Craniopharyngiomas — The Utility of Contrast Medium Enhancement for MR Imaging at 1.5 T

To evaluate the efficacy of i.v. contrast medium administration in MR imaging at 1.5 T in patients with craniopharyngiomas, MR studies of 10 men and 6 women with pathologically proven craniopharyngiomas were made. The MR images were obtained as 3- to 5-mm-thick coronal (n = 13) or axial (n = 3) T1-weighted images (T1WI) prior to and following i.v. Gd-DTPA administration. Proton density- (PD) and T2-weighted images (T2WI) were also obtained. Conspicuity of tumor margins, cystic versus solid components, size, location and effect upon adjacent structures were separately characterized in all imaging sequences. In 6 patients contrast medium-enhanced T1WI, PD and T2WI demonstrated cystic tumor components not seen on unenhanced T1WI. There were significant differences (p < 0.004) on 2-tailed Student's t-test comparing tumor conspicuity on contrast medium-enhanced T1WI with unenhanced T1WI, PD and T2WI. Optimal tumor delineation on MR imaging of patients with craniopharyngiomas justifies the use of i.v. contrast medium.

Delayed diffusion-weighted MR abnormality in a patient with an extensive acute cerebral hypoxic injury: A case report

Diffusion-weighted (DW) MR imaging usually identifies acute cerebral infarction injury in symptomatic patients. We report a patient with severe hypoxic brain injury following suicide attempt by hanging, but with normal DW MR imaging 5–6 h after the event. Follow-up DW MR imaging 3 days after the event, and subsequent autopsy, revealed extensive cerebral anoxic injury.

Volumetric brain changes in females with fragile X-associated tremor/ataxia syndrome (FXTAS)

BACKGROUND

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder occurring in male and rare female carriers of a premutation expansion (55 to 200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene.

METHODS

Volumetric MRI studies, clinical staging, cognitive testing, and molecular analysis were conducted in 15 female premutation carriers affected by FXTAS (age 59.5 +/- 10.3 years), 20 unaffected female carriers (43.3 +/- 11.2 years), 11 genetically normal female controls (51.0 +/- 10.3 years), 36 affected male carriers (65.0 +/- 5.6 years), 25 unaffected male carriers (53.5 +/- 12.5 years), and 39 male controls (58.0 +/- 15.0 years). Female and male carriers with FXTAS were matched on duration of disease.

RESULTS

We found less pronounced reductions of cerebellar volume and a lower incidence of involvement (symmetric high T2 signal) of the middle cerebellar peduncles (MCP sign) in females affected by FXTAS (13%) compared with affected males (58%). We found reduced brain volumes and increased white matter disease associated with the presence of FXTAS in females compared with female controls. We also observed significant associations between reduced cerebellar volume and both increased severity of FXTAS symptoms and increased length of the CGG repeat expansion in male premutation carriers, but not in females.

CONCLUSIONS

Females affected by fragile X-associated tremor/ataxia syndrome (FXTAS) demonstrated milder brain changes than affected males, although they showed a similar pattern of radiologic findings consistent with brain atrophy and white matter disease. FXTAS should be considered (by ordering fragile X DNA testing) in females who present with late-onset ataxia, action tremor, or neuropathy, particularly in those with a family history of mental retardation, autism, or premature ovarian failure.

Fragile-X-associated tremor/ataxia syndrome (FXTAS) in females with the FMR1 premutation

We describe five female carriers of the FMR1 premutation who presented with symptoms of tremor and ataxia and who received a diagnosis of definite or probable fragile-X-associated tremor/ataxia syndrome (FXTAS). Unlike their male counterparts with FXTAS, none of the women had dementia. Females had not been reported in previous studies of FXTAS, suggesting that they may be relatively protected from this disorder. Brain tissue was available from one of the five subjects, a women who died at age 85 years; microscopic examination revealed intranuclear neuronal and astrocytic inclusions, in accord with the findings previously reported in males with FXTAS. The work-up of families with the FMR1 mutation should include questions regarding neurological symptoms in both older male and female carriers, with the expectation that females may also manifest the symptoms of FXTAS, although more subtly and less often than their male counterparts.

