The management of bifocal intracranial germinoma in children

Objectives

Bifocal intracranial germinoma (BFG) is a tumour of the pineal and suprasellar regions, which is known to be highly radiosensitive. The definitive treatment and outcomes are not well defined, particularly in the paediatric population. We review our series of purely paediatric cases from a single institution and combine them with the limited reports in the literature to determine the results of different management strategies.

Methods

Four patients were treated at our institution with a median age of 15.3 years. A literature search identified a further 38 paediatric cases with a median age of 12.9 years.

Results

All four patients had normal serum and CSF tumour markers. One patient had a diagnosis made based on imaging findings of bifocal pineal and suprasellar lesions presenting with diabetes insipidus. Three others underwent biopsy. All had craniospinal radiotherapy, which has led to complete cure with no cases of progression at a mean follow-up of 3 years. The most common treatment modality in published cases is craniospinal irradiation. In the cases reviewed, limited radiation treatments (whole ventricle or focal) combined with chemotherapy regimens yield comparable outcomes where there is no spinal dissemination. Outcomes do not appear to be altered by biopsy in cases with negative tumour markers and characteristic imaging appearances.

Conclusion

Patients who present with a classic appearance of germinoma, negative tumour markers and diabetes insipidus probably do not require a biopsy to confirm the diagnosis. No evidence of dissemination may obviate the need for craniospinal irradiation, but good quality long-term follow-up data are required to demonstrate the benefits of combined focal radiotherapy and chemotherapy regimes.     

Lymphocytic hypophysitis with central diabetes insipidus and subsequent hypopituitarism masking a suprasellar germinoma in a 13-year-old girl

Case report We report a case of central diabetes insipidus, hypothyroidism, and subsequent hypopituitarism due to lymphocytic hypophysitis masking a germinoma in a 13-year-old pubertal girl. Magnetic resonance revealed an enlarged pituitary gland and a mass lesion in the pituitary stalk and inferior hypothalamus. Open cranial surgery of the anterior pituitary showed active hypophysitis with lymphocytic infiltrates but without necrosis. Despite prednisolone therapy, 1 year later an enlarged, irregular cystic mass lesion had developed; in the pituitary stalk and inferior hypothalamus, a endoscopic biopsy revealed germinoma.Conclusion Lymphocytic hypophysitis in children may be the first sign of a host reaction to an occult germinoma. The diagnosis of central diabetes insipidus with a thickened pituitary stalk requires long-term follow-up to establish the underlying cause.     

An unusual case of primary central nervous system germinoma with meningeal dissemination

Purpose

Central nervous system germinomas often extend or disseminate into the ventricular and subarachnoid space. We present a case of primary central nervous system germinoma consisting mainly of meningeal dissemination, which is extremely unusual.

Case report

A 16-year-old boy presented with pure germinoma, manifesting as anorexia and headache for 10 days. Radiological examinations revealed a large mass lesion in the posterior fossa and a small mass lesion on the pineal lobule with thickening of the tentorium cerebelli and falx. The patient underwent partial removal of the infratentorial tumor via open surgery. Intraoperative findings indicated extension of the dural and supracerebellar mass lesions into the epiarachnoid space. Three chemotherapy courses comprising ifosfamide, etoposide, and cisplatin were administered after the surgery. Craniospinal irradiation was administered subsequently. The adjuvant therapy had a complete response.

Conclusion

Central nervous system germinoma cells may have similar compatibility to meningeal components as they do to cerebrospinal fluid or the ventricular system. If there is a possibility of the tumor extending into the subdural space during surgical intervention or other events, a range of postdiagnostic irradiation should be considered to cover a wider range.     

Intracranial germinoma: clinical and MRI findings in 56 patients

Introduction

Intracranial germinoma is a rare malignant tumor, only constituting 0.5–2.0% of all primary intracranial tumors. It usually occurs in children and young adults, it is highly sensitive to radiotherapy or/and chemotherapy, and is potentially curable without operation. To make correct pre-operative diagnosis and spare surgical intervention, we retrospectively reviewed 56 patients in our hospital, and presented clinical findings and MRI characteristics.

