. The great majority of childhood scoliosis falls into the idiopathic category. Atypical clinical or radiographic features in a presumed idiopathic scoliosis may indicate an otherwise occult tumor or hydrosyringomyelia, or may be a consequence of increasing curvature with disk protrusion, nerve impingement, or cord attenuation. Neuroimaging beyond plain films is commonly necessary for atypical idiopathic scoliosis and for the other categories of scoliosis listed.

Scoliosis circa 2000: radiologic imaging perspective. II. Treatment and follow-up

Plain film imaging remains important for the diagnosis and surveillance of scoliosis, as well as for the detection of complications after surgery. New means of treating scoliosis have become established and should be understood by the radiologist. To the well-known postoperative complications, including pneumothorax, pneumonia, and gastrointestinal obstruction, are added new specific potential problems with the new surgical methodology.

Childhood brain tumor: neuroimaging correlated with disease outcome

The authors explored the hypothesis that functional behavior of childhood brain tumors can be estimated by serial analysis of imaging (thallium-201 [201Tl] single-photon emission computed tomography and magnetic resonance imaging [MRI]) examinations. Seventy-five patients diagnosed on clinical or histologic grounds were monitored for a period of 1 day to 3.9 years (mean +/- S.D. = 1.39 +/- 1.10 years). Abnormal 201Tl uptake appeared to denote a subgroup of lesions with distinctly greater mortality and morbidity. Of 201Tl-positive patients, 17% died within the course of this study; no deaths occurred among the 201Tl-negative group. Other parameters of disease outcome also clearly separated the 201Tl-positive and 201Tl-negative groups, with the former demonstrating a 50% shorter period of recurrence-free survival from the time of diagnosis (two-tailed t test, P < 0.01). Significant enhancement with paramagnetic contrast agents paralleled 201Tl positivity in correlating with greater mortality but failed to predict duration of recurrence-free survival. The authors conclude that 201Tl activity provides significant predictive information of the expected biologic behavior of childhood brain tumors, both for duration of recurrence-free survival and for estimated life expectancy. This information complements and extends data provided by MRI enhancement patterns.

Focal cortical dysplasia with glioproliferative changes causing seizures: report of 3 cases

In contrast to neoplasia, lesions of focal cerebral dysplasia are thought to be completed developmental processes of abnormal neuronal migration. We present three children with seizures resulting from brain lesions which pathologically demonstrate regions of both clearcut focal cortical dysplasia and also hypercellularity and monomorphism typical of proliferative lesions such as low grade glial tumor. These cases suggest the existence of a distinct subgroup of patients with prominent glioproliferative changes in association with focal cortical dysplasia, challenging the conventional dichotomy between dysplastic and proliferative categories of brain lesions. Recognition of patients with dual pathology may be of practical as well as theoretical importance.

Tectal tumors of childhood: clinical and imaging follow-up

PURPOSE

This study was done to determine which clinical and imaging findings best correlate with outcome in children with tectal tumors.

METHODS

A retrospective review was done of the medical records and imaging studies of 32 children (16 boys and 16 girls; mean age, 8 years) with tectal tumors. Eight children had CT, 11 had MR imaging, and 13 had both CT and MR studies. Findings from surgical and pathologic reports as well as from follow-up examinations (mean follow-up period, 5 years; range, 3.6 months to 17 years) were included in the review.

RESULTS

All patients had hydrocephalus and all but one required CSF diversion. The tectum was the center of the tumor in all cases and the majority of the tumors appeared isodense on CT scans, isointense on T1-weighted MR images, and hyperintense on T2-weighted images. Twenty patients required no further treatment. In this group, the mean maximum tumor diameter was 1.8 cm and enhancement occurred in two cases. At follow-up, 18 patients had stable tumor size, one had an increase in tumor size with cyst formation but no worsening of symptoms, and one had a decrease in tumor size. Twelve patients required further treatment (excision and/or radiotherapy) because of progression as indicated by either increased tumor size or worsening of symptoms. In this group, the mean maximum tumor diameter was 2.5 cm and contrast enhancement occurred in nine cases. Further follow-up in this group showed decreased tumor size in eight and stable residual tumor in three.

