Domain-specific neuropsychological investigation of CAA with and without intracerebral haemorrhage

BACKGROUND

Cerebral amyloid angiopathy (CAA) is associated with cognitive impairment, but the contributions of lobar intracerebral haemorrhage (ICH), underlying diffuse vasculopathy, and neurodegeneration, remain uncertain. We investigated the domain-specific neuropsychological profile of CAA with and without ICH, and their associations with structural neuroimaging features.

METHODS

Data were collected from patients with possible or probable CAA attending a specialist outpatient clinic. Patients completed standardised neuropsychological assessment covering seven domains. MRI scans were scored for markers of cerebral small vessel disease and neurodegeneration. Patients were grouped into those with and without a macro-haemorrhage (CAA-ICH and CAA-non-ICH).

RESULTS

We included 77 participants (mean age 72, 65% male). 26/32 (81%) CAA-non-ICH patients and 41/45 (91%) CAA-ICH patients were impaired in at least one cognitive domain. Verbal IQ and non-verbal IQ were the most frequently impaired, followed by executive functions and processing speed. We found no significant differences in the frequency of impairment across domains between the two groups. Medial temporal atrophy was the imaging feature most consistently associated with cognitive impairment (both overall and in individual domains) in both univariable and multivariable analyses.

DISCUSSION

Cognitive impairment is common in CAA, even in the absence of ICH, suggesting a key role for diffuse processes related to small vessel disease and/or neurodegeneration. Our findings indicate that neurodegeneration, possibly due to co-existing Alzheimer's disease pathology, may be the most important contributor. The observation that general intelligence is the most frequently affected domain suggests that CAA has a generalised rather than focal cognitive impact.

Application of mask images of contrast-enhanced MR angiography to detect carotid intraplaque hemorrhage in patients with moderate to severe symptomatic and asymptomatic carotid stenosis

PURPOSE

Carotid intraplaque hemorrhage (IPH) on MRI predicts stroke. Magnetization-prepared rapid acquisition gradient (MP-RAGE) is widely used to detect IPH. CE-MRA is used routinely to assess stenosis. Initial studies indicated that IPH can be identified on mask images of CE-MRA, while Time-of-Flight (TOF) images were reported to have high specificity but lower sensitivity. We investigated the diagnostic accuracy of detecting IPH on mask images of CE-MRA and TOF.

METHODS

Thirty-six patients with ≥ 50% stenosis enrolled in the ongoing 2nd European Carotid Surgery Trial underwent carotid MRI. A 5-point quality score was used. Inter-observer agreement between two independent readers was determined. The sensitivity and specificity of IPH detection on mask MRA and TOF were calculated with MP-RAGE as a reference standard.

RESULTS

Of the 36 patients included in the current analysis, 66/72 carotid arteries could be scored. The inter-observer agreements for identifying IPH on MP-RAGE, mask, and TOF were outstanding (κ: 0.93, 0.96, and 0.85). The image quality of mask (1.42 ± 0.66) and TOF (2.42 ± 0.66) was significantly lower than MP-RAGE (3.47 ± 0.61). When T1w images were used to delineate the outer carotid wall, very high specificities (>95%) of IPH detection on mask and TOF images were found, while the sensitivity was high for mask images (>81%) and poor for TOF (50-60%). Without these images, the specificity was still high (>97%), while the sensitivity reduced to 62-71%.

CONCLUSION

Despite the lower image quality, routinely acquired mask images from CE-MRA, but not TOF, can be used as an alternative to MP-RAGE images to visualize IPH.

Whole-brain diffusion tensor imaging predicts 6-month functional outcome in acute intracerebral haemorrhage

INTRODUCTION

Small vessel disease (SVD) causes most spontaneous intracerebral haemorrhage (ICH) and is associated with widespread microstructural brain tissue disruption, which can be quantified via diffusion tensor imaging (DTI) metrics: mean diffusivity (MD) and fractional anisotropy (FA). Little is known about the impact of whole-brain microstructural alterations after SVD-related ICH. We aimed to investigate: (1) association between whole-brain DTI metrics and functional outcome after ICH; and (2) predictive ability of these metrics compared to the pre-existing ICH score.

METHODS

Sixty-eight patients (38.2% lobar) were retrospectively included. We assessed whole-brain DTI metrics (obtained within 5 days after ICH) in cortical and deep grey matter and white matter. We used univariable logistic regression to assess the associations between DTI and clinical-radiological variables and poor outcome (modified Rankin Scale > 2). We determined the optimal predictive variables (via LASSO estimation) in: model 1 (DTI variables only), model 2 (DTI plus non-DTI variables), model 3 (DTI plus ICH score). Optimism-adjusted C-statistics were calculated for each model and compared (likelihood ratio test) against the ICH score.

RESULTS

Deep grey matter MD (OR 1.04 [95% CI 1.01-1.07], p = 0.010) and white matter MD (OR 1.11 [95% CI 1.01-1.23], p = 0.044) were associated (univariate analysis) with poor outcome. Discrimination values for model 1 (0.67 [95% CI 0.52-0.83]), model 2 (0.71 [95% CI 0.57-0.85) and model 3 (0.66 [95% CI 0.52-0.82]) were all significantly higher than the ICH score (0.62 [95% CI 0.49-0.75]).

CONCLUSION

Our exploratory study suggests that whole-brain microstructural disruption measured by DTI is associated with poor 6-month functional outcome after SVD-related ICH. Whole-brain DTI metrics performed better at predicting recovery than the existing ICH score.

Accelerated vascular aging: Ethnic differences in basilar artery length and diameter, and its association with cardiovascular risk factors and cerebral small vessel disease

Background and aims

Risk of stroke and dementia is markedly higher in people of South Asian and African Caribbean descent than white Europeans in the UK. This is unexplained by cardiovascular risk factors (CVRF). We hypothesized this might indicate accelerated early vascular aging (EVA) and that EVA might account for stronger associations between cerebral large artery characteristics and markers of small vessel disease.

Methods

360 participants in a tri-ethnic population-based study (120 per ethnic group) underwent cerebral and vertebral MRI. Length and median diameter of the basilar artery (BA) were derived from Time of Flight images, while white matter hyperintensities (WMH) volumes were obtained from T1 and FLAIR images. Associations between BA characteristics and CVRF were assessed using multivariable linear regression. Partial correlation coefficients between WMH load and BA characteristics were calculated after adjustment for CVRF and other potential confounders.

Results

BA diameter was strongly associated with age in South Asians (+11.3 μm/year 95% CI = [3.05; 19.62]; p = 0.008), with unconvincing relationships in African Caribbeans (3.4 μm/year [-5.26, 12.12]; p = 0.436) or Europeans (2.6 μm/year [-5.75, 10.87]; p = 0.543). BA length was associated with age in South Asians (+0.34 mm/year [0.02; 0.65]; p = 0.037) and African Caribbeans (+0.39 mm/year [0.12; 0.65]; p = 0.005) but not Europeans (+0.08 mm/year [-0.26; 0.41]; p = 0.653). BA diameter (rho = 0.210; p = 0.022) and length (rho = 0.261; p = 0.004) were associated with frontal WMH load in South Asians (persisting after multivariable adjustment for CVRF).

Conclusions

Compared with Europeans, the basilar artery undergoes more accelerated EVA in South Asians and in African Caribbeans, albeit to a lesser extent. Such EVA may contribute to the higher burden of CSVD observed in South Asians and excess risk of stroke, vascular cognitive impairment and dementia observed in these ethnic groups.

