Small vessel disease and clinical outcomes after IV rt-PA treatment.

INTRODUCTION: Cerebral small vessel disease (SVD) contributes to dementia and disability in the elderly, and may negatively affect stroke outcomes. We aimed to evaluate to what extent single features and global burden of SVD detected with magnetic resonance (MR) are associated with worse outcomes in patients with ischaemic stroke treated with intravenous thrombolysis. METHODS: We accessed anonymized data and MR images from the Stroke Imaging Repository (STIR) and the Virtual International Stroke Trials Archive (VISTA) Imaging. We described SVD features using validated scales and quantified the global burden of SVD with a combined score. Our mainoutcome was the modified Rankin Scale (mRS) at 90 days after stroke. We used logistic regression and ordinal regression models (adjusted for age, sex, stroke severity, onset to treatment time) to examine the associations between each SVD feature, SVD global burden and clinical outcomes. RESULTS: A total of 259 patients had MR scans available at baseline (mean age±SD=68.7±15.5 years; 131 [49%] males). After adjustment for confounders, severe white matter changes were associated with disability (OR=5.14; 95%CI=2.30-11.48), functional dependency (OR=4.38; 95%CI=2.10-9.13) and worse outcomes in ordinal analysis (OR=2.71; 95%CI=1.25-5.85). SVD score was associated with disability (OR=1.66; 95%CI=1.03-2.66) and functional dependency (OR=1.47; 95%CI=1.00-2.45). Lacunes, enlarged perivascular spaces and brain atrophy showed no association with clinical outcomes. CONCLUSION: Our results suggest that SVD negatively affects stroke outcomes after intravenous thrombolysis. Although white matter changes seem to be the major driver in relation to worse outcomes, global estimation of SVD is feasible and may provide helpful information.

Shared neural substrates controlling hand movements in human motor cortex.

Voluntary hand movements in humans involve the primary motor cortex (M1). A functional magnetic resonance imaging method that measures relative cerebral blood flow was used to identify a distributed, overlapping pattern of hand movement representation within the posterior precentral gyrus, which contains M1. The observed pattern resembles those reported in nonhuman primates and differs from a somatotopically organized plan typically used to portray human motor cortex organization. Finger and wrist movements activated a wide expanse of the posterior precentral gyrus, and representations for different finger movements overlapped each other and the wrist representation. Multiple sites of activation occurred in the precentral gyrus for all movements. The overlapping representations may mediate motor and cognitive functions requiring coordinated neural processing for finger and wrist actions rather than discrete control implied by somatotopic maps.

Reliability of MR perfusion-weighted and diffusion-weighted imaging mismatch measurement methods.

BACKGROUND AND PURPOSE: We investigated 2 methods of measuring MR imaging perfusion-diffusion mismatch to determine whether reliability is improved by direct measurement on a single, blended map. MATERIALS AND METHODS: Image software was used for measurement of lesion volumes from diffusion-weighted images (DWI) and mean transit time (MTT) calculated from perfusion-weighted (PWI) images on 64 patients with acute stroke. For the first method, the DWI and MTT lesions were measured separately. For the second method, the mismatch volume was measured directly on the blended images created from the registered DWI and MTT images. RESULTS: Test-retest agreement was 100% and 97% for the separate and blended methods using mismatch cutoffs of 20% or more versus less than 20%. There were no significant differences in the mismatch statistics between the methods. CONCLUSIONS: Mismatch volumes by a single reader can provide highly reliable and consistent results even when separately measuring DWI and MTT lesions. Propagation of measurement error was not demonstrated, and the methods were statistically comparable.

Higher prevalence of cortical lesions observed in patients with acute stroke using high-resolution diffusion-weighted imaging.

Ischemic lesion conspicuity on routine diffusion-weighted imaging (DWI, 30 seconds) was compared with an improved sequence (high-resolution DWI [DWI-HR], 256 seconds) having increased spatial resolution and signal to noise and decreased eddy current artifact in 42 patients with acute ischemic stroke. Total lesion volumes were similar; however, twice as many lesions were identified on DWI-HR, predominately in cortical gray matter. Modest improvements to imaging resulted in increased conspicuity, potentially affecting diagnosis, suspected pathogenic mechanism, and therapeutic decision.

Magnetic resonance imaging criteria for thrombolysis in acute cerebral infarct.