Materials and methods

We reviewed medical records and magnetic resonance imaging (MRI) of 56 patients. Information regarding sex, age at diagnosis, clinical presentation, duration of symptom, and associated neurologic deficits was noted. The tumor location, number of metastasis, size, margin, involved tissues, and characteristics of signal intensity on MRI were analyzed by two experienced radiologists, respectively.

Results

In the series, 57% of intracranial germinoma was located in pineal region, 32% in suprasellar region, and 9% in basal ganglia region. One patient was found germinoma with synchronous lesions in pineal and suprasellar region. Sixty-three percent of patients were male in pineal region, 39% and 100%, respectively, in suprasellar region and basal ganglia region. Age at diagnosis ranged from 3 to 21 years (mean, 12.5 years) with a peak between 10 and 18 years.

Conclusions

Intracranial germinoma has some features in terms of age, sex, clinical presentation, and MRI. These features are in favor of pre-operative diagnosis and thus make for good prognosis.     

Latency of intracranial germ cell tumors and diagnosis delay

Background

Intracranial germ cell tumors (GCTs) frequently take an insidious clinical course before diagnosis. To date, clinical latency has been discussed in the context of germinoma in the suprasellar area and basal ganglia.

Objective

In this study, we classified the clinical latency of intracranial GCTs into three categories and described their characteristics in order to understand the full spectrum of the phenomenon.

Methods

In a cohort of 181 patients with intracranial GCTs, 17 patients had a delayed diagnosis of more than 3 months (90 days) from the initial brain magnetic resonance imaging to the definitive GCT diagnosis. Clinical records and radiological data of the patients were reviewed.

Results

The patients with a delayed diagnosis were categorized into three groups according to their tumor location: suprasellar (nine patients), basal ganglia (six patients), and pineal (two patients). Initial symptomatology corresponded with the tumor location: central diabetes insipidus for the suprasellar group, hemiparesis for the basal ganglia group, and precocious puberty for the pineal group. The overall survival of patients with germinoma and delayed diagnosis was significantly shorter than that of patients who were diagnosed within 3 months (P?=?0.002).

Conclusions

Clinical latency and delayed diagnosis are not restricted to germinomas in the suprasellar area and basal ganglia; they are canonical features of intracranial GCTs including pineal non-germinomatous GCTs. Early detection and proactive diagnosis of these tumors are required because diagnosis delay may negatively influence patient survival.     

An unusual location for a choroid plexus papilloma: the pineal region

Purpose

Choroid plexus papillomas (CPP) are rare benign neoplasms of the central nervous system that occur most often in children during the first decade of life. They occur most often in the lateral ventricle. It is extremely rare for a CPP to occur in the pineal region. We describe the case of a child with a CPP located in the pineal region, who was initially diagnosed with obstructive hydrocephalus by cranial computed tomography (CT).

Methods

A 9-year-old female patient presented with complaints of visual disturbance, nausea, and vomiting. Magnetic resonance imaging (MRI) showed a poor contrast-enhanced pineal-localized lesion. Anatomical variations within the patient caused her surgery to proceed using a supratentorial-occipital interhemispheric approach.

Results

The tumor was totally removed, and a histological examination revealed the tumor to be a typical CPP. The patient received follow-up neurological and ophthalmologic examinations at 3, 6, 9, 12, 24, and 36 months postoperatively, which demonstrated her progressive improvement.

Conclusions

CPPs may have a wide range of locations and resulting symptoms. However, the pineal region is a rarely encountered location, particularly for pediatric patients. It is of great value to correctly differentiate neoplasms such as germ cell tumors, pineocytomas, meningiomas, and astrocytomas, so that patients receive the correct diagnosis and treatment approach.     

