ADC Histogram Analysis of Pediatric Low-Grade Glioma Treated with Selumetinib: A Report from the Pediatric Brain Tumor Consortium

BACKGROUND AND PURPOSE

Selumetinib is a promising MAP (mitogen-activated protein) kinase (MEK) 1/2 inhibitor treatment for pediatric low-grade gliomas. We hypothesized that MR imaging-derived ADC histogram metrics would be associated with survival and response to treatment with selumetinib.

MATERIALS AND METHODS

Children with recurrent, refractory, or progressive pediatric low-grade gliomas who had World Health Organization grade I pilocytic astrocytoma with KIAA1549-BRAF fusion or the BRAF V600E mutation (stratum 1), neurofibromatosis type 1-associated pediatric low-grade gliomas (stratum 3), or sporadic non-neurofibromatosis type 1 optic pathway and hypothalamic glioma (OPHG) (stratum 4) were treated with selumetinib for up to 2 years. Quantitative ADC histogram metrics were analyzed for total and enhancing tumor volumes at baseline and during treatment.

RESULTS

Each stratum comprised 25 patients. Stratum 1 responders showed lower values of SD of baseline ADC_total as well as a larger decrease with time on treatment in ADC_total mean, mode, and median compared with nonresponders. Stratum 3 responders showed a greater longitudinal decrease in ADC_total. In stratum 4, higher baseline ADC_total skewness and kurtosis were associated with shorter progression-free survival. When all 3 strata were combined, responders showed a greater decrease with time in ADC_total mode and median. Compared with sporadic OPHG, neurofibromatosis type 1-associated OPHG had lower values of ADC_total mean, mode, and median as well as ADC_enhancement mean and median and higher values of ADC_total skewness and kurtosis at baseline. The longitudinal decrease in ADC_total median during treatment was significantly greater in sporadic OPHG compared with neurofibromatosis type 1-associated OPHG.

CONCLUSIONS

ADC histogram metrics are associated with progression-free survival and response to treatment with selumetinib in pediatric low-grade gliomas.

Advanced ADC Histogram, Perfusion, and Permeability Metrics Show an Association with Survival and Pseudoprogression in Newly Diagnosed Diffuse Intrinsic Pontine Glioma: A Report from the Pediatric Brain Tumor Consortium

BACKGROUND AND PURPOSE

Diffuse intrinsic pontine glioma is a lethal childhood brain cancer with dismal prognosis and MR imaging is the primary methodology used for diagnosis and monitoring. Our aim was to determine whether advanced diffusion, perfusion, and permeability MR imaging metrics predict survival and pseudoprogression in children with newly diagnosed diffuse intrinsic pontine glioma.

MATERIALS AND METHODS

A clinical trial using the poly (adenosine diphosphate ribose) polymerase (PARP) inhibitor veliparib concurrently with radiation therapy, followed by maintenance therapy with veliparib + temozolomide, in children with diffuse intrinsic pontine glioma was conducted by the Pediatric Brain Tumor Consortium. Standard MR imaging, DWI, dynamic contrast-enhanced perfusion, and DSC perfusion were performed at baseline and approximately every 2 months throughout treatment. ADC histogram metrics of T2-weighted FLAIR and enhancing tumor volume, dynamic contrast-enhanced permeability metrics for enhancing tumors, and tumor relative CBV from DSC perfusion MR imaging were calculated. Baseline values, post-radiation therapy changes, and longitudinal trends for all metrics were evaluated for associations with survival and pseudoprogression.

