Facet joint cyst haematoma: a rare cause of cauda equina syndrome.

Facet joint cysts are a feature of lumbar spondylosis and are an uncommon cause of radiculopathy. Facet joint cyst haematoma is a very rare entity and has previously been reported as a subacute cause of leg pain, back pain, sensory deficit and lower limb weakness. We present the unique case of facet joint cyst haematoma presenting as cauda equina syndrome. An 81 year old lady presented with a 7 day history of back pain and left foot drop, a 1 day history of perineal numbness and urinary retention with absent rectal tone, perianal anaesthesia and left leg hypoaesthesia. Emergency MRI scan demonstrated spinal canal stenosis as the aetiology of her cauda equina syndrome. She was taken to theatre for emergency lumbar decompression. At operation a facet joint haematoma compressing the cauda equina was found and extirpated with complete resolution of symptoms. In this case, the aetiology of cauda equina compression was not demonstrated effectively on pre-operative MRI scanning.

Beating a skullduggerous infantile hemispheric high-grade glioma.

A case of infantile hemispheric high grade glioma in a five-month-old boy is presented. Striking images of a 'beaten copper pot' skull were concerning at first, but with a successful surgical and oncological plan he is well three years later, displaying only minor signs of developmental delay.

Development of a pre-operative scoring system for predicting risk of post-operative paediatric cerebellar mutism syndrome.

BACKGROUND: Despite previous identification of pre-operative clinical and radiological predictors of post-operative paediatric cerebellar mutism syndrome (CMS), a unifying pre-operative risk stratification model for use during surgical consent is currently lacking. The aim of the project is to develop a simple imaging-based pre-operative risk scoring scheme to stratify patients in terms of post-operative CMS risk. METHODS: Pre-operative radiological features were recorded for a retrospectively assembled cohort of 89 posterior fossa tumour patients from two major UK treatment centers (age 2-23yrs; gender 28 M, 61 F; diagnosis: 38 pilocytic astrocytoma, 32 medulloblastoma, 12 ependymoma, 1 high grade glioma, 1 pilomyxoid astrocytoma, 1 atypical teratoid rhabdoid tumour, 1 hemangioma, 1 neurilemmoma, 2 oligodendroglioma). Twenty-six (29%) developed post-operative CMS. Based upon results from univariate analysis and C4.5 decision tree, stepwise logistic regression was used to develop the optimal model and generate risk scores. RESULTS: Univariate analysis identified five significant risk factors and C4.5 decision tree analysis identified six predictors. Variables included in the final model are MRI primary location, bilateral middle cerebellar peduncle involvement (invasion and/or compression), dentate nucleus invasion and age at imaging >12.4 years. This model has an accuracy of 88.8% (79/89). Using risk score cut-off of 203 and 238, respectively, allowed discrimination into low (38/89, predicted CMS probability <3%), intermediate (17/89, predicted CMS probability 3-52%) and high-risk (34/89, predicted CMS probability ≥52%). CONCLUSIONS: A risk stratification model for post-operative paediatric CMS could flag patients at increased or reduced risk pre-operatively which may influence strategies for surgical treatment of cerebellar tumours. Following future testing and prospective validation, this risk scoring scheme will be proposed for use during the surgical consenting process.

MRI capture of intermittent ventriculomegaly in a patient with ventriculo-peritoneal shunt.

Intermittent change in ventricular size in patients with ventriculo-peritoneal shunts is a recognised complication but definitive imaging evidence is rare. We report a 3 years old boy with a medullary astrocytoma and ventriculo-peritoneal shunt placement who demonstrated intermittent ventriculomegaly during a single MRI scan.

Effect of low-and high-dose atorvastatin on carotid artery distensibility using carotid magnetic resonance imaging -a post-hoc sub group analysis of ATHEROMA (Atorvastatin Therapy: Effects On Reduction Of Macrophage Activity) Study.