Germinoma located in the basal ganglia in an 8-year-old girl

Case report The authors describe a unique case of an 8-year-old girl with a germinoma located in the left basal ganglia. Medical history begins 5 months before with a central diabetes insipidus, loss of weight (5 kg at admission), vomiting and asthenia. Computed tomography (CT) and cranial magnetic resonance imaging (MRI) are performed and demonstrate a left basal ganglia tumour (nucleus lentiformis). Diabetes insipidus is considered as non-visible germinoma localization on the pituitary stalk rather than as a possible consequence of peri-tumoural oedema surrounding the hypothalamus. Spinal MRI is normal. Neurological as well as general examination is normal.Discussion The first hypothesis is low-grade glioma, but pathological examination following a stereotactic biopsy of the lesion reveals a cerebral germinoma. A few days before the biopsy, the girl experienced a mild left facial palsy, and CT scans at the time of biopsy reveals an intra-tumoural haemorrhage. Alpha fetoprotein and human chorionic gonadotrophin were negative as blood and cerebrospinal fluid markers, whereas placental alkaline phosphatase was positive on immunohistochemical profile of the tumour samples. Dedicated chemotherapy, followed by focal irradiation (40 Gy, 30 sessions, 45 days; SIOP CNS GCT 93 protocol), is performed with a complete response. The outcome is good (Glasgow Outcome Scale=I), without any cognitive impairment and the persistence of a mild facial palsy and a slight right arm dystonia on last neurological examination. There is still no evidence of tumour recurrence.     

Solitary Langerhans cell histocytosis of skull and spine in pediatric and adult patients

Purpose

Langerhans cell histiocytosis (LCH) is a rare neoplasm and has heterogeneous clinical presentation and behavior. We analyzed solitary lytic lesions of the skull and spine in pediatric and adult patients.

Methods

Between 2001 and 2011, 42 patients underwent surgery for LCH. Skull and/or spine involvement were evident in 21 (63.6 %) of the 33 pediatric patients and 8 (88.9 %) of the 9 adults. The 21 pediatric patients showed the unifocal monosystemic lesions in 10, multifocal monosystemic in 4, and multisystemic in 7. The eight adults comprised seven unifocal lesions and one multifocal monosystemic lesion. Of these cases, we analyzed the clinical courses of solitary LCH of skull and spine in 10 pediatric patients and 7 adults.

Results

The median age was 10.1 years (range: 1.1–14.1) in pediatric patients and 34.6 years (range: 26.1–52.0) in adults. The median follow-up was 3.1 years (range: 0.6–9.5). Total excision was done in 15 patients and biopsy in 2. Postoperative adjuvant chemotherapy was done in four pediatric patients and one adult, and comprised mass with dural adhesion (N?=?2), skull base lesion (N?=?1), atlas mass (N?=?1), and vertebral lesion with soft tissue extension (N?=?1). During follow-up, recurrence occurred in one pediatric patient who had a skull LCH with a dural adhesion. The patient experienced central diabetes insipidus and scapular pain due to pituitary stalk and scapula involvement 1.3 and 2.4 years later, respectively.

Conclusion

Even if the solitary lesions of skull and spine show a favorable clinical course, some patients could show aggressive behavior.     

The efficacy of a biopsy of intrinsic brainstem lesions for decision making of the treatments

Object

The diagnosis of diffuse intrinsic pontine gliomas (DIPGs) has been generally made mainly by magnetic resonance imaging (MRI) and clinical course. However, the accuracy of MRI-based diagnosis has not been fully confirmed yet. Our aim was to review efficacy of biopsy for decision making of the treatments.

Methods

We retrospectively analyzed pediatric patients undergoing biopsy for intrinsic brainstem lesions which were considered atypical for DIPGs by MRI findings. The lesion was evaluated atypical when it extended beyond the pons or it had a well-margined localized enhancing portion.