RESULTS

Fifty children were evaluable for survival analyses. Higher baseline relative CBV was associated with shorter progression-free survival (P = .02, Q = 0.089) and overall survival (P = .006, Q = 0.055). Associations of higher baseline mean transfer constant from the blood plasma into the extravascular extracellular space with shorter progression-free survival (P = .03, Q = 0.105) and overall survival (P = .03, Q = 0.102) trended toward significance. An increase in relative CBV with time was associated with shorter progression-free survival (P < .001, Q < 0.001) and overall survival (P = .004, Q = 0.043). Associations of longitudinal mean extravascular extracellular volume fraction with progression-free survival (P = .03, Q = 0.104) and overall survival (P = .03, Q = 0.105) and maximum transfer constant from the blood plasma into the extravascular extracellular space with progression-free survival (P = .03, Q = 0.102) trended toward significance. Greater increases with time were associated with worse outcomes. True radiologic progression showed greater post-radiation therapy decreases in mode_ADC_FLAIR compared with pseudoprogression (means, -268.15 versus -26.11, P = .01.) CONCLUSIONS: ADC histogram, perfusion, and permeability MR imaging metrics in diffuse intrinsic pontine glioma are useful in predicting survival and pseudoprogression.

Brain Injury in Neonates with Complex Congenital Heart Disease: What Is the Predictive Value of MRI in the Fetal Period?

BACKGROUND AND PURPOSE

Brain injury in neonates with congenital heart disease is an important predictor of adverse neurodevelopmental outcome. Impaired brain development in congenital heart disease may have a prenatal origin, but the sensitivity and specificity of fetal brain MR imaging for predicting neonatal brain lesions are currently unknown. We sought to determine the value of conventional fetal MR imaging for predicting abnormal findings on neonatal preoperative MR imaging in neonates with complex congenital heart disease.

MATERIALS AND METHODS

MR imaging studies were performed in 103 fetuses with confirmed congenital heart disease (mean gestational age, 31.57 ± 3.86 weeks) and were repeated postnatally before cardiac surgery (mean age, 6.8 ± 12.2 days). Each MR imaging study was read by a pediatric neuroradiologist.

RESULTS

Brain abnormalities were detected in 17/103 (16%) fetuses by fetal MR imaging and in 33/103 (32%) neonates by neonatal MR imaging. Only 9/33 studies with abnormal neonatal findings were preceded by abnormal findings on fetal MR imaging. The sensitivity and specificity of conventional fetal brain MR imaging for predicting neonatal brain abnormalities were 27% and 89%, respectively.

CONCLUSIONS

Brain abnormalities detected by in utero MR imaging in fetuses with congenital heart disease are associated with higher risk of postnatal preoperative brain injury. However, a substantial proportion of anomalies on postnatal MR imaging were not present on fetal MR imaging; this result is likely due to the limitations of conventional fetal MR imaging and the emergence of new lesions that occurred after the fetal studies. Postnatal brain MR imaging studies are needed to confirm the presence of injury before open heart surgery.

Normal Developmental Globe Morphology on Fetal MR Imaging

BACKGROUND AND PURPOSE

Age-dependent structural changes of the globes occur during gestation. The posterolateral globe margins bulge outward, and the eyes are conical in early gestation. Later, the globes are ellipsoid. The purpose of this study was to establish normal developmental fetal globe morphology.

MATERIALS AND METHODS

The fetal MR imaging data base at an academic children's hospital was queried for all brain MRIs performed during 8 years. Motion artifacts, brain/craniofacial/globe malformations, and chromosomal defects were exclusion criteria. Two board-certified neuroradiologists evaluated each examination for globe shape (elliptic/nonelliptic) and hyaloid visibility. Logistic regression was used to evaluate correlations among variables. Age-specific cut-points for globe shape and hyaloid visibility were chosen to optimize specificity.

RESULTS

We identified 1243 examinations from 1177 patients. Six hundred eighty-two examinations met the inclusion criteria (17-39 weeks). Receiver operating characteristic analysis showed that age was highly predictive of globe shape (area under the curve = 0.99) and fetal vasculature visibility (area under the curve = 0.94). Nonelliptic globes were universal up to 22 weeks. Thereafter, globes gradually assumed an elliptic shape, present in nearly all patients 29 weeks and older (sensitivity, 81%; 95% CI, 76%-85%; specificity, 99%; 95% CI, 98%-100%). The hyaloid vasculature was visible in most patients up to 19 weeks and occasionally in those at 20-24 weeks, but never in those 25 weeks and older (sensitivity, 69%; 95% CI, 65%-72%; specificity, 100%; 95% CI, 95%-100%).