Delayed diffusion-weighted MR abnormality in a patient with an extensive acute cerebral hypoxic injury

Diffusion-weighted (DW) MR imaging usually identifies acute cerebral infarction injury in symptomatic patients. We report a patient with severe hypoxic brain injury following suicide attempt by hanging, but with normal DW MR imaging 5-6 h after the event. Follow-up DW MR imaging 3 days after the event, and subsequent autopsy, revealed extensive cerebral anoxic injury.

Brain structure and cognition in a community sample of elderly Latinos

BACKGROUND

Previous studies have found that hippocampal atrophy and white matter hyperintensities (WMH) on MRI are linked to cognitive impairment and dementia. The authors measured these variables in a population-based cohort of older Mexican Americans with a wide spectrum of cognitive ability, ranging from normal cognition to dementia.

OBJECTIVE

To investigate whether these structural brain changes were seen in individuals prior to the development of dementia and how these changes were related to the presence of dementia.

METHODS

A sample of 122 subjects was selected from the Sacramento Area Latino Study on Aging, and subjects were categorized into four groups of increasing levels of cognitive impairment: normal, memory impaired (MI), cognitively impaired but not demented (CIND), and demented. Hippocampal volume was quantified using a region of interest approach. WMH was rated on a semiquantitative scale as the percent of total volume of white matter.

RESULTS

Hippocampal volume was significantly reduced in CIND and demented individuals, and WMH were significantly increased in demented subjects. MI subjects did not have any significant changes in hippocampal volume or WMH. The risk for developing dementia was significantly and comparably increased in subjects with either hippocampal atrophy or high WMH. However, the risk for dementia increased dramatically in subjects with both hippocampal atrophy and a high degree of WMH.

CONCLUSION

Reductions in hippocampal volume may be present before dementia but not until cognitive impairment is relatively severe. Because there is a synergistic effect between high WMH and hippocampal atrophy, interactions between vascular and degenerative processes may be important determinants of dementia.

Hippocampus and amygdala in schizophrenia: assessment of the relationship of neuroanatomy to psychopathology

The hippocampus and amygdala are believed to be involved in the pathology of schizophrenia. In this study, we attempted to replicate the reported bilateral volume reduction of the hippocampus and amygdala and to study the relationship of the volumes of these structures to the symptoms of schizophrenia. The hippocampus-amygdala complex (HAC) was manually traced on 3-mm coronal T(1)-weighted MRIs, resampled into 1-mm coronal slices, from 20 male patients with schizophrenia and 20 age-matched male controls. The complex was divided into three parts: anterior one-third representing the amygdala and middle and posterior thirds representing the anterior and posterior halves of the hippocampus. Positive and negative symptoms and severity of hallucinations and thought disorder (conceptual disorganization) were quantified using the Brief Psychiatric Rating Scale (BPRS). None of the above structures, controlled for brain volume, differed significantly in patients compared with normal controls. When the relationship between volumes and symptoms was examined, the left HAC was found to inversely correlate with thought disorder and negative symptoms. Specifically, significant inverse correlations were found between (i) left amygdala and thought disorder, (ii) left hippocampus and negative symptoms, and (iii) left anterior and posterior hippocampus volumes and positive and negative symptoms, respectively. Our findings further support the role of the HAC in the pathophysiology of schizophrenia and suggest unique associations between individual structures and specific symptoms of the illness.

Neurodevelopmental outcome of patients after the fontan operation: A comparison between children with hypoplastic left heart syndrome and other functional single ventricle lesions

OBJECTIVE

To compare neurodevelopmental outcome (NDO) in patients with hypoplastic left heart syndrome (HLHS), other functional single ventricle lesions, and the standard population and to investigate predictors of NDO in the population of children with functional single ventricle (FSV).

STUDY DESIGN

A time- and age-defined cohort of patients with the Fontan circulation was recruited to participate in neurodevelopmental testing, behavioral evaluation, and imaging of the central nervous system. The Wechsler Intelligence test was the primary measure of NDO. Analysis included comparison of patients with HLHS with other patients with functional single ventricles. Other potential clinical predictors of NDO were investigated.