Results

Seven patients underwent biopsy. Preoperative MRI revealed a lesion extending beyond the pons in five patients and a focal enhancing lesion in four. Two patients had both of these. Open biopsy was performed via midline suboccipital approach in six patients and retrosigmoid approach in one. No intraoperative complications were observed. Histopathological examination revealed diffuse brainstem glioma in five patients, primitive neuroectodermal tumor (PNET) in one, and pilocytic astrocytoma in one. In the case with PNET, chemotherapy and radiotherapy were effective and the patient had been stable for 12 months without recurrence. The patient with pilocytic astrocytoma did not undergo radiotherapy and has been stable without regrowth of the tumor for 9 months.

Conclusions

Open biopsy of intrinsic brainstem lesions is considered to be safe and effective for selecting an appropriate course of therapy. Patients with intrinsic pontine lesions which extend beyond the pons or with localized enhancing portion seem to be benefited from the biopsy.     

Second primary brain tumors following cranial irradiation for pediatric solid brain tumors

Purpose

We describe our institution’s experience with seven patients who developed second brain tumors following cranial irradiation.

Methods

The median age at first irradiation was 8 years (range, 3–20 years). Initial diagnoses were two cases of germinoma, one non-germinomatous germ cell tumor (NGGCT), three cases of medulloblastoma, and one pineal gland tumor (pathology undetermined). All patients received craniospinal irradiation followed by local boost and the median dose to the initial tumor area was 54.0 Gy (range, 49.8–60.6 Gy). Four patients (two medulloblastomas, one germinoma, and one NGGCT) received chemotherapy.

Results

Second brain tumors were diagnosed a median of 114 months (range, 64–203) after initial radiation. Pathologic diagnoses were one glioblastoma, two cases of anaplastic astrocytoma, one medulloblastoma, one low-grade glioma, one high-grade glial tumor, and one atypical meningioma. Five patients underwent surgical resection with subsequent radiotherapy. One anaplastic astrocytoma patient received chemotherapy only following stereotactic biopsy. The meningioma patient was alive 32 months after total resection and radiosurgery for subsequent recurrences. Six patients died within 18 months and most deaths were due to disease progression.

Conclusions

Most patients diagnosed with second brain tumors had received high-dose, large-volume radiotherapy with chemotherapy at a young age. Further studies are required to determine the relationship between radiotherapy/chemotherapy and the development of secondary brain tumors.     

Melanotic medulloblastoma in children

Purpose

We report a case of melanotic medulloblastoma in a child. Reviewing the literature, we discuss the characteristics, therapeutic method, and prognosis of melanotic medulloblastoma in children.

Materials and methods

A 2-year-old girl was admitted with a mass located in the pineal region and presented obstructive hydrocephalus. The mass was subtotally resected through a slit-corpus?Cfornix approach. Thereafter, intraoperative direct third ventriculostomy was performed. The histopathological diagnosis of the mass suggested melanotic medulloblastoma.

Results

The MRI done at 4?days after surgery showed that the lateral ventricle normalized and the hydrocephalus was resolved. Thereafter, the patient underwent a Gamma Knife. The patient recovered well during the 8-month follow-up.

Conclusions

Melanotic medulloblastoma is a malignant tumor of childhood. It usually occurs at young age and might involve the vermis cerebelli, the fourth ventricle, and the pineal region. Surgery combined with radiotherapy and chemotherapy is recommended for children. But, it still requires observation to determine their long-term prognosis.     

Double localization of a cerebral germinoma. Case report

A germinoma located in both the pineal and suprasellar regions remains rare. The clinical expression can be polymorphic, although brain imaging reveals specific signs. We report the case of a 16-year-old boy who presented with diabetes insipidus of six months' standing, associated with visual loss and Parinaud's syndrome. Brain MRI showed a tumor in both the pineal and suprasellar regions. A stereotaxic biopsy targeting the infundibular growth confirmed the diagnosis of ectopic germinoma, which was successfully treated by radiotherapy and chemotherapy. The incidence of bifocal germinoma, its clinical and radiological characteristics as well as the therapeutic strategies to adopt are discussed.     