CONCLUSIONS

Physiologic nonspheric globe shapes are normal up to 29 weeks' gestation and should not be misinterpreted as pathologic. Thereafter, globes are generally elliptic. The timing of this process coincides with the resolution of the primary vitreous and may be related.

Elucidating Metabolic Maturation in the Healthy Fetal Brain Using 1H-MR Spectroscopy

BACKGROUND AND PURPOSE

(1)H-MRS provides a noninvasive way to study fetal brain maturation at the biochemical level. The purpose of this study was to characterize in vivo metabolic maturation in the healthy fetal brain during the second and third trimester using (1)H-MRS.

MATERIALS AND METHODS

Healthy pregnant volunteers between 18 and 40 weeks gestational age underwent single voxel (1)H-MRS. MR spectra were retrospectively corrected for motion-induced artifacts and quantified using LCModel. Linear regression was used to examine the relationship between absolute metabolite concentrations and ratios of total NAA, Cr, and Cho to total Cho and total Cr and gestational age.

RESULTS

Two hundred four spectra were acquired from 129 pregnant women at mean gestational age of 30.63 ± 6 weeks. Total Cho remained relatively stable across the gestational age (r(2) = 0.04, P = .01). Both total Cr (r(2) = 0.60, P < .0001) as well as total NAA and total NAA to total Cho (r(2) = 0.58, P < .0001) increased significantly between 18 and 40 weeks, whereas total NAA to total Cr exhibited a slower increase (r(2) = 0.12, P < .0001). Total Cr to total Cho also increased (r(2) = 0.53, P < .0001), whereas total Cho to total Cr decreased (r(2) = 0.52, P < .0001) with gestational age. The cohort was also stratified into those that underwent MRS in the second and third trimesters and analyzed separately.

CONCLUSIONS

We characterized metabolic changes in the normal fetal brain during the second and third trimesters of pregnancy and derived normative metabolic indices. These reference values can be used to study metabolic maturation of the fetal brain in vivo.

Interhypothalamic adhesion: a series of 13 cases

Interhypothalamic adhesion is a newly described disease entity, characterized by an abnormal parenchymal band connecting the medial margins of the hypothalami across the third ventricle. Additional anomalies, including cleft palate, gray matter heterotopia, cerebellar hypoplasia, optic atrophy, hippocampal under-rotation, and white matter lesions, may coexist. The purpose of this clinical report is to describe the imaging findings from a series of 13 patients with interhypothalamic adhesions discovered on brain MR imaging.

Prevalence and spectrum of in utero structural brain abnormalities in fetuses with complex congenital heart disease

BACKGROUND AND PURPOSE

Brain injury is a major complication in neonates with complex congenital heart disease. Preliminary evidence suggests that fetuses with congenital heart disease are at greater risk for brain abnormalities. However, the nature and frequency of these brain abnormalities detected by conventional fetal MR imaging has not been examined prospectively. Our primary objective was to determine the prevalence and spectrum of brain abnormalities detected on conventional clinical MR imaging in fetuses with complex congenital heart disease and, second, to compare the congenital heart disease cohort with a control group of fetuses from healthy pregnancies.

MATERIALS AND METHODS

We prospectively recruited pregnant women with a confirmed fetal congenital heart disease diagnosis and healthy volunteers with normal fetal echocardiogram findings who underwent a fetal MR imaging between 18 and 39 weeks gestational age.

RESULTS

A total of 338 fetuses (194 controls; 144 with congenital heart disease) were studied at a mean gestational age of 30.61 ± 4.67 weeks. Brain abnormalities were present in 23% of the congenital heart disease group compared with 1.5% in the control group (P < .001). The most common abnormalities in the congenital heart disease group were mild unilateral ventriculomegaly in 12/33 (36.4%) and increased extra-axial spaces in 10/33 (30.3%). Subgroup analyses comparing the type and frequency of brain abnormalities based on cardiac physiology did not reveal significant associations, suggesting that the brain abnormalities were not limited to those with the most severe congenital heart disease.

CONCLUSIONS

This is the first large prospective study reporting conventional MR imaging findings in fetuses with congenital heart disease. Our results suggest that brain abnormalities are prevalent but relatively mild antenatally in fetuses with congenital heart disease. The long-term predictive value of these findings awaits further study.

