Neurosarcoidosis presenting as acute infarction on diffusion-weighted MR imaging: summary of radiologic findings.

A 36-year-old woman presented with acute-onset right lower extremity paresthesias, dysarthria, right facial droop, and right hemiparesis. CT and MR imaging of the brain revealed extensive white matter disease and left basal ganglia infarction with dural and leptomeningeal enhancement. Differential considerations included vasculitis, granulomatous disease, and neoplasm. Chest, abdomen, and pelvis CTs were normal. Right temporal lobe biopsy revealed noncaseating granulomatous inflammation consistent with neurosarcoidosis.

The relation of White Matter Hyperintensities to implicit learning in healthy older adults.

OBJECTIVE: This study examined whether MRI evidence of cerebrovascular disease in the form of white matter hyperintensities (WMH) was associated with decreased implicit sequence learning performance in a high-functioning group of normal elderly volunteers. METHOD: One hundred and eight community-dwelling elderly individuals received an MRI and performed an implicit sequence learning task, the serial reaction time (SRT) task. RESULTS: Hyperintensities present in the white matter were associated with a decreased learning effect. This association was found with both deep white matter and periventricular changes. Other factors affecting SRT performance (i.e., baseline reaction time and switch-cost) were not significantly related to the presence of WMH. CONCLUSIONS: The results indicate that in addition to previously identified generalized cognitive deficits, WMH are also associated with a specific decrease in the implicit learning of sequences.

The potential risk of carotid injury in cochlear implant surgery.

BACKGROUND: The advent of cochlear implantation has revolutionized the options afforded to the deaf population. With the increase in the prevalence of this procedure have come larger experiences in the associated technical challenges and complications. RESULTS: We present the evaluation and management of a patient with an unusual complication of improper placement of the implant electrode into the carotid canal and its management. We discuss the anatomy of the carotid artery and its proximity to the cochlea to emphasize the potential risk to this large vessel. CONCLUSIONS: Damage to the carotid canal and the carotid artery is a potential risk of cochlear implant surgery. When available, we recommend intraoperative electrical testing of the cochlear implant be performed. If there is doubt as to the placement of the electrode, a radiograph should be obtained before the patient is taken out of the operating room to avoid this complication.

Venous angioma adjacent to the root entry zone of the trigeminal nerve: implications for management of trigeminal neuralgia.

Detection of a venous angioma at the root entry zone is important for surgical planning, so that the neurosurgeon will be aware that both veins and arteries may require microvascular decompression. In selected cases, alternative treatment may be indicated to avoid the potential surgical complication of a venous infarct. Trigeminal neuralgia typically occurs in the middle-aged to elderly population, usually the result of compression of the trigeminal nerve at its root entry zone by an ectatic, aging artery or, less commonly, a regional vein [1, 2, 3]. When associated with a venous angioma at the root entry zone, trigeminal neuralgia usually presents at a younger age [4, 5, 6]. We review the imaging examinations and clinical data of five patients with trigeminal neuralgia who had a venous angioma adjacent to the root entry zone of the trigeminal nerve, and discuss how the imaging findings affected their management.

CT-based assessment of acute stroke: CT, CT angiography, and xenon-enhanced CT cerebral blood flow.