BACKGROUND AND PURPOSE: Magnetic resonance imaging (MRI) selection of stroke patients eligible for thrombolytic therapy is an emerging application. Although the efficacy of therapy within 3 hours after onset of symptoms with intravenous (IV) tissue plasminogen activator (tPA) has been proven for patients selected with computed tomography (CT), no randomized, double-blinded MRI trial has been published yet. SUMMARY OF REVIEW: MRI screening of acute stroke patients before thrombolytic therapy is performed in some cerebrovascular centers. In contrast to the CT trials, MRI pilot studies demonstrate benefit of therapy up to 6 hours after onset of symptoms. This article reviews the literature that has lead to current controlled MRI-based thrombolysis trials. We examined the MRI criteria applied in 5 stroke centers. Along with the personal views of clinicians at these centers, the survey reveals a variety of clinical and MRI technical aspects that must be further investigated: the therapeutic consequence of microbleeds, the use of magnetic resonance angiography, dynamic time windows, and others. CONCLUSION: MRI is an established application in acute evaluation of stroke patients and may suit as a brain clock, replacing the currently used epidemiological time clock when deciding whether to initiate thrombolytic therapy. MRI criteria for thrombolytic therapy are applied in some cerebrovascular centers, but the results of ongoing clinical trials must be awaited before it is possible to reach consensus.

Schizophrenic subjects activate dorsolateral prefrontal cortex during a working memory task, as measured by fMRI.

BACKGROUND: Neuroimaging studies of schizophrenic subjects performing working memory (WM) tasks have demonstrated a relative hypoactivity of prefrontal cortex compared with normal subjects. METHODS: Using functional magnetic resonance imaging (fMRI), we compared dorsolateral prefrontal cortex (DLPFC) activation in 12 schizophrenic and 10 normal subjects during rewarded performance of a WM task. Subjects performed a modified version of the Sternberg Item Recognition Paradigm (SIRP), a continuous performance, choice reaction time (RT) task that requires WM. We compared a high WM load condition with a nonWM choice RT condition and with a low WM load condition. RESULTS: Schizophrenic subjects performed the tasks better than chance but worse than normal subjects. They showed greater activation than normal subjects in the left DLPFC but did not differ in the right DLPFC or in the control region. In the schizophrenic group, left DLPFC activation was inversely correlated with task performance, as measured by errors. CONCLUSIONS: These findings contrast with previous studies that demonstrated task-related hypofrontality in schizophrenia. Task parameters that may contribute to this difference are discussed. We hypothesize that the performance and activation differences we observed are also manifestations of prefrontal dysfunction in schizophrenia. They reflect inefficient functioning of the neural circuitry involved in WM.

Magnetic resonance imaging of acute stroke.

In the investigation of ischemic stroke, conventional structural magnetic resonance (MR) techniques (e.g., T1-weighted imaging, T2-weighted imaging, and proton density-weighted imaging) are valuable for the assessment of infarct extent and location beyond the first 12 to 24 hours after onset, and can be combined with MR angiography to noninvasively assess the intracranial and extracranial vasculature. However, during the critical first 6 to 12 hours, the probable period of greatest therapeutic opportunity, these methods do not adequately assess the extent and severity of ischemia. Recent developments in functional MR imaging are showing great promise for the detection of developing focal cerebral ischemic lesions within the first hours. These include (1) diffusion-weighted imaging, which provides physiologic information about the self-diffusion of water, thereby detecting one of the first elements in the pathophysiologic cascade leading to ischemic injury; and (2) perfusion imaging. The detection of acute intraparenchymal hemorrhagic stroke by susceptibility weighted MR has also been reported. In combination with MR angiography, these methods may allow the detection of the site, extent, mechanism, and tissue viability of acute stroke lesions in one imaging study. Imaging of cerebral metabolites with MR spectroscopy along with diffusion-weighted imaging and perfusion imaging may also provide new insights into ischemic stroke pathophysiology. In light of these advances in structural and functional MR, their potential uses in the study of the cerebral ischemic pathophysiology and in clinical practice are described, along with their advantages and limitations.

Clinical outcome in ischemic stroke predicted by early diffusion-weighted and perfusion magnetic resonance imaging: a preliminary analysis.