CONCLUSION

Tectal tumors in childhood have variable behavior. MR imaging assists in the clinical determination of which children need treatment beyond CSF diversion. Larger tumor size and enhancement are radiologic predictors of the need for further treatment.

Efficacy of fast screening MR in children and adolescents with suspected intracranial tumors

PURPOSE

Our purpose was to determine the sensitivity, specificity, and receiver operator characteristic (ROC) curve of a fast screening MR protocol in children and adolescents with suspected intracranial tumors.

METHODS

One hundred forty-one patients (mean age, 9.7 years; range, 2 months to 23.5 years) with suspected brain tumor were entered in a case-control study. Eighty-seven patients had intracranial tumors (31 suprasellar/hypothalamic, 27 supratentorial, 26 infratentorial, and three pineal) and 54 patients in the control group had other disorders. Two neuroradiologists reviewed blindly a detailed three-sequence conventional protocol (acquisition time, 8 minutes 27 seconds) and a two-sequence fast screening MR protocol (acquisition time, 4 minutes 44 seconds).

RESULTS

Sensitivity and specificity of the fast screening protocol for intracranial tumors was 100% and 92.6%, respectively. The areas under the ROC curves were 0.966 for the fast screening and 0.980 for the conventional MR protocol. No diagnostic performance difference was found between the ROC curves using the Az index. A kappa statistic of .93 for both examinations indicated excellent interobserver agreement. Additional MR sequences and other neuroimaging studies were not deemed necessary to exclude the presence of an intracranial tumor.

CONCLUSION

A fast dual-plane brain MR protocol may be adequate to screen children and adolescents thought to have an intracranial tumor. The less than 5 minute acquisition time allows a complete examination (including preparation) to be performed in 10 to 15 minutes. Future studies are recommended before this time-efficient neuroimaging examination is incorporated into clinical practice.

Diencephalic syndrome: clinical features and imaging findings

PURPOSE

To emphasize the importance of imaging in children with diencephalic syndrome due to hypothalamic/chiasmatic astrocytomas.

METHODS

Findings in nine patients (mean age, 26 months) with diencephalic syndrome and hypothalamic/chiasmatic astrocytomas were analyzed retrospectively, including reviewing clinical records, imaging examinations, and follow-up studies.

RESULTS

Symptoms and signs included failure to thrive (n = 9), nystagmus (n = 3), visual field defects (n = 1), optic pallor (n = 1), emesis (n = 2), and headache (n = 1). All patients had hypothalamic/chiasmatic masses. Five patients underwent biopsy, and, in all cases, specimens showed low-grade astrocytoma. Imaging studies were available in eight patients. All tumors were large (median maximum diameter, 3.5 cm), involved the chiasm and hypothalamus, and showed homogeneous enhancement. Three patients had hydrocephalus and two had metastases. At follow-up, five patients had recurrent disease and two had died.

CONCLUSION

Diencephalic syndrome is a rare cause of failure to thrive in childhood, and diagnosis of a hypothalamic/ chiasmatic astrocytoma might therefore be delayed. The astrocytomas associated with this syndrome are larger, occur at a younger age, and are often more aggressive than other astrocytomas arising in this region.

Angiographic changes after pial synangiosis in childhood moyamoya disease

PURPOSE

To describe the angiographic changes accompanying the surgical treatment of moyamoya disease by pial synangiosis and to compare these changes with patient outcome.

METHODS

The preoperative and postoperative cerebral angiograms, MR images, and clinical records of 13 children treated with pial synangiosis for moyamoya disease were reviewed.

RESULTS

After synangiosis, 10 patients had significant neurologic improvement and three had minimal or no improvement. Postoperative MR images showed no new infarctions. Well-developed (grade A or B) transpial or transdural collaterals to the brain were present at the site of synangiosis in 84% of the surgically treated hemispheres. Cerebrovascular occlusive changes increased postoperatively in 76% of hemispheres. After synangiosis, moyamoya collaterals were increased in 48%, unchanged in 16%, and decreased in 36% of surgically treated hemispheres. All 10 patients with grade A or B collaterals bilaterally after synangiosis were asymptomatic or improved on follow-up.

