Improved outcomes in stroke thrombolysis with pre-specified imaging criteria.

BACKGROUND: A 1995 National Institute of Neurological Disorders (NINDS) study found benefit for intravenous tissue plasminogen activator (tPA) in acute ischemic stroke (AIS). The symptomatic intracranial hemorrhage (SICH) rate in the NINDS study was 6.4%, which may be deterring some physicians from using this medication. METHODS: Starting December 1, 1998, patients with AIS in London, Ontario were treated according to NINDS criteria with one major exception; those with approximately greater than one-third involvement of the idealized middle cerebral artery (MCA) territory on neuroimaging were excluded from treatment. The method used to estimate involvement of one-third MCA territory involvement bears the acronym ICE and had a median kappa value of 0.80 among five physicians. Outcomes were compared to the NINDS study. RESULTS: Between December 1, 1998 and February 1, 2000, 30 patients were treated. Compared to the NINDS study, more London patients were treated after 90 minutes (p<0.00001) and tended to be older. No SICH was observed. Compared to the treated arm of the NINDS trial, fewer London patients were dead or severely disabled at three months (p=0.04). Compared to the placebo arm of the trial, more patients made a partial recovery at 24 hours (p=0.02), more had normal outcomes (p=0.03) and fewer were dead or severely disabled at three months (p=0.004). CONCLUSIONS: The results of the NINDS study were closely replicated and, in some instances, improved upon in this small series of Canadian patients, despite older are and later treatment. These findings suggest that imaging exclusion criteria may optimize the benefits of tPA.

Stroke mismatch volume with the use of ABC/2 is equivalent to planimetric stroke mismatch volume.

BACKGROUND AND PURPOSE: In the clinical setting, there is a need to perform mismatch measurements quickly and easily on the MR imaging scanner to determine the specific amount of treatable penumbra. The objective of this study was to quantify the agreement of the ABC/2 method with the established planimetric method. MATERIALS AND METHODS: Patients (n = 193) were selected from the NINDS Natural History Stroke Registry if they 1) were treated with standard intravenous rtPA, 2) had a pretreatment MR imaging with evaluable DWI and PWI, and 3) had an acute ischemic stroke lesion. A rater placed the linear diameters to measure the largest DWI and MTT lesion areas in 3 perpendicular axes-A, B, and C-and then used the ABC/2 formula to calculate lesion volumes. A separate rater measured the planimetric volumes. Multiple mismatch thresholds were used, including MTT volume - DWI volume ≥50 mL versus ≥60 mL and (MTT volume - DWI volume)/MTT volume ≥20% versus MTT/DWI = 1.8. RESULTS: Compared with the planimetric method, the ABC/2 method had high sensitivity (0.91), specificity (0.90), accuracy (0.91), PPV (0.90), and NPV (0.91) to quantify mismatch by use of the ≥50 mL definition. The Spearman correlation coefficients were 0.846 and 0.876, respectively, for the DWI and MTT measurements. The inter-rater Bland-Altman plots demonstrated 95%, 95%, and 97% agreement for the DWI, MTT, and mismatch measurements. CONCLUSIONS: The ABC/2 method is highly reliable and accurate for quantifying the specific amount of MR imaging-determined mismatch and therefore is a potential tool to quickly calculate a treatable mismatch pattern.

Blood-brain barrier disruption after cardiac surgery.

BACKGROUND AND PURPOSE: CNS complications are often seen after heart surgery, and postsurgical disruption of the BBB may play an etiologic role. The objective of this study was to determine the prevalence of MR imaging-detected BBB disruption (HARM) and DWI lesions after cardiac surgery. MATERIALS AND METHODS: All patients had an MRI after cardiac surgery. For half the patients (group 1), we administered gadolinium 24 hours after surgery and obtained high-resolution DWI and FLAIR images 24-48 hours later. We administered gadolinium to the other half (group 2) at the time of the postoperative scan, 2-4 days after surgery. Two stroke neurologists evaluated the images. RESULTS: Of the 19 patients we studied, none had clinical evidence of a stroke or delirium at the time of the gadolinium administration or the scan, but 9 patients (47%) had HARM (67% in group 1; 30% in group 2; P = .18) and 14 patients (74%) had DWI lesions (70% in group 1; 78% in group 2; P = 1.0). Not all patients with DWI lesions had HARM, and not all patients with HARM had DWI lesions (P = .56). CONCLUSIONS: Almost half the patients undergoing cardiac surgery have evidence of HARM, and three-quarters have acute lesions on DWI after surgery. BBB disruption is more prevalent in the first 24 hours after surgery. These findings suggest that MR imaging can be used as an imaging biomarker to assess therapies that may protect the BBB in patients undergoing heart surgery.

Distal hyperintense vessels on FLAIR: an MRI marker for collateral circulation in acute stroke?