Perfusion and diffusion-weighted magnetic resonance imaging (MRI) can demonstrate, respectively, cerebral ischemia and ischemic brain injury in the first several hours after onset of symptoms, when proton density and T2-weighted MRI may appear normal. It is hypothesized that these techniques could distinguish regions destined for infarction from those that will not progress to infarction. We provide preliminary evidence from an analysis of 19 patients with severely disabling clinical deficits attributable to ischemia in at least an entire division of the middle cerebral artery, that initial perfusion and diffusion MRI were more accurate than conventional MRI in predicting no, partial or complete improvement--17 of 19 cases (p < 0.0001) versus 10 of 19 cases, respectively. In the subset of patients studied within 6 h of onset, diffusion/perfusion MRI was an even better predictor than conventional MRI--11 of 12 versus four of 12, respectively. In this small sample of patients with severe clinical deficits, perfusion and diffusion MRI were highly accurate in distinguishing those who would improve from those who would not. These results need to be confirmed in a larger prospective study, which may support a future role in the initial screening, selection, and evaluation of patients with stroke for acute pharmacologic interventions.

Decreases in frontal and parietal lobe regional cerebral blood flow related to habituation.

We previously reported decreased mean CBF between consecutive resting conditions, ascribed to habituation. Here we address the regional specificity of habituation over three consecutive flow studies. Regional CBF (rCBF) was measured in 55 adults (12 right-handed men, 12 right-handed women, 14 left-handed men, 17 left-handed women), with the 133Xe inhalation technique, during three conditions: resting, verbal tasks (analogies), and spatial tasks (line orientation). Changes in rCBF attributable to the cognitive tasks were eliminated by correcting these values to a resting equivalent. There was a progressive decrease in mean rCBF over time, reflecting habituation. This effect differed by region, with specificity at frontal (prefrontal, inferior frontal, midfrontal, superior frontal) and inferior parietal regions. In the inferior parietal region, habituation was more marked in the left than the right hemisphere. Right-handers showed greater habituation than did left-handers. There was no sex difference in global habituation, but males showed greater left whereas females showed greater right hemispheric habituation. The results suggest that habituation to the experimental setting has measurable effects on rCBF, which are differently lateralized for men and women. These effects are superimposed on task activation and are most pronounced in regions that have been implicated in attentional processes. Thus, regional decrement in brain activity related to habituation seems to complement attentional effects, suggesting a neural network for habituation reciprocating that for attention.

The reproducibility of the 133Xe inhalation technique in resting studies: task order and sex related effects in healthy young adults.

Repeated applications of the 133Xe inhalation technique for measuring regional CBF (rCBF) were made during consecutive resting conditions in a sample of young healthy subjects. Subjects were grouped by order and by sex [nine had resting studies as the initial two measurements in a series of four measurement (six men, three women) and six had these measurements later (two men, four women)]. Three flow parameters were examined: f1 (fast flow) and IS (initial slope) for gray matter CBF, and CBF-15 for mean CBF (gray and white matter over 15-min integration), as well as w1, the percentage of tissue with fast clearing characteristics. With all groups combined, there were no significant differences between the two resting measurements, and high test-retest correlations were obtained for the flow parameters and w1. Analyses by order and sex grouping revealed, for the flow parameters, significant interactions of test-retest difference with order. Repeated initial studies showed reduced CBF from the first to second measurement, whereas resting studies performed later in the series showed no reduction. Interactions for test-retest difference with sex indicated that reduced CBF in serial measures was more pronounced for women. No hemispheric or regional specificity to account for these effects was found. Correction for PaCO2 differences did not alter these results. The results resemble data regarding habituation effects measured for other psychophysiologic measures, and suggest that reduction in CBF for consecutive measurements made on the same day may reflect habituation. This underscores the importance of controlling for effects of habituation on serial measurements of CBF and metabolism.

Diffusion-weighted imaging and National Institutes of Health Stroke Scale in the acute phase of posterior-circulation stroke.