Vessel wall magnetic resonance and arterial spin labelling imaging in the management of presumed inflammatory intracranial arterial vasculopathy

Optimal criteria for diagnosing and monitoring response to treatment for infectious and inflammatory medium–large vessel intracranial vasculitis presenting with stroke are lacking. We integrated intracranial vessel wall MRI with arterial spin labelling into our routine clinical stroke pathway to detect presumed inflammatory intracranial arterial vasculopathy, and monitor disease activity, in patients with clinical stroke syndromes. We used predefined standardized radiological criteria to define vessel wall enhancement, and all imaging findings were rated blinded to clinical details. Between 2017 and 2018, stroke or transient ischaemic attack patients were first screened in our vascular radiology meeting and followed up in a dedicated specialist stroke clinic if a diagnosis of medium–large inflammatory intracranial arterial vasculopathy was radiologically confirmed. Treatment was determined and monitored by a multi-disciplinary team. In this case series, 11 patients were managed in this period from the cohort of young stroke presenters (<55 years). The median age was 36 years (interquartile range: 33,50), of which 8 of 11 (73%) were female. Two of 11 (18%) had herpes virus infection confirmed by viral nucleic acid in the cerebrospinal fluid. We showed improvement in cerebral perfusion at 1 year using an arterial spin labelling sequence in patients taking immunosuppressive therapy for >4 weeks compared with those not receiving therapy [6 (100%) versus 2 (40%) P = 0.026]. Our findings demonstrate the potential utility of vessel wall magnetic resonance with arterial spin labelling imaging in detecting and monitoring medium–large inflammatory intracranial arterial vasculopathy activity for patients presenting with stroke symptoms, limiting the need to progress to brain biopsy. Further systematic studies in unselected populations of stroke patients are needed to confirm our findings and establish the prevalence of medium–large artery wall inflammation.

Small vessel disease burden and intracerebral haemorrhage in patients taking oral anticoagulants

OBJECTIVE

We investigated the contribution of small vessel disease (SVD) to anticoagulant-associated intracerebral haemorrhage (ICH).

METHODS

Clinical Relevance of Microbleeds in Stroke-2 comprised two independent multicentre observation studies: first, a cross-sectional study of patients with ICH; and second, a prospective study of patients taking anticoagulants for atrial fibrillation (AF) after cerebral ischaemia. In patients with ICH, we compared SVD markers on CT and MRI according to prior anticoagulant therapy. In patients with AF and cerebral ischaemia treated with anticoagulants, we compared the rates of ICH and ischaemic stroke according to SVD burden score during 2 years follow-up.

RESULTS

We included 1030 patients with ICH (421 on anticoagulants), and 1447 patients with AF and cerebral ischaemia. Medium-to-high severity SVD was more prevalent in patients with anticoagulant-associated ICH (CT 56.1%, MRI 78.7%) than in those without prior anticoagulant therapy (CT 43.5%, p<0.001; MRI 64.5%, p=0.072). Leukoaraiosis and atrophy were more frequent and severe in ICH associated with prior anticoagulation. In the cerebral ischaemia cohort (779 with SVD), during 3366 patient-years of follow-up the rate of ICH was 0.56%/year (IQR 0.27-1.03) in patients with SVD, and 0.06%/year (IQR 0.00-0.35) in those without (p=0.001); ICH was independently associated with severity of SVD (HR 5.0, 95% CI 1.9 to 12.2,p=0.001), and was predicted by models including SVD (c-index 0.75, 95% CI 0.63 to 0.85).

CONCLUSIONS

Medium-to-high severity SVD is associated with ICH occurring on anticoagulants, and independently predicts ICH in patients with AF taking anticoagulants; its absence identifies patients at low risk of ICH. Findings from these two complementary studies suggest that SVD is a contributory factor in ICH in patients taking anticoagulants and suggest that anticoagulation alone should no longer be regarded as a sufficient 'cause' of ICH.

TRIAL REGISTRATION

NCT02513316.

Regional and Volumetric Parameters for Diffusion-Weighted WHO Grade II and III Glioma Genotyping: A Method Comparison

BACKGROUND AND PURPOSE

Studies consistently report lower ADC values in isocitrate dehydrogenase (IDH) wild-type gliomas than in IDH mutant tumors, but their methods and thresholds vary. This research aimed to compare volumetric and regional ADC measurement techniques for glioma genotyping, with a focus on IDH status prediction.

MATERIALS AND METHODS

Treatment-naïve World Health Organization grade II and III gliomas were analyzed by 3 neuroradiologist readers blinded to tissue results. ADC minimum and mean ROIs were defined in tumor and in normal-appearing white matter to calculate normalized values. T2-weighted tumor VOIs were registered to ADC maps with histogram parameters (mean, 2nd and 5th percentiles) extracted. Nonparametric testing (eta² and ANOVA) was performed to identify associations between ADC metrics and glioma genotypes. Logistic regression was used to probe the ability of VOI and ROI metrics to predict IDH status.

RESULTS

The study included 283 patients with 79 IDH wild-type and 204 IDH mutant gliomas. Across the study population, IDH status was most accurately predicted by ROI mean normalized ADC and VOI mean normalized ADC, with areas under the curve of 0.83 and 0.82, respectively_. The results for ROI-based genotyping of nonenhancing and solid-patchy enhancing gliomas were comparable with volumetric parameters (area under the curve = 0.81-0.84). In rim-enhancing, centrally necrotic tumors (n = 23), only volumetric measurements were predictive (0.90).

CONCLUSIONS

Regional normalized mean ADC measurements are noninferior to volumetric segmentation for defining solid glioma IDH status. Partially necrotic, rim-enhancing tumors are unsuitable for ROI assessment and may benefit from volumetric ADC quantification.

Are Dynamic Arterial Spin-Labeling MRA and Time-Resolved Contrast-Enhanced MRA Suited for Confirmation of Obliteration following Gamma Knife Radiosurgery of Brain Arteriovenous Malformations?

BACKGROUND AND PURPOSE

Intra-arterial DSA has been traditionally used for confirmation of cure following gamma knife radiosurgery for AVMs. Our aim was to evaluate whether 4D arterial spin-labeling MRA and contrast-enhanced time-resolved MRA in combination can be an alternative to DSA for confirmation of AVM obliteration following gamma knife radiosurgery.

MATERIALS AND METHODS

In this prospective study, 30 patients undergoing DSA for confirmation of obliteration following gamma knife radiosurgery for AVMs (criterion standard) also underwent MRA, including arterial spin-labeling MRA and contrast-enhanced time-resolved MRA. One dataset was technically unsatisfactory, and the case was excluded. The DSA and MRA datasets of 29 patients were independently and blindly evaluated by 2 observers regarding the presence/absence of residual AVMs.

RESULTS

The mean time between gamma knife radiosurgery and follow-up DSA/MRA was 53 months (95% CI, 42-64 months; range, 22-168 months). MRA total scanning time was 9 minutes and 17 seconds. Residual AVMs were detected on DSA in 9 subjects (obliteration rate = 69%). All residual AVMs were detected on at least 1 MRA sequence. Arterial spin-labeling MRA and contrast-enhanced time-resolved MRA showed excellent specificity and positive predictive values individually (100%). However, their sensitivity and negative predictive values were suboptimal due to 1 false-negative with arterial spin-labeling MRA and 2 with contrast-enhanced time-resolved MRA (sensitivity = 88% and 77%, negative predictive values = 95% and 90%, respectively). Both sensitivity and negative predictive values increased to 100% if a composite assessment of both MRA sequences was performed. Diagnostic accuracy (receiver operating characteristic) and agreement (κ) are maximized using arterial spin-labeling MRA and contrast-enhanced time-resolved MRA in combination (area under receiver operating characteristic curve = 1, P < .001; κ = 1, P < .001, respectively).

CONCLUSIONS

Combining arterial spin-labeling MRA with contrast-enhanced time-resolved MRA holds promise as an alternative to DSA for confirmation of obliteration following gamma knife radiosurgery for brain AVMs, having provided 100% sensitivity and specificity in the study. Their combined use also enables reliable characterization of residual lesions.

Baseline factors associated with early and late death in intracerebral haemorrhage survivors

Background and purpose

The aim of this study was to determine whether early and late death are associated with different baseline factors in intracerebral haemorrhage (ICH) survivors.

Methods

This was a secondary analysis of the multicentre prospective observational CROMIS‐2 ICH study. Death was defined as ‘early’ if occurring within 6 months of study entry and ‘late’ if occurring after this time point.