CONCLUSION

Pial synangiosis typically results in an increase in collaterals from the superficial temporal artery or middle meningeal artery to the brain. Synangiosis appears to result in stabilization or improvement in neurologic symptoms but does not prevent the angiographic progression of disease or the development of moyamoya collaterals. The angiographic demonstration of well-formed collaterals after synangiosis is associated with a favorable clinical outcome.

Maternal phenylketonuria: magnetic resonance imaging of the brain in offspring

Phenylketonuria (PKU) produces white matter changes identifiable by magnetic resonance imaging. These changes occur postnatally. Offspring of untreated mothers with PKU also have a brain effect, expressed as microcephaly and mental retardation. This effect occurs prenatally. To determine whether the white matter changes seen in PKU are also present in maternal PKU offspring, despite the different developmental stages of exposure to PKU, we performed brain magnetic resonance imaging studies in seven maternal PKU offspring, five from essentially untreated pregnancies and two from treated pregnancies. None had white matter changes, although the one offspring with PKU had delayed myelination. However, hypoplasia of the corpus callosum was present in three of the four offspring from untreated pregnancies and in the offspring from a maternal PKU pregnancy not treated until the third trimester. Unlike PKU, white matter changes are not a feature of the brain effect in maternal PKU. However, hypoplasia of the corpus callosum is a feature of maternal PKU and is probably a result of inhibition of corpus callosum development at 8 to 20 weeks of gestation. The hypoplastic corpus callosum could be a marker for brain effect in maternal PKU and may have implications for the cognitive deficits in these offspring.

Structural abnormalities in brain magnetic resonance images of depressed children

OBJECTIVE

Brain magnetic resonance images (MRIs) of 65 children and adolescents who were hospitalized with depressive disorders (DD) were compared with the brain MRIs of 18 hospitalized psychiatric controls (PC) without a depressive disorder.

METHOD

Volumetric analyses were used to measure frontal lobe volumes (FLV), lateral ventricular volumes (VV), and total cerebral volumes (CV) for all subjects. To correct for differences in absolute cerebral volume associated with different body and head size, the ratios of FLV/CV and VV/CV were used to compare differences between the two groups. A multivariate analysis was used to control for the effects of several independent variables (age, sex, diagnosis).

RESULTS

Significant differences were seen in the FLV/CV ratio and the VV/CV ratio when the results were compared between the two groups (DD versus PC). The DD group had a significantly smaller FLV/CV ratio (t = 2.148, df = 79, p = .035) and a significantly larger VV/CV ratio (t = -2.093, df = 79, p = .040).

CONCLUSION

The findings are consistent with previous reports in depressed adults and may implicate the frontal lobes in the pathogenesis of early-onset depressive disorders.

Pediatric orbital and visual pathway lesions

This article presents the clinical and imaging aspects of some common and important orbital and optic pathway lesions occurring in childhood. Lesions that arise outside of and encroach on the orbit and visual pathways are included. Abnormalities intrinsic to the globe are covered elsewhere in this issue.

Hemorrhagic pituitary adenomas of adolescence

PURPOSE

To review the clinical and MR imaging findings in adolescents with hemorrhagic pituitary adenomas and to compare those findings with pathologic results and outcome.

METHODS

We reviewed the clinical records, imaging examinations, surgical and pathologic findings, and follow-up studies in 11 girls and six boys (12 to 20 years old; mean age, 16 years) with pituitary adenomas who were treated at our institution between August 1986 and June 1995.

RESULTS

Of the 17 adenomas, eight were macroadenomas (> 1 cm) in patients 14 to 18 years old (three girls, five boys). Six of the macroadenomas were grossly hemorrhagic, and appeared as high-intensity intrasellar/suprasellar masses on all MR sequences obtained before definitive diagnosis and treatment. Clinical presentation in the patients with the hemorrhagic macroadenomas included headache (five), visual field deficits (three), and neuroendocrine symptoms (three). One patient was asymptomatic. The preliminary clinical and imaging diagnoses were craniopharyngioma or Rathke's cyst in five of the six cases. Pathologic diagnoses were prolactinoma in four patients, plurihormonal (prolactin/follicle-stimulating hormone) tumor in one patient, and nonfunctioning adenoma in one patient. Surgical resection was performed in all six hemorrhagic tumors and radiation therapy was required in three cases.