CNS germ cell tumor (CNSGCT) of childhood: presentation and delayed diagnosis

OBJECTIVE

To describe the relationship between symptomatology and time to diagnosis of an institutional series of patients with CNS germ cell tumor (CNSGCT) over a 16-year period.

METHODS

Thirty consecutive patients newly diagnosed with CNSGCT (mean age 10.9 years; range 6 to 17 years; 70% boys) were evaluated at our institution between 1990 and 2006.

RESULTS

Duration of symptoms prior to diagnosis ranged from 5 days to 3 years (mean 8.4 months). Tumor location included pineal (14), suprasellar (8), pineal/suprasellar (3), pineal/thalamic (4), and basal ganglionic/thalamic (3). Five patients had disseminated disease at the time of diagnosis. Features including headache, nausea, vomiting, and visual changes led to earlier diagnosis. Symptoms including movement disorders, enuresis, anorexia, and psychiatric complaints delayed diagnosis in 9 of 30 patients, diagnosed 7 months to 3 years (mean 22.3 months) from symptom onset. In 7 of 9 patients with delayed diagnosis, enuresis was present. Seventeen of 30 patients had signs of endocrine dysfunction at presentation that included diabetes insipidus (4), hypothyroidism (8), and growth hormone deficiency (4). Ophthalmologic findings of decreased visual acuity, visual field deficits, or ocular abnormalities were present in 13 patients. Duration of symptoms did not correlate with tumor subtype or event-free survival. In three patients with basal ganglionic/temporal lobe, thalamic, or pineal/suprasellar signal abnormalities on MRI, neuroradiographic diagnosis was difficult.

CONCLUSIONS

Diagnosis of CNS germ cell tumor is often delayed, and presentation may include movement disorders or mimic psychiatric disease. MRI interpretation can be challenging and may require serum/CSF markers and biopsy for diagnosis.

Isolated absence of the optic chiasm: a rare cause of congenital nystagmus

The cases presented are rare examples of congenital nystagmus associated with isolated absence of the optic chiasm. MR imaging in both patients demonstrated unremarkable anterior optic pathways and optic tracts. No additional midline central nervous system abnormalities, migrational anomalies, space-occupying lesions, or destructive processes were noted. These cases demonstrate that the achiasmatic syndrome should be included in the differential diagnosis of congenital nystagmus and may be overlooked without careful MR imaging evaluation.

Phase I study of concurrent motexafin gadolinium (MGd) with radiation therapy for children with newly diagnosed brain stem gliomas (BSG): A Children’s Oncology Group study

9014

Background: MGd, a radiosensitizer that selectively accumulates in tumors, generates reactive oxygen species intracellularly. In preclinical experiments, MGd enhances RT-induced apoptosis. Methods: A multi-institutional Phase I dose escalation and pharmacokinetic (PK) study was performed in children with newly diagnosed BSG to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of MGd administered i.v. 2 to 5 hours prior to involved field radiotherapy (RT) (1.8 Gy/day, total 54 Gy). Cohort 1 received MGd, 1.7 mg/kg/dose M-F × 3 wks and cohort 2 received the same dose M, W and F × 6 wks. The 6 subsequent cohorts of 3 to 6 pts received MGd M-F × 6 weeks at doses of 1.9, 3.4, 4.4, 5.5, 7.1 and 9.2 mg/kg/dose. Serum for PK analysis, and MRI scans (MGd is detectable by MR), were obtained for analysis of drug accumulation and responses. Results: 44 pts (42 fully evaluable for toxicity) with a median age of 6 years (range 2–20) were enrolled. At the 9.2 mg/kg/dose, 2/2 pts experienced DLT. During subsequent expansion of the 7.1 and 5.5 mg/kg/dose cohorts, DLTs, including transaminitis, hypertension and urticaria, were observed in 2/5 and 2/6 pts. At the MTD of 4.4 mg/kg/dose, 1/6 pts had reversible grade 3 serum transaminase elevations. PK analysis showed biphasic elimination with a terminal t 1/2 of 6.4 h. At the MTD, serum MGd concentrations were >250 ng/ml for 24 h. Serum clearance and steady-state volume of distribution were 0.0243 L/h/kg and 0.162 L/kg. MRI for intra-tumoral MGd distribution is ongoing. One patient had a CR and 4 had a PR. The estimated median survival is 10.3 months (95% confidence interval: 8.1 months-11.5 months). Conclusions: The recommended phase II dose of MGd for children with BSG is 4.4 mg/kg/d administered M-F × 6 weeks with involved field RT. A COG phase II trial is planned.