Results

In our cohort (n = 1094), there were 306 deaths (per 100 patient‐years: absolute event rate, 11.7; 95% confidence intervals, 10.5–13.1); 156 were ‘early’ and 150 ‘late’. In multivariable analyses, early death was independently associated with age [per year increase; hazard ratio (HR), 1.05, P = 0.003], history of hypertension (HR, 1.89, P = 0.038), pre‐event modified Rankin scale score (per point increase; HR, 1.41, P < 0.0001), admission National Institutes of Health Stroke Scale score (per point increase; HR, 1.11, P < 0.0001) and haemorrhage volume >60 mL (HR, 4.08, P < 0.0001). Late death showed independent associations with age (per year increase; HR, 1.04, P = 0.003), pre‐event modified Rankin scale score (per point increase; HR, 1.42, P = 0.001), prior anticoagulant use (HR, 2.13, P = 0.028) and the presence of intraventricular extension (HR, 1.73, P = 0.033) in multivariable analyses. In further analyses where time was treated as continuous (rather than dichotomized), the HR of previous cerebral ischaemic events increased with time, whereas HRs for Glasgow Coma Scale score, National Institutes of Health Stroke Scale score and ICH volume decreased over time.

Conclusions

We provide new evidence that not all baseline factors associated with early mortality after ICH are associated with mortality after 6 months and that the effects of baseline variables change over time. Our findings could help design better prognostic scores for later death after ICH.

Haptoglobin genotype and outcome after spontaneous intracerebral haemorrhage

OBJECTIVE

Haptoglobin is a haemoglobin-scavenging protein that binds and neutralises free haemoglobin and modulates inflammation and endothelial progenitor cell function. A HP gene copy number variation (CNV) generates HP1 and HP2 alleles, while the single-nucleotide polymorphism rs2000999 influences their levels. The HP1 allele is hypothesised to improve outcome after spontaneous (non-traumatic) intracerebral haemorrhage (ICH). We investigated the associations of the HP CNV genotype and rs2000999 with haematoma volume, perihaematomal oedema (PHO) volume, functional outcome and mortality after ICH.

METHODS

We included patients with neuroimaging-proven ICH, available DNA and 6-month follow-up in an observational cohort study (CROMIS-2). We classified patients into three groups according to the HP CNV: 1-1, 2-1 or 2-2 and also dichotomised HP into HP1-containing genotypes (HP1-1 and HP2-1) and HP2-2 to evaluate the HP1 allele. We measured ICH and PHO volume on CT; PHO was measured by oedema extension distance. Functional outcome was assessed by modified Rankin score (unfavourable outcome defined as mRS 3-6).

RESULTS

We included 731 patients (mean age 73.4, 43.5% female). Distribution of HP CNV genotype was: HP1-1 n=132 (18.1%); HP2-1 n=342 (46.8%); and HP2-2 n=257 (35.2%). In the multivariable model mortality comparisons between HP groups, HP2-2 as reference, were as follows: OR HP1-1 0.73, 95% CI 0.34 to 1.56 (p value=0.41) and OR HP2-1 0.5, 95% CI 0.28 to 0.89 (p value=0.02) (overall p value=0.06). We found no evidence of association of HP CNV or rs200999 with functional outcome, ICH volume or PHO volume.

CONCLUSION

The HP2-1 genotype might be associated with lower 6-month mortality after ICH; this finding merits further study.

Cardiovascular Risk Factors and White Matter Hyperintensities: Difference in Susceptibility in South Asians Compared With Europeans

Background

Cardiovascular risk factors vary between ethnicities but little is known about their differential effects on white matter hyperintensities (WMH), an indicator of brain aging and burden of cerebrovascular disease.

Methods and Results

Brain magnetic resonance imaging scans from 213 people of South Asian and 256 of European ethnicity (total=469) were analyzed for global and regional WMH load. Associations with cardiovascular risk factors and a composite cardiovascular risk score (National Cholesterol Education Programme Adult Treatment Panel III) were compared by ethnicity, diabetes mellitus, smoking, and hypertension status. Distributional patterns of WMH were similar by ethnicity but the vulnerability to specific risk factors differed. Associations between WMH and age or National Cholesterol Education Programme Adult Treatment Panel III scores were stronger in South Asians compared with Europeans. For instance, a year of age led to an excess of 3.8% (confidence interval=[0.2, 7.6]; P=0.04) of WMH load in frontal regions in South Asians compared with Europeans. In the diabetic subgroup, South Asians had more WMH than Europeans (+63.3%, confidence interval=[14.1, 133.9]; P=0.007), particularly in the deeper regions (+102% confidence interval=[24, 329]; P=0.004). In the population as a whole, diabetes mellitus was not, or only weakly, related to an increase in WMH volume (12.4%, confidence interval=[−10.7, 41.3]; P=0.32), and diabetes mellitus duration was a positive predictor of frontal periventricular WMH load in Europeans but not in South Asians. In turn, diastolic blood pressure was positively associated with WMH volumes in South Asians but not in Europeans. Hypertension was not associated with WMH load (P=0.9).

Conclusions

Distribution patterns of WMH are similar in South Asians and Europeans but older age and higher cardiovascular risk are associated with more WMH in South Asians.

Potential missed opportunities to prevent ischaemic stroke: prospective multicentre cohort study of atrial fibrillation-associated ischaemic stroke and TIA

OBJECTIVE

We report on: (1) the proportion of patients with known atrial fibrillation (AF); and (2) demographic, clinical or radiological differences between patients with known AF (and not treated) and patients with newly diagnosed AF, in a cohort of patients who presented with ischaemic stroke or transient ischaemic attack (TIA) not previously treated with anticoagulation.

DESIGN

We reviewed cross-sectional baseline demographic and clinical data from a prospective observational cohort study, (CROMIS-2).

SETTING

Patients were recruited from 79 hospital stroke centres throughout the UK and one centre in the Netherlands.

PARTICIPANTS

Patients were eligible if they were adults who presented with ischaemic stroke or TIA and AF and had not been previously treated with oral anticoagulation.

MAIN OUTCOME MEASURES

Proportion of patients with known AF before index ischaemic stroke or TIA from a cohort of patients who have not been previously treated with oral anticoagulation. Secondary analysis includes the comparison of CHA2DS2-VASc and HAS-BLED scores and other demographics and risk factors between those with newly diagnosed AF and those with previously known AF.

RESULTS

Of 1470 patients included in the analysis (mean age 76 years (SD 10)), 622 (42%) were female; 999 (68%) patients had newly diagnosed AF and 471 (32%) patients had known AF. Of the 471 patients with known AF, 68% had a strong indication for anticoagulation and 89% should have been considered for anticoagulation based upon CHA2DS2-VASc score. Patients with known AF were more likely to have a prior history of dementia (4% vs 2%, p=0.02) and had higher HAS-BLED scores (median 3 vs 2). CHA2DS2-VASc, other risk factors and demographics were similar.

CONCLUSIONS

About 1/3 of patients who present with stroke and have AF who have not been treated with oral anticoagulation have previously known AF. Of these patients, at least 68% were not adequately treated with oral anticoagulation.

TRIAL REGISTRATION NUMBER

NCT02513316.