CONCLUSION

Pituitary adenomas uncommonly occur in childhood and are usually seen in adolescence. The majority of the macroadenomas are hemorrhagic and often occur in male subjects. The clinical and MR imaging features may mimic craniopharyngioma or Rathke's cyst. These tumors often require surgery and/or radiation therapy.

Hemorrhagic vasculopathy after treatment of central nervous system neoplasia in childhood: diagnosis and follow-up

PURPOSE

To review the clinical data, imaging findings, and intermediate outcomes of a series of children with hemorrhagic vasculopathy after treatment for intracranial neoplasia.

METHODS

We retrospectively analyzed the medical records and imaging examinations of 20 pediatric patients (ages 1 to 15 years) with intracranial neoplasia in whom delayed intracranial hemorrhage developed after cranial irradiation or radiation combined with systemic or intrathecal chemotherapy. Patients with intracranial hemorrhage from other identifiable causes were excluded. Histopathologic analysis was available in four patients.

RESULTS

Twenty patients with delayed intracranial hemorrhage received cranial irradiation alone (n = 9) or combined radiation and chemotherapy (n = 11) for primary brain tumors (n = 13), leukemia (n = 6), or lymphoma (n = 1). Imaging findings were consistent with hemorrhages of varying ages. The hemorrhages were not associated with tumor recurrence nor second tumors. Except for location of the hemorrhage, no significant relationship was established between outcome and original diagnosis, radiation dose (range, 1800 to 6000 centigray), chemotherapeutic agent or dosage, age at treatment, or interval between therapy and hemorrhage (mean, 8.1 years). Only brain stem hemorrhage was associated with a poor outcome.

CONCLUSION

In children with central nervous system neoplasia who have undergone cranial irradiation, or radiation combined with chemotherapy, delayed intracranial hemorrhage may develop.

Dysraphic myelodysplasias associated with urogenital and anorectal anomalies: prevalence and types seen with MR imaging

OBJECTIVE

The purpose of this study was to determine by MR imaging the prevalence and types of dysraphic abnormalities of the spinal cord (i.e., myelodysplasias) associated with urogenital and anorectal malformations of childhood.

MATERIALS AND METHODS

Since 1987, 92 patients with imperforate anus complex, cloacal malformation, and cloacal exstrophy have had MR imaging as a screening examination for occult dysraphic myelodysplasia. The prevalence and types of myelodysplasia were determined for each group.

RESULTS

The prevalence of dysraphic myelodysplasia in each group of children was 17% (1/6) for low imperforate anus (ectopic anus), 34% (11/32) for high imperforate anus (with fistulization), 46% (19/41) for cloacal malformation, and 100% (13/13) for cloacal exstrophy. The most common abnormalities in each group were tethered cord with intradural or filar lipoma in imperforate anus; low-placed or dysplastic conus medullaris and tethered cord with lipoma or myelolipoma in cloacal malformation; and lipomyelocele, lipomyelomeningocele, or lipomyelocystocele in cloacal exstrophy.

CONCLUSION

Our results show that the prevalence of myelodysplasia as seen on MR imaging is high in patients with urogenital and anorectal anomalies.

Cystic retrocerebellar malformations: unification of the Dandy-Walker complex and the Blake's pouch cyst

Twenty-six cases of developmental retrocerebellar cyst (RCC) formation are studied with respect to determining the usefulness and anatomic relevance of separate terms currently in use, including Dandy-Walker complex, Dandy-Walker malformation, Dandy-Walker variant, mega-cisterna magna (MCM), and Blake's pouch cyst. An anatomic and embryological continuum between Dandy-Walker complex and Blake's pouch cyst is proposed. A method for the useful assessment of RCC is outlined. The patency or closure of the aqueduct is crucial to the evaluation and management of hydrocephalus associated with RCC formation.