BACKGROUND: Occlusive disease of the posterior circulation represents a heterogeneous group of strokes that differ in etiology, clinical presentation, and prognosis. Computed tomography provides suboptimal visualization of posterior-circulation infarcts. Anatomic definition of traditional magnetic resonance imaging sequences has been used for clinicoradiologic correlation in patients with posterior-circulation disease. These studies focused on the subacute rather than the acute phase of ischemia. Lesion volumes on diffusion-weighted imaging (DWI) and perfusion imaging were found to have a good correlation with 24-hour National Institutes of Health stroke scale (NIHSS) score in ischemia of the anterior circulation. Correlation between NIHSS score and lesion volume in posterior-circulation infarcts is unknown. OBJECTIVES: To investigate whether DWI is useful for clinicoradiologic correlation of posterior-circulation ischemia within 24 hours after symptom onset and whether NIHSS score correlates with lesion volumes in patients with posterior-circulation stroke. PATIENTS AND METHODS: In a database analysis of 631 patients with stroke from June 26, 1996, to July 30, 1999, 115 patients (18%) had symptoms of posterior-circulation ischemia by imaging and clinical criteria. Among these 115, we included all patients (n = 40) who underwent DWI within 24 hours from symptom onset (mean, 9.7 +/- 7.1 hours). All 40 patients also underwent magnetic resonance angiography and T2-weighted imaging. Seventy-five did not meet inclusion criteria: in 45, magnetic resonance imaging was performed more than 24 hours after symptom onset; 12 did not have DWI; in 11 patients, symptoms resolved within 24 hours; 6 had hemorrhages; and 1 had a border zone infarct. RESULTS: An acute lesion on DWI corresponding to the patient's symptoms was detected in all 40 patients, 16 (40%) of whom had detectable acute lesions on T2-weighted images. The lesions on DWI were larger in 11 of the 16 patients with positive T2-weighted images. Acute lesion volume did not correlate with NIHSS score (n = 40; rho = 0.30; P =.06, Spearman rank) also when DWI lesion volumes were divided by cause and territory. CONCLUSIONS: Diffusion-weighted imaging is more effective than T2-weighted imaging in patients with acute posterior-circulation strokes. The DWI lesion volume did not significantly correlate with NIHSS score, suggesting that NIHSS is more weighted toward anterior-circulation stroke symptoms.

Relationship between magnetic resonance arterial patency and perfusion-diffusion mismatch in acute ischemic stroke and its potential clinical use.

BACKGROUND: In patients with acute ischemic stroke the magnetic resonance (MR) perfusion-diffusion mismatch pattern (perfusion lesion at least 20% larger than the lesion on diffusion-weighted imaging) may indicate ischemically threatened but viable tissue. To our knowledge, the relationship of this MR pattern to serial changes in MR angiography (MRA) has not been reported. OBJECTIVES: To investigate the relationship between MRA changes and patterns of diffusion-weighted imaging and perfusion abnormalities and to determine if the information obtained could be used in clinical management. METHODS: The MR studies of 35 patients who had undergone sequential multimodality MR imaging studies within the first 4 days of stroke were reviewed. All lesions were in the internal carotid artery territory distribution. Magnetic resonance angiographies were read by 2 observers blinded to the clinical data. RESULTS: During the first 24 hours a perfusion-diffusion mismatch was present in 22 (92%) of the 24 patients with an MRA arterial occlusive lesion. (At this time 5 [46%] of the 11 patients with a normal MRA [P =.006] also had a mismatch.) Two to 4 days after stroke, of these 22 patients resolution of the mismatch occurred in 8 (87%) of 9 patients with recanalization on MRA compared with 5 (39%) of 13 patients without arterial recanalization (P =.03). Resolution of mismatch occurred in 3 (60%) of 5 patients with a normal MRA and a mismatch at the first time point. CONCLUSIONS: Concordance between MRA and the MR perfusion-diffusion mismatch pattern provides supportive evidence for an arterial vascular basis for this MR signature in acute stroke. Discordance between MRA lesions and mismatch may result from arterial branch occlusions undetected by MRA or from an alternate mechanism for the mismatch. The MR imaging patterns identified extend our understanding of the pathophysiology of stroke and may contribute to the improvement of stroke management in the future.

New imaging strategies for patient selection for thrombolytic and neuroprotective therapies.

Ischemic stroke trials have traditionally sought to limit the range of disease studied according to several dimensions based on clinical examination and CT scan results. It has been proposed that the optimal sample for stroke trials would include a positive imaging diagnosis of a pathology rationally linked to the drug's mechanisms of action and that this would improve the likelihood of positive results. This principle has been supported by the results of the Prolyse in Acute Cerebral Thromoembolism II (PROACT II) study. Whereas trials of iv thrombolysis between 3 and 6 hours after symptom onset in a general sample of patients were not positive, selection of a subgroup by angiography was an effective strategy in this time period for PROACT II. This study contradicted the hypothesis that treatment of stroke beyond 3 hours would not be successful. MRI with diffusion and perfusion has been an appealing imaging modality because it provides pretreatment angiography, perfusion, and lesion volume information during a brief, non-invasive assessment. Current literature supports the validity of MRI as a marker for clinical severity and clinical improvement. The diffusion-perfusion mismatch, the MRI marker for the ischemic penumbra, is a very strong predictor of lesion volume growth. Several acute trials in progress use a positive imaging diagnosis for the basis of selection. As the field of stroke clinical trials examines opportunities for improving trial design, positive imaging diagnoses in patient selection are likely to assume an increasingly useful role.

