Ashok Raghavan

Role of imaging in the diagnosis of acute bacterial meningitis and its complications.

Acute bacterial meningitis is a common neurological emergency and a leading cause of death and neurological disability worldwide. Diagnosis is based on clinical and microbiological findings with neuroimaging in the form of CT reserved for those with specific adverse clinical features or when an underlying cause such as mastoiditis is suspected. MRI is extremely useful for detecting and monitoring the complications of meningitis. These can be remembered by the mnemonic HACTIVE (hydrocephalus, abscess, cerebritis/cranial nerve lesion, thrombosis, infarct, ventriculitis/vasculopathy and extra-axial collection). Diffusion weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) are useful to distinguish abscess from other ring enhancing lesions.

Craniospinal Abnormalities and Neurologic Complications of Osteogenesis Imperfecta: Imaging Overview

Osteogenesis imperfecta is a rare genetic disorder that leads to progressive skeletal deformities due to deficits in type I collagen, the main pathophysiologic effect of the disease. In addition, it may lead to a wide range of associated neurologic abnormalities: The central nervous system is usually involved because of softening of bone at the base of the skull, with resultant upward migration of the upper cervical spine and odontoid process into the skull base. Upward migration of the spine may cause compression of the brainstem, mechanical impingement of the spinal canal with restriction of cerebrospinal fluid circulation, and impingement of the cranial nerves. Osteogenesis imperfecta also may directly involve neurovascular structures, leading to cavernous fistulas of the carotid artery, dissection of the cervical arteries, and cerebral aneurysms. The brain parenchyma is frequently affected by the disease, with manifestations including cerebral atrophy, communicating hydrocephalus, and cerebellar hypoplasia. The imaging features of the disorder vary as widely as its clinical manifestations, depending on the severity of disease. Severe forms accompanied by debilitating skeletal fractures and progressive neurologic impairments may lead to perinatal death, whereas milder asymptomatic forms might cause only a modest reduction in life span. The most important advance in medical therapy for osteogenesis imperfecta has been the introduction of bisphosphonate therapy to slow the resorption of bone in patients with moderate to severe forms of the disease (ie, type III or IV). In some patients, neurosurgery may be necessary to correct the effects of severe basilar invagination by the odontoid process.

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.

Management of isolated syringomyelia in the paediatric population – a review of imaging and follow-up in a single centre

Abstract Objective. To assess the natural history of isolated syringomyelia in children. Methods. MRI reports from February 2007 to August 2011 mentioning syrinx were identified on Sheffield Childrens PACS database. Scans with syringes having an AP diameter of > 1 mm and extending over at least two vertebral bodies were reviewed. Patients with an identifiable cause such as a Chiari malformation were then excluded. Results. Thirty-nine patients were included with a mean age at diagnosis of 10.6 years. The average syrinx AP diameter was 3.30 mm. The rostrocaudal length of the syringes varied between 2 and 19 vertebral bodies. Twenty-seven out of 39 syringes were thoracic in origin. There were 3 and 6 syringes involving the cervicothoracic and thoracolumbar regions, respectively, with 3 involving the cervical area only. Eleven out of 39 (Group I) patients were found “incidentally” during work-up for adolescent idiopathic scoliosis and these were considered as a separate group. These patients did not have any significant symptoms and were discharged following their scoliosis correction surgery. Syrinx was incidental in 14 further patients (Group II). Of the 14 patients, 11 remained asymptomatic with no change in syrinx morphology throughout follow up. Of the 14 patients, 3 were lost to follow-up. Of the 39 patients, 14 (Group III) presented with progressive back pain without any obvious clinical cause. Of the 14, 10 either improved or remained the same. Of the14 patients, 3 underwent lumbar puncture, 1/14 having myelography. All 4/14 patients reported significant pain reduction on follow up following intervention. Conclusion. Idiopathic syrinx is a benign pathology, which can be managed expectantly. Most cases remain stable or improve over time. In a small minority who have progressive back pain, we have found that lumbar puncture may be helpful in reducing symptoms.

Thoracic Kyphosis is Now Uncommon Amongst Children and Adolescents with Cystic Fibrosis.

Historically, thoracic kyphosis has been reported to be common amongst patients with cystic fibrosis (CF). The mechanisms leading to the development of this abnormality of the chest wall are not fully understood. In order to explore the prevalence of the condition amongst children with CF in the early twenty-first century and to explore factors that might be contributing to its development, a retrospective cross sectional study was undertaken in a regional CF unit. Data were obtained from 74 children with CF aged 8–16 years attending for their annual review. Thoracic kyphosis was measured from lateral chest X-ray using an alternative Cobb method. Lung function, disease severity, and nutritional status were also recorded. Correlations between measures were explored using a multiple linear regression model. The range of Cobb angles measured was 5.4–44.3° with thoracic kyphosis identified in only two subjects. There was no correlation between age and thoracic kyphosis, however, there was a significant correlation between lung function and thoracic kyphosis (p = 0.004). Regression coefficient (b) was −0.26 (95% CI: −0.44, −0.08). The prevalence of thoracic kyphosis is significantly less amongst children with CF than previously reported. This appears likely to be associated with the overall improvements in pulmonary status. Studies of older populations may bring further understanding of increasing thoracic kyphosis in people with CF.