AIM: To assess the effect of low-(10 mg) or high-(80 mg) dose atorvastatin on carotid artery distensibility in patients with asymptomatic carotid artery disease using carotid magnetic resonance imaging. METHODS: Eighteen patients underwent initial 2-dimensional ECG gated-phase contrast carotid MR imaging and off-line applanation tonometry for distensibility assessment before randomisation to receive low- or high-dose statins and this was repeated at 12 weeks. Phase and magnitude images from the 2-D phase contrast acquisitions were used for quantification of distensibility and compliance coefficients and were compared between the low- and high-dose statin groups. RESULTS: Both groups were comparable with regards to their demographics, co-morbidities and baseline cholesterol levels. After 12 weeks of high-dose statin administration, a significant decrease in LDL (p=0.003) and CRP (p=0.03) was observed. At 12 weeks, the distensibility coefficient of the common and internal carotid artery was found to be significantly higher (with respect to baseline) in the high-dose group (p=0.004 and p=0.007, respectively). The compliance coefficient was likewise found to be raised in the high-dose group when compared with the low-dose group [common carotid (p=0.002), internal carotid (p=0.009)]. CONCLUSIONS: High-dose atorvastatin tends to reduce carotid arterial stiffness, as suggested by increased distensibility and compliance coefficients; however, these results need validation through large-scale trials to fully establish their possible use in clinical practice.

Sequential imaging of asymptomatic carotid atheroma using ultrasmall superparamagnetic iron oxide-enhanced magnetic resonance imaging: a feasibility study.

BACKGROUND: Inflammation within atheromatous plaques is a known risk factor for plaque vulnerability. This can be detected in vivo on high-resolution magnetic resonance imaging (MRI) using ultrasmall superparamagnetic iron oxide (USPIO) contrast medium. The purpose of this study was to assess the feasibility of performing sequential USPIO studies over a 1-year period. METHODS: Ten patients with moderate asymptomatic carotid stenosis underwent carotid MRI imaging both before and 36 hours after USPIO infusion at 0, 6, and 12 months. Images were manually segmented into quadrants, and the signal change per quadrant was calculated at these time points. A mixed repeated measures statistical model was used to determine signal change attributable to USPIO uptake over time. RESULTS: All patients remained asymptomatic during the study. The mixed model revealed no statistical difference in USPIO uptake between the 3 time points. Intraclass correlation coefficients revealed a good agreement of quadrant signal pre-USPIO infusion between 0 and 6 months (0.70) and 0 and 12 months (0.70). Good agreement of quadrant signal after USPIO infusion was shown between 0 and 6 months (0.68) and moderate agreement was shown between 0 and 12 months (0.33). CONCLUSIONS: USPIO-enhanced sequential MRI of atheromatous carotid plaques is clinically feasible. This may have important implications for future longitudinal studies involving pharmacologic intervention in large patient cohorts.

Use of tissue glue to prevent collapse of the cortical mantle during and after cranial surgery in children: a technical note.

INTRODUCTION: Young children with significant ventricular dilatation or large intracranial fluid spaces often have a very thin cortical mantle as a result of persistently raised intracranial pressure. This rim of cortex has a tendency to fall away from the dura into the cavity during and after intracranial surgery, due to the lack of support, once the pressure in the fluid cavity has been reduced. This can lead to tearing of cortical bridging veins and the formation of post-operative subdural haematomas. METHODS: We describe a simple technique that attempts to prevent this phenomenon occurring using tissue glue. Once the craniotomy has been performed and the dura has been formally opened, tissue glue is applied to the underside of the dura around the edge of the wound, prior to corticotomy. RESULTS AND CONCLUSION: This results in the cortical mantle adhering to the undersurface of the dura and prevents the mantle from falling into the cavity either during the procedure or post-operatively.

The ATHEROMA (Atorvastatin Therapy: Effects on Reduction of Macrophage Activity) Study. Evaluation using ultrasmall superparamagnetic iron oxide-enhanced magnetic resonance imaging in carotid disease.

