Reproducibility of detecting silent cerebral infarcts in pediatric sickle cell anemia

Detecting silent cerebral infarcts on magnetic resonance images (MRIs) in children with sickle cell anemia is challenging, yet reproducibility of readings has not been examined in this population. We evaluated consensus rating, inter-, and intra-grader agreement associated with detecting silent cerebral infarct on screening MRI in the Silent Infarct Transfusion Trial. Three neuroradiologists provided consensus decisions for 1073 MRIs. A random sample of 53 scans was reanalyzed in blinded fashion. Agreement between first and second consensus ratings was substantial (κ = 0.70, P < .0001), as was overall intergrader agreement (κ = 0.76, P < .0001). In the test-retest sample, intragrader agreement ranged from κ of 0.57 to 0.76. Consensus decisions were more concordant when MRIs contained more than one larger lesions. Routine use of MRI to screen for silent cerebral infarcts in the research setting is reproducible in sickle cell anemia and agreement among neuroradiologists is sufficient.

Controlled trial of transfusions for silent cerebral infarcts in sickle cell anemia

BACKGROUND

Silent cerebral infarcts are the most common neurologic injury in children with sickle cell anemia and are associated with the recurrence of an infarct (stroke or silent cerebral infarct). We tested the hypothesis that the incidence of the recurrence of an infarct would be lower among children who underwent regular blood-transfusion therapy than among those who received standard care.

METHODS

In this randomized, single-blind clinical trial, we randomly assigned children with sickle cell anemia to receive regular blood transfusions (transfusion group) or standard care (observation group). Participants were between 5 and 15 years of age, with no history of stroke and with one or more silent cerebral infarcts on magnetic resonance imaging and a neurologic examination showing no abnormalities corresponding to these lesions. The primary end point was the recurrence of an infarct, defined as a stroke or a new or enlarged silent cerebral infarct.

RESULTS

A total of 196 children (mean age, 10 years) were randomly assigned to the observation or transfusion group and were followed for a median of 3 years. In the transfusion group, 6 of 99 children (6%) had an end-point event (1 had a stroke, and 5 had new or enlarged silent cerebral infarcts). In the observation group, 14 of 97 children (14%) had an end-point event (7 had strokes, and 7 had new or enlarged silent cerebral infarcts). The incidence of the primary end point in the transfusion and observation groups was 2.0 and 4.8 events, respectively, per 100 years at risk, corresponding to an incidence rate ratio of 0.41 (95% confidence interval, 0.12 to 0.99; P=0.04).

CONCLUSIONS

Regular blood-transfusion therapy significantly reduced the incidence of the recurrence of cerebral infarct in children with sickle cell anemia. (Funded by the National Institute of Neurological Disorders and Stroke and others; Silent Cerebral Infarct Multi-Center Clinical Trial ClinicalTrials.gov number, NCT00072761, and Current Controlled Trials number, ISRCTN52713285.).

Acute silent cerebral ischemic events in children with sickle cell anemia

BACKGROUND

Irregular, sporadic episodes of ischemic brain injury are known to occur in sickle cell anemia (SCA), resulting in overt stroke and silent cerebral infarction. Ongoing ischemia in other organs is common in SCA but has never been documented in the brain.

OBJECTIVE

To test the hypothesis that acute silent cerebral ischemic events (ASCIEs) are frequent and potentially transient.

DESIGN

Cross-sectional and cohort study of children with SCA screened by magnetic resonance imaging (MRI) of the brain for a randomized clinical trial.

SETTING

Clinical trial setting in tertiary care centers.

PATIENTS

Asymptomatic children with SCA without known stroke, neurologic injury, or epilepsy not receiving treatment with transfusions or hydroxyurea.

MAIN OUTCOME MEASURE

Incidence of ASCIEs calculated using single diffusion-weighted MRI scans (acute ischemic events that occurred within 10 days of the MRI).