Magnetic Resonance Imaging of Cerebral Small Vessel Disease in Men Living with HIV and HIV-Negative Men Aged 50 and Above

We assessed whether HIV status was associated with white matter hyperintensities (WMH), a neuroimaging correlate of cerebral small vessel disease (CSVD), in men aged ≥50 years. A cross-sectional substudy was nested within a larger cohort study. Virologically suppressed men living with HIV (MLWH) and demographically matched HIV-negative men aged ≥50 underwent magnetic resonance imaging (MRI) at 3 Tesla. Sequences included volumetric three-dimensional (3D) T1-weighted, fluid-attenuated inversion recovery and pseudocontinuous arterial spin labeling. Regional segmentation by automated image processing algorithms was used to extract WMH volume (WMHV) and resting cerebral blood flow (CBF). The association between HIV status and WMHV as a proportion of intracranial volume (ICV; log-transformed) was estimated using a multivariable linear regression model. Thirty-eight MLWH [median age 59 years (interquartile range, IQR 55-64)] and 37 HIV-negative [median 58 years (54-63)] men were analyzed. MLWH had median CD4⁺ count 570 (470-700) cells/μL and a median time since diagnosis of 20 (14-24) years. Framingham 10-year risk of cardiovascular disease was 6.5% in MLWH and 7.4% in controls. Two (5%) MLWH reported a history of stroke or transient ischemic attack and five (13%) reported coronary heart disease compared with none of the controls. The total WMHV in MLWH was 1,696 μL (IQR 1,229-3,268 μL) or 0.10% of ICV compared with 1,627 μL (IQR 1,032-3,077 μL), also 0.10% of ICV in the HIV-negative group (p = .43). In the multivariable model, WMHV/ICV was not associated with HIV status (p = .86). There was an age-dependent decline in cortical CBF [-3.9 mL/100 mL/min per decade of life (95% confidence interval 1.1-6.7 mL)] but no association between CBF and HIV status (p > .2 in all brain regions analyzed). In conclusion, we found no quantitative MRI evidence of an increased burden of CSVD in MLWH aged 50 years and older.

Imaging biomarkers of vulnerable carotid plaques for stroke risk prediction and their potential clinical implications

Stroke represents a massive public health problem. Carotid atherosclerosis plays a fundamental part in the occurence of ischaemic stroke. European and US guidelines for prevention of stroke in patients with carotid plaques are based on quantification of the percentage reduction in luminal diameter due to the atherosclerotic process to select the best therapeutic approach. However, better strategies for prevention of stroke are needed because some subtypes of carotid plaques (eg, vulnerable plaques) can predict the occurrence of stroke independent of the degree of stenosis. Advances in imaging techniques have enabled routine characterisation and detection of the features of carotid plaque vulnerability. Intraplaque haemorrhage is accepted by neurologists and radiologists as one of the features of vulnerable plaques, but other characteristics-eg, plaque volume, neovascularisation, and inflammation-are promising as biomarkers of carotid plaque vulnerability. These biomarkers could change current management strategies based merely on the degree of stenosis.

Cortical cerebral blood flow in ageing: effects of haematocrit, sex, ethnicity and diabetes

OBJECTIVES

Cerebral blood flow (CBF) estimates from arterial spin labelling (ASL) show unexplained variability in older populations. We studied the impact of variation of haematocrit (Hct) on CBF estimates in a tri-ethnic elderly population.

MATERIALS AND METHODS

Approval for the study was obtained from the Fulham Research Ethics Committee and participants gave written informed consent. Pseudo-continuous arterial spin labelling was performed on 493 subjects (age 55-90) from a tri-ethnic community-based cohort recruited in London. CBF was estimated using a simplified Buxton equation, with and without correction for Hct measured from blood samples. Differences in perfusion were compared, stratified by sex, ethnicity and diabetes. Results of Student's t tests were reported with effect size.

RESULTS

Hct adjustment decreased CBF estimates in all categories except white European men. The decrease for women was 2.7 (3.0, 2.4) mL/100 g/min) (mean (95% confidence interval (CI)), p < 0.001 d = 0.38. The effect size differed by ethnicity with estimated mean perfusion in South Asian and African Caribbean women found to be lower by 3.0 (3.6, 2.5) mL/100 g/min, p < 0.001 d = 0.56 and 3.1 (3.6, 2.5) mL/100 g/min), p < 0.001 d = 0.48, respectively. Estimates of perfusion in subjects with diabetes decreased by 1.8 (2.3, 1.4) mL/100 g/min, p < 0.001 d = 0.23) following Hct correction. Correction for individual Hct altered sample frequency distributions of CBF values, especially in women of non-European ethnicity.

CONCLUSION

ASL-derived CBF values in women, non-European ethnicities and individuals with diabetes are overestimated if calculations are not appropriately adjusted for individual Hct.

KEY POINTS

• CBF quantification from ASL using a fixed Hct of 43.5%, as recommended in the ISMRM white paper, may lead to erroneous CBF estimations particularly in non-European and female subjects. • Individually measured Hct values improve the accuracy of CBF estimation and, if these are not available, an adjusted value according to gender, ethnicity or diabetes status should be considered. • Hct-corrected ASL could be potentially important for CBF threshold decision making in the fields of neurodegenerative disease and neuro-oncology.

A visual quality control scale for clinical arterial spin labeling images

BACKGROUND

Image-quality assessment is a fundamental step before clinical evaluation of magnetic resonance images. The aim of this study was to introduce a visual scoring system that provides a quality control standard for arterial spin labeling (ASL) and that can be applied to cerebral blood flow (CBF) maps, as well as to ancillary ASL images.

METHODS

The proposed image quality control (QC) system had two components: (1) contrast-based QC (cQC), describing the visual contrast between anatomical structures; and (2) artifact-based QC (aQC), evaluating image quality of the CBF map for the presence of common types of artifacts. Three raters evaluated cQC and aQC for 158 quantitative signal targeting with alternating radiofrequency labelling of arterial regions (QUASAR) ASL scans (CBF, T1 relaxation rate, arterial blood volume, and arterial transient time). Spearman correlation coefficient (r), intraclass correlation coefficients (ICC), and receiver operating characteristic analysis were used.

RESULTS

Intra/inter-rater agreement ranged from moderate to excellent; inter-rater ICC was 0.72 for cQC, 0.60 for aQC, and 0.74 for the combined QC (cQC + aQC). Intra-rater ICC was 0.90 for cQC; 0.80 for aQC, and 0.90 for the combined QC. Strong correlations were found between aQC and CBF maps quality (r = 0.75), and between aQC and cQC (r = 0.70). A QC score of 18 was optimal to discriminate between high and low quality clinical scans.

CONCLUSIONS

The proposed QC system provided high reproducibility and a reliable threshold for discarding low quality scans. Future research should compare this visual QC system with an automatic QC system.

Predicting the presence of macrovascular causes in non-traumatic intracerebral haemorrhage: the DIAGRAM prediction score

OBJECTIVE

A substantial part of non-traumatic intracerebral haemorrhages (ICH) arises from a macrovascular cause, but there is little guidance on selection of patients for additional diagnostic work-up. We aimed to develop and externally validate a model for predicting the probability of a macrovascular cause in patients with non-traumatic ICH.

METHODS

The DIagnostic AngioGRAphy to find vascular Malformations (DIAGRAM) study (n=298; 69 macrovascular cause; 23%) is a prospective, multicentre study assessing yield and accuracy of CT angiography (CTA), MRI/ magnetic resonance angiography (MRA) and intra-arterial catheter angiography in diagnosing macrovascular causes in patients with non-traumatic ICH. We considered prespecified patient and ICH characteristics in multivariable logistic regression analyses as predictors for a macrovascular cause. We combined independent predictors in a model, which we validated in an external cohort of 173 patients with ICH (78 macrovascular cause, 45%).

RESULTS

Independent predictors were younger age, lobar or posterior fossa (vs deep) location of ICH, and absence of small vessel disease (SVD). A model that combined these predictors showed good performance in the development data (c-statistic 0.83; 95% CI 0.78 to 0.88) and moderate performance in external validation (c-statistic 0.66; 95% CI 0.58 to 0.74). When CTA results were added, the c-statistic was excellent (0.91; 95% CI 0.88 to 0.94) and good after external validation (0.88; 95% CI 0.83 to 0.94). Predicted probabilities varied from 1% in patients aged 51-70 years with deep ICH and SVD, to more than 50% in patients aged 18-50 years with lobar or posterior fossa ICH without SVD.

CONCLUSION

The DIAGRAM scores help to predict the probability of a macrovascular cause in patients with non-traumatic ICH based on age, ICH location, SVD and CTA.