RESULTS

The mean Full Scale Wechsler Intelligence score was 101.4+/-5.4. For the HLHS subgroup the mean Full Scale Wechsler score was 93.8+/-7.3, and for the non-HLHS subgroup it was 107.0+/-7.0. Although the HLHS group had significantly lower scores than the non-HLHS subgroup, neither subgroup scored significantly different from the standard population on the Wechsler Scales. Socioeconomic status, circulatory arrest, and perioperative seizures also were predictive of neurodevelopmental outcome.

CONCLUSION

Neurodevelopmental and behavioral outcome in patients who have undergone the Fontan procedure including patients with HLHS is good in the preschool and early school years, with Wechsler Intelligence scores generally in the normal range.

Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA)

RATIONALE AND OBJECTIVES

The objective of the two pivotal phase 3 studies was to evaluate the safety and efficacy of OptiMARK (Gd-DTPA-bis(methoxyethylamide) [Gd-DTPA-BMEA]) compared with Magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system.

METHODS

Two multicenter, randomized, double-blind, parallel group studies were conducted in 395 patients with known or suspected central nervous system pathology. Subjects were randomized to receive a single 0.1 mmol/kg intravenous injection of either Gd-DTPA-BMEA or Gd-DTPA. The safety of Gd-DTPA-BMEA and Gd-DTPA was monitored for up to 72 hours after study drug administration. Precontrast and postcontrast administration magnetic resonance scans were acquired using identical imaging planes and techniques.

RESULTS

No deaths or unexpected adverse events were reported in either group. A comparison of adverse events by intensity and relation demonstrated no statistically significant differences between the two groups. Gd-DTPA-BMEA and Gd-DTPA were equivalent with respect to confidence in diagnosis, conspicuity, and border delineation.

CONCLUSIONS

Gd-DTPA-BMEA and Gd-DTPA demonstrated comparable efficacy profiles, and the safety profiles were considered similar.

Treatment of Wilson's disease with zinc: XV long-term follow-up studies

Wilson's disease is an inherited disease of copper accumulation caused by a failure of biliary excretion of excess copper. Accumulated copper causes liver disease in these patients, and in perhaps two thirds of patients, it causes brain damage leading to clinical neurologic or psychiatric dysfunction. Maintenance treatment involves reversing the positive copper balance. The earliest approaches have used chelators, such as penicillamine or trientine, which increase the urinary excretion of copper. A more recent approach has used zinc, which blocks the absorption of copper and increases copper excretion in the stool. Because of the high level of endogenously secreted copper in alimentary secretions, the reabsorption of which is partially blocked by zinc therapy, zinc acts to remove accumulated copper from the body as well as prevent its reaccumulation. In the present article we present data on the long-term follow-up (up to 10 years) of maintenance zinc treatment of 141 patients with Wilson's disease. The data presented document that zinc is effective as a sole therapy in the long-term maintenance treatment of Wilson's disease and that it has a low toxicity. The results demonstrate the efficacy of zinc therapy in treating the presymptomatic patient from the beginning of therapy. We also present limited data on the use of zinc in the treatment of pregnant patients and children who have Wilson's disease; these data also indicate efficacy and low toxicity. The median follow-up period for the group as a whole is 4.8 years; for the presymptomatic patients it is 6.5 years; for the children it is 3.6 years.

Imaging of spinal intradural arachnoid cysts: MRI, myelography and CT

Imaging studies in eight patients with surgically-confirmed spinal arachnoid cysts were analyzed retrospectively. All patients had preoperative MRI of the spine and seven preoperative myelography with postmyelographic CT. In all cases the correct diagnosis could be made preoperatively on the basis solely of MRI. The diagnosis could also be established from myelography and postmyelographic CT in six of the seven cases. In one case myelography and CT simply demonstrated an intradural extramedullary mass.

Spinal cord infection: myelitis and abscess formation

PURPOSE

Our purpose was to describe the MR findings and evolution of spinal cord abscess and to define those MR features that allow differentiation of cord infection from other intramedullary abnormalities.

