The findings at magnetic resonance (MR) imaging in a group of 36 pathologically verified supratentorial gliomas were analyzed and compared with the biopsy diagnoses (a) to determine whether MR imaging could be used to classify astrocytic-series tumors into a three-tiered system of low-grade astrocytoma, anaplastic astrocytoma, and glioblastoma multiforme; and (b) to evaluate MR imaging features that may aid in this classification. The MR characteristics evaluated were crossing of the midline, edema, tumor signal heterogeneity, hemorrhage, border definition, cyst formation or necrosis, and mass effect. The statistically significant MR characteristics (positive predictors) were mass effect (P = .0000) and cyst formation or necrosis (P = .0512). The MR accuracy rate approached that of neuropathologic diagnosis, which is subject to sampling errors. MR imaging may serve as an adjunct in case management when the clinical course and MR findings appear to be at odds with the neuropathologic diagnosis.

While head motion is considered a significant problem in magnetic resonance imaging (MRI), there is no data to quantify its extent, severity, or effect on image quality. PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) MRI offers a novel means of quantifying and compensating for head motion. We performed axial T2-weighted PROPELLER (motion corrected: P-CR; uncorrected: P-UNCR) and conventional MRI (CONV), with equal scan times, in five normal volunteers and 35 clinical subjects. Volunteers were examined lying still and performing two separate head movements (shake "no" and nod "yes") to assess detection and compensation of in-plane motion by PROPELLER MRI. Images were examined by three radiologists for motion artifact and for overall image quality. Head rotation and translation was detected in all subjects during each slice acquisition, with expected changes occurring with volunteer head motion. Motion artifact was less commonly seen on PROPELLER than CONV MR ( 2 test P < 0.001). PROPELLER was preferred over CONV in all subjects (P < 0.05) and P-CR was judged superior to P-UNCR (P ‫؍‬ 0.02). Intracranial pathology was equally or better demonstrated with PROPELLER. PROPELLER MRI offers a means of quantifying head motion, reducing motion artifact, and improving image quality.

Results suggest that in neonates and infants, water diffusion is highly dependent on both subject age and brain location.

To assess the clinical efficacy of two-dimensional time-of-flight magnetic resonance (MR) angiography in the evaluation of carotid artery stenosis, a group of patients was evaluated in which 73 vessels were studied with both MR and conventional angiography. Four experienced neuroradiologists each scored both the MR and conventional angiograms in a blinded manner by using a standardized scoring scheme. Comparison of the scores revealed a high degree of correlation. In particular, MR angiography served to discriminate reliably between mildly narrowed and severely narrowed or occluded vessels. Furthermore, severe stenoses were accurately discriminated from occlusions in all cases. MR angiography is a robust and accurate modality for the characterization of carotid artery stenosis. It is useful in conjunction with routine MR imaging of the brain in the evaluation of the patient with suspected carotid arterial disease.

Fumaric aciduria (fumaric acidemia, fumarase deficiency) is a rare inborn error of metabolism caused by deficient activity of fumarate hydratase, one of the constituent enzymes of the Krebs tricarboxylic acid cycle. We describe the clinical and imaging features of this disease arising from a consanguineous pedigree in 8 patients in the southwestern United States. Thirteen patients have been previously described in the medical literature. Our patients presented with an early infantile encephalopathy with profound developmental retardation and hypotonia, and most experienced seizures. Previously unreported characteristics described here include structural brain malformations, dysmorphic facial features, and neonatal polycythemia. Magnetic resonance imaging showed multiple abnormalities, including diffuse polymicrogyria, decreased cerebral white matter, large ventricles, and open opercula. Fumaric aciduria should be included in the differential diagnosis of inborn errors of metabolism that cause cerebral malformations and dysmorphic features. The possibility that inborn errors of energy metabolism may cause structural malformations deserves increased recognition. Ann Neurol 2000;47:583–588

OBJECTIVE For a diagnosis of brain death (BD), ancillary testing is performed if patient factors prohibit a complete clinical examination and apnea test. The American Academy of Neurology (AAN) guidelines identify cerebral angiography (CA), cerebral scintigraphy, electroencephalography, and transcranial Doppler ultrasonography as accepted ancillary tests. CA is widely considered the gold standard of these, as it provides the most reliable assessment of intracranial blood flow. CT angiography (CTA) is a noninvasive and widely available study that is also capable of identifying absent or severely diminished intracranial blood flow, but it is not included among the AAN's accepted ancillary tests because of insufficient evidence demonstrating its reliability. The objective of this study was to assess the statistical performance of CTA in diagnosing BD, using clinical criteria alone or clinical criteria plus CA as the gold-standard comparisons. METHODS The authors prospectively enrolled 22 adult patients undergoing workup for BD. All patients had cranial imaging and clinical examination results consistent with BD. In patients who met the AAN clinical criteria for BD, the authors performed CA and CTA so that both tests could be compared with the gold-standard clinical criteria. In cases that required ancillary testing, CA was performed as a confirmatory study, and CTA was then performed to compare against clinical criteria plus CA. Radiographic data were evaluated by an independent neuroradiologist. Test characteristics for CTA were calculated. RESULTS Four patients could not complete the standard BD workup and were excluded from analysis. Of the remaining 18 patients, 16 met AAN criteria for BD, 9 of whom required ancillary testing with CA. Of the 16 patients, 2 who also required CA ancillary testing were found to have persistent intracranial flow and were not declared brain dead at that time. These patients also underwent CTA; the results were concordant with the CA results. Six patients who were diagnosed with BD on the basis of clinical criteria alone also underwent CA, with 100% sensitivity. For all 18 patients included in the study, CTA had a sensitivity of 75%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 33%. CONCLUSIONS Clinical examination with or without CA remains the gold standard in BD testing. Studies assessing the statistical performance of CTA in BD testing should compare CTA to these gold standards. The statistical performance of CTA in BD testing is comparable to several of the nationally accepted ancillary tests. These data add to the growing medical literature supporting the use of CTA as a reliable ancillary test in BD testing.

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