Glioma imaging in Europe: A survey of 220 centres and recommendations for best clinical practice

Objectives

At a European Society of Neuroradiology (ESNR) Annual Meeting 2015 workshop, commonalities in practice, current controversies and technical hurdles in glioma MRI were discussed. We aimed to formulate guidance on MRI of glioma and determine its feasibility, by seeking information on glioma imaging practices from the European Neuroradiology community.

Methods

Invitations to a structured survey were emailed to ESNR members (n=1,662) and associates (n=6,400), European national radiologists’ societies and distributed via social media.

Results

Responses were received from 220 institutions (59% academic). Conventional imaging protocols generally include T2w, T2-FLAIR, DWI, and pre- and post-contrast T1w. Perfusion MRI is used widely (85.5%), while spectroscopy seems reserved for specific indications. Reasons for omitting advanced imaging modalities include lack of facility/software, time constraints and no requests. Early postoperative MRI is routinely carried out by 74% within 24–72 h, but only 17% report a percent measure of resection. For follow-up, most sites (60%) issue qualitative reports, while 27% report an assessment according to the RANO criteria. A minority of sites use a reporting template (23%).

Conclusion

Clinical best practice recommendations for glioma imaging assessment are proposed and the current role of advanced MRI modalities in routine use is addressed.

Key Points

• We recommend the EORTC-NBTS protocol as the clinical standard glioma protocol.

• Perfusion MRI is recommended for diagnosis and follow-up of glioma.

• Use of advanced imaging could be promoted with increased education activities.

• Most response assessment is currently performed qualitatively.

• Reporting templates are not widely used, and could facilitate standardisation.

Electronic supplementary material

The online version of this article (10.1007/s00330-018-5314-5) contains supplementary material, which is available to authorized users.

Carotid Artery Wall Imaging: Perspective and Guidelines from the ASNR Vessel Wall Imaging Study Group and Expert Consensus Recommendations of the American Society of Neuroradiology

Identification of carotid artery atherosclerosis is conventionally based on measurements of luminal stenosis and surface irregularities using in vivo imaging techniques including sonography, CT and MR angiography, and digital subtraction angiography. However, histopathologic studies demonstrate considerable differences between plaques with identical degrees of stenosis and indicate that certain plaque features are associated with increased risk for ischemic events. The ability to look beyond the lumen using highly developed vessel wall imaging methods to identify plaque vulnerable to disruption has prompted an active debate as to whether a paradigm shift is needed to move away from relying on measurements of luminal stenosis for gauging the risk of ischemic injury. Further evaluation in randomized clinical trials will help to better define the exact role of plaque imaging in clinical decision-making. However, current carotid vessel wall imaging techniques can be informative. The goal of this article is to present the perspective of the ASNR Vessel Wall Imaging Study Group as it relates to the current status of arterial wall imaging in carotid artery disease.

Microbleeds, Cerebral Hemorrhage, and Functional Outcome After Stroke Thrombolysis

Background and Purpose—

We assessed whether the presence, number, and distribution of cerebral microbleeds (CMBs) on pre-intravenous thrombolysis MRI scans of acute ischemic stroke patients are associated with an increased risk of intracerebral hemorrhage (ICH) or poor functional outcome.

Methods—

We performed an individual patient data meta-analysis, including prospective and retrospective studies of acute ischemic stroke treated with intravenous tissue-type plasminogen activator. Using multilevel mixed-effects logistic regression, we investigated associations of pre-treatment CMB presence, burden (1, 2–4, ≥5, and >10), and presumed pathogenesis (cerebral amyloid angiopathy defined as strictly lobar CMBs and noncerebral amyloid angiopathy) with symptomatic ICH, parenchymal hematoma (within [parenchymal hemorrhage, PH] and remote from the ischemic area [remote parenchymal hemorrhage, PHr]), and poor 3- to 6-month functional outcome (modified Rankin score >2).

Results—

In 1973 patients from 8 centers, the crude prevalence of CMBs was 526 of 1973 (26.7%). A total of 77 of 1973 (3.9%) patients experienced symptomatic ICH, 210 of 1806 (11.6%) experienced PH, and 56 of 1720 (3.3%) experienced PHr. In adjusted analyses, patients with CMBs (compared with those without CMBs) had increased risk of PH (odds ratio: 1.50; 95% confidence interval: 1.09–2.07; P =0.013) and PHr (odds ratio: 3.04; 95% confidence interval: 1.73–5.35; P <0.001) but not symptomatic ICH. Both cerebral amyloid angiopathy and noncerebral amyloid angiopathy patterns of CMBs were associated with PH and PHr. Increasing CMB burden category was associated with the risk of symptomatic ICH ( P =0.014), PH ( P =0.013), and PHr ( P <0.00001). Five or more and >10 CMBs independently predicted poor 3- to 6-month outcome (odds ratio: 1.85; 95% confidence interval: 1.10–3.12; P =0.020; and odds ratio: 3.99; 95% confidence interval: 1.55–10.22; P =0.004, respectively).

Conclusions—

Increasing CMB burden is associated with increased risk of ICH (including PHr) and poor 3- to 6-month functional outcome after intravenous thrombolysis for acute ischemic stroke.

MRI-visible perivascular space location is associated with Alzheimer's disease independently of amyloid burden

Perivascular spaces that are visible on magnetic resonance imaging (MRI) are a neuroimaging marker of cerebral small vessel disease. Their location may relate to the type of underlying small vessel pathology: those in the white matter centrum semi-ovale have been associated with cerebral amyloid angiopathy, while those in the basal ganglia have been associated with deep perforating artery arteriolosclerosis. As cerebral amyloid angiopathy is an almost invariable pathological finding in Alzheimer's disease, we hypothesized that MRI-visible perivascular spaces in the centrum semi-ovale would be associated with a clinical diagnosis of Alzheimer's disease, whereas those in the basal ganglia would be associated with subcortical vascular cognitive impairment. We also hypothesized that MRI-visible perivascular spaces in the centrum semi-ovale would be associated with brain amyloid burden, as detected by amyloid positron emission tomography using 11C-Pittsburgh B compound (PiB-PET). Two hundred and twenty-six patients (Alzheimer's disease n = 110; subcortical vascular cognitive impairment n = 116) with standardized MRI and PiB-PET imaging were included. MRI-visible perivascular spaces were rated using a validated 4-point visual rating scale, and then categorized by severity ('none/mild', 'moderate' or 'frequent/severe'). Univariable and multivariable regression analyses were performed. Those with Alzheimer's disease-related cognitive impairment were younger, more likely to have a positive PiB-PET scan and carry at least one apolipoprotein E ɛ4 allele; those with subcortical vascular cognitive impairment were more likely to have hypertension, diabetes mellitus, hyperlipidaemia, prior stroke, lacunes, deep microbleeds, and carry the apolipoprotein E ɛ3 allele. In adjusted analyses, the severity of MRI-visible perivascular spaces in the centrum semi-ovale was independently associated with clinically diagnosed Alzheimer's disease (frequent/severe grade odds ratio 6.26, 95% confidence interval 1.66-23.58; P = 0.017, compared with none/mild grade), whereas the severity of MRI-visible perivascular spaces in the basal ganglia was associated with clinically diagnosed subcortical vascular cognitive impairment and negatively predicted Alzheimer's disease (frequent/severe grade odds ratio 0.03, 95% confidence interval 0.00-0.44; P = 0.009, compared with none/mild grade). MRI-visible perivascular space severity in either location did not predict PiB-PET. These findings provide further evidence that the anatomical distribution of MRI-visible perivascular spaces may reflect the underlying cerebral small vessel disease. Using MRI-visible perivascular space location and severity together with other imaging markers may improve the diagnostic value of neuroimaging in memory clinic populations, in particular in differentiating between clinically diagnosed Alzheimer's and subcortical vascular cognitive impairment.

