Daniel J. Warren

Cerebral arteriovenous malformations: comparison of novel magnetic resonance angiographic techniques and conventional catheter angiography.

OBJECTIVEnTo investigate the potential of novel magnetic resonance (MR) angiographic techniques for the assessment of cerebral arteriovenous malformations.nnnMETHODSnForty patients who were about to undergo stereotactic radiosurgery were prospectively recruited. Three-dimensional, sliding-slab interleaved ky (SLINKY), time-of-flight acquisition was performed, as was a dynamic MR digital subtraction angiography (DSA) procedure in which single thick slices (6-10 cm) were obtained using a radiofrequency spoiled Fourier-acquired steady-state sequence (1 image/s). Sixty images were acquired, in two or three projections, during passage of a 6- to 10-ml bolus of gadolinium chelate. Subtraction and postprocessing were performed, and images were viewed in an inverted cine mode. SLINKY time-of-flight acquisition was repeated after the administration of gadolinium. Routine stereotactic conventional catheter angiography was performed after MR imaging. All images were assessed (in a blinded randomized manner) for Spetzler-Martin grading and determination of associated vascular pathological features.nnnRESULTSnForty-one arteriovenous malformations were assessed in 40 patients. Contrast-enhanced (CE) SLINKY MR angiography was the most consistent MR imaging technique, yielding a 95% correlation with the Spetzler-Martin classification defined by conventional catheter angiography; MR DSA exhibited 90% agreement, and SLINKY MR angiography exhibited 81% agreement. CE SLINKY MR angiography provided improved nidus delineation, compared with non-CE SLINKY MR angiography. Dynamic information from MR DSA significantly improved the observation of early-draining veins and associated aneurysms.nnnCONCLUSIONnCE SLINKY MR angiographic assessment of cerebral arteriovenous malformations offers significant advantages, compared with the use of non-CE SLINKY MR angiography, including improved nidus demonstration. MR DSA shows promise as a noninvasive method for dynamic angiography but is presently restricted by limitations in both temporal and spatial resolution.

Comparison of endoscopic and microscopic trans-sphenoidal pituitary surgery: early results in a single centre

Abstract Introduction. Pituitary surgery has seen a recent shift from a microscopic to an endoscopic trans-sphenoidal approach. We present our early experience with endoscopic surgery and compare the outcome with our recent microscopic experience. Methods. From January 2008 until present time, 80 consecutive patients underwent trans-sphenoidal pituitary surgery in our institution. Until September 2009, all patients had a microscopic trans-septal approach. After this time, the patients underwent endoscopic trans-sphenoidal surgery. All patients underwent pre- and post-operative MRI and full endocrinological evaluation. Data was collected prospectively including tumour volume, endocrine function, visual function, length of stay and complications. Results. There were 40 patients in each group. In the microscopic group, there were 26 non-functioning tumours and 14 functioning tumours. In the endoscopic group, there were 24 non-functioning and 16 functioning tumours. There were significantly better results in terms of tumour resection (p =u20090.002) and remission (p =u20090.018) in the endoscopic group. In this group there was also a lower incidence of CSF leaks and a shorter length of stay for secreting tumours (p =u20090.005). 1 patient in the endoscopic group died at day 43 post-operatively, having initially presented in a poor clinical state with pituitary apoplexy. Conclusion. Microscopic trans-sphenoidal surgery remains the benchmark for future surgical techniques. Our early results suggest that endoscopic trans-sphenoidal surgery provides favourable results in both tumour resection and control of secreting tumours in comparison with microscopic surgery. Further longer-term evaluation is required to ensure the outcome of endoscopic surgery.

Imaging in acute ischaemic stroke: essential for modern stroke care

Stroke is the second most common cause of death worldwide and the third most common in the UK. ‘Time is brain’ in ischaemic stroke; early reperfusion has been shown to lead to improved clinical outcomes, yet the majority of patients with acute stroke do not attend in time for thrombolysis as it is currently licensed, hence the interest in trials extending the therapeutic window. Defining the ischaemic penumbra is of crucial importance in choosing the appropriate patients for thrombolytic therapy who attend outside the optimal therapeutic window. Integrated stroke imaging, including demonstration of potentially salvageable tissue with either MR perfusion/diffusion studies or CT perfusion, is increasingly likely to play a central role in future management strategies and widening of the potential therapeutic window. This review highlights the basic imaging findings of acute stroke and discusses the role of advanced CT and MR techniques as well as options for vascular imaging.