RESULTS

Acute silent cerebral ischemic events were detected on 1.3% of MRIs (10 of 771) in 652 children (mean age, 10.0 years), with an incidence of 47.3 events per 100 patient-years (95% CI, 22.7-87.2). Two of 10 children with ASCIEs had follow-up MRIs of the brain; only 1 had silent cerebral infarction in the same location as the previously detected ASCIE.

CONCLUSIONS

Children with SCA experience ongoing (chronic, intermittent) cerebral ischemia, sometimes reversible, far more frequently than previously recognized. The brain in SCA is at constant threat of ischemia.

Incidental findings on brain magnetic resonance imaging of children with sickle cell disease

OBJECTIVE

We describe the prevalence and range of incidental intracranial abnormalities identified through MRI of the brain in a large group of children screened for a clinical trial.

METHODS

We included 953 children between 5 and 14 years of age who were screened with MRI of the brain for the Silent Infarct Transfusion Trial. All had sickle cell anemia or sickle beta-null thalassemia. MRI scans were interpreted by 3 neuroradiologists. MRI scans reported to have any abnormality were reviewed by 2 study neuroradiologists. Incidental findings were classified into 4 categories, that is, no, routine, urgent, or immediate referral recommended. Cerebral infarctions and vascular lesions were not considered incidental and were excluded.

RESULTS

We identified 63 children (6.6% [95% confidence interval: 5.1%-8.4%]) with 68 incidental intracranial MRI findings. Findings were classified as urgent in 6 cases (0.6%), routine in 25 cases (2.6%), and no referral required in 32 cases (3.4%). No children required immediate referral. Two children with urgent findings underwent surgery in the subsequent 6 months.

CONCLUSION

In this large cohort of children, incidental intracranial findings were identified for 6.6%, with potentially serious or urgent findings for 0.6%.

Silent Cerebral Infarct Transfusion (SIT) trial imaging core: application of novel imaging information technology for rapid and central review of MRI of the brain

The Silent Cerebral Infarct Multicenter Transfusion (SIT) Trial is a multi-institutional intervention trial in which children with silent cerebral infarcts are randomized to receive either blood transfusion therapy or observation (standard care) for 36 months. The SIT Trial is scheduled to enroll approximately 1,880 children with sickle cell disease from 29 clinical sites in the United States, Canada, UK, and France. Each child undergoes a screening magnetic resonance imaging (MRI) of the brain to detect the presence of silent cerebral infarct-like lesions, a pre-randomization (baseline) MRI and exit MRI to determine if there are new or enlarged cerebral infarcts, using a designated, prospective imaging protocol. The objective of this manuscript is to describe the innovative method used to process and adjudicate imaging studies for an international trial with a primary endpoint that includes neuroimaging. Institution investigators at each site were provided with computer hardware and software for transmission of MRI images that allow them to strip the scans of all personal information and add unique study identifiers. Three neuroradiologists at separate academic centers review MRI studies and determine the presence or absence of silent cerebral infarct-like lesions. Their findings are subsequently placed on web-based case report forms and sent to the Statistical Coordinating Center. The average time from imaging center receipt of the MRI study to the radiology committee report back to the local site is less than two working days. This novel strategy was designed to maximize efficiency and minimize cost of a complex large multicenter trial that depends heavily on neuroimaging for entry criteria and assessment for the primary outcome measures. The technology, process, and expertise used in the SIT Trial can be adapted to virtually any clinical research trial with digital imaging requirements.

Elevated lactate as an early marker of brain injury in inflicted traumatic brain injury

BACKGROUND

Traumatic brain injury is a major cause of disability and death in the pediatric population. The metabolic and neurochemical abnormalities that underlie traumatic brain injury remain poorly understood, but hypoxia-ischemic injury might play an important role.

OBJECTIVE

This study evaluated children with inflicted traumatic brain injury using magnetic resonance spectroscopy (MRS). We postulated that children with hypoxic-ischemic injury indicated by elevated lactate in the acute phase of injury will have worse early neurological status and short-term clinical outcomes than those without lactate upon MRS.

