Clinical assessment of standard and generalized autocalibrating partially parallel acquisition diffusion imaging: effects of reduction factor and spatial resolution.

BACKGROUND AND PURPOSE: PI improves routine EPI-based DWI by enabling higher spatial resolution and reducing geometric distortion, though it remains unclear which of these is most important. We evaluated the relative contribution of these factors and assessed their ability to increase lesion conspicuity and diagnostic confidence by using a GRAPPA technique. MATERIALS AND METHODS: Four separate DWI scans were obtained at 1.5T in 48 patients with independent variation of in-plane spatial resolution (1.88 mm(2) versus 1.25 mm(2)) and/or reduction factor (R = 1 versus R = 3). A neuroradiologist with access to clinical history and additional imaging sequences provided a reference standard diagnosis for each case. Three blinded neuroradiologists assessed scans for abnormalities and also evaluated multiple imaging-quality metrics by using a 5-point ordinal scale. Logistic regression was used to determine the impact of each factor on subjective image quality and confidence. RESULTS: Reference standard diagnoses in the patient cohort were acute ischemic stroke (n = 30), ischemic stroke with hemorrhagic conversion (n = 4), intraparenchymal hemorrhage (n = 9), or no acute lesion (n = 5). While readers preferred both a higher reduction factor and a higher spatial resolution, the largest effect was due to an increased reduction factor (odds ratio, 47 ± 16). Small lesions were more confidently discriminated from artifacts on R = 3 images. The diagnosis changed in 5 of 48 scans, always toward the reference standard reading and exclusively for posterior fossa lesions. CONCLUSIONS: PI improves DWI primarily by reducing geometric distortion rather than by increasing spatial resolution. This outcome leads to a more accurate and confident diagnosis of small lesions.

Predicting outcome after acute basilar artery occlusion based on admission characteristics.

OBJECTIVE: To develop a simple prognostic model to predict outcome at 1 month after acute basilar artery occlusion (BAO) with readily available predictors. METHODS: The Basilar Artery International Cooperation Study (BASICS) is a prospective, observational, international registry of consecutive patients who presented with an acute symptomatic and radiologically confirmed BAO. We considered predictors available at hospital admission in multivariable logistic regression models to predict poor outcome (modified Rankin Scale [mRS] score 4-5 or death) at 1 month. We used receiver operator characteristic curves to assess the discriminatory performance of the models. RESULTS: Of the 619 patients, 429 (69%) had a poor outcome at 1 month: 74 (12%) had a mRS score of 4, 115 (19%) had a mRS score of 5, and 240 (39%) had died. The main predictors of poor outcome were older age, absence of hyperlipidemia, presence of prodromal minor stroke, higher NIH Stroke Scale (NIHSS) score, and longer time to treatment. A prognostic model that combined demographic data and stroke risk factors had an area under the receiver operating characteristic curve (AUC) of 0.64. This performance improved by including findings from the neurologic examination (AUC 0.79) and CT imaging (AUC 0.80). A risk chart showed predictions of poor outcome at 1 month varying from 25 to 96%. CONCLUSION: Poor outcome after BAO can be reliably predicted by a simple model that includes older age, absence of hyperlipidemia, presence of prodromal minor stroke, higher NIHSS score, and longer time to treatment.

The neurocritical care research network: NCRN.

Neurocritical care diseases carry a high morbidity and mortality. Therapeutic and technological advances in neurocritical care have greatly improved the outcome of a variety of life-threatening disorders including traumatic brain injury, acute ischemic stroke, intracerebral and subarachnoid hemorrhage, and anoxic injury following cardiac arrest. These advances have stemmed from a better understanding of the physiology of neurocritical care illnesses, improved neuromonitoring techniques, and the introduction of more efficacious treatments. Despite all the advances in neuromonitoring, diagnostic imaging, and emerging treatments, much research needs to be undertaken in neurocritical care. Many of the clinical trials carried out in the general critical care population have excluded neurocritical care patients. For instance, the landmark ARDSNET trial that demonstrated the beneficial effects of low tidal volume ventilation in patients with ARDS cannot be directly applied to neurocritical care patients who frequently may experience this pulmonary complication. There is a need for a more cohesive and integrated research system or network to establish a track record for high-quality, investigator-initiated clinical research in neurocritical care. Such a system may help us overcome potential impediments to the future advancement of neurocritical care research. We propose the creation of the neurocritical care research network. The mission of the Network is to facilitate multicenter and multidisciplinary collaboration and patient enrollment in clinical trials of specific neurocritical care diseases.

Research priorities in neurocritical care.

This summary of the last session of the First Neurocritical Care Research Conference reviews the discussions about research priorities in neurocritical care. The first presentation reviewed current projects funded by the National Institute of Neurological Disorders and Stroke at the National Institutes of Health and potential models to follow including an independent Neurocritical Care Network or the creation of such a network with the goal of collaborating with already existing ones. Experienced neurointensivists then presented their views on the most common and important research questions that need to be answered and investigated in the field. Finally, utility of clinical registries was discussed emphasizing their importance as hypothesis generators. During the group discussion, interests in comparative effectiveness research, the use of physiological endpoints from monitoring and alternate trial design were expressed.