METHODS

We retrospectively reviewed the MR studies of all patients in whom intramedullary spinal cord abscess was proved either by blood or cerebrospinal fluid culture or by serologic examination at our institution between January 1988 and January 1996. The study group included four adults and two children, 7 to 74 years old (mean age, 38 years).

RESULTS

Initial MR studies showed intramedullary high signal on T2-weighted sequences with poorly defined marginal enhancement on T1-weighted images. On follow-up contrast-enhanced T1-weighted studies, the lesions had well-defined enhancing margins with central low signal intensity. After the initiation of therapy, T2 signal abnormalities decreased markedly and contrast-enhanced studies showed ring enhancement. These T1 findings resolved with treatment over serial studies in four patients. The organisms identified were Streptococcus milleria, S pyogenes, atypical mycobacteria, Mycobacterium tuberculosis, and Schistosoma mansoni (both children).

CONCLUSION

A characteristic sequence of imaging findings aids in the differentiation of cord infection from other intramedullary lesions.

Magnetic resonance evaluation of ventrolateral medullary compression in essential hypertension

OBJECT

The authors designed a blinded prospective study comparing patients with essential hypertension to patients without hypertension in which magnetic resonance (MR) imaging was used to evaluate the role of lateral medullary compression by adjacent vascular structures as a cause of neurogenic hypertension.

METHODS

Patients with documented essential hypertension were recruited to undergo thin-slice axial brainstem MR imaging evaluation. Nonhypertensive (control) patients scheduled to undergo MR imaging for other reasons also underwent thin-slice MR imaging to form a basis for comparison. Magnetic resonance images obtained in patients from the hypertensive (30 patients) and the control (45 patients) groups were then compared by four independent reviewers (two neuroradiologists and two neurosurgeons) who were blinded to the patients' diagnosis and hypertensive status. Images were reviewed with regard to left versus right vertebral artery (VA) dominance, compression of the medulla on the left and/or right side, and brainstem rotation. Medullary compression was graded as either vessel contact without associated brainstem deformity or vessel contact with associated brainstem deformity.

CONCLUSIONS

There was a tendency toward left VA dominance in the hypertensive group compared with the control group, although a significant difference was shown by only one of the four reviewers. There were no differences in brainstem compression or rotation between the hypertensive and nonhypertensive groups. These results are contrary to those of recently published studies in which MR imaging and/or MR angiography revealed lateral brainstem vascular compression in hypertensive patients but not in nonhypertensive (control) patients. Reasons for this discrepancy are discussed. On the basis of their own experience and that of others, the authors believe that neurogenic hypertension does exist. However, thin-slice MR imaging may not be a reliable method for detecting neurovascularly induced essential hypertension and the prevalence of neurovascular compression as the source of hypertension may be overestimated when using current imaging techniques.

Does neuroanatomy predict ECT response?

1. Structural neuropathologic abnormalities have been associated with severe psychiatric illnesses, including bipolar disorder, major depressive disorder, and schizophrenia. In the latter, ventricular enlargement has been variably associated with symptom severity and poor treatment response. In patients with severe depressive disorders, the relationship between cortical and subcortical pathology and ventricle enlargement, symptom severity, and response to treatment is far from clear. 2. The present study investigated the relationship between structural CNS pathology, symptom severity and treatment response in patients undergoing ECT. It was hypothesized that patients with greater neuroanatomic abnormalities would demonstrate greater initial symptom severity and poorer response to ECT. 3. The subjects were 57 patients with unipolar or bipolar depression admitted for ECT treatment. Symptom severity was quantified using the Hamilton Depression Rating Scale (HRSD) at baseline and post-ECT. 4. Lateral and third ventricle-brain ratio (LVBR, 3VBR) were determined from CT scans and cortical atrophy was rated by a faculty neuroradiologist. 5. Contrary to our first hypothesis, structural pathology was not associated with baseline symptom severity. In terms of treatment response, the number of treatments required to achieve benefit was correlated with larger 3VBR; CT variables were not related to total post-treatment or change in HRSD score. Third ventricle enlargement may be an index of generalized pathology or regional brainstem abnormalities that influence ECT response rate by limiting individual seizure efficacy or neurochemical responsiveness, thereby necessitating a greater number of ECT treatments, without significant impact on overall response.