MATERIALS AND METHODS

This prospective study employed proton MRS to sample bilaterally the frontal lobes and the parasagittal cortex within the parietal and occipital lobes of 11 patients with inflicted traumatic brain injury who were undergoing a clinical MRI examination. Patients' measured clinical course while hospitalized included initial neurological evaluation, presence of seizure activity, need for admission to the pediatric intensive care unit (PICU), number of days hospitalized, presence of retinal hemorrhages and presence of bone fractures. Measurement of outcome was determined using the Pediatric Overall Performance Category Scale (POPCS; 1=good performance; 6=death).

RESULTS

Four children demonstrated elevated lactate and diminished N-acetyl aspartate (a neuronal marker) within several regions, indicating global ischemic injury (lactate-positive global group). These four children all had seizure activity and abnormal initial neurological examinations and required admission to the PICU. The mean POPCS for this group was 3.25. In four other children, lactate was detected within at least one region, indicating a focal ischemic injury (lactate-positive focal group); two of these children had seizure activity, and two had an abnormal initial neurological examination. The mean POPCS score was 1.5 for this group. The remaining three children had no evidence of lactate upon MRS (lactate-negative group). These children did not have seizure activity, did not require admission to the PICU, nor did they have initial abnormal neurological examinations. The mean POPCS score was 1.3 for this group.

SUMMARY

Patients with inflicted traumatic brain injury and evidence of hypoxic-ischemic injury as indicated by elevated lactate on MRS tend to have worse early neurological status and early outcome scores. Lactate levels as sampled by MRS might predict early clinical outcome in inflicted traumatic brain injury.

Functional magnetic resonance imaging in pediatrics

Functional magnetic resonance imaging (fMRI) allows non-invasive assessment of human brain function in vivo by detecting blood flow differences. In this review, we want to illustrate the background and different aspects of performing functional magnetic resonance imaging (fMRI) in the pediatric age group. An overview over current and future applications of fMRI will be given, and typical problems, pitfalls, and benefits of doing fMRI in the pediatric age group are discussed. We conclude that fMRI can successfully be applied in children and holds great promise for both research and clinical purposes.

The clinical syndrome of creatine transporter deficiency

To describe the clinical, spectroscopic and neuropsychological features of the first family diagnosed with a defect in the creatine transporter. Proton Magnetic Resonance Spectroscopy (MRS) indicated an absence of creatine and phosphocreatine in the brain of a male patient characterized by developmental delay, mild epilepsy and severe expressive language impairment. Subsequent genetic testing revealed a defect in the X-linked creatine transporter (SLC6A8/CT1), with a hemizygous mutation in the patient and a heterozygous mutation for the female carriers. Magnetic resonance imaging and spectroscopy examinations were performed on a 1.5T clinical MR Scanner. Neuropsychological examinations were performed on the index patient and maternal relatives. Preliminary spectroscopy results indicate the disorder prevents transport of creatine and phosphocreatine in the brain of the affected male. However, the skeletal muscle demonstrates the presence of creatine and phosphocreatine which correlates clinically with normal structure and function. Female carriers demonstrated impairments in confrontational naming and verbal memory assessments. This new neurological syndrome is associated with developmental delay, mild epilepsy, severe language impairment. MR Spectroscopy is a non-invasive method for obtaining a preliminary diagnosis of this disorder. Muscle creatine uptake may be normal in this disorder.

Language processing during natural sleep in a 6-year-old boy, as assessed with functional MR imaging

Functional MR imaging for language lateralization was performed in a 6-year-old child before neurosurgical intervention. A passive story-listening task was used; this revealed a bilateral language network. The task was repeated during the same session when the child had fallen asleep and surprisingly yielded strong activation in similar language areas. Our findings suggest that language processing does occur during natural sleep, even in young children. This potentially allows for an assessment of language functions, even in sleeping children.

