Advanced diffusion weighted (DW) MRI of the brain in the fatal outbreak of Nipah viral encephalitis among pig workers in Malaysia and Singapore revealed a pattern similar to ischaemic infarction caused by obstruction of small cerebral blood vessels. However, relapse and late-onset cases in Malaysia, and other outbreaks of Nipah virus in Bangladesh and the Hendra virus infection in Australia, showed a different MRI pattern of predominantly confluent cortical lesions. MRI was useful in characterizing the disease in acute infection, as well as detection of spine abnormalities and subclinical infection.

Reeent advances in magnetic resonance imaging (MRI), in particular diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI), have allowed clinicians to have the ability to differentiate between irreversible cerebral infarction and the potentially reversible ischemic penumbra. This article examines the principles and practice of DWI and PWI. With continued advances in thrombolysis and other therapy for acute cerebral ischemia, neuroimaging is poised to play an increasingly important role in decisionmaking in aeute stroke.

INTRODUCTIONRadiologists may encounter bilaterally symmetrical abnormalities of the basal ganglia on magnetic resonance imaging (MRI), typically in the context of diffuse systemic, toxic or metabolic diseases. A systematic approach and broad knowledge of pathology causing this uncommon group of conditions would be useful.

MATERIALS AND METHODSThis review uses illustrative images to highlight metabolic conditions, such as Leigh's syndrome, citrullinaemia, hypoglycaemia or carbon monoxide poisoning, as well as other causes of bilateral basal ganglia lesions such as osmotic myelinolysis, deep cerebral venous thrombosis and Creutzfeldt-Jakob disease.

RESULTSCareful assessment of radiological findings outside the basal ganglia, such as involvement of the cortex, white matter, thalamus and pons, together with clinical correlation, may be helpful in narrowing the differential diagnosis, and directing further radiological, biochemical or genetic investigations. Recent advances in MR technology have resulted in newer techniques including diffusion-weighted (DW) MR imaging and MR spectroscopy (MRS); these may be helpful if appropriately used.

CONCLUSIONSAbnormal MRI findings in the basal ganglia should not be interpreted in isolation. A systematic approach including DW MR imaging, MRS, and a broad knowledge of diffuse systemic, toxic or metabolic diseases is helpful.

Basal Ganglia Diseases ; diagnosis ; diagnostic imaging ; physiopathology ; Brain Diseases, Metabolic ; diagnosis ; diagnostic imaging ; Diagnosis, Differential ; Humans ; Magnetic Resonance Imaging ; Radiography

Anticoagulants ; therapeutic use ; Carotid Arteries ; diagnostic imaging ; pathology ; Cerebral Infarction ; diagnostic imaging ; drug therapy ; pathology ; Female ; Humans ; Male ; Middle Aged ; Retrospective Studies ; Risk Factors ; Thromboembolism ; complications ; diagnostic imaging ; drug therapy ; Ultrasonography

Radiology education is heavily dependent on visual images, and case-based teaching files comprising medical images can be an important tool for teaching diagnostic radiology. Currently, hardcopy film is being rapidly replaced by digital radiological images in teaching hospitals, and an electronic teaching file (ETF) library would be desirable. Furthermore, a repository of ETFs deployed on the World Wide Web has the potential for e-learning applications to benefit a larger community of learners. In this paper, we describe a Singapore National Medical Image Resource Centre (SN.MIRC) that can serve as a World Wide Web resource for teaching diagnostic radiology. On SN.MIRC, ETFs can be created using a variety of mechanisms including file upload and online form-filling, and users can search for cases using the Medical Image Resource Center (MIRC) query schema developed by the Radiological Society of North America (RSNA). The system can be improved with future enhancements, including multimedia interactive teaching files and distance learning for continuing professional development. However, significant challenges exist when exploring the potential of using the World Wide Web for radiology education.
Computer-Assisted Instruction ; Education, Distance ; Education, Medical, Continuing ; Humans ; Internet ; Radiology ; education ; Radiology Information Systems ; Singapore ; User-Computer Interface

INTRODUCTIONWe reviewed the clinical features, brain and spinal cord magnetic resonance (MR) imaging findings and associated abnormalities in six patients with spinal cavernous malformations (CMs).