Convexity subarachnoid haemorrhage has a high risk of intracerebral haemorrhage in suspected cerebral amyloid angiopathy

The risk of future symptomatic intracerebral haemorrhage (sICH) remains uncertain in patients with acute convexity subarachnoid haemorrhage (cSAH) associated with suspected cerebral amyloid angiopathy (CAA). We assessed the risk of future sICH in patients presenting to our comprehensive stroke service with acute non-traumatic cSAH due to suspected CAA, between 2011 and 2016. We conducted a systematic search and pooled analysis including our cohort and other published studies including similar cohorts. Our hospital cohort included 20 patients (mean age 69 years; 60% male); 12 (60%) had probable CAA, and 6 (30%) had possible CAA according to the modified Boston criteria; two did not meet CAA criteria because of age <55 years, but were judged likely to be due to CAA. Fourteen patients (70%) had cortical superficial siderosis; 12 (60%) had cerebral microbleeds. Over a mean follow-up period of 19 months, 2 patients (9%) suffered sICH, both with probable CAA (annual sICH risk for probable CAA 8%). In a pooled analysis including our cohort and eight other studies (n = 172), the overall sICH rate per patient-year was 16% (95% CI 11–24%). In those with probable CAA (n = 104), the sICH rate per patient-year was 19% (95% CI 13–27%), compared to 7% (95% CI 3–15%) for those without probable CAA (n = 72). Patients with acute cSAH associated with suspected CAA are at high risk of future sICH (16% per patient-year); probable CAA might carry the highest risk.

Subarachnoid haemorrhage guidelines and clinical practice: a cross-sectional study of emergency department consultants' and neurospecialists' views and risk tolerances

OBJECTIVES

To establish if emergency medicine and neuroscience specialist consultants have different risk tolerances for investigation of suspected spontaneous subarachnoid haemorrhage (SAH), and to establish if their risk-benefit appraisals concur with current guidelines.

SETTING

4 major neuroscience centres in London.

PARTICIPANTS

58 consultants in emergency medicine and neuroscience specialities (neurology, neurosurgery and neuroradiology) participated in an anonymous survey.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the highest stated acceptable risk of missing SAH in the neurologically intact patient presenting with sudden onset headache. Secondary outcome measures included agreement with guideline recommendations, risk/benefit appraisal and required performance of diagnostic tests, including lumbar puncture.

RESULTS

Emergency department clinicians accepted almost 3 times the risk of a missed SAH diagnosis compared with the neuroscience specialists (2.8% vs 1.1%; p=0.02), were more likely to accept a higher risk of missed diagnosis for the benefit of a non-invasive test (p=0.04) and were more likely to disagree with current published guidelines stipulating the need for LP in all CT-negative cases (p=0.001).

CONCLUSIONS

Divergence from recognised procedures for SAH investigation is often criticised and attributed to a lack of knowledge of guidelines. This study indicates that divergence from guidelines may be explained by alternative risk-benefit appraisals made by doctors with their patients. Guideline recommendations may gain wider acceptance if they accommodate the requirements of the doctors and patients using them. Further study of clinical risk tolerance may help explain patterns of diagnostic test use and other variations in healthcare delivery.

Diffusion- and Perfusion-Weighted MR Imaging in Persistent Migrainous visual Disturbances

Pathological changes on diffusion-weighted MR scans had been described in hemiplegic migraine and perfusion changes had been demonstrated in typical migraine aura with radio-isotope studies and, more recently, MR perfusion imaging. However, there is relatively little knowledge of the pathophysiology of long-lasting migraine aura and its possibly variant phenotype, visual snow. Our aim was to investigate with advanced MR techniques whether patients with long-lasting visual disturbance showed regional alterations in cerebral water diffusion and perfusion. We have studied four patients using MR perfusion and MR diffusion imaging. Two patients had typical visual aura and two had a primary persistent visual disturbance (visual snow phenomenon). All patients had normal conventional structural MR imaging. MR diffusion-weighted images were acquired with a b-value of up to 1000 s/mm2. From the diffusion weighted images we generated maps of apparent diffusion coefficient (ADC), which were inspected visually and used for ADC measurements of predefined regions of interest, which included the visual, frontal, insular and temporal cortices. MR perfusion imaging was performed using a bolus tracking technique with dynamic susceptibility-weighted images. Colour coded maps of relative cerebral blood volume, mean transit time and bolus arrival time were generated, as well as time-signal intensity curves over the anterior, middle and posterior cerebral artery territories. The maps of the ADC and above perfusion parameters appeared symmetrical in all patients with no evidence of decreased water diffusion or cerebral perfusion in the occipital regions, or elsewhere. There was no statistically significant difference between the ADC measurements of the primary visual cortices and other cortical regions. Our findings suggest that regional changes in cerebral water diffusion and perfusion do not play an important part in the pathophysiology of persistent migraine aura or primary persistent visual disturbance.

Anticoagulation for Atrial Fibrillation in Patients with Cerebral Microbleeds

Intracranial haemorrhage (ICH) is the most feared and devastating complication of oral anticoagulation, with high mortality and disability in survivors. Oral anticoagulant-related ICH is increasing in incidence, most likely in part due to the increased use of anticoagulation for atrial fibrillation in the elderly populations with a high prevalence of bleeding-prone cerebral small vessel diseases. Risk scores have been developed to predict bleeding, including ICH, as well as the risk of ischaemic stroke. Recently, attention has turned to brain imaging, in particular, MRI detection of potential prognostic biomarkers, which may help better predict outcomes and individualize anticoagulant decisions. Cerebral microbleeds (CMBs)--small, round areas of signal loss on blood-sensitive MR sequences--have been hypothesized to be a marker for bleeding-prone small vessel pathology, and thus, future symptomatic ICH risk. In this review, we outline the prevalence and prognostic value of CMBs in populations affected by AF for whom anticoagulation decisions are relevant, including healthy older individuals and survivors of ischaemic stroke or ICH. We consider the limitations of currently available evidence, and discuss future research directions in relation to both prognostic markers and treatment options for atrial fibrillation.

Carotid Anatomy Does Not Predict the Risk of New Ischaemic Brain Lesions on Diffusion-Weighted Imaging after Carotid Artery Stenting in the ICSS-MRI Substudy

INTRODUCTION

The International Carotid Stenting Study (ICSS, ISRCTN25337470) randomized patients with recently symptomatic carotid artery stenosis > 50% to carotid artery stenting (CAS) or endarterectomy. CAS increased the risk of new brain lesions visible on diffusion-weighted magnetic resonance imaging (DWI-MRI) more than endarterectomy in the ICSS-MRI Substudy. The predictors of new post-stenting DWI lesions were assessed in these patients.

METHODS

ICSS-MRI Substudy patients allocated to CAS were studied. Baseline or pre-stenting catheter angiograms were rated to determine carotid anatomy. Baseline patient demographics and the influence of plaque length, plaque morphology, internal carotid angulation, and external or common carotid atheroma were examined in negative binomial regression models.

RESULTS

A total of 115 patients (70% male, average age 70.4) were included; 50.4% had at least one new DWI-MRI-positive lesion following CAS. Independent risk factors increasing the number of new lesions were a left-sided stenosis (incidence risk ratio [IRR] 1.59, 95% CI 1.04-2.44, p = .03), age (IRR 2.10 per 10-year increase in age, 95% CI 1.61-2.74, p < .01), male sex (IRR 2.83, 95% CI 1.72-4.67, p < .01), hypertension (IRR 2.04, 95% CI 1.25-3.33, p < .01) and absence of cardiac failure (IRR 6.58, 95% CI 1.23-35.07, p = .03). None of the carotid anatomical features significantly influenced the number of post-procedure lesions.

CONCLUSION

Carotid anatomy seen on pre-stenting catheter angiography did not predict of the number of ischaemic brain lesions following CAS.

Cerebral microbleeds and postthrombolysis intracerebral hemorrhage risk Updated meta-analysis

OBJECTIVE

We performed a systematic review and meta-analysis to assess whether the presence of cerebral microbleeds (CMBs) on pretreatment MRI scans of patients with acute ischemic stroke treated with thrombolysis is associated with an increased risk of symptomatic intracerebral hemorrhage (ICH).