BACKGROUND AND PURPOSE: Only a small percentage of acute-stroke patients receive thrombolytic therapy because of time constraints and the risks associated with thrombolytic therapy. We sought to determine whether xenon-enhanced CT (XeCT) cerebral blood flow (CBF) and/or CT angiography (CTA) in conjunction with CT can distinguish subgroups of acute ischemic stroke victims and thereby better predict the subgroups most likely to benefit and not to benefit from thrombolytic therapy. METHODS: An analysis of 51 patients who had a CT, CTA, and stable XeCT CBF examination within 24 hours of stroke symptom onset was conducted. These initial radiographic studies and National Institutes of Health Stroke Scale score on admission were assessed to determine whether they could predict new infarction on follow-up CT or discharge disposition by use of the Fisher exact test to determine statistical significance. RESULTS: Patients with no infarction on initial CT and normal XeCT CBF had significantly fewer new infarctions and were discharged home more often than those with compromised CBF. The same held true for patients with an open internal carotid artery and middle cerebral artery by CTA and normal CT compared with those with an occluded internal carotid artery and/or middle cerebral artery by CTA. Either was superior to CT and the National Institutes of Health Stroke Scale in prediction of outcome. Both enable the selection of a group of patients not identifiable by CT alone that would do well without being exposed to the risks of thrombolytic therapy. This study included too few patients to statistically assess the role of combining CTA and XeCT CBF information. CONCLUSIONS: The combination of CT, CTA, and Xe/CT CBF does define potentially significant subgroups of patients. The utility of this classification is supported by the observation that CTA and XeCT CBF are superior to CT alone in predicting infarction on follow-up CT and clinical outcome. This information may be useful in selecting patients for acute-stroke treatment.

Vertebral mass resulting from a chronic-contained rupture of an abdominal aortic aneurysm repair graft.

We describe a case of a 63-year-old man with chronic-contained rupture of an abdominal aortic aneurysm at the site of prior graft repair of the aneurysm. Initially misinterpreted as osteomyelitis on the basis of CT findings, this chronic-contained rupture of the abdominal aorta eroding the vertebrae was preoperatively diagnosed at MR imaging and confirmed at surgery. A conventional angiogram failed to show the pseudoaneurysm. Owing to a major difference in the management of a contained aortic aneurysm rupture versus that for osteomyelitis, MR imaging with CT or MR angiography is recommended before any operative or invasive procedure.

CT and MR imaging features of pyogenic ventriculitis.

BACKGROUND AND PURPOSE: Pyogenic ventriculitis is an uncommon manifestation of severe intracranial infection that might be clinically obscure. We hypothesized that determining characteristic imaging features of pyogenic ventriculitis in patients with appropriate risk factors might improve recognition of this severe infection. METHODS: Review of the medical records from 1990 to 2000 revealed 17 cases (12 men, five women) that satisfied inclusion criteria of abscess (n = 3) and/or positive cultures or increased white cells and protein in ventricular (n = 12) or cisternal (n = 1) cerebrospinal fluid. In one case, the diagnosis of ventriculitis was based on the combination of bacterial growth in lumbar cerebrospinal fluid and follow-up imaging. Staphylococcus species and Enterobacter species were the most common organisms. Two neuroradiologists independently evaluated imaging studies for hydrocephalus, ventricular debris, periventricular attenuation or signal abnormality, ependymal enhancement, and signs of meningitis or abscess. Sixteen studies in 11 patients were performed after the intravenous administration of contrast material. RESULTS: Ventricular debris was detected in 16 (94%) of 17 cases and was irregular in 13 (81%) of 16 cases. Hydrocephalus was present in 13 (76%) of 17 cases. Periventricular hyperintense signal was present in most (seven [78%] of nine) cases with MR imaging and was most conspicuous on fluid-attenuated inversion recovery sequences. Ependymal enhancement was detected in seven (64%) of 11 cases in which contrast material was administered. Signs of meningitis (eg, pial or duraarachnoid signal abnormality or enhancement) were present in 13 (76%) of 17 cases. Three cases had imaging signs of abscess. CONCLUSION: Ventricular debris was the most frequent sign of ventriculitis in this series. An irregular level was characteristic of debris in ventriculitis. Hydrocephalus and ependymal enhancement were less frequent signs. Detection of ventricular debris might facilitate diagnosis of pyogenic ventriculitis, a potentially fatal infection, and thus permit appropriate therapy.

Relationship of deep white matter hyperintensities and apolipoprotein E genotype to depressive symptoms in older adults without clinical depression.