OBJECTIVES: The aim of this study was to evaluate the effects of low-dose (10 mg) and high-dose (80 mg) atorvastatin on carotid plaque inflammation as determined by ultrasmall superparamagnetic iron oxide (USPIO)-enhanced carotid magnetic resonance imaging (MRI). The hypothesis was that treatment with 80 mg atorvastatin would demonstrate quantifiable changes in USPIO-enhanced MRI-defined inflammation within the first 3 months of therapy. BACKGROUND: Preliminary studies indicate that USPIO-enhanced MRI can identify macrophage infiltration in human carotid atheroma in vivo and hence may be a surrogate marker of plaque inflammation. METHODS: Forty-seven patients with carotid stenosis >40% on duplex ultrasonography and who demonstrated intraplaque accumulation of USPIO on MRI at baseline were randomly assigned in a balanced, double-blind manner to either 10 or 80 mg atorvastatin daily for 12 weeks. Baseline statin therapy was equivalent to 10 mg of atorvastatin or less. The primary end point was change from baseline in signal intensity (DeltaSI) on USPIO-enhanced MRI in carotid plaque at 6 and 12 weeks. RESULTS: Twenty patients completed 12 weeks of treatment in each group. A significant reduction from baseline in USPIO-defined inflammation was observed in the 80-mg group at both 6 weeks (DeltaSI 0.13; p = 0.0003) and at 12 weeks (DeltaSI 0.20; p < 0.0001). No difference was observed with the low-dose regimen. The 80-mg atorvastatin dose significantly reduced total cholesterol by 15% (p = 0.0003) and low-density lipoprotein cholesterol by 29% (p = 0.0001) at 12 weeks. CONCLUSIONS: Aggressive lipid-lowering therapy over a 3-month period is associated with significant reduction in USPIO-defined inflammation. USPIO-enhanced MRI methodology may be a useful imaging biomarker for the screening and assessment of therapeutic response to "anti-inflammatory" interventions in patients with atherosclerotic lesions. (Effects of Atorvastatin on Macrophage Activity and Plaque Inflammation Using Magnetic Resonance Imaging [ATHEROMA]; NCT00368589).

Iron oxide particles for atheroma imaging.

The selection of patients for vascular interventions has been solely based on luminal stenosis and symptomatology. However, histological data from both the coronary and carotid vasculature suggest that other plaque features such as inflammation may be more important in predicting future thromboembolic events. Ultrasmall superparamagnetic iron oxide (USPIO) contrast agents have been used for noninvasive MRI assessment of atherosclerotic plaque inflammation in humans. It has reached the stage of development to have been recently used in an interventional drug study to not only assess inflammatory progression but also select patients at high risk. This article reviews the basic science behind the use of USPIO contrast agents in atheroma MR imaging, experimental work in animals, and how this has led to the emergence of this promising targeted imaging platform for assessment of high risk carotid atherosclerosis in humans.

In vivo positive contrast IRON sequence and quantitative T(2)* measurement confirms inflammatory burden in a patient with asymptomatic carotid atheroma after USPIO-enhanced MR imaging.

The authors report an in vivo human examination of carotid atheroma by using the inversion-recovery ON resonance (IRON) sequence, which is able to produce positive contrast after the infusion of an ultrasmall super paramagnetic iron oxide (USPIO) contrast medium. This technique provides a method of potentially identifying inflammatory burden within carotid atheroma. This may be particularly useful in patients who currently do not meet criteria for intervention (ie, moderate symptomatic stenosis or <70% asymptomatic stenosis) to further risk-stratify this important patient cohort. A 63-year-old man was imaged at 1.5 T before and 36 hours after USPIO infusion by using the IRON sequence. Regions of interest showing profound signal loss at T(2)*-weighted imaging corresponded well with regions of positive contrast at IRON imaging after the administration of USPIO. These regions also showed a profound decrease in T(2)* measurements after USPIO infusion, whereas surrounding tissue did not. It has been shown that such strong signal loss on T(2)*-weighted images after USPIO infusion is indicative of USPIO uptake.

Does calcium deposition play a role in the stability of atheroma? Location may be the key.