[Table: see text]

Phase II trial of intravenous lobradimil and carboplatin in childhood brain tumors: a report from the Children’s Oncology Group

BACKGROUND

[corrected] Lobradimil is a synthetic bradykinin analog that rapidly and transiently increases the permeability of the blood-brain barrier (BBB). The combination of lobradimil and carboplatin was studied in pediatric patients with primary brain tumors in a phase II trial, the primary endpoints of which were to estimate the response rate and time to disease progression.

PATIENTS AND METHODS

Patients were stratified by histology into five cohorts: brainstem glioma, high-grade glioma, low-grade glioma, medullobastoma/primitive neuroectodermal tumor (PNET), and ependymoma. Patients received carboplatin adaptively dosed to achieve a target AUC of 3.5 mg min/ml per day (7 mg.min/ml/cycle) intravenously over 15 min on 2 consecutive days and lobradimil 600 ng/kg ideal body weight/day on 2 consecutive days each 28 day cycle.

RESULTS

Forty-one patients, age 2-19 years, were enrolled; 38 patients, including 1 patient ultimately determined to have atypical neurocytoma, were evaluable for response. No objective responses were observed in the brainstem glioma (n=12) and high-grade glioma (n = 9) cohorts, although two patients with high-grade glioma had prolonged disease stabilization (>6 months). The study was closed for commercial reasons prior to achieving the accrual goals for the ependymoma (n = 8), medulloblastoma/PNET (n = 6) and low-grade glioma (n = 2) cohorts, although responses were observed in 1 patient with PNET and 2 patients with ependymoma.

CONCLUSION

The combination of lobradimil and carboplatin was inactive in childhood high-grade gliomas and brainstem gliomas.

Plexiform neurofibromas in NF1: toward biologic-based therapy

Neurofibromatosis type 1 (NF1) is one of the most common neurogenetic diseases affecting adults and children. Neurofibromas are one of the most common of the protean manifestations of NF1. Plexiform neurofibromas, which will frequently cause cosmetic abnormalities, pain, and neurologic deficits, are composed of "neoplastic" Schwann cells accompanied by other participating cellular and noncellular components. There is increasing evidence that loss of NF1 expression in neoplastic Schwann cells is associated with elevated levels of activated RAS, supporting the notion that the NF1 gene product, neurofibromin, acts as a growth regulator by inhibiting ras growth-promoting activity. In addition, there is increasing evidence that other cooperating events, which may be under cytokine modulation, are important for neurofibroma development and growth. Treatment of plexiform neurofibromas has been empiric, with surgery being the primary option for those with progressive lesions causing a major degree of morbidity. The efficacy of alternative treatment approaches, including the use of antihistamines, maturation agents, and antiangiogenic drugs, has been questionable. More recently, biologic-based therapeutic approaches, using drugs that target the molecular genetic underpinnings of plexiform neurofibromas or cytokines believed important in tumor growth, have been initiated. Evaluation of such trials is hindered by the unpredictable natural history of plexiform neurofibromas and difficulties in determining objective response in tumors that are notoriously large and irregular in shape. Innovative neuroimaging techniques and the incorporation of quality-of-life scales may be helpful in evaluation of therapeutic interventions. The ability to design more rational therapies for NF1-associated neurofibromas is heavily predicated on an improved understanding of the molecular and cellular biology of the cells involved in neurofibroma formation and growth.