OBJECTIVE: This study examined whether evidence of cerebrovascular disease in the form of magnetic resonance imaging (MRI) signal hyperintensities in white matter was associated with depressive symptoms in a high-functioning group of normal elderly volunteers. METHOD: Ninety-two community-dwelling elderly individuals participating in a study of white matter hyperintensities (WMHs) in normal aging whose apolipoprotein E (APOE) genotype had been determined completed the Geriatric Depression Scale and received an MRI scan. Univariate analyses of variance were used to examine the relationship between depressive symptoms and the location of WMHs (in deep white matter versus in periventricular white matter) and to determine whether WMHs were more likely to be associated with symptoms of impaired motivation and concentration or with mood symptoms. The effect on depressive symptoms of the interaction between severity of cerebrovascular disease as evidenced by WMHs and APOE genotype was also examined. RESULTS: Hyperintensities in the deep white matter, but not in the periventricular white matter, were associated with depressive symptoms, especially symptoms of impaired motivation, concentration, and decision making. The relationship between deep WMHs and depressive symptoms was especially strong in individuals carrying the APOE-4 allele. CONCLUSIONS: The pattern of depressive symptoms associated with WMHs in this study was similar to the pattern described in the literature as characterizing "vascular" depression in older persons with major depression. The results suggest that cerebrovascular disease may also underlie the depressive symptoms often found in older individuals who are not clinically depressed.

Superphysiologic FDG Uptake in the Non-Paralyzed Vocal Cord. Resolution of a False-Positive PET Result with Combined PET-CT Imaging.

The application of positron emission tomography imaging with 18F-fluorodeoxyglucose (FDG) to the extracranial head and neck has been proven to be effective in the detection and staging of malignancy. The FDG uptake of normal laryngeal tissue is symmetric and low, while benign lesions typically have only slight increases in FDG uptake. We report a case of asymmetric, superphysiologic FDG uptake in the contralateral vocal cord of a patient with a unilateral vocal cord paralysis secondary to sacrifice of the recurrent laryngeal nerve during pneumonectomy for lung cancer. The FDG uptake of the non-paralyzed vocal cord was increased multiple-fold, placing it well within the range of malignancy. Use of unique, combined PET-CT imaging localized the high FDG uptake to the non-paralyzed vocal cord, and laryngoscopy confirmed no evidence of malignancy in the vocal cord. This case demonstrates that a benign cause of false-positive FDG-PET imaging may be encountered during evaluation of the extracranial head and neck for malignancy. We aim to alert the reader to this potential pitfall in the interpretation of FDG-PET imaging, which can be resolved with the use of combined PET-CT imaging and clinical correlation.

Survival of patients with high grade glioma treated with intrathecal thiotriethylenephosphoramide for ependymal or leptomeningeal gliomatosis.

BACKGROUND: The diagnosis of leptomeningeal dissemination of malignant glioma (meningeal gliomatosis) is associated with poor survival. Intrathecal (IT) chemotherapeutic agents used to achieve tumor control and improve survival include methotrexate, cytosine arabinoside (ara-C), thiotriethylenephosphoramide (thio-TEPA), neocarzinostatin, and 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitros ourea hydrochloride (ACNU). Little information exists about survival following administration of IT chemotherapy. The authors report survival data from a series of patients with supratentorial anaplastic astrocytoma (AA) or glioblastoma multiforme (GBM) treated for ependymal or leptomeningeal gliomatosis with IT thio-TEPA. METHODS: The authors reviewed the records of 14 patients treated between 1991 and 1997 (GBM: n = 9; AA: n = 5). All patients were diagnosed with ependymal (n = 8) or leptomeningeal (n = 6) dissemination of tumor on the basis of clinical signs and symptoms, ependymal or leptomeningeal contrast enhancement on magnetic resonance imaging (MRI), and/or cerebrospinal fluid analysis. All 14 patients underwent placement of a ventricular reservoir system and subsequent instillation of IT thio-TEPA on a weekly basis for 6-12 weeks. Response to treatment was evaluated clinically and by MRI at intervals of 1-3 months and 3-6 months from the initiation of IT thio-TEPA. Data on survival from the time of diagnosis of dissemination was assessed. RESULTS: The median survival, from the time of diagnosis of ependymal or leptomeningeal dissemination, of patients who received IT thio-TEPA was 10 months (AA = 19 months; GBM = 10 months). Five of 14 patients had a radiographic response to treatment within 6 months. The median survival of patients with a radiographic response was 15.5 months, compared with 10 months for nonresponders. No significant neurotoxicity or myelopathy was observed. CONCLUSIONS: Early treatment with IT thio-TEPA may result in improved survival with minimal morbidity. Radiographic response may predict prolonged survival.