Limited dorsal myeloschisis: a not-so-rare form of primary neurulation defect

Purpose

Limited dorsal myeloschisis (LDM) is a distinctive form of spinal dysraphism characterized by two constant features: a focal “closed” midline skin defect and a fibroneural stalk that links the skin lesion to the underlying cord. The embryogenesis is hypothesized to be incomplete disjunction between cutaneous and neural ectoderms, thus preventing complete midline skin closure and allowing persistence of a physical link (fibroneural stalk) between the disjunction site and the dorsal neural tube.

Objective

We utilize the experience gained from the management of 63 patients with LDM to illustrate these features.

Methods

All patients were studied with MRI or CT myelogram, operated on, and followed for a mean of 9.4 years.

Results

There were 11 cervical, 16 thoracic, 8 thoracolumbar, and 28 lumbar lesions. Two main types of skin lesion were: saccular (26 patients; consisting of a skin base cerebrospinal fluid sac topped with squamous epithelial dome or a thin membranous sac) and nonsaccular (37 patients; with a flat or sunken squamous epithelial crater or pit). The internal structure of a saccular LDM could be a basal neural nodule, a stalk that inserts on the dome, or a segmental myelocystocoele. In nonsaccular LDMs, the fibroneural stalk has variable thickness and complexity. All fibroneural stalks contain glioneuronal tissues accompanied by variable quantities of nerves and mesodermal derivatives. In all LDMs, the fibroneural stalk was tethering the cord. Twenty-nine patients had neurological deficits. There was a positive correlation between neurological grade and age suggesting progression with chronicity. Treatment consisted of detaching the stalk from the cord. Most patients improved or remained stable. LDMs were associated with three other dysraphic malformations in more than coincidental frequencies: six LDMs were contiguous with dorsal lipomas, four LDMs shared the same tract or traveled in parallel with a dermal sinus tract, and seven LDMs were related to a split cord malformation. The embryogenetic implications of these associations are discussed.

Conclusion

LDM is a distinctive clinicopathological entity and a tethering lesion with characteristic external and internal features. We propose a new classification incorporating both saccular and flat lesions.     

Intracerebral cystic rhabdoid papillary meningioma in an 11-year-old patient

Introduction

Rhabdoid papillary meningioma is a rare meningioma variant categorized as WHO grade III. We report an 11-year-old girl with an intracerebral rhabdoid papillary meningioma.

Materials and methods

An 11-year-old girl presented to our hospital with a short history of severe headache and vomiting. MRI revealed a left frontal intracerebral cystic lesion with rim enhancement. The tumor, including the cyst wall, was totally removed. Since the histological diagnosis was rhabdoid papillary meningioma, she was treated with postoperative radiotherapy. She is currently undergoing routine follow-up without any symptoms of recurrence.

Conclusion

We discuss the clinical picture of this patient with reference to the published literature on this uncommon diagnosis.     

The pathogenesis of intracranial growing teratoma syndrome: proliferation of tumor cells or formation of multiple expanding cysts? Two case reports and review of the literature

Purpose

Growing teratoma syndrome (GTS) is a rare clinical phenomenon defined as the paradoxical growth of mature teratoma components during or after chemotherapy. The mechanism of this phenomenon is not well understood. We present two cases of pineal mixed germ cell tumors that exhibited the similar course to GTS and speculate its pathogenesis.

Case report

The first case was accompanied by slightly elevated alpha-fetoprotein (8.8 ng/ml; normal <6.6 ng/ml). The tumor rapidly grew from 1.5 to 2.7 cm in diameter within 4 weeks. Despite this rapid preoperative growth, thorough pathological investigation found only mature teratoma components along with multiple micro- and macro-cysts. The other case was diagnosed as a pure germinoma based on biopsy and serological examinations. During three courses of chemotherapy, this tumor presented a honeycomb-like appearance on magnetic resonance (MR) images and an exceptionally rapid enlargement. Second-look surgery confirmed the histological diagnosis of a mature teratoma. In both cases, meticulous pathological examination of all whole tumor sections revealed no malignant histological features, and the MIB-1 labeling indices were too low to account for the extremely rapid tumor growth. Instead, both MR images and histological findings demonstrated a predominant formation of multiple cysts.