Medulloblastoma: clinical and biologic aspects

Medulloblastoma is the most common childhood primary CNS tumor, and treatment approaches have evolved over the past three decades. The biologic underpinnings of medulloblastoma are not fully characterized, but recent work has identified new, important directions for research. Stratification of patients with medulloblastoma into risk groups is the backbone of most ongoing therapeutic studies. Patients are usually characterized as being either average risk or poor risk, although an intermediate risk group may exist. Standard treatment for older children with medulloblastoma consists of radiation and, for most, chemotherapy. Children with nondisseminated disease at the time of diagnosis have been reported to have as high as an 80% five-year disease-free survival rate after treatment with reduced dose (2340 cGy) craniospinal irradiation, local boost radiation therapy (5500 cGy), and chemotherapy, given during and after radiation therapy. Preradiation chemotherapy has yet to be shown to be of benefit for children with medulloblastoma. Children with disseminated disease are a highly problematic subgroup of patients to treat. A variety of new approaches are being studied, most of which are intensifying chemotherapy either prior to or after radiation. Long-term survivors of medulloblastoma are at significant risk for permanent endocrinologic, cognitive, and psychological sequelae. Infants and very young children with medulloblastoma remain a difficult therapeutic challenge because they have the most virulent form of the disease and are at highest risk for treatment-related sequelae.

Accuracy and usefulness of radiographic assessment of cervical neck infections in children

OBJECTIVE

To determine the accuracy and usefulness of computed tomography (CT) in diagnosis and management of lateral and deep neck infections

METHODS

An 11-year retrospective review of 110 children (age range 1 months to 17 years) was conducted at a tertiary care children's hospital.

RESULTS

Fifteen patients treated medically (8 with cellulitis, 7 with early abscess) improved. Of the remaining 95 patients who had 107 cervical sites drained surgically, CT predicted accurately operative findings in 81 (76%) cases (72 with abscess, 9 with cellulitis). In the 26 (24%) cases with discrepancy between CT interpretation and operative findings, the most common problem was differentiating early abscess from cellulitis with 18 false positives (no abscess at surgery). In 8 cases, CT diagnosis other than abscess was made (4 cellulitis, 1 inflammatory mass, 1 hematoma, 1 lymphangioma, and 1 tumour); however, when the patients were operated on because of lack of improvement, an abscess was found.

CONCLUSIONS

Although CT is helpful both in determining the presence and location of neck infections in children, the CT scan is less helpful in differentiating abscess from lymphadenitis, cellulitis, and some complex cervical masses.

MR imaging of the corpus callosum in pediatric patients with neurofibromatosis type 1

BACKGROUND AND PURPOSE

Many pediatric patients with neurofibromatosis type 1 (NF-1) have an apparent increased thickness of the corpus callosum (CC) on sagittal T1-weighted images compared with patients not affected by NF-1. In this study, we compared the surface area of the CC in children with NF-1 with that of healthy pediatric control subjects to determine if this was another common intracranial manifestation of NF-1.

METHODS

Midsagittal T1-weighted MR images of 43 consecutive children with NF-1 and 43 age- and gender-matched healthy control subjects were reviewed retrospectively. The surface area of the CC and the midsagittal intracranial skull surface (MISS) area were measured five times each on all midsagittal images. A mean CC to mean midline intracranial surface area ratio (CC/MISS) was calculated for each.

RESULTS

There is a statistically significant increase in the mean CC surface area in pediatric patients with NF-1 (680 mm2 +/- 98, range 509-974 mm2) compared with control subjects (573 mm2 +/- 83, range 404-797 mm2). The mean MISS is significantly increased in patients with NF-1 (16568 mm2 +/- 1161, range 14107-19394 mm2 vs 15402 mm2 +/- 1133, range 12951-17905 mm2 for control subjects). CC/MISS was also significantly increased in the patients with NF-1 relative to the control subjects (.0410 +/- .0043, range .0330-.0530 vs .0372 +/- .0043, range .0270-.0470 for control subjects).

CONCLUSION

A larger midsagittal surface area of the CC is another intracranial manifestation of NF-1 that can be demonstrated by sagittal MR imaging. The etiology is unclear, but could be related to abnormal neurofibromin and Ras protein activity. Potential clinical relevance is discussed herein.