Clinical trial design in the neurocritical care unit.

Clinical trials provide a robust mechanism to advance science and change clinical practice across the widest possible spectrum. Fundamental in the Neurocritical Care Society's mission is to promote Quality Patient Care by identifying and implementing best medical practices for acute neurological disorders that are consistent with the current scientific knowledge. The next logical step will be to foster rapid growth of our scientific body of evidence, to establish and disseminate these best practices. In this manuscript, five invited experts were impaneled to address questions, identified by the conference organizing committee as fundamental issues for the design of clinical trials in the neurological intensive care unit setting.

The critical care research networks experience.

Neurocritical care is a subspecialty of critical care medicine, dedicated to the care and the advancement of care of critically ill patients with neurosurgical or neurological diseases. Neurocritical care patients are heterogeneous, in both their disease process and the therapies they receive, however, several studies demonstrate that care of these patients in dedicated NeuroIntensive Care Units (neuroICUs) by neurointensivists, who coordinate their care is associated with reduced mortality and resource utilization. NeuroICUs foster innovation, and yet despite all the recent advances, much research needs to be undertaken in neurocritical care to better understand the disease pathophysiology and to demonstrate improved outcome with the use of goal-directed therapy based on evolving techniques and therapies.

Research and technology in neurocritical care.

The daily practice of neurointensivists focuses on the recognition of subtle changes in the neurological examination, interactions between the brain and systemic derangements, and brain physiology. Common alterations such as fever, hyperglycemia, and hypotension have different consequences in patients with brain insults compared with patients of general medical illness. Various technologies have become available or are currently being developed. The session on "research and technology" of the first neurocritical care research conference held in Houston in September of 2009 was devoted to the discussion of the current status, and the research role of state-of-the art technologies in neurocritical patients including multi-modality neuromonitoring, biomarkers, neuroimaging, and "omics" research (proteomix, genomics, and metabolomics). We have summarized the topics discussed in this session. We have provided a brief overview of the current status of these technologies, and put forward recommendations for future research applications in the field of neurocritical care.

Outcome prediction in mechanically ventilated neurologic patients by junior neurointensivists.

OBJECTIVE: Physician prediction of outcome in critically ill neurologic patients impacts treatment decisions and goals of care. In this observational study, we prospectively compared predictions by neurointensivists to patient outcomes at 6 months. METHODS: Consecutive neurologic patients requiring mechanical ventilation for 72 hours or more were enrolled. The attending neurointensivist was asked to predict 6-month 1) functional outcome (modified Rankin scale [mRS]), 2) quality of life (QOL), and 3) whether supportive care should be withdrawn. Six-month functional outcome was determined by telephone interviews and dichotomized to good (mRS 0-3) and poor outcome (mRS 4-6). RESULTS: Of 187 eligible patients, 144 were enrolled. Neurointensivists correctly predicted 6-month functional outcome in 80% (95% confidence interval [CI], 72%-86%) of patients. Accuracy for a predicted good outcome was 63% (95% CI, 50%-74%) and for poor outcome 94% (95% CI, 85%-98%). Excluding patients who had life support withdrawn, accuracy for good outcome was 73% (95% CI, 60%-84%) and for poor outcome 87% (95% CI, 74%-94%). Accuracy for exact agreement between neurointensivists' mRS predictions and actual 6-month mRS was only 43% (95% CI, 35%-52%). Predicted accuracy for QOL was 58% (95% CI, 39%-74%) for good/excellent and 67% (95% CI, 46%-83%) for poor/fair. Of 27 patients for whom withdrawal of care was recommended, 1 patient survived in a vegetative state. CONCLUSIONS: Prediction of long-term functional outcomes in critically ill neurologic patients is challenging. Our neurointensivists were more accurate in predicting poor outcome than good outcome in patients requiring mechanical ventilation >or=72 hours.

[Hypertensive encephalopathy: does not only occur at high blood pressure]. / Hypertensieve encefalopathie: niet alleen bij zeer hoge bloeddrukwaarden.

A 45-year-old man presented with severe hypertension, headache, cortical blindness, and a depressed level of consciousness. A second patient, a 33-year-old woman, was admitted with pre-eclampsia. She developed lethargy, headache, bilateral extensor plantar responses, and seizures. The third patient, a 62-year-old man, presented with acute renal failure due to necrotising vasculitis and glomerulonephritis. Five days after treatment with immunosuppressive drugs had been initiated, he developed headache, confusion, seizures, and cortical blindness. Hypertensive encephalopathy is characterised by headache, vomiting, disturbances in cognition and level of consciousness, visual abnormalities, and seizures. Imaging studies often demonstrate oedema of the white matter in the posterior parietal and occipital areas of the brain. This so-called reversible posterior leucoencephalopathy syndrome is well known in patients with severe hypertension, but it is also associated with immunosuppressive drug use and renal failure. It can be recognised by its fairly characteristic clinical features (different combinations of headache, vomiting, changes in cognition and level of consciousness, seizures, muscle weakness, and visual symptoms) and by its specific imaging findings. Treatment consists of reducing the blood pressure and reducing or discontinuing the use of immunosuppressive drugs. If the treatment is started promptly, symptoms and imaging abnormalities are usually reversible.