Annette C. Douglas-Akinwande

Diffusion-Weighted Imaging Characteristics of Primary Central Nervous System Germinoma with Histopathologic Correlation : A Retrospective Study

RATIONALE AND OBJECTIVES The aim of this study was to quantify, using diffusion-weighted magnetic resonance imaging, the microscopic rate of water diffusion in pure germinoma and to determine whether or not the apparent diffusion coefficient (ADC) values correlated with the different histologic components. MATERIALS AND METHODS A retrospective analysis of echoplanar diffusion-weighted magnetic resonance images was conducted on 10 patients with 11 germinoma lesions. All images were obtained using 1.5-T magnets with a b value of 1000 s/mm(2). Regions of interest were drawn separately within the solid and the cystic or necrotic components of each germinoma, as well as within the normal gray and white matter of the respective cases, to calculate ADCs. The diffusion characteristics of the germinomas were assessed using mean and normalized ADC values. Histologic samples from all cases were blindly reviewed and then correlated with the ADC values. RESULTS Data are expressed as mean +/- standard error. Evaluation of the solid components revealed that 36% of germinomas (4 of 11) had predominantly restricted diffusion (ADC(solid), 694.71x10(-6)+/-74.54x10(-6) s/mm(2); ADC ratio, 0.84+/-0.07) compared to normal brain. The majority (55% [6 of 11]) had normal diffusion (ADC(solid), 947.64x10(-6)+/-54.38x10(-6) s/mm(2); ADC ratio, 1.14+/-0.10). Only 9% (1 of 11) had increased diffusion (ADC(solid), 1172.30x10(-6)+/-48.52x10(-6) s/mm(2); ADC ratio, 1.67+/-0.16). The cystic and necrotic components had a mean ADC ratio of 2.55+/-0.25. There was no significant correlation between the histologic components and the ADC values of germinomas. CONCLUSIONS The vast majority of germinomas demonstrated predominantly restricted (36%) or normal (55%) diffusion. The histologic components were not correlated with the ADC values.

Medulloblastoma mimicking Lhermitte-Duclos disease on MRI and CT

BACKGROUND Although previous reports purport that the unique magnetic resonance imaging (MRI) features of Lhermitte-Duclos disease (LDD) obviates the need for biopsy, medulloblastoma can have an indistinguishable imaging appearance. CASE DESCRIPTION We present a patient who suffered from a medulloblastoma that demonstrated no enhancement and had imaging characteristics that were indistinguishable from LDD. This atypical imaging appearance, which could potentially be confused with LDD, may lead to misdiagnosis and inappropriate treatment in the absence of tissue sampling. CONCLUSION In those patients where imaging is highly suggestive of LDD but lack other manifestations of Cowden syndrome, biopsy is required and advanced imaging with magnetic resonance spectroscopy (MRS) should be strongly considered.

Accuracy of contrast-enhanced MDCT and MRI for identifying the severity and cause of neural foraminal stenosis in cervical radiculopathy: A prospective study

OBJECTIVE The purpose of this study was to determine the accuracy of IV contrast-enhanced MDCT and MRI for evaluation of the severity and cause of neural foraminal stenosis in patients with cervical radiculopathy. SUBJECTS AND METHODS Eighteen patients with cervical radiculopathy prospectively underwent contrast-enhanced MDCT and MRI. Contrast-enhanced MDCT scans were acquired at 1-mm thickness and reconstructed in oblique axial (parallel to disk) and sagittal (perpendicular to neural foramen) 2-mm sections without a gap. The MRI sequences used were sagittal T1-weighted, fast spin-echo T2-weighted, 3D fast spin-echo T2-weighted, axial T2-weighted, and 3D gradient-recalled echo. Three neuroradiologists independently and blindly rated the severity and cause of neural foraminal stenosis on a 4-point scale. Using the same scale at surgery, one of three surgeons rated the severity and cause of neural foraminal stenosis, and the results were used as the reference standard. Interobserver and intraobserver agreement (kappa) was calculated. RESULTS For severity of neural foraminal stenosis, the sensitivities of contrast-enhanced MDCT (50/55, 91%) and MRI (55/57, 96%) were similar, as were their specificities (contrast-enhanced MDCT, 13/24, 54%; MRI, 11/24, 46%). For cause of neural foraminal stenosis, the accuracies of contrast-enhanced MDCT (46/54, 85%) and MRI (45/57, 79%) were similar. Interobserver agreement on severity of neural foraminal stenosis was moderate to almost perfect for contrast-enhanced MDCT (kappa=0.50-1.00) and MRI (kappa=0.43-1.00). For cause of neural foraminal stenosis, interobserver agreement was moderate to substantial for contrast-enhanced MDCT (kappa=0.52-0.76) but only fair for MRI (kappa=0.23-0.39). Intra observer agreement was very high for severity of neural foraminal stenosis (contrast-enhanced MDCT, kappa=0.85; MRI, kappa=0.80) and cause of neural foraminal stenosis (contrast-enhanced MDCT, kappa=0.86; MRI, kappa=1.00). CONCLUSION Contrast-enhanced MDCT is as accurate as MRI in evaluation of the severity and cause of neural foraminal stenosis and may have better interobserver agreement.