Vein of Galen aneurysmal malformation: diagnosis and treatment of 13 children with extended clinical follow-up

BACKGROUND AND PURPOSE

We herein present our experience in diagnosing and treating 13 children with vein of Galen aneurysmal malformations (VGAM), with an emphasis on possible prognostic indicators, endovascular strategies, factors affecting treatment during the neonatal period, and long-term follow-up. With this review, we hope to identify those factors that have the most significant prognostic value in determining long-term outcomes in children with VGAM.

METHODS

We retrospectively reviewed the radiology studies, hospital charts, and outpatient clinic chart notes (when applicable) of 13 children evaluated and treated for VGAM at a single tertiary care pediatric hospital. Clinical presentation, diagnostic methods, treatment strategies, and outcome were documented for each child. The present neurologic status and level of function of each patient was determined by review of the outpatient charts and direct contact with the clinicians who were conducting the follow-up. Outcome was graded on a 5-point scale, ranging from 0 (death) to 4 (normal), taking into account only neurologic and developmental characteristics.

RESULTS

Eight of 13 patients presented as neonates with congestive heart failure. The other five patients ranged in age from 4 months to 13 years at the time of presentation. The five patients presenting outside of the neonatal period achieved normal or near-normal outcomes. Two of the eight patients presenting during the neonatal period achieved normal or near-normal outcomes, one experienced significant impairment, and the other five died. We were unable to identify significant differences in outcome on the basis of differences in treatment strategies.

CONCLUSION

Our experience confirms that children with VGAM presenting during the neonatal period have a generally much worse prognosis than do those presenting later in childhood. Complicating factors in the management and treatment of these children are discussed in light of their impact on outcome.

Identification of an arteriovenous fistula in a child. Case report and review of the literature

BACKGROUND

A 6-year-old girl sustained a subarachnoid hemorrhage after a mild head injury and was discovered to have an arteriovenous fistula (AVF).

INVESTIGATIONS AND TREATMENT

The etiology of subarachnoid hemorrhage was not evident on the initial brain CT. Brain CT with CT angiography identified the lesion. The AVF was further imaged with brain MRI followed by cerebral angiography and successfully embolized.

OUTCOME

The child did not suffer any neurological sequelae.

Normal fMRI brain activation patterns in children performing a verb generation task

Although much is known concerning brain-language relations in adults, little is known about how these functions might be represented during the developmental period. We report results from 17 normal children, ages 7-18 years, who have successfully completed a word fluency paradigm during functional magnetic resonance imaging at 3 Tesla. Regions of activation replicate those reported for adult subjects. However, a statistically significant association between hemispheric lateralization of activation and age was found in the children. Specifically, although most subjects at all ages showed left hemisphere dominance for this task, the degree of lateralization increased with age. This study demonstrates that fMRI can reveal developmental shifts in the pattern of brain activation associated with semantic language function.

X-linked creatine-transporter gene (SLC6A8) defect: a new creatine-deficiency syndrome

We report the first X-linked creatine-deficiency syndrome caused by a defective creatine transporter. The male index patient presented with developmental delay and hypotonia. Proton magnetic-resonance spectroscopy of his brain revealed absence of the creatine signal. However, creatine in urine and plasma was increased, and guanidinoacetate levels were normal. In three female relatives of the index patient, mild biochemical abnormalities and learning disabilities were present, to various extents. Fibroblasts from the index patient contained a hemizygous nonsense mutation in the gene SLC6A8 and were defective in creatine uptake. The three female relatives were heterozygous for this mutation in SLC6A8, which has been mapped to Xq28.

Popliteal vein compression by a fibular osteochondroma. A case report

A 15-year-old female presented with chronic right lower leg swelling and pain. Her symptomatology proved to be as a result of popliteal vein compression by a fibular osteochondroma. Clinical improvement followed surgical resection of the osteocartilaginous exostosis.