BACKGROUND: Rupture of vulnerable atheromatous plaque in the carotid and coronary arteries often leads to stroke and heart attack respectively. The role of calcium deposition and its contribution to plaque stability is controversial. This study uses both an idealized and a patient-specific model to evaluate the effect of a calcium deposit on the stress distribution within an atheromatous plaque. METHODS: Using a finite-element method, structural analysis was performed on an idealized plaque model and the location of a calcium deposit within it was varied. In addition to the idealized model, in vivo high-resolution MR imaging was performed on 3 patients with carotid atheroma and stress distributions were generated. The individual plaques were chosen as they had calcium at varying locations with respect to the lumen and the fibrous cap. RESULTS: The predicted maximum stress was increased by 47.5% when the calcium deposit was located in the thin fibrous cap in the model when compared with that in a model without a deposit. The result of adding a calcium deposit either to the lipid core or remote from the lumen resulted in almost no increase in maximal stress. CONCLUSION: Calcification at the thin fibrous cap may result in high stress concentrations, ultimately increasing the risk of plaque rupture. Assessing the location of calcification may, in the future, aid in the risk stratification of patients with carotid stenosis.

Correlation of macrophage location and plaque stress distribution using USPIO-enhanced MRI in a patient with symptomatic severe carotid stenosis: a new insight into risk stratification.

High resolution, USPIO-enhanced MR imaging can be used to identify inflamed atherosclerotic plaque. We report a case of a 79-year-old man with a symptomatic carotid stenosis of 82%. The plaque was retrieved for histology and finite element analysis (FEA) based on the preoperative MR imaging was used to predict maximal Von Mises stress on the plaque. Macrophage location correlated with maximal predicted stresses on the plaque. This supports the hypothesis that macrophages thin the fibrous cap at points of highest stress, leading to an increased risk of plaque rupture and subsequent stroke.

Comparison of the inflammatory burden of truly asymptomatic carotid atheroma with atherosclerotic plaques contralateral to symptomatic carotid stenosis: an ultra small superparamagnetic iron oxide enhanced magnetic resonance study.

BACKGROUND: Inflammation is a recognised risk factor for the vulnerable atherosclerotic plaque. The aim of this study was to explore whether there is a difference in the degree of magnetic resonance (MR) defined inflammation using ultra small superparamagnetic iron oxide (USPIO) particles within carotid atheroma in completely asymptomatic individuals and the asymptomatic carotid stenosis contralateral to the symptomatic side. METHODS: 20 symptomatic patients with contralateral disease and 20 completely asymptomatic patients underwent multi-sequence MR imaging before and 36 h after USPIO infusion. Images were manually segmented into quadrants and signal change in each quadrant was calculated following USPIO administration. Mean signal change was compared across all quadrants in the two groups. RESULTS: The mean percentage of quadrants showing signal loss was 53% in the contralateral group compared with 31% in completely asymptomatic individuals (p = 0.025). The mean percentages showing enhancement were 44% and 65%, respectively (p = 0.024). The mean signal difference between the two groups was 8.6% (95% CI 1.6% to 15.6%; p = 0.017). CONCLUSIONS: Truly asymptomatic plaques seem to demonstrate inflammation but not to the extent of the contralateral asymptomatic stenosis to the symptomatic side. Inflammatory activity may be a significant risk factor in asymptomatic disease.

Structural analysis and magnetic resonance imaging predict plaque vulnerability: a study comparing symptomatic and asymptomatic individuals.

BACKGROUND: More than half of all cerebral ischemic events are the result of rupture of extracranial plaques. The clinical determination of carotid plaque vulnerability is currently based solely on luminal stenosis; however, it has been increasingly suggested that plaque morphology and biomechanical stress should also be considered. We used finite element analysis based on in vivo magnetic resonance imaging (MRI) to simulate the stress distributions within plaques of asymptomatic and symptomatic individuals. METHODS: Thirty non-consecutive subjects (15 symptomatic and 15 asymptomatic) underwent high-resolution multisequence in vivo MRI of the carotid bifurcation. Stress analysis was performed based on the geometry derived from in vivo MRI of the carotid artery at the point of maximal stenosis. The finite element analysis model considered plaque components to be hyperelastic. The peak stresses within the plaques of symptomatic and asymptomatic individuals were compared. RESULTS: High stress concentrations were found at the shoulder regions of symptomatic plaques, and the maximal stresses predicted in this group were significantly higher than those in the asymptomatic group (508.2 +/- 193.1 vs 269.6 +/- 107.9 kPa; P = .004). CONCLUSIONS: Maximal predicted plaque stresses in symptomatic patients were higher than those predicted in asymptomatic patients by finite element analysis, suggesting the possibility that plaques with higher stresses may be more prone to be symptomatic and rupture. If further validated by large-scale longitudinal studies, biomechanical stress analysis based on high resolution in vivo MRI could potentially act as a useful tool for risk assessment of carotid atheroma. It may help in the identification of patients with asymptomatic carotid atheroma at greatest risk of developing symptoms or mild-to-moderate symptomatic stenoses, which currently fall outside current clinical guidelines for intervention.