METHODSLesions were defined on gradient-recalled echo (GRE) images but measured on T2-weighted images performed on 1.5- and 3-tesla clinical scanners.

RESULTSFour patients had associated multiple cranial CMs and one patient had multiple spinal CMs. All spinal CMs were predominantly hypointense on GRE images, and most were predominantly hyperintense and surrounded by hypointense edge on T2-weighted images. Other associations included asymptomatic vertebral body and splenic haemangiomas.

CONCLUSIONWe conclude that intramedullary spinal CMs typically have 'mulberry' or 'popcorn' appearances similar to those of cranial CM. The presence of associated haemangioma or familial cranial CM syndrome on MR imaging may suggest the correct diagnosis without requiring invasive investigations.

Adult ; Aged ; Brain Neoplasms ; pathology ; Central Nervous System Vascular Malformations ; pathology ; Child, Preschool ; Diagnosis, Differential ; Female ; Hemangioma, Cavernous, Central Nervous System ; pathology ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Neoplastic Syndromes, Hereditary ; pathology ; Retrospective Studies ; Spinal Cord Diseases ; pathology ; Spinal Cord Neoplasms ; pathology

A 58-year-old Indian woman presented with asystole after an episode of haemetemesis, with a patient downtime of 20 mins. After initial resuscitation efforts, computed tomography of the brain, obtained to evaluate neurological injury, demonstrated evidence of severe hypoxic ischaemic brain injury. The imaging features of hypoxic ischaemic brain injury and the potential pitfalls with regard to image interpretation are herein discussed.
Adolescent ; Brain Ischemia ; diagnosis ; diagnostic imaging ; Cerebellum ; diagnostic imaging ; Critical Care ; Female ; Heart Arrest ; diagnosis ; diagnostic imaging ; Humans ; Male ; Middle Aged ; Shock, Cardiogenic ; complications ; Subarachnoid Hemorrhage ; diagnosis ; diagnostic imaging ; Tomography, X-Ray Computed

INTRODUCTIONSystemic and local intra-arterial thrombolysis in patients with large vessel ischaemic stroke is hampered by poor re-canalisation rates and risk of haemorrhage. The Merci Retrieval System is an endovascular device for removal of acute intracranial thrombus. We present our initial experience using this device in conjunction with existing thrombolytic therapy already in place in our institute.

MATERIALS AND METHODSProspective data in all patients presenting with large vessel ischaemic stroke treated using the Merci Retrieval System from July 2007 to March 2009 were analysed. Selection criteria for patients were similar to the multi- Merci trial of 2008. We compared re-canalisation rate, National Institutes of Health Stroke Score (NIHSS) and modified Rankin score (mRS) outcomes to the published trial results.

RESULTSSeventeen patients were reviewed; none suffered immediate post-procedural complications. Fifteen underwent successful thrombus retrieval but in 2 cases the device failed due to technical considerations. Sites of vascular occlusion included: ICA/ICA-'T' junctions 27%, middle cerebral artery 13% and vertebrobasilar artery 60%. Of the 15 patients treated by MERCI with or without adjuvant thrombolytic therapy, complete re-canalisation was achieved in 60%, partial re-canalisation in 20%, partial re-canalisation with persistent distal vessel occlusion in 6% and failure of re-canalisation in 14%. Asymptomatic haemorrhage occurred in 33% and there was 1 death (6%) from symptomatic haemorrhage. Pre-treatment median NIHSS was 17.88 and 9.5 immediately post-treatment. Median mRS at 30 days was 2.6 for patients who achieved complete re-canalisation and 4.5 in failure or partial re-canalisation with or without persistent distal vessel occlusion.

CONCLUSIONRe-canalisation rates using the Merci Retrieval System was comparable to the multi-Merci trial. Haemorrhagic complications and safety were also found to be satisfactory. Importantly, treatment success with eventual good clinical outcome hinges strongly on the ability of the device to achieve complete re-canalisation.

Acute Disease ; Aged ; Cerebral Arteries ; diagnostic imaging ; physiopathology ; Cerebral Revascularization ; Female ; Humans ; Intracranial Thrombosis ; radiotherapy ; Male ; Middle Aged ; Outcome Assessment (Health Care) ; Prospective Studies ; Radiography ; Singapore ; Stroke ; pathology ; radiotherapy ; Thrombectomy ; instrumentation