Cranial chordomas in infancy and childhood. A report of two cases and review of the literature

Cranial chordomas are uncommon, accounting for less than 1% of all intracranial neoplasms. Although they are presumed to arise from congenital notochordal remnants, it is rare for these tumors to present in childhood. Only 35 cases of cranial chordomas have been reported in children 16 years of age or younger. We report 2 additional cases of pediatric cranial chordomas. One occurred in a 4 month old infant and to our knowledge represents the earliest age of presentation yet reported. The second case documents the value of MR imaging in delineating the extent of the tumor and defining its relationship to adjacent structures.

Magnetic resonance imaging of fourth ventricular choroid plexus neoplasms in childhood. A report of two cases

Choroid plexus neoplasms (CPN) are rare tumors occurring with a relative incidence of 0.5% of intracranial neoplasms in all age groups and 1.5-6.4% of all pediatric brain tumors. In children, the most common site of origin is the atria of the lateral ventricles where the CPN may represent either a carcinoma or a benign papilloma. CPN arising in the fourth ventricle are more common in adults, and are more likely to represent a benign papilloma. We present 2 children with CPN arising from the inferior fourth ventricle with similar features on MRI, one of which represented a benign papilloma and the other a malignant carcinoma. CPN should be included, even in young children, in the differential diagnosis of any infratentorial, intraventricular tumor.

Irreversible brain creatine deficiency with elevated serum and urine creatine: a creatine transporter defect?

Recent reports highlight the utility of in vivo magnetic resonance spectroscopy (MRS) techniques to recognize creatine deficiency syndromes affecting the central nervous system (CNS). Reported cases demonstrate partial reversibility of neurologic symptoms upon restoration of CNS creatine levels with the administration of oral creatine. We describe a patient with a brain creatine deficiency syndrome detected by proton MRS that differs from published reports. Metabolic screening revealed elevated creatine in the serum and urine, with normal levels of guanidino acetic acid. Unlike the case with other reported creatine deficiency syndromes, treatment with oral creatine monohydrate demonstrated no observable increase in brain creatine with proton MRS and no improvement in clinical symptoms. In this study, we report a novel brain creatine deficiency syndrome most likely representing a creatine transporter defect.

NMR relaxation times in the human brain at 3.0 tesla

Relaxation time measurements at 3.0 T are reported for both gray and white matter in normal human brain. Measurements were made using a 3.0 T Bruker Biospec magnetic resonance imaging (MRI) scanner in normal adults with no clinical evidence of neurological disease. Nineteen subjects, 8 female and 11 male, were studied for T1 and T2 measurements, and 7 males were studied for T2. Measurements were made using a saturation recovery method for T1, a multiple spin-echo experiment for T2, and a fast low-angle shot (FLASH) sequence with 14 different echo times for T2. Results of the measurements are summarized as follows. Average T1 values measured for gray matter and white matter were 1331 and 832 msec, respectively. Average T2 values measured for gray matter and white matter were 80 and 110 msec, respectively. The average T2 values for occipital and frontal gray matter were 41.6 and 51.8 msec, respectively. Average T2 values for occipital and frontal white matter were 48.4 and 44.7 msec, respectively. ANOVA tests of the measurements revealed that for both gray and white matter there were no significant differences in T1 from one location in the brain to another. T2 in occipital gray matter was significantly higher (0.0001 < P < .0375) than the rest of the gray matter, while T2 in frontal white matter was significantly lower (P < 0.0001). Statistical analysis of cerebral hemispheric differences in relaxation time measurements showed no significant differences in T1 values from the left hemisphere compared with the right, except in insular gray matter, where this difference was significant at P = 0.0320. No significant difference in T2 values existed between the left and right cerebral hemispheres. Significant differences were apparent between male and female relaxation time measurements in brain.