Imaging of nodal metastases in the head and neck

Therapeutic outcome of head and neck cancer is influenced strongly by the presence of nodal metastases. Sensitivity and specificity of the physical examination for the diagnosis of nodal metastasis is unsatisfactory, resulting in both false negatives and false positives of 25 to 40%. Preoperative detection of nodal metastases therefore becomes one of the important goals of imaging studies of patients with head and neck cancer. Despite several advanced techniques and the wide clinical use of MR, MR has surprisingly added little to the diagnostic accuracy of contrast-enhanced CT. Although CT and MR allow detection of abnormally enlarged nodes or necrotic nodes, neither borderline-sized nodes without necrosis nor extracapsular spread are reliably differentiated from reactive or normal nodes in patients with head and neck cancer. Lack of definitive diagnostic methods of metastatic lymph nodes is a serious shortcoming in the preoperative workup for patients with head and neck cancer. To avoid missing small metastatic nodes, a large number of patients clinically staged as N0 have undergone elective neck dissection to exclude metastases. With development of more tissue-specific imaging techniques, patients can be better characterized according to the status of nodal disease so that an appropriate therapeutic protocol can be designed for an individual case.

A comparison of the predictive power for survival in gliomas provided by MIB-1, bromodeoxyuridine and proliferating cell nuclear antigen with histopathologic and clinical parameters

The purpose of this prospective study of 65 patients was to compare side-by-side the predictive power for survival of (a) MIB-1, (b) bromodeoxyuridine (BUDR), and (c) proliferating cell nuclear antigen (PCNA). They were compared (a) with each other, (b) with several clinical predictors, and (c) with histopathologic grade under actual clinical biopsy conditions in a study of 1993 World Health Organization (WHO) grade II to IV adult supratentorial gliomas. There was a strong positive relationship between MIB-1 and BUDR by Spearman Rank correlation. In univariate analysis, MIB-1 (logrank p = 0.06) was more predictive of survival than BUDR or PCNA. Longer survivors were distinguished from others by the lowest MIB-1 labeling indices (LI < or = 2.5%) better than by the lowest histopathologic grade. However, histopathologic grades were highly predictive among the entire group (logrank p < 0.0001). Young age (p < 0.0001) and high Karnofsky performance status (p < 0.0001) were the clinical factors most predictive of longer survival. Female gender correlated with longer survival (logrank p = 0.02). In multivariate Cox proportional hazards models, age, Karnofsky performance status, and histopathologic grading remained statistically significant after full reduction of the model. We conclude that Ki-67 measured by MIB-1 monoclonal antibody was superior to other markers of proliferation. When all factors are considered simultaneously over all 3 grades of malignancy, greatest predictive power resides in histopathologic grade and clinical variables. MIB-1 is expected to be most important in cases where clinical or histopathologic factors are ambiguous or where they cannot be fully assessed.

Leptomeningeal fibrosis and the delayed diagnosis of a central nervous system neoplasm (primitive neuroectodermal tumor)

We report a unique case of histologically confirmed meningeal fibrosis in a child who had progressive ischemic neurologic symptoms before the delayed diagnosis of an intracranial primitive neuroectodermal tumor (PNET) was made > 1 year after initial presentation. This pathology has previously been described after neurosurgical procedures, subarachnoid hemorrhage, cranial irradiation, and with no known etiology, but has never been reported in association with a central nervous system neoplasm. In a 6-year-old boy with headaches of several months' duration MRI demonstrated hydrocephalus, a right cerebellopontine angle cyst, and dural enhancement. Biopsies of the thickened meninges taken when the cyst was surgically fenestrated demonstrated only fibrosis with no evidence of infection, hemorrhage, or neoplasm. In the next 6 months, the child had two acute stroke-like episodes with alternating hemiparesis that gradually improved. There were ischemic changes in the diencephalon on MRI. Repeat dural biopsies were unchanged. One year after the initial operation, a left hemiparesis recurred and MRI demonstrated multiple intracranial masses in the cerebral cortex, cerebellum, suprasellar area, and cauda equina. After surgical resection, the cortical mass was found to be a PNET. All the lesions regressed after treatment with radiation and chemotherapy. We hypothesize that the meningeal fibrosis represented a "desmoplastic" reaction to an occult PNET, similar to the fibrous proliferation with cerebellar desmoplastic medulloblastoma except for the extent of the meningeal involvement and the long undetected parenchymal tumor. The mechanism of the ischemic brain injury was most likely vascular involvement by the fibrotic process, either directly or by predisposition to vasoconstriction.