Comparison of EPISTAR and T2*-weighted gadolinium-enhanced perfusion imaging in patients with acute cerebral ischemia.

PURPOSE: To compare echo-planar imaging with signal targeting and alternating radiofrequency (EPISTAR), an arterial spin-labeling technique, to a T2*-weighted gadolinium-enhanced (T2*-WGE) MR perfusion technique for the evaluation of acute cerebrovascular disease. METHOD: Twenty-one EPISTAR and T2*-WGE perfusion studies were performed on 18 patients with the clinical diagnosis of acute stroke (12 men, 6 women, age range 34 to 89 years, mean age 68 years). For qualitative analysis, perfusion studies of both techniques were grouped into categories (hyperperfusion, normal perfusion, delayed perfusion, or absent perfusion) and compared with a Wilcoxon signed rank test. Quantitative analysis was performed using signal intensity measurements in a region of interest that was defined by diffusion-weighted imaging abnormalities. These signal intensity measurements were compared with a mirror region in the contralateral unaffected hemisphere. Signal intensity ratios (infarcted region versus the unaffected contralateral region) were calculated and compared using a paired t test. RESULTS: Qualitative analysis demonstrated agreement between the two techniques in 17 of 21 studies (hyperfusion, n = 3 patients; normal perfusion, n = 3; delayed perfusion, n = 4; and absent perfusion, n = 7). In four studies, the two techniques disagreed when EPISTAR demonstrated absent and T2*-WGE perfusion demonstrated delayed perfusion (p > 0.05). Quantitative analysis revealed a mean signal intensity ratio of 0.73 +/- 0.79 for the T2*-WGE perfusion technique and 0.69 +/- 0.68 for the EPISTAR technique (p > 0.05). CONCLUSION: The noninvasive EPISTAR technique can assess perfusion abnormalities similarly to the T2*-WGE perfusion technique and may provide a valuable alternative in the diagnosis of acute stroke patients. Differences between the two techniques can be explained by the applied inflow times in the EPISTAR technique.

Fast magnetic resonance diffusion-weighted imaging of acute human stroke.

Rapid MRI of the molecular diffusion of water demonstrated cerebral infarcts in 32 patients. We studied these patients at various times following the onset of ischemic symptoms and found that diffusion-weighted imaging revealed the infarcts sooner than conventional T2-weighted spin-echo imaging did; four hyperacute infarcts were shown only by diffusion-weighted imaging. Acute infarcts had lower apparent diffusion coefficients (ADCs) than noninfarcted regions did. This relative difference in ADC reached a nadir in the first 24 hours and rose progressively thereafter. Chronic infarcts showed a relative increase in diffusion and were readily distinguishable from acute infarcts. The technique takes less than 2 minutes to apply using a standard 1.5-tesla scanner in the clinical setting. Diffusion-weighted imaging has the potential to play a role in improving the early anatomic diagnosis of stroke and therefore in the development and implementation of early stroke interventions.

Time course of the apparent diffusion coefficient (ADC) abnormality in human stroke.

Diffusion-weighted MRI can rapidly detect acute cerebral ischemic injury as hyperintense signal changes, reflecting a decline in the apparent diffusion coefficient (ADC) of water through brain parenchyma, whereas ADC is elevated in the chronic stage because of increased extracellular water content. To determine the time course of these ADC changes, we analyzed 157 diffusion-weighted MRI studies performed at varying time points from the initial ischemic event from 101 patients. Data were expressed as the relative ADC (rADC), the ratio of lesion to control regions of interest. We observed two phases in the time course of rADC changes in acute human stroke: a significant (p < 0.005) reduction in rADC lasting for at least 96 hours from stroke onset (mean, 58.3% of control; SEM, 1.47) and an increasing trend from reduction to pseudonormalization to elevation of rADC values at later subacute to chronic time points (> or = 7 days). We suggest that the persistent reduction of rADC within the first four days may reflect ongoing or progressive cytotoxic edema to a greater degree than extracellular edema and cell lysis.

Noninvasive perfusion MRI in Alzheimer's disease: a preliminary report.