BACKGROUND: Hyperintense vessels (HV) on fluid-attenuated inversion recovery imaging are frequently observed in acute ischemic stroke patients. However, the exact mechanism and clinical implications of this sign have not yet been clearly defined. The features of HV and its relevance to other imaging factors are presented here. METHODS: Prominence and location of HV were documented in 52 consecutive patients with middle cerebral artery (MCA) territory infarction, before treatment with IV recombinant tissue plasminogen activator. Pretreatment ischemic lesion volume, perfusion lesion volume, and vessel occlusion were determined in addition to recanalization status and ischemic lesion volume on follow-up imaging. NIH Stroke Scale (NIHSS) was used as a measure of clinical severity. RESULTS: HV distal to arterial occlusion was observed in 73% of patients; more frequent in proximal than distal MCA occlusion patients. Among the 38 patients with proximal MCA occlusion, initial perfusion lesion volume was comparable among patients with different grade distal HV. However, patients with more prominent distal HV had smaller initial, 24-hour, and subacute ischemic lesion volumes and lower initial NIHSS scores. CONCLUSIONS: The presence of distal hyperintense vessels before thrombolytic treatment is associated with large diffusion-perfusion mismatch and smaller subacute ischemic lesion volumes in patients with proximal middle cerebral artery occlusion. DWI = diffusion-weighted imaging; FLAIR = fluid-attenuated inversion recovery; GRE = gradient recalled echo; HV = hyperintense vessels; MCA = middle cerebral artery; MRA = magnetic resonance angiography; MTT = mean transit time; NIHSS = NIH Stroke Scale; PWI = perfusion-weighted imaging; rt-PA = recombinant tissue plasminogen activator; TE = echo time; TI = inversion time; TIMI = thrombolysis in myocardial infarction; TR = repetition time.

Racial differences in microbleed prevalence in primary intracerebral hemorrhage.

BACKGROUND: Primary intracerebral hemorrhage is two to three times more common in many racial populations, including black patients. Previous studies have shown that microbleeds, identified on gradient echo MRI (GRE), are present in 50-80% of patients with primary ICH. The objective of this study was to compare, by race, the rates, risk factors, and topography of microbleeds in patients hospitalized for primary ICH. METHODS: Patients diagnosed with primary ICH at two metropolitan stroke centers were included. Clinical and neuroimaging data were recorded for each patient. Analyses were performed to compare baseline characteristics as well as imaging findings by race. RESULTS: A total of 87 patients met inclusion criteria (42 black subjects, 45 white subjects). The black cohort was younger (p < 0.001), and had a greater rate of hypertension (p = 0.001), but not other vascular risk factors. Microbleeds were more prevalent in the black population, with 74% of blacks having one or more microbleeds compared to 42% of whites (p = 0.005). The black population also tended to have a greater frequency of microbleeds in multiple territories than the white population (38% vs 22%, p = 0.106). When adjusting for age, hypertension, and alcohol use, race was an independent predictor of microbleeds (OR 3.308, 95% CI 1.144-9.571, p = 0.027). CONCLUSIONS: These pilot data suggest that significant racial differences exist in the frequency and topography of microbleeds in patients with primary ICH. Microbleeds may be an important emerging imaging biomarker with the potential to provide insights into ICH pathophysiology, prognosis, and disease progression, as well as possible therapeutic strategies, particularly in medically underserved populations.

Subcortical vascular dementia: integrating neuropsychological and neuroradiologic data.

BACKGROUND: Research criteria for subcortical vascular dementia are based on radiologic evidence of vascular pathology and greater impairment on tests of executive control than memory. The relationship(s) between neuroradiological evidence of subcortical vascular disease and neuropsychological impairments has not been specified. OBJECTIVE: To define these research criteria, the authors rated the severity of MRI white matter abnormalities (WMAs) and neuropsychological data from patients with dementia. METHODS: Sixty-nine outpatients who met the criteria for dementia were studied with neuropsychological tests that assessed executive (mental) control, declarative memory, visuoconstruction (clock drawing), and language (semantic category fluency). MRI-WMAs were rated using a leukoaraiosis (LA) scale (range 0 to 40). RESULTS: First, regression analyses demonstrated that neuropsychological measures accounted for 60.7% of the variance in WMA severity (47.3% of this variance attributable to executive/visuoconstructive test performance, 13.4% attributable to memory/language test performance). Second, patients were grouped according to the severity of WMAs (i.e., low, moderate, and severe white matter groups). Only patients with mild WMA (mean LA = 3.61 +/- 2.63, approximately 2.4 to 15.6% of the subcortical white matter) presented with greater impairment on memory/language tests vs executive control/visuoconstructive tests, a neuropsychological profile typically associated with Alzheimer disease. Patients with moderate WMA (mean LA = 12.76 +/- 2.49, approximately 25.6 to 38.1% of the subcortical white matter) presented with equal impairment on executive/visuoconstructional vs memory/language tests. Patients with severe WMA (mean LA = 21.76 +/- 2.97, approximately 46.9 to 62.4% of the subcortical white matter) displayed a profile of greater executive/visuoconstructional impairment relative to memory/language disabilities. CONCLUSION: A profile of equal impairment on tests of executive control and memory along with radiologic evidence involving about one-fourth of the cerebral white matter as measured by the Leukoaraiosis Scale may be sufficient for a diagnosis of subcortical vascular dementia.

[Dementia and stroke: the importance of coexisting brain pathologies]. / Demencia e ictus: la importancia de la patologia cerebral coexistente.

AIM: In this paper we present evidence to support the idea that vascular and degenerative pathological processes interact synergically in the genesis of post stroke dementia. METHOD: Characteristics of vascular lesions have been identified that are linked to the development of a clinical picture of dementia. Yet, the characteristics of the brain in which infarction or brain haemorrhage occur are equally important. Recent (clinical, epidemiological and neuropathological) studies highlight the high frequency with which neurodegenerative and vascular processes coexist in the same brain, and the fact that both processes share environmental and genetic risk factors. The diagnostic criteria currently in use consider the existence of a vascular pathology as being an exclusion criterion for the diagnosis of an Alzheimer type dementia, and thus rule out the possibility of studying the interaction between the two processes. Instead of restrictive criteria, pragmatic instruments must be used to classify the possible aetiology in these patients. CONCLUSIONS: It is important to study the coexistence of vascular and degenerative pathologies in the brains of patients with a post stroke deterioration. Proving the existence of a synergic relation between the two processes would open up the possibility of performing an operation to prevent and treat the dementia displayed by these patients.