Acute spontaneous spinal epidural hematomas.

BACKGROUND AND PURPOSE: Although previous reports have characterized MR imaging features of spinal epidural hematomas (EDH), few cases have been reported during the acute or hyperacute phase within the first 48 hours. Our goal in this investigation was to correlate the MR imaging features of acute (< or =48 hours) spontaneous EDH with clinical management and outcome. METHODS: Eight patients with acute spontaneous EDH (five men and three women; age range, 31-81 years) underwent MR imaging at 1.5 T (T1-weighted, n = 8; T1-weighted after the administration of 0.1 mmol/kg contrast material, n = 6; T2-weighted, n = 8; and T2-weighted, n = 4). The interval from symptom onset to hospital admission ranged from immediate to 5 days. Two neuroradiologists reviewed the MR images for signal characteristics, contrast enhancement, and cord compression. Treatment and clinical outcome were correlated with the imaging findings. RESULTS: The EDH were located in the cervical (n = 3), cervicothoracic (n = 2), thoracolumbar (n = 2), and lumbar (n = 1) regions. On T1-weighted images, the signal intensity of the EDH was isointense to spinal cord in five cases, hyperintense in two cases, and hypointense in one case and did not correlate with time to imaging. Isointensity on T1-weighted images persisted for 5 days in one case. On T2-weighted images, all EDHs were hyperintense with focal, heterogeneous hypointensity. Cord compression was severe in six patients, moderate in one patient, and minimal in one patient. Four cases were treated conservatively with complete resolution or improvement of symptoms within 1 to 3 weeks. CONCLUSION: MR imaging findings were useful in establishing the diagnosis of EDH but did not influence management or predict outcome in this series. Heterogeneous hyperintensity to cord with focal hypointensity on T2-weighted images should suggest the diagnosis of acute spinal EDH. Severity of neurologic impairment had the greatest impact on management and outcome. Nonoperative treatment may be successful in cases with minimal neurologic deficits, despite cord compression revealed by MR imaging.

Brain tumor volume measurement: comparison of manual and semiautomated methods.

PURPOSE: To compare the reliability of two approaches to measuring enhancing brain tumor volumes--the conventional manual trace method and a threshold-based, semiautomated computer software method. MATERIALS AND METHODS: Two operators rated contrast material-enhanced, T1-weighted axial magnetic resonance (MR) image data sets from 16 patients aged 21-71 years with high-grade gliomas. Each MR data set was rated twice by using manual tracing and twice by using the semiautomated method. The semiautomated measurement method involved a thresholding algorithm based on mixture modeling. The data collection time for each method was recorded. Reliability was measured by using inter- and intraoperator agreement indexes. RESULTS: Mean intraoperator agreement indexes (+/- SD) were 0.90 +/- 0.09 (operator 1) and 0.83 +/- 0.15 (operator 2) for the manual trace method and 0.83 +/- 0.17 (operator 1) and 0.84 +/- 0.16 (operator 2) for the semiautomated measurement method. The mean interoperator agreement was 0.85 +/- 0.14 for the manual method and 0.82 +/- 0.18 for the semiautomated method. The semiautomated method was faster than the manual trace method by an average of 4.6 minutes per patient. CONCLUSION: The semiautomated computer method of measuring tumor volume was faster than the manual trace method. Semiautomated computer approaches offer an alternative to manual tracing for measuring serial tumor volumes in patients with high-grade brain neoplasms.