METHODS

We searched PubMed for relevant studies and calculated pooled odds ratios (ORs) for symptomatic ICH, using the Mantel–Haenszel fixed-effects method, among individuals with vs without CMBs on pretreatment MRI scans. To minimize potential bias, sensitivity analysis was performed including studies providing data on patients treated only with IV thrombolysis.

RESULTS

Ten eligible studies including 2,028 patients were pooled in meta-analysis. The overall prevalence of CMBs was 23.3%. Among patients with CMBs, 40 of 472 (8.5%; 95%confidence interval [CI]: 6.1%–11.4%) experienced a symptomatic ICH after thrombolysis compared with 61 of 1,556 patients (3.9%; 95% CI: 3%–5%) without CMBs. The pooled OR of ICH across all studies was 2.26 (95%CI: 1.46–3.49; p , 0.0001). Eight studies, including 1,704 patients (n 5 401 with CMBs), provided data on patients treated with IV thrombolysis only; OR for the presence of CMBs and the development of symptomatic ICH was 2.87 (95%CI: 1.76–4.69; p , 0.0001).

CONCLUSIONS

Our meta-analysis of the available published data demonstrates an increased risk of symptomatic ICH after thrombolysis for acute ischemic stroke in patients with CMBs. However, we cannot fully exclude bias or confounding, so our results should be considered hypothesis generating. Detecting CMBs should not prevent thrombolytic treatment based on present evidence. Further analyses, taking into account CMB number and location, as well as measures of functional outcome, are needed.

New vistas in clinical practice: susceptibility-weighted imaging

Susceptibility-weighted imaging (SWI) is a recently developed magnetic resonance imaging (MRI) technique where image contrast represents 'magnetic susceptibility effects'-a natural property of tissues. The applications of SWI are rapidly increasing, with much work being carried out to determine the usefulness of the technique in multiple disease states. Current clinical applications of the technique include detection of microbleeds, subarachnoid hemorrhage (SAH), ferromagnetic deposition in neurodegenerative disease, and characterization of cerebral tumors.

Cross-sectional study of unexplained white matter lesions in HIV positive individuals undergoing brain magnetic resonance imaging

White matter (WM) abnormalities are frequently seen on brain MRI of HIV positive (HIV+) patients. We aimed to determine the prevalence of unexplained WM abnormalities and their associations with HIV disease and cardiovascular risk factors. We conducted a retrospective, cross-sectional study of brain MRI of HIV+ patients conducted between 2004 and 2009 at our center. Clinical and laboratory data were compiled, and images were independently reviewed for WM lesions. Images were obtained from 254 patients: 70% male, 53% white, 40% black, mean age 42 years, median current CD4 count 240 cells/mm(3), and 41% not taking antiretroviral therapy (ART). Hyperintense WM lesions were present in 161 patients (63.4%): 89 scans (35.0%) showed diffuse WM signal abnormality (DWMSA), 61 (24.0%) were consistent with small vessel disease (SVD, graded by Fazekas' scale), and 37 (14.6%) showed large asymmetrical focal WM lesions. SVD changes were associated with age and cardiovascular risk factors, and while cerebral SVD may be related to HIV infection, the MRI findings were not associated with HIV-related factors. The only risk factor for DWMSA was black race, and no correlation with cardiovascular risk factors, CD4 count, or clinical presentation was identified. DWMSA are therefore of uncertain neurological significance in HIV+ patients and could represent more than one clinicopathological entity.

HIV, dementia and antiretroviral drugs: 30 years of an epidemic

Neurological complications due to the HIV itself became apparent early on in the course of the AIDS epidemic. The most feared were the cognitive and motor complications termed AIDS dementia complex or HIV-associated dementia. With the introduction of combination antiretroviral therapy, the incidence of HIV-associated dementia has been dramatically reduced. However, the prevalence of less severe forms of the disorder remains around 20%. There is controversy about whether some patients may continue with progressive cognitive decline despite adequate suppression of the HIV. The salient issues are those of cerebrospinal fluid (CSF) drug penetration, drug neurotoxicity and persistent immune activation and inflammation. This review will also discuss other newly encountered complications, including the compartmentalisation (or CSF escape) and immune reconstitution inflammatory syndromes.

Multiparameter MR imaging in the 6-OPRI variant of inherited prion disease

BACKGROUND AND PURPOSE

Inherited prion diseases represent over 15% of human prion cases and are a frequent cause of early onset dementia. The purpose of this study was to define the distribution of changes in cerebral volumetric and microstructural parenchymal tissues in a specific inherited human prion disease mutation combining VBM with VBA of cerebral MTR and MD.

MATERIALS AND METHODS

VBM and VBA of cerebral MTR and MD were performed in 16 healthy control participants and 9 patients with the 6-OPRI mutation. An analysis of covariance consisting of diagnostic grouping with age and total intracranial volume as covariates was performed.

RESULTS

On VBM, there was a significant reduction in gray matter volume in patients compared with control participants in the basal ganglia, perisylvian cortex, lingual gyrus, and precuneus. Significant MTR reduction and MD increases were more anatomically extensive than volume differences on VBM in the same cortical areas, but MTR and MD changes were not seen in the basal ganglia.

CONCLUSIONS

Gray matter and WM changes were seen in brain areas associated with motor and cognitive functions known to be impaired in patients with the 6-OPRI mutation. There were some differences in the anatomic distribution of MTR-VBA and MD-VBA changes compared with VBM, likely to reflect regional variations in the type and degree of the respective pathophysiologic substrates. Combined analysis of complementary multiparameter MR imaging data furthers our understanding of prion disease pathophysiology.

Cerebral microbleeds and long-term cognitive outcome: longitudinal cohort study of stroke clinic patients

BACKGROUND

Vascular cognitive impairment causes significant disability in the elderly and is common following ischaemic stroke. Although the underlying mechanisms and prognostic factors remain unclear, small vessel diseases are known to contribute. Cerebral microbleeds (CMBs) are a magnetic resonance imaging (MRI) manifestation of small vessel diseases and may contribute to vascular cognitive impairment, particularly frontal-executive functions. We hypothesized that baseline CMBs would predict long-term cognitive outcome, specifically frontal-executive function.

METHODS

A cohort of consecutive patients found to have CMBs when first referred to a stroke clinic, together with a CMB-free control group matched for age, gender and clinicoradiological characteristics, were invited for follow-up cognitive assessment a median of 5.7 years later. MRI and detailed cognitive assessment (including current intellectual function, verbal memory, visual memory, naming skills, perceptual functions, frontal-executive functions; and speed and attention) were performed at baseline and follow-up. Patients were classified (blinded to MRI and clinical data) as impaired or unimpaired in each domain using predefined criteria. We compared the prevalence of cognitive impairments in each domain at baseline and follow-up and investigated clinical and radiological predictors [including baseline CMBs and white matter changes (WMCs)] of frontal-executive cognitive impairment.

RESULTS

Of the original cohort of 55 patients, 13 died without follow-up. Twenty-six of the surviving patients (9 with, 17 without baseline CMBs) agreed to follow-up neuropsychological assessment; 21 of these patients had a repeat MRI scan. The median number of cognitive domains impaired increased, regardless of the presence of baseline CMBs (with baseline CMBs: median 3, range 0-5 at follow-up vs. median 2, range 0-2 at baseline, p = 0.016; without CMBs: median 1.0, range 0-5 at follow-up vs. median 0, range 0-5 at baseline, p = 0.035). Frontal-executive impairment at follow-up was more prevalent in patients with baseline CMBs than in those without (78 vs. 29%, p = 0.038). The presence of baseline CMBs predicted frontal-executive impairment at follow-up (OR 8.40, 95% CI 1.27-55.39, p = 0.027). Fifty percent of patients with CMBs versus 8% of patients without baseline CMBs developed new CMBs (p = 0.047). The severity of WMCs increased; the difference was statistically significant only in patients without baseline CMBs (p = 0.027). There were no new cortical infarcts.