Discrepancy in reporting among specialist registrars and the role of a paediatric neuroradiologist in reporting paediatric CT head examinations

AIM To evaluate the discrepancy rate among specialist registrars (SPR) to assess whether seniority had a bearing on the discrepancy rate. To investigate which were the commonly missed abnormalities and the consequences for teaching purposes. To investigate the role of a specialist consultant neuroradiologist in reporting paediatric head computed tomography examinations. MATERIALS AND METHODS The study was carried out over a 9-month period at the regional paediatric hospital during which time 270 CT head examinations were reported. Reporting in the department is carried out by one of the five general paediatric radiologists (GR) and also a specialist paediatric neuroradiologist (NR). The NR was considered the reference standard, who corroborated in areas of discrepancy with a second senior NR for this study. Of the 270 examinations, 260 were reported by the paediatric NR, 160 were reported by the SPR, GR, and NR, and 51 were reported by an SPR and the NR. In addition, four were reported by the GR and the NR, 45 by the NR only, seven by the GR only, and three cases were reported by the GR and an SPR. The discrepancy rates were calculated for GR versus NR, and SPR versus NR. All the discrepancies were re-evaluated by a second senior NR and confirmed in all cases. The reports of the SPR were further scrutinized. The trainees of training years 1-3 were considered junior and 4-5 were considered senior. RESULTS There was a discrepancy in 26/164 cases (15.9%) reported by the GR and NR. There was a discrepancy in 59/211 cases (28%) reported by an SPR and NR. The chi-squared test (two-sided) showed a significant difference (p=0.005) between the two groups. There was a discrepancy in 36/118 cases (30.5%) reported by the junior SPR and NR. There was a discrepancy in 23/93 cases (24.7%) reported by a senior SPR and NR. The chi-squared test (two-sided) showed a non-significant difference (p=0.353) between the two groups. CONCLUSION The performance of the SPR was considered to be significantly different than the GR in this study. The year of training did not have a statistically significant bearing on the discrepancy rates. This study has been useful in guiding SPR with regards to paediatric CT head examination reporting. The NR played an important role, particularly in picking up subtle fractures and congenital abnormalities, which were missed by both the SPR and GR.

CT of the neonatal head

Computed tomography (CT) is used less often than other techniques on neonatal units. However, in the acute setting, CT can be invaluable in diagnosing or excluding potentially life-threatening conditions and guiding initial management in neonates. Common indications for scanning include trauma, suspected non-accidental injury, infection, or an acute hypoxic or metabolic event. The aim of this review is to provide an overview of the normal neonatal head at CT and compare this to the common pathological abnormalities. Several key features of each condition will be highlighted. It is important to note that some pathological conditions can have overlapping features at CT and, therefore, the clinical history and additional investigations are also of key importance in determining the diagnosis.

MRI protocols for imaging paediatric brain tumours

AIMS To establish whether paediatric centres within the Childrens Cancer and Leukaemia Group (CCLG) network employ magnetic resonance imaging (MRI) protocols for brain tumours according to the revised guidance. MATERIALS AND METHODS Questionnaires were sent to both consultants and superintendent radiographers in the 21 centres within the CCLG network that perform MRI on paediatric brain tumour patients. Information was requested as to whether the centre had a protocol for imaging paediatric brain tumours, which sequences were performed, and whether these were used by all consultants. RESULTS Twenty-seven completed questionnaires out of the 42 sent were returned, which included responses from 17 of the 21 UK centres. The majority of centres had a protocol for MRI of paediatric brain tumours at all stages of treatment. The standardized CCLG MRI sequences were incorporated in full at only five of the 17 centres. CONCLUSION The standard sequences of the CCLG brain imaging protocol are poorly adhered to nationally. Further awareness of the revised protocol is needed, with improved access to the guidelines for non-CCLG members on the CCLG and Royal college of Radiologists website.

The Encephalopathic Child

Encephalopathy is a common paediatric emergency associated with a high risk of morbidity, mortality and long term neurodevelopmental delay in survivors. Prompt diagnosis of the cause of encephalopathy enables the paediatrician to deliver specific medical or surgical treatment that will facilitate a better short and long term outcome. Diagnostic imaging plays a pivotal role in diagnosis. Encephalopathy has many causes. The differential diagnosis includes non accidental injury, trauma, metabolic syndromes, meningo-encephalitis, toxins, hypoxia, demyelination, stroke, haemorrhage and tumours. We describe an approach that helps us formulate an imaging strategy using US, CT and MRI that facilitates patient care.

Congenital nasal piriform aperture stenosis with vestibular abnormality

We present a neonate with congenital nasal piriform aperture stenosis associated with an abnormal vestibular aperture. Radiological evaluation with CT is essential to confirm the diagnosis and delineate the anatomy for surgical planning. Extension of the scan field of view to include the petrous temporal bone is essential to identify associated abnormalities of the vestibule.