Anaplastic Astroblastoma Presenting as Massive, Sudden-Onset, Intraparenchymal Hemorrhage

Astroblastoma is a rare primary glial tumor of children and young adults, typically located in the cerebral hemispheres and presenting as a well-circumscribed, nodular, often cystic enhancing mass. The existence of astroblastoma as a distinct clinicopathologic entity has long been debated but is recognized in the 2007 WHO classification of CNS tumors. The grading of these tumors remains unsettled. Currently, no grade has been established and there are no clearly defined diagnostic criteria for low- or high-grade tumors. Astroblastomas in general are thought to have a favorable outcome with low rates of recurrence following gross total resection. We report a case of astroblastoma with ‘high-grade/anaplastic’ histology in a 12-year-old, previously healthy girl. The patient experienced severe, sudden-onset headache, and quickly became comatose. Head CT showed a massive intraparenchymal hemorrhage in the right frontal lobe with surrounding edema. She underwent emergent posterior frontal craniotomy for decompression and hematoma evacuation. Pathologic examination revealed a sharply demarcated hemorrhagic heterogeneous glial tumor with focal papillary architecture, densely hyalinized blood vessels, and intensely GFAP-positive perivascular cells. The tumor showed unequivocal high-grade features including an elevated proliferative index. The diagnosis of anaplastic astroblastoma was rendered. The patient expired on postoperative day 30. This case illustrates the potential poor outcome of high-grade astroblastoma and highlights the morphologic heterogeneity of this rare neoplasm.

A 41-YEAR-OLD WOMAN WITH VON HIPPEL-LINDAU AND A CEREBELLAR LESION

A 41-year-old woman with a 12-year history of von Hippel-Lindau disease presented with progressive quadriparesis and difficulty swallowing. MRI revealed a well-circumscribed, partially cystic cerebellar neoplasm, consistent with hemangioblastoma. The tumor was resected and the diagnosis of hemangioblastoma confirmed. Embedded within the hemangioblastoma was a small focus of metastatic renal cell carcinoma (RCC). RCC metastatic to a CNS hemangioblastoma is the second most common type of tumor-to-tumor metastasis, which may be due to a number of factors. Proper immunostaining panels are required to clearly identify these cases since both tumor may have similar histology.

Glioblastoma occurring at the site of a previous medulloblastoma following a 5-year remission period