NMR relaxation times in the human brain at 3.0 tesla

Relaxation time measurements at 3.0 T are reported for both gray and white matter in normal human brain. Measurements were made using a 3.0 T Bruker Biospec magnetic resonance imaging (MRI) scanner in normal adults with no clinical evidence of neurological disease. Nineteen subjects, 8 female and 11 male, were studied for T1 and T2 measurements, and 7 males were studied for T2. Measurements were made using a saturation recovery method for T1, a multiple spin-echo experiment for T2, and a fast low-angle shot (FLASH) sequence with 14 different echo times for T2. Results of the measurements are summarized as follows. Average T1 values measured for gray matter and white matter were 1331 and 832 msec, respectively. Average T2 values measured for gray matter and white matter were 80 and 110 msec, respectively. The average T2 values for occipital and frontal gray matter were 41.6 and 51.8 msec, respectively. Average T2 values for occipital and frontal white matter were 48.4 and 44.7 msec, respectively. ANOVA tests of the measurements revealed that for both gray and white matter there were no significant differences in T1 from one location in the brain to another. T2 in occipital gray matter was significantly higher (0.0001 < P < .0375) than the rest of the gray matter, while T2 in frontal white matter was significantly lower (P < 0.0001). Statistical analysis of cerebral hemispheric differences in relaxation time measurements showed no significant differences in T1 values from the left hemisphere compared with the right, except in insular gray matter, where this difference was significant at P = 0.0320. No significant difference in T2 values existed between the left and right cerebral hemispheres. Significant differences were apparent between male and female relaxation time measurements in brain.

Central nervous system relapse of treated stage IV neuroblastoma

Neuroblastoma is the most common extracranial solid tumor in pediatrics. The long-term survival of patients with advanced-stage neuroblastoma has remarkably improved secondary to aggressive treatment protocols including autologous bone marrow transplant (BMT). As a result, a different natural history of this disease is being reported with unusual, late manifestations. The central nervous system (CNS), once a rare site of disease, is being involved with increasing frequency. Appropriate neuroimaging in these patients is important. Two cases of patients with treated stage IV neuroblastoma who developed isolated CNS metastases are presented. The proposed pathogenesis and neuroradiologic manifestations of this complication are reviewed.

Research in pediatric radiology: preparing for our future

The changing healthcare environment challenges the traditional role of academic medicine. Pediatric radiologists involved in research, education and teaching are under pressure to forego such endeavors in favor of increased clinical responsibilities. How we perform research must change if our subspecialty is to survive into the future, as we cannot afford to give up our traditional duties as researchers and educators. To do so could summon the beginning of the end for pediatric radiology. Rather, we must begin the process of restructuring research in pediatric radiology to take into account the efficient use of our resources which provide the greatest return on our investment.

Atretic parietal cephaloceles revisited: an enlarging clinical and imaging spectrum?

PURPOSE

We describe imaging features that are clues to the diagnosis of atretic cephaloceles and discuss clinical findings and a possible mechanism by which these lesions develop.

METHODS

Eight children (five girls and three boys) ranging in age from 1 day to 3 years 4 months with midline subscalp lesions underwent radiologic examination with CT or MR imaging. In all cases, the lesions were surgically excised and subjected to pathologic examination. Imaging studies and medical records were reviewed retrospectively.

RESULTS

Six of eight children had vertical embryonic positioning of the straight sinus with a prominent superior cerebellar cistern. A "spinning-top" configuration of the tentorial incisura, a "cigar-shaped" CSF tract within the interhemispheric fissure, fenestration of the superior sagittal sinus, and "peaking" of the tentorium were associated findings helpful in making this diagnosis. Two of the eight children had findings indistinguishable from focal dermoid, six were developmentally normal, one had mild motor delay, and one died at the age of 3 years. Pathologic examination revealed glial, meningeal (arachnoid), fibrous, and dermal elements.

CONCLUSION

Characteristic findings on MR images and CT scans provide clues to the diagnosis of atretic cephalocele. However, even in the presence of abnormal imaging findings, these children may be developmentally normal.

Proton MR spectroscopic characteristics of pediatric pilocytic astrocytomas

PURPOSE

We report the common characteristics of juvenile pilocytic astrocytomas revealed by proton MR spectroscopy.