CONCLUSION

In stroke clinic patients, CMBs are consistently associated with frontal-executive impairment; baseline CMBs are associated with frontal-executive impairment at follow-up after 5.7 years. The presence of CMBs has prognostic relevance for long-term cognitive outcome in stroke clinic patients, and may help to optimally target preventive strategies in individuals at highest risk of cognitive decline.

Quantitative magnetisation transfer imaging in glioma: preliminary results

Quantitative magnetisation transfer imaging (qMTI) is an extension of conventional MT techniques and allows the measurement of parameters that reflect tissue ultrastructure through the properties of macromolecule-bound protons; these include the bound proton fraction and the relaxation times of free and bound proton pools. It has been used in multiple sclerosis and Alzheimer's disease, and has shown changes in some of the parameters, particularly the bound proton fraction. The purpose of this pilot study was to assess whether qMTI could distinguish between gliomas and normal brain tissue, and provide proof of principle for its use in tumour characterisation. Eight subjects [three men, five women; mean age, 44 years; range, 27-66 years; seven World Health Organization (WHO) Grade II, one Grade III] with biopsy-proven glioma were imaged with a structural MRI protocol that included three-dimensional qMTI. qMTI parameters were extracted from regions of interest selected from different tumour components visible on conventional MR sequences, normal-appearing peritumoral tissue and distant normal-appearing white matter. All patients gave informed consent and the study was approved by the Local Research Ethics Committee. Almost all of the qMTI parameters detected abnormalities in both glioma and the peritumoral region relative to the distant white matter. In particular, the bound proton fraction was reduced significantly from 6.0 percentage units (pu) [standard deviation (SD), 0.5 pu] in normal-appearing white matter to 1.7 pu (SD = 0.5 pu) in solid tumour and 2.2 pu (SD = 0.5 pu) in peritumoral areas. This work shows that qMTI reveals abnormalities, not only in glioma, but also in the apparently normal tissue surrounding the conventionally defined tumour. Thus, qMTI shows promise for tumour characterisation and for studying tumour boundaries. These preliminary data justify larger studies in a range of different tumour types and grades.

Brain microbleeds as a potential risk factor for antiplatelet-related intracerebral haemorrhage: hospital-based, case-control study

BACKGROUND

Intracerebral haemorrhage (ICH) is an uncommon but devastating complication of regular antiplatelet use: identifying high-risk patients before treatment could potentially reduce this hazard. Brain microbleeds on gradient-recalled echo (GRE) T2*-weighted MRI are considered a biomarker for bleeding-prone small-vessel diseases. The authors hypothesised that microbleeds are a risk factor for antiplatelet-related ICH, and investigated this in a hospital-based matched case-control study.

METHODS

Cases of spontaneous ICH were ascertained, using overlapping methods, from a prospective database of 1017 consecutive unselected patients referred to our stroke unit and associated clinics. For each case of antiplatelet-related ICH, two controls matched for age, sex and hypertension without history of ICH on antiplatelet therapy were selected. Microbleeds were identified by a trained observer blinded to clinical details.

RESULTS

Microbleeds were more frequent in antiplatelet users with ICH than in matched antiplatelet users without ICH (13/16 (81%) vs 6/32 (19%), p=0.004) and patients with non-antiplatelet-related ICH (13/16 (81%) vs 15/33 (45%), p=0.03). The frequency of lobar microbleeds was 11/16 (69%) in antiplatelet-related ICH versus 11/33 (33%) in non antiplatelet-related ICH (p=0.032). Microbleeds were more numerous in antiplatelet users with ICH compared with controls (p=0.016). The number of microbleeds was associated with the risk of antiplatelet-related ICH (adjusted OR 1.33 per additional microbleed, 95% CI 1.06 to 1.66, p=0.013).

CONCLUSIONS

Brain microbleeds are associated with antiplatelet-related ICH. In patients with a large number of lobar microbleeds, the risk of ICH could outweigh the benefits of antiplatelet therapy. Larger prospective studies to investigate the prognostic significance of microbleeds in regular antiplatelet users are warranted.

High-b-value diffusion MR imaging and basal nuclei apparent diffusion coefficient measurements in variant and sporadic Creutzfeldt-Jakob disease

BACKGROUND AND PURPOSE

DWI using a standard b-value of 1000 s/mm(2) has emerged as the most sensitive sequence for the diagnosis of CJD. The purpose of this study was to investigate whether DWI at a high b-value (b = 3000 s/mm(2)) and ADC measurements in the basal nuclei improve the diagnosis of vCJD and sCJD compared with visual assessment of DWI at a standard b-value (b = 1000 s/mm(2)).

MATERIALS AND METHODS

Eight patients with vCJD, 9 patients with sCJD, and 5 healthy volunteers underwent DWI at b = 1000 s/mm(2), and 5 vCJD patients, 4 sCJD patients, and 1 growth hormone-related CJD patient underwent DWI at b = 3000 s/mm(2). Two consultant neuroradiologists performed a visual comparison of the b = 1000 and b = 3000 images. Mean MR SI and ADC values were determined for C, P, and DM thalamus ROIs bilaterally at each b-value. SI ratios for each ROI relative to white matter were calculated.

RESULTS

In 9 out of 10 patients, the higher b-value images were more sensitive to SI change, particularly in cortex and thalamus, with higher SI ratios at b = 3000 in the DM thalamus. For sCJD at b = 1000, we found significantly lower ADC values in the C and P compared with controls (mean C ADC = 587.3 +/- 84.7 mm(2)/s in sCJD patients versus 722.7 +/- 16.6 mm(2)/s in controls; P = .007), and at b = 3000, the differences were more pronounced. In comparison, in vCJD at b = 1000, ADC values were elevated in the Pu (mean Pu ADC = 837.6 +/- 33.0 mm/s(2) in vCJD patients versus 748.0 +/- 17.3 mm/s(2) in controls; P < .001) but failed to reach significance at b = 3000.

CONCLUSIONS

Our results demonstrate that b = 3000 DWI, being more sensitive to slowly diffusing tissue water, is more sensitive to pathology in sCJD than is conventional DWI. High-b-value DWI increases confidence in the radiologic diagnosis of human prion disease.

Neuroimaging of CNS involvement in HIV

Central nervous system involvement in HIV-positive patients is common with 40% of patients suffering neurological disease at some point in their lives. Neuroimaging is important to properly diagnose treatable conditions and to monitor response to treatment. In this article, we describe and illustrate the main CNS imaging findings. The following categories of pathology are addressed: direct neurological effects of HIV, opportunistic CNS infections and neoplasms, cerebrovascular complications of HIV and CNS effects of highly active retroviral therapy (HAART). Imaging techniques employed include computed tomography, magnetic resonance imaging, diffusion-weighted imaging, functional magnetic resonance imaging and magnetic resonance spectroscopy.

Volumes and growth rates of untreated adult low-grade gliomas indicate risk of early malignant transformation

Adult low-grade gliomas (LGG) grow slowly, but most eventually undergo malignant transformation. The relationship between tumour volume, growth rate and the likelihood of transformation is unknown. Twenty-seven patients with biopsy-proven, untreated LGG had at least three MRI studies at 6 monthly intervals. Tumour volumes and growth rates were calculated using semi-automated segmentation, and analysed in a hierarchical regression model. In a 3-year period, patients who showed clinical deterioration and/or new (or significantly increased) contrast enhancement were classified as transformers (T), whilst non-transformers (NT) remained stable clinically and by conventional radiological criteria. All LGG showed progressive growth. Volumes at study entry were smaller in 9NT (57 ml, 95% CI 35-80 ml) than in 18T (83 ml, 95% CI 70-96 ml) (p=0.03). Average annual growth rates were lower in NT (16% (95% CI 9-23%)) than in T (26% (95% CI 20-31%)) (p=0.046), until the penultimate study. Growth in T increased to 56% p.a. (95% CI 20-92%) in the 6 months prior to transformation. In T, tumour volume was the most significant predictor of transformation in the following 12 months. Sequential measurement of LGG volume allows accurate determination of growth rates and identification of patients whose tumours are at high risk of early transformation.