Magnetic resonance spectroscopy changes following haemopoietic stem cell transplantation in children with cerebral adrenoleukodystrophy.

X‐linked cerebral adrenoleukodystrophy is an aggressive, rapidly progressive disorder resulting in considerable morbidity and, left untreated, mortality. Patients typically present before the age of 10 years with progressive symptomatology including ataxia, spasticity, and focal neurological deficits. Current therapeutic options are limited, the treatment of choice being haemopoietic stem cell transplantation (HSCT). Intervention is beneficial to those children with early disease and characteristic magnetic resonance (MR) imaging changes. Developments in MR imaging have led to the incorporation of MR spectroscopy in the assessment tools; however, it is yet to be included in stratified assessment tools to guide treatment choice. Furthermore, there remains a paucity of outcome data on MR spectroscopy changes following HSCT. We describe our experience in two males with confirmed cerebral adrenoleukodystrophy treated, at the mean age of 5 years 6 months, with HSCT and report the pronounced spectroscopic changes observed following treatment. Both children, observed for a minimum period of 14 months following treatment, demonstrate complete reversal in previously deteriorating spectroscopy with marked increase in N‐acetyl‐aspartate (NAA)/choline (Cho) ratios and reduction in Cho/creatine (Cr) ratios following HSCT treatment with concomitant stabilization of clinical status.

The use of MR imaging and spectroscopy of the brain in children investigated for developmental delay: What is the most appropriate imaging strategy?

ObjectivesDevelopmental delay is a common problem in paediatric practice and many children with developmental delay are referred for MR imaging. Our study was performed as part of a continuing audit process to optimise our MR protocol and case selection.Materials and methodsWe performed MR imaging and spectroscopy protocol on 157 children with developmental delay. We analysed the effect of these interventions by looking at the overall detection rate of relevant pathology and in particular subgroups of the children.Results71% of the children had normal MR imaging, 10% had non-specific findings and 19% had specific abnormalities on MR imaging. The overall risk of having a specific structural abnormality with isolated developmental was 7.5% but if other neurological symptoms/signs were present the risk was 28%. Two children had abnormal spectroscopic findings, one with tuberous sclerosis and the other with absent brain creatine.ConclusionCase selection for MR imaging is important in children with developmental delay. The best strategies for selecting children for MR are either; not performing MR with developmental delay in one domain only or performing MR with developmental delay in three or four domains or if there are other neurological features.

Imaging in childhood scoliosis: a pictorial review

Childhood scoliosis is a common clinical entity with a number of different causes. In the majority of cases, the scoliosis is idiopathic, but it may be the manifestation of an occult spinal pathology. The clinical history and examination may elicit certain worrying features such as pain, neurological symptoms or an atypical curve pattern. These findings should prompt advanced imaging, as early and accurate detection of an underlying cause allows optimal planning and timing of surgery and helps reduce associated risks. The most common occult pathologies detected by advanced imaging are Arnold Chiari malformations, syringohydromyelia and closed spinal dysraphism such as diastematomyelia. Advanced imaging techniques, in particular multiplanar MRI, are also increasingly requested in children with known congenital scoliosis associated with spinal dysraphism and developmental causes of scoliosis such as neurofibromatosis and Klippel–Feil syndrome, as it allows superior delineation of the spinal column without the radiation risk. This review aims to examine the different imaging techniques currently used in the evaluation of scoliosis and provide a pictorial summary of the more common causes and associations.

Assessment of Sulcation of the Fetal Brain in Cases of Isolated Agenesis of the Corpus Callosum Using In Utero MR Imaging

BACKGROUND AND PURPOSE: There is gathering evidence to suggest that agenesis of the corpus callosum is associated with delayed fetal sulcation; it is possible that the corpus callosum facilitates normal gyral development. In this paper we sought to confirm whether delayed sulcation is found in fetuses with isolated agenesis of the corpus callosum as judged by in utero MR imaging. MATERIALS AND METHODS: Retrospective analysis of 20 fetuses with isolated corpus callosum agenesis investigated by in utero MR imaging and 20 aged-matched normal fetuses was performed in the second or third trimester. All fetuses were singleton pregnancies with known gestational age, imaged on a 1.5T superconducting MR system. Estimation of sulcation maturity was made with reference to a standard atlas and subgroup analysis of earlier gestation (group 1, 21–26 weeks) and later gestation (group 2, 30–34 weeks) fetuses was performed. RESULTS: Group 1 (n = 12) did not show a statistically significant difference between the 2 subgroups (P = .44) in terms of sulcation. A significant difference was demonstrated in the later gestation, group 2 (n = 8) fetal analyses; mean difference between consensus and actual gestation for normal fetuses was 0.9 weeks (SD of 1.5 weeks) versus −0.5 weeks (SD of 1.1 weeks) for the agenesis of corpus callosum cases (P = .046), suggestive of delayed sulcation in callosal agenesis. CONCLUSIONS: Delayed sulcation encountered in third trimester fetuses with agenesis of the corpus callosum may be seen and does not in itself imply an additional brain abnormality.