Effect of ultrasmall superparamagnetic iron oxide nanoparticles (Ferumoxtran-10) on human monocyte-macrophages in vitro.

Ferumoxtran-10, a dextran-coated ultrasmall superparamagnetic iron oxide particle, has the potential to reveal macrophages in vivo using magnetic resonance imaging potentially acting as a marker of inflammatory status. Pending clinical trials, we examined the interactions of Ferumoxtran-10 with human monocyte-macrophages (HMMs) in vitro to assess its safety and lack of pro-inflammatory activity. After 72 h, Ferumoxtran-10 was not toxic at 1 mg/ml and may be only mildly toxic at 10 mg/ml. Viability in cells with a high intracellular Ferumoxtran-10 load was not affected over 14 days. Ferumoxtran-10 did not interfere with baseline or stimulated cytokine (interleukin-12, interleukin-6, tumour necrosis factor-alpha or interleukin-1beta) or superoxide anion production or with Fc-receptor-mediated phagocytosis. Similarly, Ferumoxtran-10 did not induce cytokine production and was not chemotactic. High-resolution electron microscopy and selected-area electron diffraction confirmed the core of Ferumoxtran-10 is composed of crystalline magnetite. Bright field transmission electron microscopy of thin sections demonstrated that Ferumoxtran-10 was retained in lysosomes of HMM for several days. Ferumoxtran-10 is not toxic to HMMs in vitro, does not activate them to produce pro-inflammatory cytokines or superoxide anions, is not chemotactic and does not interfere with Fc-receptor-mediated phagocytosis. Furthermore, extremely high intracellular Ferumoxtran-10 concentrations had only slight or no effects on these key activities.

Assessment of inflammatory burden contralateral to the symptomatic carotid stenosis using high-resolution ultrasmall, superparamagnetic iron oxide-enhanced MRI.

BACKGROUND AND PURPOSE: It is well known that the vulnerable atheromatous plaque has a thin, fibrous cap and large lipid core with associated inflammation. This inflammation can be detected on MRI with use of a contrast medium, Sinerem, an ultrasmall superparamagnetic iron oxide (USPIO). Although the incidence of macrophage activity in asymptomatic disease appears low, we aimed to explore the incidence of MRI-defined inflammation in asymptomatic plaques in patients with known contralateral symptomatic disease. METHODS: Twenty symptomatic patients underwent multisequence MRI before and 36 hours after USPIO infusion. Images were manually segmented into quadrants, and the signal change in each quadrant was calculated after USPIO administration. A mixed mathematical model was developed to compare the mean signal change across all quadrants in the 2 groups. Patients had a mean symptomatic stenosis of 77% compared with 46% on their asymptomatic side, as measured by conventional angiography. RESULTS: There were 11 (55%) men, and the median age was 72 years (range, 53 to 84 years). All patients had risk factors consistent with severe atherosclerotic disease. All symptomatic carotid stenoses had inflammation, as evaluated by USPIO-enhanced imaging. On the contralateral sides, inflammatory activity was found in 19 (95%) patients. Contralaterally, there were 163 quadrants (57%) with a signal loss after USPIO when compared with 217 quadrants (71%) on the symptomatic side (P=0.007). CONCLUSIONS: This study adds weight to the argument that atherosclerosis is a truly systemic disease. It suggests that investigation of the contralateral side in patients with symptomatic carotid stenosis can demonstrate inflammation in 95% of plaques, despite a mean stenosis of only 46%. Thus, inflammatory activity may be a significant risk factor in asymptomatic disease in patients who have known contralateral symptomatic disease. Patients with symptomatic carotid disease should have their contralateral carotid artery followed up.