Fungal spinal osteomyelitis in the immunocompromised patient: MR findings in three cases.

The MR imaging findings of fungal spinal osteomyelitis in three recipients of organ transplants showed hypointensity of the vertebral bodies on T1-weighted sequences in all cases. Signal changes and enhancement extended into the posterior elements in two cases. Multiple-level disease was present in two cases (with a total of five intervertebral disks involved in three cases). All cases lacked hyperintensity within the disks on T2-weighted images. In addition, the intranuclear cleft was preserved in four of five affected disks at initial MR imaging. MR features in Candida and Aspergillus spondylitis that are distinct from pyogenic osteomyelitis include absence of disk hyperintensity and preservation of the intranuclear cleft on T2-weighted images. Prompt recognition of these findings may avoid delay in establishing a diagnosis and instituting treatment of opportunistic osteomyelitis in the immunocompromised patient.

Ischemic core and penumbra in human stroke.

BACKGROUND AND PURPOSE: The ischemic core and penumbra have not been thoroughly characterized after acute cerebral thromboembolic occlusion in humans. Differentiation between areas of potentially viable and irreversibly injured ischemic tissue may facilitate assessment and treatment of stroke patients. METHODS: Cerebral blood flow (CBF) was measured in 20 patients with acute middle cerebral artery (MCA) occlusion between 60 and 360 minutes after stroke onset, with the stable xenon computerized tomography (CT) technique. Threshold displays were generated at a single level, and the percentages of hemisphere with CBF 30 cm3. 100 g-1. min-1 were measured. The corresponding images on 12 available follow-up CT scans were similarly assessed to determine the area of final infarct. Comparisons were analyzed with a paired Student's t test and Pearson's correlation coefficient. RESULTS: Discrete and confluent areas of CBF

Relationship between cerebral blood flow and the development of swelling and life-threatening herniation in acute ischemic stroke.

OBJECT: The purpose of this study was to determine whether cerebral blood flow (CBF) measurements in acute stroke could be correlated with the subsequent development of cerebral edema and life-threatening brain herniation. METHODS: Twenty patients with aggressively managed acute middle cerebral artery (MCA) territory strokes who underwent xenon-enhanced computerized tomography (Xe-CT) CBF scanning within 6 hours of onset of symptoms were retrospectively reviewed. The relationship among CBF and follow-up CT evidence of edema and clinical evidence of brain herniation during the 36 to 96 hours following stroke onset was analyzed. Initial CT scans displayed abnormal findings in 11 patients (55%), whereas the Xe-CT CBF scans showed abnormal findings in all patients (100%). The mean CBF in the symptomatic MCA territory was 10.4 ml/100 g/minute in patients who developed severe edema compared with 19 ml/100 g/minute in patients who developed mild edema (p < 0.05). The mean CBF in the symptomatic MCA territory was 8.6 ml/100 g/minute in patients who developed clinical brain herniation compared with 18 ml/100 g/minute in those who did not (p < 0.01). The mean CBF in the symptomatic MCA territory that was 15 ml/100 g/minute or lower was significantly associated with the development of severe edema and herniation (p < 0.05). CONCLUSIONS: Within 6 hours of acute MCA territory stroke, Xe-CT CBF measurements can be used to predict the subsequent development of severe edema and progression to clinical life-threatening brain herniation. Early knowledge of the anatomical and clinical sequelae of stroke in the acute phase may aid in the triage of such patients and alert physicians to the potential need for more aggressive medical or neurosurgical intervention.

Cerebral MR imaging in intravascular lymphomatosis.

MR imaging data were reviewed retrospectively in four male patients (32 to 74 years old) with histologically confirmed intravascular lymphomatosis (IVL), a rare, aggressive form of non-Hodgkin lymphoma. MR findings included infarct-like lesions (n = 2), focal parenchymal enhancement (n = 3), dural/arachnoid enhancement (n = 2), and, in one case, nonspecific, patchy foci of increased signal in the white matter on long-TR images. All patients had multifocal lesions. Knowledge of the spectrum of MR imaging features in this unusual disorder may aid in diagnosis and potentially enhance the role of imaging in following response to therapy.