We performed functional MRI using the echo-planar imaging and signal targeting with alternating radio frequency (EPISTAR) technique in 11 patients with Alzheimer's disease (AD) and 8 age-matched control subjects. Seven of the AD patients had qualitatively apparent focal areas of hypoperfusion in the posterior temporoparietal-occipital regions. At the earliest inversion time producing cortical enhancement, the ratios of parieto-occipital and temporo-occipital to whole slice signal intensity were significantly lower in the AD patients than in the controls. Parieto-occipital hypoperfusion correlated with dementia severity as measured by the Blessed Dementia Scale. EPISTAR may prove to be a rapid, noninvasive alternative to other functional neuroimaging modalities in the evaluation of patients with dementia.

A randomized dose-response trial of citicoline in acute ischemic stroke patients. Citicoline Stroke Study Group.

Citicoline (CDP-choline) is a key intermediary in the biosynthesis of phosphatidylcholine, an important component of the neural cell membrane. It has been shown to produce beneficial effects in both animal models and non-US clinical stroke trials. This study comprised a randomized (3 doses of citicoline to 1 placebo), vehicle-controlled, double-blind trial at 21 US centers. Treatment was to be started within 24 hours of stroke onset and was continued orally for 6 weeks. Final outcome assessments were at 12 weeks. Two hundred fifty-nine patients were enrolled, with approximately 65 in each of the four groups. Mean time from stroke onset to treatment was 14.5 hours, and there were no significant differences in baseline characteristics between the four groups except for patient weight. A significant difference between the groups, favoring citicoline treatment, was seen in terms of functional outcome as measured by the Barthel Index and Rankin scale, neurologic evaluation as measured by the National Institutes of Health (NIH) stroke scale, and cognitive function as measured by the Mini Mental Status Examination. When the baseline NIH stroke scale was used as a covariate, both the 500-mg citicoline group and the 2,000-mg citicoline group had a significant improvement in terms of the percent of patients who had a favorable outcome on the Barthel Index at 90 days. There were no drug-related serious adverse events or deaths in this study. This study suggests that oral citicoline can be used safely with minimal side effects in acute stroke treatment. Citicoline appears to improve functional outcome and reduce neurologic deficit with 500 mg of citicoline appearing to be the optimal dose.

Multiple acute stroke syndrome: marker of embolic disease?

OBJECTIVE: To determine the frequency and etiologic significance of multiple acute ischemic lesions in stroke. BACKGROUND: Although patients may have more than one stroke during the course of their lives, acute ischemic stroke is usually thought of as a single event. Using diffusion-weighted imaging (DWI), an MRI technique that detects ischemic injury within minutes after onset, we have often observed multiple acute ischemic lesions. METHODS: The MRI scans of 59 consecutively studied patients were reviewed to determine the frequency and etiologic significance of multiple acute ischemic lesions on DWI. RESULTS: Multiple acute ischemic lesions were present in 10 (17%) of 59 patients. The lesions usually occurred within one major circulation (anterior or posterior), but in two patients (3%), lesions occurred in both cerebral hemispheres or in the anterior and the posterior circulations. The lesions often were small and resulted from presumed multiple emboli or the break-up of an embolus. Two patients had internal carotid artery occlusive disease and four had a cardiac or aortic source. In the other four patients the source was not determined. Lesions larger than 1 cm in diameter progressed to infarction, but some smaller lesions were not seen on follow-up T2-weighted imaging. CONCLUSIONS: Multiple acute stroke lesions on DWI are common and could be caused by multiple emboli or the breakup of an embolus. In some cases it might become possible to make early inferences concerning the stroke mechanism that could be of use for immediately directing the clinical work-up and treatment of the patient.

EEG-triggered echo-planar functional MRI in epilepsy.

We investigated whether: (1) EEG recordings could be successfully performed in an MRI imager, (2) subclinical epileptic discharges could be used to trigger ultrafast functional MRI images, (3) artifact-free functional MRI images could be obtained while the patient was having the EEG monitored, and (4) the functional MRI images so obtained would show focal signal increases in relation to epileptic discharges. We report our results in two patients who showed focally higher signal intensity, reflective of increased local blood flow, in ultrafast functional MRI timed to epileptic discharges recorded while the patients were in the imager and compared with images not associated with discharges. One patient showed a focal increase despite a clinical and EEG history of generalized discharges. This approach may have the potential to identify brain regions activated during brief focal epileptic discharges.