Conclusion

We speculate that this paradoxical growth might not be tumorous proliferation but instead the formation and expansion of multiple cysts inside mature teratoma components and that the presence or absence of growth might be a subsidiary phenomenon. Our hypothesis appears consistent with the characteristic radiological findings of GTS reported in the literature.     

Neuroendoscopic biopsy of pediatric brain tumors with small ventricle

Purpose

Intraventricular endoscopic procedures to resect or biopsy peri- or intraventricular tumors may have not been used in patients with small ventricles due to the presumed difficulties with ventricular cannulation and the perceived risk of morbidity. The purpose of this study is to review the feasibility and safety of neuroendoscopic procedures in the biopsy of pediatric brain tumors with a small ventricle.

Methods

Between January 2006 and January 2013, 72 children were identified with brain tumors confirmed by transventricular endoscopic biopsy. Patients were divided into non-hydrocephalus and hydrocephalus groups, and the ratio of the two groups was 20:52.

Results

In 20 pediatric brain tumors with small ventricle, the targeted lesion was successfully approached under the guidance of neuronavigation. Navigational tracking was especially helpful in entering small ventricles and in approaching the third ventricle through the narrow foramen of Monro. The histopathologic diagnosis was established in all 20 patients: nine germinomas, three mixed germ cell tumors, two pilomyxoid astrocytomas, and two pilocytic astrocytomas. The tumor biopsy sites were the suprasellar area (n?=?10), pineal area (n?=?4), lateral ventricular wall (n?=?4), and mammillary body (n?=?1). There were no major morbidities related to the endoscopic procedure.

Conclusion

Neuroendoscopic biopsy or resection of peri- or intraventricular tumors in pediatric patients without hydrocephalus is feasible. Navigation-guided neuroendoscopic procedures improved the accuracy of the neuroendoscopic approach and minimized brain trauma. The absence of ventriculomegaly in patients with brain tumor may not serve as a contraindication to neuroendoscopic tumor biopsy.     

Bifocal germinomas in the pineal region and hypothalamo-neurohypophyseal axis: Primary or metastasis?

Whether bifocal germinomas (BFGs) synchronously presenting within the pineal region and the hypothalamo-neurohypophyseal axis (HNA) are primary germinomas of dual-origin remains to be elucidated. We analyzed MRI images and clinical features of 95 neurohypophyseal germinomas and 21 BFG patients and developed a tentative definition of the BFGs. We found dual-primary BFGs (true BFGs) do exist. The fundamental difference between primary and metastatic HNA germinomas was the direction of tumor growth. For a true BFG, the primary HNA tumor grew from the neurohypophysis toward the hypothalamus and almost invaded the whole pituitary stalk. For a false BFG (primary pineal germinoma with HNA metastasis), the metastatic HNA tumor first appeared at the third ventricular floor (TVF), grew toward the neurohypophysis, but commonly did not invade the inferior pituitary stalk. Compared to false BFGs, true BFGs commonly had diabetes insipidus as the first symptom, dysfunction of the anterior pituitary, no high-intensity MRI signal at the posterior pituitary, a larger extension of the HNA tumor, and fewer numbers of remote lesions from cerebrospinal fluid seeding. Accordingly, 12.8% (12/96) of our germinoma patients had true BFGs, and of these, 58.3% (7/12) were free of remote metastases and warranted treatment with limited radiotherapy. True BFGs with remote metastases and all false BFGs should be treated with craniospinal irradiation. We provided evidence for the diagnosis of true BFGs that is useful for radiotherapy strategy, suggesting that the existence of metastasis to other locations is not a diagnostic criterion for a true BFG.     