We describe a case of a 14‐year‐old boy who developed a cerebellar and brainstem glioblastoma 5 years after treatment for a medulloblastoma. The patient first presented in 2003 with 9 months of vomiting and a 9‐kg weight loss. A head MRI showed a heterogeneously enhancing posterior fossa mass with hydrocephalus. Gross total resection was performed and the tumor was consistent with a classic medulloblastoma. Postoperative chemotherapy and craniospinal radiation was administered. The patient remained tumor‐free until 2008, at which time he presented with right‐sided weakness and numbness, left eye pain, vomiting and weight loss. Imaging showed abnormalities within the posterior pons, medulla, inferior cerebellar peduncles, cerebellar hemispheres and cervicomedullary junction with expansion of the medulla and cervical spinal cord. Due to the location of the lesion, biopsy was felt to be too risky and was avoided. Despite receiving chemotherapy, his symptoms continued to worsen and he died 4 months later. Post mortem examination limited to the brain and spinal cord confirmed the radiographic extent of the tumor. Microscopic examination showed a highly cellular infiltrative glial neoplasm with extensive palisading necrosis. A diagnosis of glioblastoma was rendered. The question of whether the first and second tumors were related is of potential clinical and academic interest. The first tumor was synaptophysin‐positive and GFAP‐negative, consistent with medulloblastoma. The second tumor was synaptophysin‐negative and focally GFAP‐positive, consistent with glioblastoma. The glioblastoma displayed EGF receptor amplification, and interestingly, it also displayed MYCN amplification; both tumors showed low level PTEN deletion. The medulloblastoma displayed a signal pattern consistent with an isochromosome 17q, while the glioblastoma showed some cells with an isochromosome 17q signal pattern amid a background of cells with abundant chromosomal instability. The relationship between these two tumors, particularly with regard to various molecular events, is discussed.

Multichannel Computed Tomography Angiography and its Role in the Evaluation of Rotational Vertebrobasilar Insufficiency

We present a case of rotational vertebrobasilar insufficiency diagnosed and followed by computed tomography angiography. Diagnosis of this entity provides a unique challenge in that the patient must be positioned properly to avoid a false-negative result without causing ischemic brain injury. The evaluation of rotational vertebrobasilar insufficiency with computed tomography angiography has never been described in the literature to the best of our knowledge. We highlight the advantages of using this technique in the diagnosis and follow-up of this uncommon entity.

A foramen of Monro tumor.

A previously healthy 14-year-old boy presented to our facility with a 2-month history of headaches. His headaches were progressively worsening in intensity and though not positional, were reportedly worse in the morning. He developed nausea and vomiting multiple times per week and was given antiemetics and migraine medications on several previous visits to outside hospitals. His symptoms progressed over 48 h to severe headaches with multiple episodes of emesis prompting MRI and subsequent referral. On presentation, his neurological examination was normal, except for grade I bilateral papilledema. Past medical history and family history were unremarkable. MRI of the brain revealed a well-circumscribed, contrast-enhancing mass adherent to the septum pellucidum in the frontal horn of the right lateral ventricle, measuring 1.7 ¥ 2.0 ¥ 1.8 cm, extending into the left foramen of Monro and into the third ventricle (Fig. 1a–f). The left lateral ventricle was dilated with shift of the septum from left to right, and transependymal flow of CSF was noted. There was no evidence of hypothalamic or parenchymal extension. The lesion was hypointense on T1and hyperintense on T2-weighted images (Fig. 1a,d). Diffusionweighted MRI (Fig. 1b) and apparent diffusion coefficient map (Fig. 1c) showed restricted diffusion, indicative of a hypercellular neoplasm. MR spectroscopy demonstrated elevated choline and reduced N-actylyaspartate, consistent with a neoplastic process (Fig. 2). A glial neoplasm was considered unlikely since there was no demonstrated connection to the extraventricular brain parenchyma. However, on MR spectroscopy, the elevated choline and reduced N-actylyaspartate were indicative of a glial neoplasm. Pilocytic astrocytoma typically has relatively normal MR spectroscopy.An external ventricular drain was placed into the left lateral ventricle and was followed by craniotomy for gross total resection. Intraoperatively, the tumor was found to be adherent to the medial and anterior portions of the foramen of Monro where it was in close proximity to limbic structures. It was intimately associated with the choroid plexus posteriorly, from which the tumor was tediously dissected free. The more superior and lateral aspects of the tumor were not attached to any structures and were in the body of the ventricle. Postoperatively, the patient experienced improvement in his headaches, allowing the external ventricular drain to be clamped. On postoperative day 6, he was found to have a CSF collection under his operative flap. He underwent placement of a left parieto-occipital ventriculoperitoneal shunt with resolution of this collection. Postoperative MRI revealed a small 1.7 ¥ 0.7 cm area of heterogeneous tissue in the foramen of Monro felt to be a surgically inaccessible residual tumor. The patient later received proton beam radiation therapy. The most recent noncontrasted head CT scan performed 15 months after surgery demonstrated decrease in the size of the ventricles without evidence of tumor growth.