Prospective comparison of late 3T MRI with conventional angiography in evaluating the patency of cerebral arteriovenous malformations treated with stereotactic radiosurgery

IntroductionRisk of further haemorrhage in patients suffering from arteriovenous malformation (AVM) would be eliminated only if complete obliteration of the AVM is obtained. Therefore, these patients frequently need long-term follow-up. Conventional catheter angiography (CCA) with a risk of 0.5xa0%.to 1.6xa0% of significant neurological complications has traditionally been used for this purpose. However, magnetic resonance imaging (MRI) at 3T may be a safer alternative. The aim of this study was to evaluate if MRI at 3T can accurately evaluate closure of AVM in 2xa0years after stereotactic radiosurgery.MethodsTwenty-three patients with both MRI at 3T and a CCA study were examined. The residual AVMs were evaluated by MRI at 3T against CCA in a prospective study.ResultsThe time interval between radiosurgery and neuroimaging was on average of 25xa0months (range, 15–30xa0months) for MRI study and 33xa0months (range, 25–46xa0months) for CCA study. Ten patients showed closure of the AVM on MRI, all of which were confirmed on CCA.ConclusionThere was a complete agreement between late MRI at 3T scan and CCA in evaluation of AVM patency.

The Anatomy of the Medial Lemniscus within the Brainstem Demonstrated at 3 Tesla with High Resolution Fat Suppressed T1-Weighted Images and Diffusion Tensor Imaging

The medial lemniscus is part of the main somatosensory pathways ascending within the brainstem. It is formed by the heavily myelinated axons of the second order neurones of the dorsal column nuclei. This pathway ascends through the rostral medulla, pons and mesencephalon to finally terminate by synapsing with third order neurones in the ventral posterior nucleus of the thalamus. The medial lemniscus conveys proprioception and fine tactile discrimination as part of the somatosensory system. Conventional MRI studies of the brainstem have been relatively poor in demonstrating these fibre pathways. Diffusion tensor imaging and tractography may demostrated fibre pathways in the brainstem. These techniques do however suffer from relatively poor spatial resolution and some degree of image distortion – especially if based on echo planar imaging techniques. Knowledge of the anatomical relationships of the medial lemniscus is important for the understanding of clinical manifestations of disease processes affecting the somatosensory pathways and also to demonstrate important adjacent structures. Specifically, the pedunculopontine nucleus (PPN) lies in close anatomical relationship to the medial lemniscus and the decussation of the superior cerebellar peduncle. This nucleus is a promising target for deep brain stimulator placement for alleviation of non-dopamine responsive dystonias. Six healthy male volunteers (mean age 33 years) were imaged at 3 Tesla. Imaging protocols consisted of thin section, high resolution, fat suppressed T1-weighted sequences as well as thin section, high isotropic resolution diffusion tensor imaging (DTI), which was analysed to generate colour fractional anisotropy (FA) maps. These were correlated with the fat suppressed T1 weighted images. In all volunteers the medial lemniscus was seen as a pair of bands of low signal on axial, high resolution, fat suppressed T1-weighted images. They were indentified through the upper medulla, pons and mesencephalon. They correlated well with the head to foot orientated fibres on the colour FA maps generated from the DTI data. This study of normal volunteers has illustrated the value of high resolution, fat suppressed T1-weighted images in demonstrating the anatomy of the heavily myelinated medial lemniscus within the brainstem. These high resolution images with good spatial accuracy can potentially be used to aid the localisation of other nuclei, such as the PPN.

Spontaneous abscess of the lumbar spine presenting as subacute back pain.

A 52-year-old lady was admitted with back pain, fever and reduced sensation in her left leg. Soon after admission she developed acute urinary retention. She underwent urgent MRI of the spine which showed an epidural abscess compressing the thecal sac which was treated with neurosurgical decompression and intravenous/oral antibiotics. Cultures from theatre grew Staphylococcus aureus sensitive to flucloxacillin. After 12 weeks of intravenous/oral antibiotics, she was discharged without any neurological disability.