METHODS

Eight children with pilocytic astrocytomas were studied with proton MR spectroscopy. The selected sampling volume was approximately 4 cm3, obtained from solid tumor. To localize the sampling volume, we used point-resolved spectroscopy (PRESS) and stimulated-echo acquisition mode (STEAM) techniques to acquire long- and short-TE spectra, respectively. Spectra from PRESS and STEAM sequences were processed using Lorentzian-to-Gaussian transformation and exponential apodization, respectively. For PRESS (2000/270) spectra, peaks of creatine, choline, N-acetylaspartate (NAA), and lactate resonances were integrated; for STEAM (2000/20) spectra, we measured the amplitude of the peaks at 3.2, 2.0, 1.3 and 0.9 ppm.

RESULTS

An elevated lactate doublet was observed in the PRESS spectra. The choline/NAA ratio was 3.40. The amplitude ratios of the lipid pattern (0.9, 1.3 and 2.0 ppm) to choline were all below one.

CONCLUSION

Despite the benign histology of the tumor, which generally lacks necrosis, a lactate signal was detected in all eight patients studied. A dominant lipid pattern was not observed.

Formation of intracerebral cavernous malformations after radiation treatment for central nervous system neoplasia in children

OBJECT

Radiation is a common treatment modality for pediatric brain tumors. The authors present a retrospective review of six children who developed cerebral cavernous malformations after they underwent radiation treatment for central nervous system (CNS) neoplasia and propose two possible models to explain the formation of cavernous malformations.

METHODS

Three boys, aged 13, 9, and 17 years, suffered intracerebral hemorrhages from cerebral cavernous malformations 87, 94, and 120 months, respectively, after they received whole-brain radiation therapy (WBRT) for acute lymphocytic leukemia. A 10-year-old girl and a 19-year-old man developed temporal lobe cavernous malformations 46 and 48 months, respectively, after they received radiation therapy for posterior fossa astrocytomas. A 12-year-old girl developed a temporal lobe cavernous malformation 45 months after WBRT was administered for a medulloblastoma. In all of these cases the cavernous malformation appeared in the irradiated field, was not known to be present prior to radiation therapy, and developed after a latency period following treatment. The incidence of cavernous malformations in these patients suggests that children who undergo radiation therapy of the brain may have an increased risk of hemorrhage.

CONCLUSIONS

Two possible models may explain the formation of cavernous malformations following brain radiation in these patients. First, the cavernous malformations may form de novo in response to the radiation. Second, the cavernous malformations may have been present, but radiographically occult, at the time of radiation therapy and may have hemorrhaged in response to the radiation. The authors conclude that cavernous malformations may develop after brain radiation and propose a possible mechanism for this formation.

Parry-Romberg syndrome: follow-up imaging during suppressive therapy

Parry-Romberg syndrome is a poorly--understood disorder characterized by progressive hemifacial atrophy involving the skin, soft tissue, and bone. Involvement of the central nervous system with impairment in neurologic function occurs infrequently. We describe a child with this syndrome in whom central nervous system involvement, documented on serial MRI, played a prominent role. We have attempted to correlate the clinical course with the radiologic findings, and to determine the impact of prednisone and methotrexate on the intracranial lesions.

Safety and efficacy of sedation in children using a structured sedation program

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of sedating pediatric outpatients in a radiology department using a structured sedation program modeled after the guidelines of the American Academy of Pediatrics.

MATERIALS AND METHODS

Medical records of 6006 pediatric outpatients who underwent sedation for imaging studies under the guidelines of a structured sedation program were retrospectively reviewed for safety and efficacy of sedation, complications related to sedation, and rate of successful sedation.

RESULTS

No cases of cardiovascular or respiratory arrest or fatalities occurred. Four children who required overnight hospitalization because of CNS depression had no sequelae. Forty-eight patients experienced transient respiratory depression that proved responsive to supplemental oxygen. Delayed complications were found in 29 children, none of whom required hospitalization. The rate of sedation failure was approximately 1%.