Intracranial calcifications in childhood medulloblastoma: relation to nevoid basal cell carcinoma syndrome

BACKGROUND AND PURPOSE

Medulloblastoma is one of the most common posterior fossa tumors to occur in children. Our purpose was to document the frequency, location, and time of occurrence of intracranial calcifications in cranial CT studies of children with medulloblastoma.

METHODS

We retrospectively reviewed cranial CT studies of 56 patients diagnosed with medulloblastoma from 1983 through 1997 for the presence of intracranial calcifications. The findings were compared with 159 cranial CT studies of patients who were evaluated in the emergency department (control group). Thirty-two patients with medulloblastoma without shunts were compared with 118 patients from the control group without shunts. Similarly, 24 patients with medulloblastoma with shunts were compared with 41 patients from the control group with shunts.

RESULTS

Overall, three (9%) patients with medulloblastoma without shunts, four (16%) patients with medulloblastoma with shunts, and four (10%) patients from the control group with shunts had falx calcification. Only the two children carrying the diagnoses of medulloblastoma and nevoid basal cell carcinoma syndrome, however, had calcification of the falx cerebri shown on the cranial CT scans obtained during the peridiagnostic period. Both were diagnosed with medulloblastoma before the age of 3 years and later developed jaw cysts and multiple basal cell carcinomas in the radiation field.

CONCLUSION

Previous studies have shown that falx calcification is a major component of nevoid basal cell carcinoma syndrome. Our two cases illustrate the importance of considering the diagnosis of nevoid basal cell carcinoma syndrome when falx calcification is present in young patients with medulloblastoma. If the concomitant diagnosis of nevoid basal cell carcinoma syndrome is made, alternative types of therapy should be sought to minimize radiation therapy sequelae.

Treatment of progressive or recurrent pediatric malignant supratentorial brain tumors with herpes simplex virus thymidine kinase gene vector-producer cells followed by intravenous ganciclovir administration

OBJECT

The outcome for children with recurrent malignant brain tumors is poor. The majority of patients die of progressive disease within months of relapse, and other therapeutic options are needed. The goal of this Phase I study was to evaluate the safety of in vivo suicide gene therapy in 12 children with recurrent, malignant, supratentorial brain tumors.

METHODS

After optimal repeated tumor resection, multiple injections of murine vector-producing cells shedding murine replication-defective retroviral vectors coding the herpes simplex virus thymidine kinase type 1 (HSV-Tk1) gene were made into the rim of the resection cavity. Fourteen days after the vector-producing cells were injected, ganciclovir was administered for 14 days. The retroviral vector that was used only integrated and expressed HSV-Tk1 in proliferating cells, which are killed after a series of metabolic events lead to cell death. The median age of the patients was 11 years (range 2-15 years). Treated brain tumors included seven malignant gliomas, two ependyminomas, and three primitive neuroectodermal tumors. The patients were treated with one of three escalating dose concentrations of vector-producer cells. Four transient central nervous system adverse effects were considered possibly related to the vector-producing cells. In no child did permanent neurological worsening or ventricular irritation develop, and tests for replication-competent retroviruses yielded negative findings.

CONCLUSIONS

This Phase I study demonstrates that in vivo gene therapy in which a replication-defective retroviral vector in murine vector-producing cells is delivered by brain injections can be performed with satisfactory safety in a select group of children with localized supratentorial brain tumors.