Adult claustrophobia, anxiety and sedation in MRI

The purpose of this study was to identify the proportion of adult patients at our institution who require sedation to tolerate MR imaging. We also wished to identify whether the type of study and patient age or sex was associated with a variation in the use of sedation. A total of 939 patients, 18 years of age or older, underwent MR imaging at a large university hospital during a randomly selected 7-week period. Age, sex, type of study, number of prior MRI's, and use of sedation were identified in this group. Patients requiring sedation were compared by these criteria to all non-sedated members over 18 years of age in the cohort who acted as a control. Of the 939 patients 134 (14.3%) required oral sedation, i.v. sedation, or general anesthesia to tolerate MRI. This group was 35.8% male, 64.1% female (control group 48.1% male, 51.9% female). Of those requiring sedation, 89 patients (66.4%) were having brain MRI (male n = 29 or 32.6%, female n = 60 or 67.4%). In the control group 461 patients (57.3%) were having brain MRI (male n = 209 or 45.3%, female n = 252 or 54.6%). The mean age of the sedated group was 60.75 (range 19-91). The non-sedated group had a mean age of 67.3 (range 28-93). The sedated group had undergone a mean of 1.56 prior MR studies (range 0-16); the control group had a mean of 0.9 prior studies (range 0-7). Sedation was more commonly utilized in women than men, in patients having brain MRI, and in patients who had undergone prior MRI procedures. The identification of a population having the greatest need for sedation may aid in the development and selection of methods of stress reduction which will result in greater patient comfort, reduction in motion artifact, and fewer prematurely terminated studies.

Treatment of Wilson disease with ammonium tetrathiomolybdate. II. Initial therapy in 33 neurologically affected patients and follow-up with zinc therapy

OBJECTIVE

To test the efficacy and toxic effects of ammonium tetrathiomolybdate in the initial treatment of a relatively large series of patients with neurologic symptoms and signs caused by Wilson disease. Two key aspects of efficacy are to preserve the neurologic function present at the onset of therapy and to maximize the opportunity for long-term recovery.

DESIGN

An open study of 33 patients treated for 8 weeks each, including further follow-up data on the original 17 patients. Neurologic function was evaluated by frequent quantitative neurologic and speech pathology examinations. Several copper-related variables were studied to evaluate the effect of the drug on copper, and several biochemical and clinical variables were studied to evaluate potential toxic effects. Patients were then followed up at yearly intervals, with follow-up periods of 1 to 8 years reported.

SETTING

A university hospital referral setting.

INTERVENTION

Patients were generally treated for 8 weeks with tetrathiomolybdate, followed by zinc maintenance therapy.

MAIN OUTCOME MEASURES

Neurologic function was evaluated by quantitative neurologic and motor speech examinations and magnetic resonance imaging scans of the brain.

RESULTS

During the 8 weeks of tetrathiomolybdate administration, only 1 of the 33 patients showed deterioration in neurologic function. Copper status and potential further toxic effects were generally well controlled quickly. Evaluation of data from individual patients revealed evidence of a toxic side effect in only 1 patient, who exhibited reversible anemia. During the ensuing period of follow-up of 1 to 6 years, neurologic recovery in most patients was good to excellent.

CONCLUSIONS

Tetrathiomolybdate appears to be an excellent form of initial treatment in patients with Wilson disease who present with neurologic symptoms and signs. In contrast to penicillamine therapy, initial treatment with tetrathiomolybdate rarely allows further, often irreversible, neurologic deterioration.

Solitary fibrous tumor of the paranasal sinuses: CT and MR appearance

We describe the CT and MR appearance of a solitary fibrous tumor of the paranasal sinuses with intracranial invasion. The tumor was hypointense on T2-weighted MR images and had a large calcific component that proved to be reactive remodelling of native bone.