CONCLUSION

Sedation of children can be done in a safe and highly efficacious manner in a hospital radiology department using a structured sedation program modeled after the guidelines of the American Academy of Pediatrics.

Trilateral retinoblastoma with suprasellar involvement

"Trilateral retinoblastoma" (TRB) is the association of a midline intracranial tumor with familial bilateral retinoblastoma. Classically, the intracranial tumor is a pineal region tumor (pineoblastoma) with histology similar to retinoblastoma. We present a 7-month-old child with bilateral orbital retinoblastoma with a third tumor arising in the chiasmatic cistern. The presentation and prognosis of patients with this association differ from those children with "classical" TRB. The presentation, treatment, and outcome are described, with a review of the literature.

Intracranial tumors in children: small single-voxel proton MR spectroscopy using short- and long-echo sequences

We report preliminary experience using single-voxel, proton MR spectroscopy (MRS) employing small voxels of interest, in combination with short and long echo-time protocols, for the assessment of primary intracranial tumors in children. We examined 23 children with primary intracranial tumors detected by MRI, and 32 controls with similar ages, using MRS on a 1.5 T system. Localized single-voxel (3.7 +/- 1.3 cc) proton spectra were obtained with short-echo (2,000/18), stimulated-echo (STEAM) and long-echo (2,000/270) spin-echo (PRESS) protocols. All spectra were evaluated qualitatively; 10 tumor and 19 control spectra were processed for peak area quantification. Small voxels of interest were able to account for tissue heterogeneity. Combined acquisition of short- and long-echo spectra increased the number of detectable metabolites. The solid portion of all tumors exhibited reduced N-acetyl-aspartate (NAA), strong contribution from cholines (Cho) and inositols or glycine, minimal presence of total creatine (tCr), enhanced broad mobile lipid resonances and accumulated lactate. Calculated selected metabolite ratios of Cho/tCr and Cho/NAA were substantially increased from control values. The cystic portions of the masses showed only lipid and lactate peaks.

Alexander disease: a case report and review of the literature

Alexander disease (AD) is a rare progressive lethal leukodystrophy usually affecting infants and characterized by progressive failure of central myelination and accumulation of Rosenthal fibers (RFs) in astrocytes. Despite strong male predilection and infrequency of involved siblings, an autosomal recessive mode of inheritance is presumed. We report a typical case of infantile AD with imaging studies, a complete autopsy, and a critical literature review. Recent studies of AD have identified several stress proteins plus glial fibrillary protein as major constituents of RFs but have not clarified the basic defect. Advances in understanding of astrocyte function suggest an important role in the process of myelination that may be interrupted in AD. The nosology of putative juvenile-onset and adult-onset examples continues to be uncertain.

Quantitative sonographic feature analysis of clinical infant hypoxia: a pilot study

PURPOSE

To determine whether textural features derived from sonographic pixel intensities differ significantly between healthy infants and infants who have had acute clinical hypoxic episodes.

METHODS

Neurosonographic and calibration phantom-processed image data were evaluated prospectively from 9 infants (age range, 1 to 163 days) with at least 1 episode of hypoxia and compared with image data from a control population of 16 healthy infants (age range, 1 to 191 days). Custom software was used to make 45 textural feature measurements on 40 x 40-pixel regions of interest within brain parenchyma in the distribution of each major cerebral artery, the thalami, and the cerebellum and in a tissue-mimicking calibration phantom. Means comparison testing was followed by logistic regression to assess statistical variation between the patients and the control group.

RESULTS

Nine of 45 textural features showed statistically significant differences between mean values comparing the two groups. Mean gray level was the most sensitive predictor of differences between the two populations (mean gray level for healthy subjects was 46.8; mean gray level for patients was 56.3). An average of mean gray values in areas supplied by the posterior cerebral arteries and the cerebellum was even more sensitive for differentiating healthy subjects from patients.

CONCLUSIONS

Quantitative sonographic textural feature analysis showed differences between the brains of healthy infants and those of infants with clinical hypoxia.