Medulloblastoma: clinical and biologic aspects

Medulloblastoma is the most common childhood primary CNS tumor, and treatment approaches have evolved over the past three decades. The biologic underpinnings of medulloblastoma are not fully characterized, but recent work has identified new, important directions for research. Stratification of patients with medulloblastoma into risk groups is the backbone of most ongoing therapeutic studies. Patients are usually characterized as being either average risk or poor risk, although an intermediate risk group may exist. Standard treatment for older children with medulloblastoma consists of radiation and, for most, chemotherapy. Children with nondisseminated disease at the time of diagnosis have been reported to have as high as an 80% five-year disease-free survival rate after treatment with reduced dose (2340 cGy) craniospinal irradiation, local boost radiation therapy (5500 cGy), and chemotherapy, given during and after radiation therapy. Preradiation chemotherapy has yet to be shown to be of benefit for children with medulloblastoma. Children with disseminated disease are a highly problematic subgroup of patients to treat. A variety of new approaches are being studied, most of which are intensifying chemotherapy either prior to or after radiation. Long-term survivors of medulloblastoma are at significant risk for permanent endocrinologic, cognitive, and psychological sequelae. Infants and very young children with medulloblastoma remain a difficult therapeutic challenge because they have the most virulent form of the disease and are at highest risk for treatment-related sequelae.

Intracranial abnormalities in infants treated with extracorporeal membrane oxygenation: update on sonographic and CT findings

PURPOSE

To determine the frequency of intracranial lesions in infants treated with extracorporeal membrane oxygenation (ECMO), to evaluate trends in frequency during an 8-year period, and to determine which infants are at highest risk for intracranial injury.

METHODS

Daily sonograms were obtained in 386 infants during treatment with ECMO. Cranial CT scans were acquired after decannulation in 286 of 322 survivors. Abnormalities were classified as major or minor and hemorrhagic or nonhemorrhagic. Results were correlated with infant demographic data.

RESULTS

Intracranial abnormalities were detected in 203 (52%) of the 386 infants; 73 (19%) hemorrhagic, 86 (22%) nonhemorrhagic, and 44 (11%) combined lesions. Eighty-two lesions (21%) were classified as major. Forty-six (94%) of 49 major hemorrhages were identified at sonography. CT contributed additional information in 73% of neonates with intracranial abnormalities, of which 17 were major lesions not identified at sonography. The frequency of intracranial hemorrhage was increased in infants who were septic or premature or weighed less than 2.5 kg. An increase in time spent on ECMO bypass increased the risk for nonhemorrhagic injury. During an 8-year period, the frequency of hemorrhagic and major nonhemorrhagic lesions remained constant, whereas minor nonhemorrhagic abnormalities increased significantly.

CONCLUSION

Infants treated with ECMO continue to be at high risk for cerebrovascular injury. Although daily sonograms are useful in identifying major hemorrhages, follow-up CT scans are crucial for accurate evaluation of intracranial abnormalities.

Spinal cord compression in widely metastatic Wilms' tumor. Paraplegia in two children with anaplastic Wilms' tumor

Spinal cord compression in Wilms' tumor is a rare event, generally caused by invasion of the canal by paraspinal lesions or metastatically involved vertebral bodies. This case report reviews the clinical presentation, radiologic evaluation, and emergent therapy in two cases of spinal cord compromise involving patients with widely metastatic Wilms' tumor. One of these is the only known report of intradural metastasis in a child with this malignancy. Both cases illustrate the importance of anticipating and rapidly responding to neurologic complications that may arise in patients with aggressively metastatic Wilms' tumor.

Choroid plexus carcinoma of childhood

The presentation, growth patterns, and response to therapy of 11 consecutive children with choroid plexus carcinomas were analyzed, and the results were compared with the outcome reported in other series. Patients were a median of 26 months of age at diagnosis. Two patients had thalamic tumors, one had a posterior fossa primary, and the rest had ventricular lesions. Five of 11 (45%) children remain in continuous progression-free remission a median of 48 months from diagnosis. Four of the five in continuous remission had a "gross total" surgical resection, and only one received radiation therapy. Five of six patients with subtotal resections relapsed despite postoperative treatment with radiation therapy (three) and chemotherapy (one). The response to treatment with radiation therapy or chemotherapy at relapse was disappointing, with only one child (treated with etoposide) responding. In combination with other series, 11 of 14 children had prolonged progression-free survival after gross total resection (only two of whom received adjuvant therapy) compared with two of 20 after less than total resections, independent of the type of adjuvant therapy given. Adjuvant therapy for children with choroid plexus carcinomas is of unproven benefit, and this must be considered when analyzing innovative treatment trials for such children, especially for those with totally resected tumors. Patients with partially resected lesions fare poorly with present forms of treatment.