Adverse reactions to gadolinium contrast media: a review of 36 cases

OBJECTIVE

We investigated the frequency, manifestations, and severity of reactions to gadolinium contrast media in patients who underwent MR imaging at a single institution.

MATERIALS AND METHODS

We reviewed the quality assurance records of 21,000 patients to whom gadolinium contrast media were administered at our institution between January 1990 and October 1994. Of these patients, 36 had adverse reactions. All 36 patients were evaluated by a radiologist at the time of the adverse reaction, and a written report of the findings was completed immediately.

RESULTS

We classified adverse reactions into four groups: mild nonallergic reactions (15 patients with nausea or vomiting), mild reactions resembling allergy (12 patients with hives, diffuse erythema, or skin irritation), moderate reactions resembling allergy (seven patients with respiratory symptoms), and life-threatening reactions resembling allergy (two patients with severe chest tightness, respiratory distress, and periorbital edema). Eleven of these 36 patients who had adverse reactions also had an unusual local reaction of skin discomfort in the extremity through which gadolinium was injected. Four of the 36 patients with adverse reactions had histories of adverse reactions to iodinated contrast media. All four of these patients and one of the remaining 32 patients with adverse reactions required treatment. No patients with adverse reactions died.

CONCLUSION

Although gadolinium contrast media are safe, we found that patients had adverse reactions at a frequency greater than we expected. Severe anaphylactoid reactions occurred in two patients (0.01%). This rate exceeds the rate of 0.0003% reported in the literature. The indexes of suspicion for the occurrence of reactions to gadolinium, and both the documentation and the management of adverse reactions, must be as rigorous for reactions associated with MR imaging contrast agents as they are for reactions associated with iodinated contrast media.

Orbital plain films as a prerequisite for MR imaging: is a known history of injury a sufficient screening criterion?

OBJECTIVE

Before undergoing MR imaging at our institution, all patients with potential occupational, recreational, or educational exposure or known accidental exposure to kinetic metal fragments have orbital radiographs to evaluate for the continued presence of intraorbital metallic foreign bodies. The purpose of this study was to evaluate the potential safety of a protocol that would call for obtaining plain films of the orbit before MR imaging only for patients with a definite history of a known metallic foreign body in the eye or orbit.

MATERIALS AND METHODS

A total of 2626 patients underwent plain radiography of the orbit to exclude metallic foreign bodies before MR imaging between March 1991 and January 1995. These patients were identified by a billing code number. Reports from these studies, all interpreted by board-certified radiologists, were reviewed. When a metallic foreign body was detected, we reviewed the patient's response during the initial interview when asked about a history of orbital injury or surgery.

RESULTS

Of 2626 patients undergoing orbital radiographic studies, 17 (0.65%) had radiographic evidence of intraorbital metallic foreign bodies. Sixteen of these patients gave a history of known injury or had knowledge of probable orbital metallic fragments. The remaining patient, a welder screened because of occupational history, had a 3 x 1 mm metallic foreign body in his left orbit without a history of injury.

CONCLUSION

Screening plain films of the orbit are necessary when a patient has a history of a known intraocular or periorbital foreign body or when a patient has a history of occupational exposure to potential metallic ocular injury, as do welders, grinders, and metalworkers.

Intracerebral depth electrode monitoring in partial epilepsy: the morbidity and efficacy of placement using magnetic resonance image-guided stereotactic surgery

OBJECTIVE

To determine the indications for, efficacy of, and safety of depth electrode placement using magnetic resonance imaging (MRI)-guided stereotactic surgery in patients with intractable epilepsy.

METHODS

We analyzed retrospectively the results of depth electrode usage in 50 consecutive patients at the University of Michigan Hospitals studied in the years 1991 through 1994, using MRI-guided stereotactic implantation, in conjunction with simultaneous subdural strip electrode recordings.

RESULTS

There were no deaths, no infections, and no new neurological deficits. One small subdural hematoma adjacent to a subdural strip electrode was evacuated to prevent interference with ictal recording. Two cylindrical subdural electrodes were found to be intraparenchymal, as revealed by postoperative MRI, and were removed. One patient was unintentionally left alone briefly, and he pulled out the electrodes while confused postictally, requiring a subsequent operation for replacement. Ictal onset zones were successfully localized in 47 patients.