Central nervous system lesions in liver transplant recipients: prospective assessment of indications for biopsy and implications for management.

BACKGROUND: Precise diagnosis of central nervous system (CNS) lesions in liver transplant recipients remains problematic. Brain biopsies are often not feasible as a result of coagulopathy. We sought to determine whether selected clinical or radiologic characteristics can predict the likely etiology of CNS lesions in liver transplant recipients and thus obviate the need for diagnostic brain biopsies. METHODS: A 4-year prospective, observational, cohort study was conducted at liver transplant centers at four geographically diverse medical institutions. A total of 1730 consecutive liver transplant recipients were evaluated for CNS lesions; 60 patients with radiologically documented CNS lesions comprised the study sample. RESULTS: Vascular events (52%, 31/60), infections (181%, 11/60), immunosuppressive associated leukoencephalopathy (12%, 7/60), central pontine myelinolysis (8%, 5/60), and malignancy (3%, 2/60) were the predominant etiologies of CNS lesions. CNS lesions were most likely to occur within 30 days of transplantation (43%, 26/60); central pontine myelinolysis, subdural hematoma, acute infarcts, and Aspergillus brain abscesses were the predominant etiologies during this time. All brain abscesses were fungal; 73% (8/11) of these patients concurrently had documented extraneural (pulmonary) infection as a result of the same fungal pathogen. Thus, a diagnostic brain biopsy is not warranted in these patients. Patients on dialysis were more likely to have ischemic or infectious CNS lesions (P=0.03). Vascular events were more likely to occur in repeat transplant recipients (P=0.03). Twenty-five percent (15/60) of the CNS lesions occurred more than 1 year after transplantation; small vessel ischemic lesions, malignancy, or non-Aspergillus fungal brain abscesses accounted for all such lesions. CONCLUSIONS: A presumptive etiologic diagnosis can be established in a vast majority of CNS lesions in liver transplant recipients based on identifiable presentation that includes time of onset, unique risk factors, and neuroimaging characteristics. Empiric therapy of brain abscesses in liver transplant recipients should include antifungal and not antibacterial agents.

Quantitative cerebral blood flow determinations in acute ischemic stroke. Relationship to computed tomography and angiography.

BACKGROUND AND PURPOSE: The advent of new modalities to treat acute ischemic stroke presents the need for accurate, early diagnosis. In acute ischemic stroke, CT scans are frequently normal or reveal only subtle hypodense changes. This study explored the utility and increased sensitivity of xenonenhanced CT (XeCT) in the diagnosis of acute cerebral ischemia and investigated the relationship between cerebral blood flow (CBF) measurements and early CT and angiographic findings in acute stroke. METHODS: The CT scans, XeCT scans, and angiograms of 20 patients who presented within 6 hours of acute anterior circulation ischemic strokes were analyzed. RESULTS: CT scans were abnormal in 11 (55%) of 20 patients. XeCT scans were abnormal in all 20 (100%) patients, showing regions of interest with CBF < 20 (mL/100 g per minute) in the symptomatic middle cerebral artery (MCA) territories. The mean CBF in the symptomatic MCA territories was significantly lower than than of the asymptomatic MCA territories (P < .0005). In patients with basal ganglia hypodensities, the mean symptomatic MCA territory CBF was significantly lower than that of patients who did not exhibit these early CT findings (P < .05). The mean symptomatic MCA territory CBF in patients with angiographic M1 occlusions was significantly lower than that of patients whose infarcts were caused by MCA branch occlusions (P < .01). CONCLUSIONS: These results show that XeCT is more sensitive than CT in detecting acute strokes and that CBF measurements correlate with early CT and angiographic findings. XeCT may allow for the hyperacute identification of subsets of patients with acute ischemic events who are less likely to benefit and more likely to derive complications from aggressive stroke therapy.