Spinal epidural venous angioma: a case report and review of the literature

Background

As a vascular malformation, venous angioma in the spinal cord is extremely rare. To our knowledge, there are only five case reports in the literature, and it has not been previously reported in the pediatric age group.

Case report

In this paper, we report on a 3-year-old patient who presented with progressive weakness in his left upper limb. Spinal magnetic resonance imaging (MRI) revealed an epidural cystic mass at the C6–T2 level. The lesion was diagnosed as venous angioma after total removal with laminectomy. Postoperatively, the patient remained symptom free, and no tumor recurrence was confirmed based on MRI at the time of the 18-month follow-up. The clinical, radiological, surgical, and pathological features of this abnormality are discussed, and all six reported cases were reviewed.

Conclusion

Venous angiomas should be included in the differential diagnosis of spinal cystic lesions in children. A definitive diagnosis is difficult based on MRI alone. This rare lesion is amenable to surgery, and gross total removal (GTR) is usually achievable due to a well-demarcated dissection plane. A good clinical outcome after GTR can be expected.     

Familial neurofibromatosis 1 with germinoma involving the basal ganglion and thalamus

Intracranial germinoma associated with neurofibromatosis 1 (NF-1) has never been documented previously. We report a case of familial NF-1 with a germinoma involving the right basal ganglion and thalamus. A 12-year-old boy presented with multiple café-au-lait spots and a family history of neurofibromatosis in his mother, one of two siblings, and his maternal grandfather. His intracranial lesion was subtotally resected. Histologically, it was a pure germinoma. Serum -feto protein and -human chorionic gonadotropin levels were within the normal range. Postoperative myelographic examination and cerebrospinal fluid cytology study showed no evidence of subarachnoid seeding. The patient received postoperative combination chemotherapy resulting in complete response and clearance of the residual tumor. Although this finding of an intracranial germinoma in a patient with familial NF-1 may be coincident, it is suggestive of a potential genetic predisposition. Longitudinal evaluation for the possibility of neoplasm, especially germ cell tumor, in basal ganglion lesions in NF-1 patients is necessary.     

Integrated PET/MRI for planning navigated biopsies in pediatric brain tumors

Introduction

An integrated PET/MRI scanner has been used in selected cases of pediatric brain tumor patients to obtain additional metabolic information about lesions for preoperative biopsy planning and navigation.

Patients and methods

Four patients, age 9–16 years, received PET/MRI scans employing [¹¹C]methionine positron emission tomography (PET) and contrast-enhanced 3D-MR sequences for neuronavigation. PET and MR sequences have been matched for neurosurgical guidance. An infrared camera-based neuronavigation system was employed with co-registered MR and PET images fused to hybrid images for preoperative planning, stereotactic biopsy planning, and/or intraoperative guidance.

Results

All patients showed hot spots of increased amino acid transport in PET and contrast-enhancing lesions in MRI. In three of the four patients, PET hot spots were congruent with contrast-enhancing areas in MRI. In two patients, frame-based stereotactic biopsies were taken from thalamo-mesencephalic lesions. One patient underwent second-look surgery for the suspicion of recurrent malignant glioma of the posterior fossa. One incidental frontal mass lesion was subtotally resected. No complications occurred. Hybrid imaging was helpful during the procedures to obtain representative histopathologic specimens and for surgical guidance during resection. Co-registered images did match with intraoperative landmarks, tumor borders, and histopathologic specimens.

Conclusion

The integrated PET/MRI scanner offers co-registered multimodal, high-resolution data for neuronavigation with reduced radiation exposure compared to PET/CT scans. One examination session provides all necessary data for neuronavigation and preoperative planning, avoiding additional anesthesia in the small patients. Hybrid multimodality imaging may improve safety and yield additional information when obtaining representative histopathologic specimens of brain tumors.