CONCLUSION

We have found intracerebral electrode placement to be as safe as subdural strip electrode placement and have found combined depth and strip electrode monitoring to be highly effective in localizing the onset zones of complex partial seizures. Intracranial monitoring was particularly useful in the detection of a single ictal onset zone in the absence of neuroimaging abnormality and in the definitive diagnosis of bilateral independent ictal onset zones in the temporal lobe epilepsy syndrome. The specific technical aspects of the procedure that contribute to a successful outcome are reviewed. A comparison with earlier reported series suggests that MRI-guided stereotaxy and pial inspection may reduce complications of depth electrode placement.

Spatial relationships of neuroanatomic landmarks in schizophrenia

Two new morphometric techniques, landmark-based shape analysis and landmark-based image averaging, were applied to magnetic resonance images (MRIs) to investigate the sites and extent of structural neuropathology in schizophrenia. These analyses allow the identification of averaged anatomy through joint registration on multiple landmarks simultaneously. MRI scans obtained in the midsagittal plane were compared between 14 patients with schizophrenia and 14 normal subjects. The relation between averaged landmark configuration in the two groups was visualized as a deformation. There were no large-scale shape abnormalities noted, although the patients had significantly smaller brains. The data suggest that the neuroanatomic abnormality associated with schizophrenia, in the midsagittal plane, is circumscribed (focal), involving primarily the region of the posterior corpus callosum, upper brainstem, and quadrigeminal cistern. Also, the thickness of the corpus callosum is reduced all along its length. The findings are consistent with prior studies suggesting involvement in schizophrenia of the cerebellum, the corpus callosum and, possibly, the limbic structures contributing to the corpus callosum. The methods of image averaging and shape analysis used in this study complement the 'region of interest' method of investigating morphometric abnormalities by characterizing the precise locations and spatial relationships among relevant structural brain abnormalities in schizophrenia.

3D gadolinium-enhanced MR angiography of the carotid arteries

PURPOSE

To compare gadolinium-enhanced magnetic resonance angiography (MRA) of the carotid bifurcation with 2D time-of-flight (TOF) MR angiography with regard to image quality and duration of examination.

MATERIALS AND METHODS

Gadolinium contrast was administered intravenously during 3D MR imaging at 1.5 Tesla in 46 patients presenting with suspected carotid occlusive disease. 2D time-of-flight MR angiography of the carotid bifurcation had been performed in each patient prior to gadolinium-enhanced MR angiography.

RESULTS

Gadolinium MRA eliminated slice misregistration and in-plane saturation artifacts that occasionally degrades 2D TOF MR angiography. Gadolinium MRA required less than 4 min to image from the aortic arch to the skull base compared to 11 min for 2D TOF with comparable signal-to-noise ratio (SNR). Postprocessing was required to eliminate overlapping venous enhancement. Both techniques had susceptibility related artifactual loss of signal at the skull base and both demonstrated a linear artifact paralleling the long axis of arteries.

CONCLUSION

Gadolinium-enhanced MR angiography is a promising technique for the evaluation of patients with carotid occlusive disease because it rapidly images the carotid arteries from the aortic arch to the skull base and eliminates some of the artifacts that degrade 2D TOF MR angiography.

Infarction of basal ganglia associated with California encephalitis virus

A child developed acute hemiparesis due to infarction of basal ganglia and internal capsule. Pleocytosis of cerebrospinal fluid and elevated immunoglobulin M antibodies suggest that California encephalitis virus infection caused the stroke.

Postvaricella basal ganglia infarction in children

Two patients presented with acute neurologic deficits attributable to contralateral basal ganglia infarction 1 to 3 months after episodes of chickenpox. Both presented with hemiparesis with one patient also demonstrating ipsilateral choreoathetosis. In both patients MR revealed unilateral basal ganglia infarction. Cerebral angiography findings in one patient were normal; in the second, there was unilateral narrowing of the common carotid artery and of proximal branches of the anterior and middle cerebral artery.